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Chesters, Jennifer. "Enhancing speech fluency using transcranial direct current stimulation". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:79459ff6-975f-4bd9-8679-1290b20da8b8.
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Producing speech is a highly complex task, involving the integration of sensory and linguistic information, with the precise, high-speed, co-ordination of muscles controlling breathing and the movement of the vocal folds and articulators. In spite of this complexity, producing fluent speech - moving smoothly from one speech sound to the next - can appear effortless. Speech fluency is highly socially valued, and the personal and societal costs of living with a disorder of fluency, such as developmental stuttering, are considerable. The outcomes of behavioural therapies to increase fluency are limited, however, especially for those seeking treatment in adulthood. The overarching aim of this thesis was to investigate how anodal transcranial direct current stimulation (A-TDCS) can be used to increase speech fluency, with a particular focus on the potential application to developmental stuttering. A-TDCS is a noninvasive brain stimulation technique that can enhance the effects of motor, speech, and language training. First, in a series of single-session experiments in typically fluent speakers, I demonstrated that applying A-TDCS over the left IFC increased speech motor learning relative to a sham control, but did not improve consolidation of this learning (chapter 2). Furthermore, I found that neither increasing stimulation intensity from 1 mA to 2 mA, nor changing from a unihemispheric to a bihemispheric configuration, had an additional effect on learning. Next, in single-session study with adults who stutter, I assessed the feasibility of using A-TDCS to improve fluency (chapter 3). Fluency was temporarily induced, by speaking in unison with another person, but the concurrent application of 1-mA unihemispheric A-TDCS over left inferior frontal cortex did not significantly prolong this fluency. Nevertheless, a trend towards stuttering reduction gave some indication that fluency might be increased using a multiple-session approach. Furthermore, I gained a number of important insights from these single-session studies, which I used to inform the design of the final multiple-session trial. In this final study, I completed a randomised controlled trial in 30 adult males with moderate to severe stuttering. Participants were randomized to receive either 1-mA A-TDCS or sham stimulation over left inferior frontal cortex combined with temporary fluency inducing behavioural techniques, for 20 minutes a day over 5 days (chapter 4). A-TDCS significantly reduced disfluency for at least 5 weeks following this intervention. The effect was specific to the speech impairment of development stuttering, as measures of the psycho-social consequences of stuttering were not modulated by A-TDCS. The findings of these studies offer significant promise for the future application of non-invasive stimulation as an adjunctive therapy for adults who stutter. In the concluding chapter, I discuss the important implications of my findings for the future use of this technique.
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Bridges, Nathaniel Reese. "Predicting Vigilance Performance Under Transcranial Direct Current Stimulation". Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1309616451.
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Dyke, Katherine. "Investigating transcranial direct current stimulation and its therapeutic potential". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41642/.
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Transcranial direct current stimulation (tDCS) is a popular non-invasive brain stimulation technique, which has the potential to modulate cortical excitability. The effects of tDCS are known to outlast the stimulation period, and in some cases, repeated applications have been found to produce long lasting clinically relevant effects. The primary aim of this thesis was to explore the reliability and therapeutic potential of this technique. In Chapters 3 and 4 transcranial magnetic stimulation (TMS) was used to measure tDCS effects. These experiments revealed substantial variability regarding the way in which healthy adults responded to stimulation. Notably, there were differences between participants regarding the direction and magnitude of change in cortical excitability. Furthermore, even when group level effects were found reliably, there was substantial intra-subject variability across repeated testing sessions. Subsequent experiments in Chapters 5 and 6, explored the biological and behavioural effects of tDCS in individuals with Gille de la Tourette’s syndrome (GTS). GTS is a neurodevelopmental disorder characterised by motor and phonic tics which have been linked to hyper excitability within motor-cortical regions. Therefore, these experiments aimed to reduce cortical excitability of targeted regions in the hope that this would impact on tics. Disappointingly, no such effects were found immediately after a single session of tDCS (Chapter 5). Consequently, it was hypothesised that repeated applications may be necessary for significant reductions in tics to occur. This was investigated in Chapter 6 using an in-depth case study. The results were encouraging, in particular there was a substantial drop in tics following 10 days of tDCS at 1.5mA intensity. The stimulation was well tolerated and the treatment regimens were closely adhered to, despite tDCS being delivered in the participants own home with remote supervision. A weaker stimulation intensity was not as effective. The findings of Chapters 3-6 highlight that the optimal stimulation parameters may vary from person to person, and that exploration of individual data is critical in therapeutic contexts. The results also suggest that tDCS may be helpful as a treatment for GTS and furthermore highlight the feasibility of home use stimulation.
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Javadi, Arjomand A. H. "Memory modulation by offline consolidation and transcranial direct current stimulation". Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1306720/.
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Two groups of experiments are discussed in this thesis, (a) procedural memory consolidation during sleep and wakefulness, to study the contribution of emotion in consolidation of procedural skill learning, and (b) memory modulation using electrical brain stimulation, to study the effects of long‐ and short‐duration stimulation of left dorsolateral prefrontal cortex (DLPFC) on verbal episodic memory. Memory consolidation; The first study showed that participants who were trained in a mirror tracing task with negative emotional stimuli benefited more compared to the participants who were trained with neutral or positive emotional stimuli. The second experiment aimed to investigate the modulatory effect of stimuli with emotional content in a modified serial reaction time task (SRTT). This experiment failed to achieve any main effect of emotional content, retention type, their interaction or their interaction with session number. The only significant effect was found for the session number in which participants showed significantly higher performance in the second session. It is more likely that this outcome is due to the training effects over blocks. Brain stimulation; The first study showed that 20min anodal stimulation enhanced memory performance while the stimulation was delivered during the encoding phase, 20min cathodal stimulation impaired memory performance for the words that were encoded prior to the stimulation and impaired the recognition performance while it was delivered during the testing phase. The second study was similar to the first experiment with the exception that stimulation was delivered for 1.6s for each presented word in three different conditions: no stimulation, early‐stimulation and late‐stimulation. Results showed that early stimulation has significantly stronger effects on the memory performance of the participants compared to nostimulation and late‐stimulation in both anodal and cathodal stimulation types. Results also showed that early anodal stimulation enhanced the memory performance and early cathodal stimulation impaired the memory performance.
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Angius, Luca. "The effect of transcranial direct current stimulation on exercise performance". Thesis, University of Kent, 2015. https://kar.kent.ac.uk/56645/.
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The physical limits of the human being have been the object of study for a considerable time. Human and exercise physiology, in combination with multiple other related disciplines, studied the function of the organs and their relationship during exercise. When studying the mechanisms causing the limits of the human body, most of the research has focused on the locomotor muscles, lungs and heart. Therefore, it is not surprising that the limit of the performance has predominantly been explained at a "peripheral" level. Many studies have successfully demonstrated how performance can be improved (or not) by manipulating a "peripheral" parameter. However, in most cases it is the brain that regulates and integrates these physiological functions, and much of the contemporary literature has ignored its potential role in exercise performance. This may be because moderating brain function is fraught with difficulty, and challenging to measure. However, with the recent introduction and development of new non-invasive devices, the knowledge regarding the behaviour of the central nervous system during exercise can be advanced. Transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) are two such methods. These methods can transiently moderate the activity of a targeted brain area, potentially altering the regulation of a particular physiological (or psychological) system, and consequently eliciting a change in exercise performance. Despite the promising theory, there is little or no experimental data regarding the potential to moderate neurophysiological mechanisms through tDCS to improve exercise performance. Consequently, the experiments performed as part of this thesis investigated the capacity for tDCS to alter physical performance. The ability of tDCS as a targeted and selective intervention at the brain level provides the unique opportunity to reduce many methodological constraints that might limit or confound understanding regarding some of the key physiological mechanisms during exercise. Therefore, the primary aim of this thesis was to investigate how tDCS may moderate both central and peripheral neurophysiological mechanisms, and how this may effect various exercise tasks. The first study investigated the effect of a well-documented analgesic tDCS montage on exercise-induced muscle pain. This study demonstrated for the first time, that although anodal tDCS of the motor cortex (M1) reduces pain in a cold pressor task, it does not elicit any reduction in exercise-induced muscle pain and consequently has no effect on exercise performance. As reductions in exercise-induced pain have previously been documented to improve performance, probably the lack of effect was due to either the M1 having a limited processing role in exercise-induced pain, or that the cathodal stimulation of the prefrontal cortex negated any positive impact of anodal M1 stimulation. Given the lack of guidelines for tDCS electrode montage for exercise, the second study examined the effect of different electrode montages on isometric performance and the neuromuscular response of knee extensor muscle. Given that the anode increases excitability and the cathode decreases excitability, the placement of these has the potential to elicit significant effects on exercise performance. The results showed that exercise performance improved only when an extrachepalic tDCS montage was applied to the M1, but in the absence of changes to the measured neuromuscular parameters. These results suggest that tDCS can have a positive effect on single limb submaximal exercise, but not on maximal muscle contraction. The improvement in performance was probably the consequence of the reduction in perceived exertion for a given load. This is the first experiment showing an improvement in exercise performance on single joint exercise of the lower limbs following tDCS. The results suggest that the extrachepalic set-up is recommended for exercise studies in order to avoid any potential negative effect of the cathodal electrode. Previous studies investigating tDCS have shown its potential to alter autonomic activity, and in some circumstances reduce the cardiovascular response during exercise. Considering the emerging studies and applications of tDCS on exercise and the potential benefits of tDCS in the treatment of cardiovascular diseases, the third study monitored multiple cardiovascular variables following tDCS in a group of healthy volunteers. Using more advanced techniques and methods compared to previous research, including the post exercise ischemia technique and transthoracic bioimpedance, the results suggest that tDCS administration has no significant effect on the cardiovascular response in healthy individuals. The final study sought to apply the findings obtained in the study 2 to whole body exercise. The same extrachepalic set up was applied over both the motor cortices, with both anodal and cathodal stimulation conditions. The neuromuscular response and cycling performance was also monitored. Following anodal tDCS, time to exhaustion and motor cortex excitability of lower limbs increased. Interestingly, cathodal stimulation did not induce any change in cycling performance or neuromuscular response. This study demonstrated for the first time the ability of anodal tDCS to improve performance of a constant load cycling task, and highlights the inability of cathodal tDCS to decrease cortical activation during muscle contraction. Taken together, the experiments performed as part of this thesis provide new insights on how brain stimulation influences exercise performance, with notable findings regarding the role of M1 excitability and perception of effort. Furthermore, considering the lack of knowledge regarding the use of tDCS on exercise, these findings will help further understanding of how to apply tDCS in exercise science. This consequently improves the knowledge base regarding the effect of tDCS on exercise and provides both a methodological and theoretical foundation on which future research can be based.
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Fleming, Melanie Kate. "Neuromodulation with transcranial direct current stimulation : the influence of electrode arrangement". Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/neuromodulation-with-transcranial-direct-current-stimulation(3554a8bf-0435-4925-9d83-99d35811ae25).html.
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Transcranial direct current stimulation (tDCS) could improve plasticity and motor function, but the influence of electrode arrangement is unclear. The aim of this PhD was to develop and utilise a sequential learning paradigm involving gross movements of the hand to assess the effect of tDCS electrode arrangement on; i) motor sequence learning in healthy young and older adults, ii) motor sequence learning and upper limb function in chronic stroke survivors and iii) retention of learning in healthy adults, and to determine whether the response to tDCS is dependent on changes in transcallosal inhibition (TCI). Study one tested the motor sequence learning paradigm. Young adults, stroke survivors and age-matched controls all demonstrated improvements in motor preparation with 25 repetitions of a movement sequence. However, stroke survivors showed impaired sequence specific learning. Study two demonstrated that healthy ageing was associated with reduced motor sequence learning, but tDCS did not affect performance for either younger or older adults. Bihemispheric tDCS led to an increase in TCI (ipsilateral silent period duration) for the younger group only. There were no significant relationships between changes in TCI and learning. Study three demonstrated a significant effect of tDCS electrode arrangement on upper limb function in stroke survivors, with improvements after unilateral tDCS (anodal or cathodal), but not after bihemispheric. However, there was no effect of tDCS on motor sequence learning or the change in TCI from either hemisphere. Study four showed no effect of tDCS on 48 hour retention of learning for healthy adults. However, cathodal tDCS delivered during training impaired later re-learning of the movement sequence. The findings of these studies suggest that tDCS does not improve learning of a sequence of gross hand movements. High variability in response is observed and there is no consistent effect of tDCS on TCI.
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Tsovilis, Ekaterini. "Anodal transcranial direct current stimulation: A potential treatment for chronic pain". Thesis, Tsovilis, Ekaterini (2019) Anodal transcranial direct current stimulation: A potential treatment for chronic pain. Honours thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/55032/.
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Purpose: Current treatments available for chronic pain either do not provide patients with adequate pain relief, are invasive, expensive or cause negative side effects. Transcranial direct current stimulation (tDCS) delivered to the primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC) brain regions has been identified as a potential treatment. However, the literature regarding is effectiveness is mixed. This study aimed to clarify if tDCS at M1 and DLPFC reduces healthy participants’ pain. In addition, it aimed to identify whether simultaneous stimulation of M1 and DLPFC results in greater pain reduction than stimulation at one cortical site alone.
Method: A randomized, crossover, within-subjects, double-blinded sham controlled design was utilized. Twenty healthy participants (10 female; aged 18 to 59) underwent four conditions, 20 minutes of 1 mA anodal tDCS at M1 and DLPFC concurrently, M1, DLPFC and sham. A low-frequency electrical current administered to participants’ right volar forearm induced pain. Pain was assessed pre and post tDCS by pain ratings to pinprick and the electrical current level required during electrical stimulation to induce moderate level pain.
Results: Analysis revealed a significant difference between pre and post tDCS pain assessment, however, this difference was present irrespective of tDCS condition. Participant habituation to low-frequency electrical stimulation may explain these results.
Conclusions: TDCS within this study did not reduce healthy participants’ pain. This study identified methodological considerations and tDCS parameters that should be implemented in future replication studies to further explore tDCS as a potential chronic pain treatment.
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Feredoes, Eva Psychiatry Faculty of Medicine UNSW. "Investigating the neural correlates of higher cognitive functions in humans using transcranial magnetic stimulation and transcranial direct current stimulation". Awarded by:University of New South Wales. Psychiatry, 2005. http://handle.unsw.edu.au/1959.4/23460.
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An important aspect of cognitive neuroscience is to localise specific brain regions involved in cognitive tasks, and to determine the mediating brain processes. There are several investigative approaches towards this, but amongst them, only transcranial magnetic stimulation (TMS) is able to interfere with the brain in such a way as to show the critical involvement of a brain region in a particular behaviour. TMS can be applied in normal subjects during the performance of a cognitive task and the resulting disruption of activity in the targeted brain region leads to an alteration in, or suspension of, behaviour consequent upon that brain activity. More recently, another brain stimulation technique has emerged that may also be able to contribute to the investigation of human cognition. Transcranial direct current stimulation (tDCS) applies a weak direct current to a targeted brain region, modulating cortical excitability and thereby altering the behavioural output. tDCS may be able to provide information that complements TMS and other investigative techniques by modulating behaviour in a way that depends on the role the brain region is carrying out in the task. This thesis describes a series of experiments in which TMS and tDCS were applied to two well-studied cognitive behaviours, working memory (WM) and mental rotation (MR). WM is the temporary retention of information that can be manipulated in order to guide behaviour. The most popular psychological model of WM proposes a multi-modal central executive (CE) that acts upon information stored in dedicated buffers (Baddeley, 1986). The dorsolateral prefrontal cortex (DLPFC) is a strong candidate as a key CE node (D'Esposito & Postle, 2000; Petrides, 2000b; Smith & Jonides, 1997; Stuss & Knight, 2002). MR is a visuo-cognitive process by which an image can be mentally modified into an orientation other than the one in which it is displayed (Corballis & McLaren, 1984). The area centred around the intraparietal sulcus is a brain key region for MR (Alivisatos & Petrides, 1996; Harris et al., 2000; Jordan et al., 2001). The work presented in this thesis examines the roles of the DLPFC and posterior parietal cortex (PPC) in WM and MR, respectively, and also highlights some of the methodological issues that are necessary to consider in order to produce reliable virtual lesions. The studies were carried out in young healthy volunteers, and were approved by the institutional ethics committee. In one study, repetitive TMS (rTMS) was shown to disrupt the manipulation of verbal information held in WM when administered over the right DLPFC, a result which supports a process-based segregation of the human prefrontal cortex for WM. Low- and high-frequency rTMS did not disrupt performance on another popular test of executive processing, n-back, a result which suggests that specific stimulation and task conditions must be met in order to produce virtual lesions, but also questions the critical importance of recruitment of the DLPFC for a running span task. rTMS applied to the right PPC replicated results from a previous TMS investigation, supporting the critical role this region in the rotation of images (Harris & Miniussi, 2003). When the left PPC was stimulated, impairment was produced only for the rotation of inverted stimuli. A role for the left PPC in the rotation of objects-as-a-whole is proposed based on these findings. The use of tDCS in the investigation of WM and MR is amongst the first to be described. Stimulation of the left DLPFC led to decreased performance accuracy on a verbal WM task in a polarity-specific manner. The pattern of results produced supports the role of the DLPFC as a node of a CE. tDCS over the left DLPFC did not modulate n-back task performance, a result which supports the TMS results that the involvement of the left DLPFC is not critical to the successful performance of the n-back task, although methodological issues remain of concern in relation to this conclusion. MR was not affected by tDCS applied to the right PPC and this result is most likely a direct demonstration of the importance of electrode montage. In conclusion, these studies show that rTMS and tDCS can be usefully applied to create virtual cortical lesions or modulate cortical excitability during the performance of cognitive tasks in humans, and can play an important role in investigating cognitive neuropsychological models. More widespread use of these techniques to complement lesion studies and functional neuroimaging is recommended.
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Ebajemito, James K. "The modulatory effect of sleep on transcranial direct current stimulation-enhanced learning". Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/845444/.
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Transcranial direct current stimulation (tDCS) as a means for enhancing learning and memory has received a lot of attention in recent times. However, its applicability in a wider context has been limited due to lack of replicability across the literature. This may likely stem from inter-individual differences such as age, gender, nutrition, stress, brain morphology and sleep. Sleep in particular may be a source of inter-individual differences in tDCS-effect because of its link to brain plasticity mechanism such as long-term potentiation (LTP). The extent to which sleep may account for inter-individual differences in tDCS outcomes has not been assessed in the literature. Therefore, the central aim of this thesis is to investigate 1) the effect of sleep quality 2) circadian mis- /alignment 3) prior sleep compared to wake on tDCS-enhanced learning. Findings from this thesis suggests that sleep quality does not affect variability in tDCS-effect on cognitive performance, while circadian mis/-alignment and prior wakefulness before task may modulate tDCS-efficacy. In conclusion, data suggests that tDCS-effect is greater in a brain which is in a non-optimal state in terms of circadian misalignment and prolonged wake, and in this context, sleep may be responsible for variabilities in tDCS studies. These findings have implications for researchers and clinicians using tDCS. Further studies are required to fully characterise the findings from this thesis.
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Impey, Danielle. "Assessment of Transcranial Direct Current Stimulation (tDCS) on MMN-Indexed Auditory Sensory Processing". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35576.
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Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation which uses a very weak constant current to temporarily excite or inhibit activity in the brain area of interest via electrodes placed on the scalp, depending on the polarity and strength of the current. Presently, tDCS is being used as a tool to investigate frontal cognition in healthy controls and to improve symptoms in neurological and psychiatric patients. Relatively little research has been conducted with respect to tDCS and the auditory cortex (AC). The primary aim of this thesis was to elucidate the effects of tDCS on auditory sensory discrimination, assessed with the mismatch negativity (MMN) event-related potential (ERP). In the first pilot study, healthy participants were assessed in a randomized, double-blind, sham-controlled design, in which participants received anodal tDCS over the primary AC (2 mA for 20 minutes) in one session and ‘sham’ stimulation (i.e. no stimulation) in the other. Pitch MMN was found to be enhanced after receiving anodal tDCS, with the effects being evidenced in individuals with relatively low (vs. high) baseline amplitudes. No significant effects were seen with sham stimulation. A second study examined the separate and interacting effects of anodal and cathodal tDCS on MMN measures. MMN was assessed pre- and post-tDCS (2 mA, 20 minutes) in 2 separate sessions, one involving sham stimulation, followed by anodal stimulation, and one involving cathodal stimulation, followed by anodal stimulation. Only anodal tDCS over the AC increased pitch MMN in baseline-stratified groups, and while cathodal tDCS decreased MMN, subsequent anodal stimulation did not significantly alter MMNs. As evidence has shown that tDCS lasting effects may be dependent on N-methyl-D-aspartate (NMDA) receptor activity, a pharmacological study investigated the use of dextromethorphan (DMO), an NMDA antagonist, to assess possible modulation of tDCS’ effects on both MMN and working memory (WM) performance. The study involved four test sessions that compared pre- and post-anodal tDCS over the AC and sham stimulation with both DMO (50 mL) and placebo administration. MMN amplitude increases were only seen with anodal tDCS with placebo administration, not with sham stimulation, nor with DMO administration. In the sham condition, DMO decreased MMN amplitudes. Anodal tDCS improved WM performance in the active drug condition. Findings from this study contribute to the understanding of underlying neurobiological mechanisms mediating tDCS-sensory and memory improvements. As cognitive impairment has been proposed to be the core feature of schizophrenia disorder (Sz) and MMN is a putative biomarker of Sz, a pilot study was conducted to assess the effects of pre- and post-tDCS on MMN measures in 12 Sz patients, as well as WM performance. Temporal, frontal and sham tDCS were applied in separate sessions. Results demonstrated a trend for pitch MMNs to increase with anodal temporal tDCS, which was significant in a subgroup of Sz individuals with auditory hallucinations, who had low MMNs at baseline. Anodal frontal tDCS significantly increased WM performance, which was found to positively correlate with MMN-tDCS effects. The findings contribute to our understanding of tDCS effects for MMN-indexed sensory discrimination and WM performance in healthy participants and individuals with Sz disorder and may have implications for treatment of sensory processing deficits in neuropsychiatric illness.
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Hohmann, Anja [Verfasser]. "Modulating vocal pitch perception and production with transcranial direct current stimulation / Anja Hohmann". Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2014. http://d-nb.info/1052529836/34.
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Besson, Pierre. "Using of transcranial direct-current stimulation during motor task for a better outcome". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONT4004/document.
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De tout temps, les humains ont cherché différents moyens pour améliorer leur quotidien. Avec les avancées technologiques actuelles, cette quête s’en trouve facilitée, notamment dans la volonté d’accroître leurs capacités cognitives et/ou motrices. La neuro imagerie permet dorénavant de renseigner les aires cérébrales activées lors de différentes tâches fonctionnelles. Il est aussi possible de moduler l’activité cérébrale en stimulant localement le cerveau avec de faibles courants électriques. Une des techniques les plus répandues à cet effet est appelée tDCS pour transcranial direct current stimulation. Il s’agit en fonction de la polarité du courant induit de moduler à la hausse (stimulation anodale) ou à la baisse (stimulation cathodale) l’excitabilité cortico-spinale en dépolarisant ou en hyperpolarisant la membrane des neurones, respectivement. Malgré une démocratisation grandissante de la neuromodulation via tDCS, les résultats rapportés par la communauté scientifique sont relativement hétérogènes. Les travaux initiés au début des années 2000 sont remis en cause par des résultats actuels faisant état d’une variabilité inter et intra individuelle assez importante. Cette pierre d’achoppement nécessite de développer de nouveaux protocoles d’application de la tDCS. Dans cette thèse, nous avons étudié plusieurs modalités d’application de la tDCS afin d’accroître la persistance des effets neuroplastiques induits et d’augmenter les performances comportementales. Deux études ont été menées afin de révéler dans un premier temps les apports induits par le couplage tâche motrice-tDCS pour ensuite mettre en avant les effets cumulatifs de la répétition de sessions de tâche motrice-tDCS avec pré conditionnement sur la performance motrice. La première étude à travers l’utilisation de la spectroscopie dans le proche infrarouge a permis de rapporter des changements hémodynamiques distincts subséquents au couplage tâche motrice-tDCS par rapport à des protocoles tDCS plus conventionnels. La primauté de l’utilisation concomitante de la tDCS à la tâche motrice a été révélée par la moindre activation du cortex sensorimoteur durant la stimulation ainsi que par une activation cérébrale retardée accrue qui pourrait représenter une réorganisation neuroplastique. La seconde étude s’est intéressée aux effets de la polarité du conditionnement lors de sessions répétées avec comme objectif d’améliorer l’apprentissage et la rétention du système sensorimoteur. Le conditionnement par tDCS était plus propice lors de sessions répétées à engendrer des performances motrices supérieures contrairement à la condition sham. La polarité cathodale engendrait une persistance prolongée. Les premiers résultats de ces travaux de thèse ont permis de défendre l’usage concomitant de la tDCS avec la tâche motrice. De futures recherches sont nécessaires afin d’étudier le transfert de ces résultats dans le monde de l’entraînement ainsi que celui de la réhabilitationHistorically, humans have sought various ways to improve their daily lives. With the current technological advances, this quest is facilitated, especially in the desire to increase their cognitive and / or motor skills. Neuro imagery now makes it possible to inform the areas activated during different functional tasks. Today, it is now possible to modulate brain activity by stimulating the brain locally with weak electrical currents. One of the most common techniques for this purpose is called tDCS for transcranial direct current stimulation. The polarity of the induced current (anodal or cathodal stimulation) allows to modulate upward or downward cortico-spinal excitability by depolarizing or hyperpolarizing the membrane of the neurons, respectively. Despite a growing interest of neuromodulation techniques via tDCS, the results reported by the scientific community are relatively heterogeneous. The work initiated at the beginning of the 2000s is called into question by current results showing a rather large inter and intra variability. This stumbling block requires the development of new protocols for the application of anodal tDCS (atDCS). In this thesis, we were interested in optimizing atDCS protocols in order to increase the persistence of the induced-neuroplastic effects and to increase the behavioral performances. Two studies were carried out in order to first reveal the impact from the motor task/atDCS coupling and then to highlight the cumulative effects of multiple motor-tDCS task sessions with priming atDCS on motor performance. The first study through the use of near infrared spectroscopy allowed to report various hemodynamic changes subsequent to the motor task/atDCS coupling with respect to independent and controlled stimulation protocols. The primacy of the concomitant use of tDCS with the motor task was revealed by the slightest activation of the sensorimotor cortex during stimulation and by an increased delayed cerebral activation which could represent a neuroplastic reorganization. The second study examined the effects of repeated atDCS sessions with anoadal or cathodal tDCS priming in order to improve the learning and retention gains of the sensorimotor system. TDCS priming was more favorable for repeated atDCS sessions to generate higher motor performances contrary to sham. The cathodal polarity produced prolonged persistence. The major findings of this work allow to support the concomitant use of atDCS with the motor task. Future research is needed to study the transfer of these results into the fields of coaching and rehabilitation
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Wagner, Jessica. "Effects of Transcranial Direct Current Stimulation on Expression of Immediate Early Genes (IEG’s)". Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1407255006.
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Stafford, Justin Andrew. "Translocation and Phosphorylation of AMPA Receptors Following Transcranial Direct Current Stimulation in vivo". Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1480096423230882.
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Reidler, Jay S. "Modulation of Pain with Transcranial Direct Current Stimulation and Diffuse Noxious Inhibitory Controls". Thesis, Harvard University, 2014. http://etds.lib.harvard.edu/hms/admin/view/48.
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Background: While pain is essential for physiological functioning, chronic or pathologic pain is responsible for a major burden of disease in society. Novel approaches to treating acute and chronic pain have employed neuromodulatory tools to target the central and peripheral neural structures that mediate pain. Transcranial direct current stimulation (tDCS), for example, is a safe, non-invasive brain stimulation technique that has been shown in preliminary studies to reduce chronic pain when applied to the primary motor cortex. In contrast to this exogenous neuromodulatory approach, diffuse noxious inhibitory controls (DNIC) refers to endogenous pain regulatory mechanisms that decrease pain following introduction of heterotopic noxious stimuli. This thesis explores whether combining these exogenous and endogenous pain modulation approaches synergistically increases the threshold at which pain is perceived.
Methods: We conducted a double-blinded, randomized, placebo-controlled trial with a crossover design to investigate the effects of tDCS and DNIC on pain thresholds in 15 healthy human subjects. Pain thresholds were assessed prior to and following administration of active tDCS, sham tDCS, cold-water-induced DNIC, and combined active tDCS and DNIC. Using magnetic resonance spectroscopy, we examined whether baseline concentrations of brain metabolites such as N-acetylaspartate in pain-related regions of interest were associated with responses to the varying neuromodulatory conditions.
Results: Pain thresholds significantly increased following both active tDCS and the DNIC paradigm. These modulatory approaches appeared to have additive effects when combined. Pain threshold increases after active tDCS were positively correlated with baseline levels of N-acetylaspartate, a marker of good neural function, in the anterior cingulate cortex and negatively correlated with baseline levels of glutamine in the thalamus.
Conclusions: Combining endogenous pain regulatory mechanisms with exogenous stimulation of the motor cortex can more effectively increase pain thresholds in healthy humans. Future studies should examine whether existing pain therapies may be enhanced with noninvasive brain stimulation and activation of DNIC. They should also assess whether brain metabolite levels can be utilized to predict clinical response to therapeutic interventions.
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Feeser, Melanie [Verfasser]. "Modulating Social Cognition: Effectiveness of Oxytocin Application and Transcranial Direct Current Stimulation / Melanie Feeser". Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1069872644/34.
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Luedtke, Kerstin. "Transcranial direct current stimulation for the reduction of chronic non-specific low back pain". Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5248/.
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Non-specific chronic low back pain has serious personal and socio-economic consequences. International guidelines recommend multimodal cognitive behavioural management (CBT). The effectiveness of CBT might be enhanced by directly targeting central nervous system pain processing. Transcranial direct current stimulation (tDCS) is a novel approach aiming to influence pain by altering cortical excitability. An evaluation of existing reviews indicated the need for an up-to-date review of clinical and experimental pain trials. A systematic review including 14 trials (published 2006-2012) evaluating tDCS for the reduction of clinical and experimental pain identified a low level of evidence for its effectiveness. Only 1 trial had a low risk of bias. A meta-analysis of trials on clinical pain identified a small pain reducing effect that just reached clinical importance. To investigate the effectiveness of tDCS alone and in combination with CBT, a double-blind RCT was conducted; preceded by a feasibility study confirming practicability of trial procedures and patient acceptability of tDCS. Results indicated that tDCS alone or in combination with CBT did not significantly influence pain or disability. An updated meta-analysis, including this trial’s results, lowered the pain reducing effect of tDCS below clinical importance, and increased the level of evidence for its effectiveness to "high".
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Meron, Daniel. "Novel treatment approaches for anxiety disorders : mindfulness-based approaches and Transcranial Direct Current Stimulation". Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/411278/.
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Anxiety disorders are an important cause of morbidity worldwide. Existing treatments for anxiety disorders have considerable shortcomings and new treatments are needed. Anxiety impairs attentional control through effects on central executive functions, whereas Mindfulness training has effects on executive function and attention. This thesis explores the potential for using mindfulness and transcranial direct current stimulation (tDCS) as treatment modalities for anxiety disorders, beginning with a literature review, and going on to describe a series of investigations in healthy volunteers. The first study compared the effects of two types of mindfulness training: focused attention (FA) vs. open monitoring (OM), on attention network function, using the Attention Network Test (ANT). The second study explored the effects of a strengthened, integrated FA and OM mindfulness training on attention to threat, using an antisaccade task. A third study examined the effects of a single session of guided FA vs. OM mindfulness on attention to threat (measured using an antisaccade task), during inhalation of air enriched with 7.5% carbon dioxide (CO2). The fourth study evaluated the effect of a single session of tDCS on attention network function (measured using the ANT). The final study examined the effect of a single session of tDCS on attention to threat (measured using the antisaccade task), during inhalation of 7.5% CO2. The main findings of these studies are as follows: A literature review demonstrated that Mindfulness-based interventions have a substantial evidence base for efficacy in depression and a growing evidence base in anxiety disorders. A meta-analysis of randomised controlled trials (RCTs) comparing active vs. sham tDCS in depression found that in patients with major depressive episodes, tDCS offers an effective and tolerable alternative to antidepressant medication for those who do not wish to take or cannot take tolerate medication, or cannot tolerate it: current evidence does not support the use of tDCS in treatment resistant depression, or as an augmentation treatment with antidepressant medication or Cognitive Control Training (CCT). There are no published RCTs of tDCS in anxiety disorders. Mindfulness interventions were associated with enhanced executive control function on the ANT, and attenuated the effects of 7.5% CO2 inhalation on anxiety A single session of tDCS was associated with enhanced executive control function on the ANT, but did not protect against anxiety during inhalation of 7.5% CO2. These findings suggest tDCS may be best utilised during the early stages of depression treatment pathways, and have implications for future design of mindfulness interventions for anxiety.
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Hanley, Claire J. "The neurobiological mechanisms of transcranial direct current stimulation : insights from human neuroimaging and psychophysics". Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/91336/.
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The research aimed to investigate the neurobiological basis of transcranial direct current stimulation (tDCS); a neuromodulation technique capable of inducing prolonged changes in behavioural performance. The past 15 years have seen a dramatic increase in tDCS-oriented studies, yet the underpinnings of the method are not completely understood. Consequently, this series of experiments was designed to investigate the mechanisms that contribute to the effects of the method. Focusing on neuroimaging, modulations of excitatory and inhibitory neurochemicals were assessed using Magnetic Resonance Spectroscopy (MRS); incorporating distinct spectral editing sequences to define the precise role of inhibitory neurotransmission. Additionally, concurrent DC stimulation and Magnetoencephalography (MEG) was developed, which permitted the novel investigation of excitatory and inhibitory processes via the influence of tDCS on electrophysiological responses in the motor and visual systems. This simultaneous tDCS-MEG investigation is one of only a few existing studies and was the first such endeavour by a group based in the United Kingdom. Finally, a unique psychophysical approach was adopted whereby variations of a vibrotactile adaptation task were utilised to assess the effects of tDCS on amplitude discrimination ability. The paradigms used were specifically chosen due to their physiological similarity to tDCS, thereby enabling inferences on the underpinnings of the method on the basis of changes in somatosensory task performance. These studies provided varying degrees of support for the neurobiological mechanisms proposed in the existing literature, most likely reflecting the influence of distinctions in stimulation protocols and the presence of individual difference factors thought to modify responses to stimulation. Consequently, in addition to the established insights regarding the underpinnings of tDCS, valuable perspectives on the optimisation of stimulation-based methodology were achieved by conducting the outlined investigations.
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Kekic, Maria. "An investigation into the therapeutic utility of transcranial direct current stimulation in bulimia nervosa". Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/an-investigation-into-the-therapeutic-utility-of-transcranial-direct-current-stimulation-in-bulimia-nervosa(7ac353e0-0e73-4b37-b192-632c5ed7c6c8).html.
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Background: Recent neurobiological insights gained from functional neuroimaging studies suggest that bulimia nervosa (BN) is underpinned by dysregulated frontostriatal circuitry, which supports self-regulatory control and food reward processing capacities. Brain-directed interventions may therefore hold promise as treatments for the disorder. The overarching aim of this research was to investigate the therapeutic utility of transcranial direct current stimulation (tDCS; a form of non-invasive brain stimulation) in patients with BN. Methods: Four studies were conducted: (1) a systematic review of the clinical efficacy of tDCS across all psychiatric disorders; (2) a randomised controlled trial (RCT) of single-session tDCS applied to the dorsolateral prefrontal cortex (DLPFC) in healthy individuals with frequent food cravings; (3) a cross-sectional study of temporal discounting (a marker of poor self-regulatory control) in patients with BN and healthy controls; and (4) an RCT of single-session tDCS applied to the DLPFC in BN. Results: The main findings were as follows: (1) existing data indicate that tDCS interventions comprising multiple sessions can ameliorate symptoms of several major psychiatric disorders, both acutely and in the long-term; (2) a single session of sham-controlled DLPFC tDCS transiently suppressed craving for sweet foods (i.e., altered food reward processing) among individuals with frequent food cravings; (3) patients with BN showed greater temporal discounting (i.e., poorer self-regulatory control) relative to healthy participants; and (4) a single session of sham-controlled DLPFC tDCS temporarily reduced symptoms, improved mood, and lowered temporal discounting (i.e., increased self-regulatory control) in individuals with BN. Conclusions: Taken together, the results provide preliminary support for the therapeutic utility of tDCS over the DLPFC in BN, and offer justification for multi-session trials in this patient population.
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Lommen, Jonathan Lyon Jacob. "Effects of Transcranial Direct-Current Stimulation on Gait Initiation in People with Parkinson’s Disease". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39959.
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Background: Gait initiation is a major issue in Parkinson’s disease (PD). Moreover, the effect of current treatment on motor deficits vary alongside individual differences and disease severity. In some cases, postural instability has been documented as a major side-effect and refractory symptom to dopaminergic medication. Despite these shortcomings, research involving other forms of therapy including deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS), has evidenced the improvement of postural deficits in PD. In this regard, there is a strong rational for the modulation of subcortical brain activity via the application of non-invasive transcranial direct current stimulation (tDCS) to interconnected cortical brain structures. Purpose: Therefore, we sought to determine the effect of tDCS applied to the supplementary motor area (SMA), on gait initiation preparation and performance in PD. Methods: A within subjects repeated measures quasi-experimental design was used to investigate the effects of a 10-minute sham-controlled tDCS intervention. Clinically diagnosed participants (n=12) with idiopathic PD were tested on medication during two sessions that bookended one week. Those who had previously undergone other forms of brain stimulation, had diabetes, severe freezing of gait, or any other neurological or functional limitations that could interfere with gait initiation were excluded from the study. Statistical Analyses/Results: Two-way repeated measures ANOVAs with Bonferroni corrections and a post-hoc analyses when appropriate, revealed a significant reduction in the magnitude of center of pressure (CoP) displacement and velocity in the mediolateral (ML) direction following tDCS. Conclusions: Findings from this study provide insights that may guide scientific research regarding the effects of tDCS on gait initiation among those with PD. Additionally, our work may highlight the importance of ML postural stability for individuals with comorbid and/or pharmacologically induced postural instabilities.
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Scherrer, Brandon A. "Anodal transcranial direct current stimulation does not induce analgesic effects on experimentally induced pain". Thesis, Scherrer, Brandon A. (2018) Anodal transcranial direct current stimulation does not induce analgesic effects on experimentally induced pain. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/43628/.
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Chronic pain is a disabling condition in which the adaptive link between pain intensity and tissue damage is lacking. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that induces analgesic effects on experimentally induced pain when applied at the primary motor cortex (M1), and the dorsolateral prefrontal cortex (DLPFC). However, whether greater analgesic effects occur when tDCS is applied simultaneously at the M1 and the DLPFC is unknown, and is the primary aim of the current study. Nineteen healthy adult volunteers (12 male; Mage = 29.21, SD = 10.78, range 20 to 52) participated in a double blinded, crossover, sham controlled, randomised design. Dependent variables were self-reported pain ratings to punctuate pinprick stimuli, and the current level required of electrical stimulation to elicit moderate pain. These ratings were obtained pretest, posttest, and follow up of 20 min of anodal tDCS applied at the M1, DLPFC, M1 + DLPFC, or sham tDCS. Results indicate that pain to pinprick stimuli and the current level required to elicit moderate increased from pretest, posttest, and follow up. However, this was irrespective of the tDCS condition administered. Methodological inconsistencies pertaining to the administration of tDCS in the current study include lower current intensity and smaller electrode size as compared to past research. Thus, the tDCS stimulation parameters employed in the current study may have not been efficacious to inducing analgesic effects. Therefore, the current study highlights theoretical implications for future research to employ established tDCS parameters.
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Bachtiar, Velicia Elizabeth. "Transcranial stimulation of the human primary motor cortices". Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:0a0f5502-e07c-4d8c-bc04-10c0a1f107f3.
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The primary aim of this thesis is to investigate the physiological effects of transcranial direct current stimulation (tDCS) as applied to the primary motor cortex (M1). This research was largely motivated by the need to understand the basic physiological changes of tDCS, in order to evaluate its use as a potential tool in recovery after stroke, as well as its more general applicability as a tool to modulate plasticity. The experiments in this thesis assess the ability of tDCS to modulate the primary motor cortex in healthy controls. The effects of tDCS on cortical GABA and motor resting state functional connectivity were measured with magnetic resonance spectroscopy (MRS) and resting functional MRI (fMRI). Anodal stimulation reduced GABA concentration and increased functional connectivity in the stimulated M1. Testing these changes within the same individuals demonstrated that the magnitude of changes do not correlate across subjects. Novel evidence on the timecourse of GABA change demonstrated that the reduction in GABA is most prominent in the 30-minute period after stimulation. To determine whether the tDCS-induced modulations in inhibition is restricted to the stimulated hemisphere or whether inhibitory changes could be observed in the nonstimulated M1, or in the interhemispheric connections between the M1s, transcranial magnetic stimulation (TMS) was used to measure intracortical inhibition in each M1 and interhemispheric inhibition and facilitation in the contralateral M1. There were no polarity-specifc effects on intracortical inhibition within either M1, and no changes in interhemispheric excitability from the stimulated to non-stimulated M1. Development of a two-voxel MRS method at ultra high field (7 Tesla) allowed for concurrent measurements of cortical neurotransmitters from both M1s with excellent spectral quality and GABA quantifcation. This method was used to demonstrate the timecourse of tDCS-induced changes in neurochemicals concurrently from both M1s. Anodal stimulation reduced GABA in both the anode-targeted and non-stimulated M1. Cathodal stimulation decreased GABA and glutamate in the non-stimulated M1, with no concurrent changes in the cathode-targeted M1. Bilateral stimulation reduced glutamate in both M1 with no change in GABA.
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Alizad, Vida. "Effects of transcranial direct current stimulation on gait in people with and without Parkinson's disease". Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/129454/1/Vida_Alizad_Thesis.pdf.
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This study was conducted to examine the effects of transcranial direct current stimulation (tDCS) on gait in people with and without Parkinson's disease. tDCS is a non-invasive brain stimulation, which uses weak direct current (1–2 mA) to the brain via electrodes applied on the skin of the scalp. The findings of this study provided future direction, particularly in terms of configuration of tDCS for gait improvement in people with PD and helped move the emerging brain stimulation approach to PD closer to clinical practice.
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Bryant, Andrew M. "Effects of Transcranial Direct Current Stimulation on Working Memory Performance in Older Adults: Potential Moderators". Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1595952473754039.
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Heimrath, Kai [Verfasser]. "Changed temporal processing in the human auditory cortex by transcranial direct current stimulation / Kai Heimrath". Magdeburg : Universitätsbibliothek, 2017. http://d-nb.info/1128726440/34.
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Qin, Jing. "The effects of transcranial direct current stimulation (tDCS) on balance control in Parkinson's disease (PD)". Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/211438/1/Jing_Qi_Thesis.pdf.
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Tan, Angela. "Effects of primed anodal transcranial direct current stimulation on the psychomotor function of older adults". Thesis, Tan, Angela (2016) Effects of primed anodal transcranial direct current stimulation on the psychomotor function of older adults. Honours thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/40684/.
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Declines in cognitive and motor functions as a result of ageing have an adverse impact on the quality of life. One such decline takes the form of poorer psychomotor performance, which involves both cognitive and motor processes in terms of perceiving and processing external stimuli, and executing motor responses. Recent research using transcranial direct current stimulation (tDCS) has shown that priming the corticospinal system by lowering the threshold for the induction of long-term potentiation facilitates subsequent motor performance. Here we utilised this priming approach in a double-blind sham-controlled experiment to investigate the efficacy of the application of tDCS to the dorsolateral prefrontal cortex (DLPFC) in improving the psychomotor performance of older adults. A group of 10 healthy older individuals (mean age 71.60 years; 5 males and 5 females) participated in 2 sessions on separate days, with 1 session involving a 10-minute cathodal tDCS followed by a 20-minute anodal tDCS (C-A), and the other involving a 10-minute cathodal tDCS followed by sham stimulation (C-S) over the left DLPFC. Psychomotor performance was determined through the accuracy and response speeds on a task measuring sustained, selective, and divided attention. The accuracy scores for divided attention were significantly higher in the C-A condition compared with the C-S condition, suggesting that anodal tDCS primed with cathodal tDCS is effective in improving divided attention, and shows promise as a clinical intervention for improving psychomotor function in older adults.
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Olson, Claire. "No analgesic effect for anodal transcranial direct current stimulation on induced pain in healthy participants". Thesis, Olson, Claire (2019) No analgesic effect for anodal transcranial direct current stimulation on induced pain in healthy participants. Honours thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/55033/.
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Pain is protective, but when it becomes a chronic condition, such as complex regional pain syndrome (CRPS), it has outlived its protective use and is now a burden on the sufferer. There are few effective treatments for CRPS. Transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, has demonstrated efficacy in reducing both chronic and induced pain when administered at the primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC). This study investigated tDCS protocols that could be replicated in CRPS patients. Twenty healthy participants (10 male, 10 female; age M = 25.10, SD = 8.87) received anodal tDCS at 1mA intensity for 20 minutes at M1 only, DLPFC only, M1 + DLPFC simultaneously, or sham. The study was a within-subjects, double-blind study, with each participant receiving each form of tDCS in sessions separated by one week. Participants were asked to rate pain in response to electrical and pinprick stimulation. Results indicated no significant pain-relieving effect for anodal tDCS in comparison to sham. However, results were limited by low tDCS current intensity and individual differences in tDCS responsivity. TDCS shows promise as a non-invasive treatment for chronic pain; it is recommended that future research focus on clinical populations.
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Floyd, John Tyler. "Lower Extremity Transcranial Direct Current Stimulation (TDCS)| The Effect of Montage and Medium on Cortical Excitability". Thesis, University of Central Arkansas, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10686422.
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The dissertation consists of three parts. The first part is a systematic review of the literature regarding transcranial direct current stimulation (tDCS) and its effects on lower extremity motor behaviors and corticospinal excitability of the lower extremity representation of the motor cortex in healthy subjects. The second part investigates how different electrode montages and electrode conductance mediums affect corticospinal excitability of the tibialis anterior (TA) representation of the motor cortex in healthy subjects. The third part studies how different electrode montage and electrode conductance medium combinations affect ankle tracking accuracy in healthy subjects regarding the dominant lower extremity.
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Schwippel, Tobias Udo [Verfasser]. "The effect of transcranial direct current stimulation (tDCS) on working memory in schizophrenia / Tobias Udo Schwippel". Tübingen : Universitätsbibliothek Tübingen, 2020. http://d-nb.info/1218073756/34.
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Fonteneau, Clara. "Impact of a single frontal transcranial direct current stimulation on the dopaminergic network in healthy subjects". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1079/document.
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La stimulation transcrânienne par courant continu (tDCS) sert à moduler l’activité neuronale. Elle consiste à appliquer un faible courant constant entre deux électrodes placées sur le cuir chevelu. Deux montages semblent efficaces pour moduler les capacités cognitives et/ou soulager des symptômes cliniques. Cependant, les effets neurobiologiques de la tDCS sont encore mal connues. Ce travail de thèse a tenté de clarifier les mécanismes cérébraux de la tDCS chez les sujets sains, en particulier en lien avec le système dopaminergique. En utilisant un design randomisée en double aveugle, nous avons combiné une session de tDCS online avec plusieurs modalités d'imagerie (PET ou PET-IRM simultanée) chez le sujet au repos. Une première étude (n=32, 2mA, 20min) a montré que la tDCS bifrontale induit une augmentation de la dopamine extracellulaire dans le striatum ventral, impliqué dans le réseau de récompense-motivation, après la stimulation. Une seconde étude (n=30, 1mA, 30min) a montré que la tDCS fronto-temporale induit une augmentation de la dopamine extracellulaire dans la partie exécutive du striatum et une diminution de la perfusion dans une région du réseau du default mode (DMN), après la stimulation. L'analyse des données de cette étude est toujours en cours. Dans l’ensemble, ce travail fournit la preuve qu'une seule session de tDCS frontale peut impacter le système dopaminergique dans des régions connectées aux zones corticales stimulées. Par conséquent, les niveaux d'activité et réactivité dopaminergique doivent être de nouveaux éléments à considérer dans l’hypothèse globale de modulation de l’activité cérébrale par la tDCS frontaleTranscranial direct current stimulation (tDCS) is used to modulate neuronal activity in the brain. It consists in applying a small constant current between two electrodes placed over the scalp. Two frontal tDCS montages have shown promises in modulating cognitive abilities and/or helping to alleviate clinical symptoms. However, the effects of tDCS on brain physiology are still poorly understood. The aim of this thesis work was to clarify brain mechanisms underlying frontal tDCS in healthy subjects, specifically in relation to the dopaminergic system. Using a double blind sham-controlled design, we combined a single session of tDCS online with several imaging techniques (PET or simultaneous PET-MRI) with the subject at rest. A first study (n=32, 2mA, 20min) showed that bifrontal tDCS induced an increase in extracellular dopamine in the ventral striatum, involved in the reward-motivation network, after the stimulation period. A second study (n=30, 1mA, 30min) showed that fronto-temporal tDCS induced an increase in extracellular dopamine in the executive part of striatum as well as a decrease in perfusion in a region part of the default mode network (DMN), after the stimulation period. The data analysis of this study is still ongoing. Overall, the present work provides evidence that a single session of frontal tDCS impacts the dopaminergic system in regions connected to the stimulated cortical areas. Therefore, levels of dopamine activity and reactivity should be new elements to consider for a general hypothesis of brain modulation by frontal tDCS
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Hoseini, Najmeh. "The effect of motor point associative stimulation (MPAS) and transcranial direct current stimulation (tDCS) on manual dexterity and sensorimotor neurophysiology". Thesis, Indiana University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3712436.
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Manual dexterity, the ability to manipulate objects with the hands, and the related position sense, or proprioception, are often impaired after stroke. Associative stimulation of motor points (MPAS) in hand muscles is known to modify motor cortex excitability and improve manual dexterity (McDonnell and Ridding, 2006).
However, it is not known whether the effect of this peripheral stimulation can be increased by central stimulation of sensorimotor cortex, in terms of function, proprioception, or cortical neurophysiology. Here we compare the functional and neurophysiological consequences of MPAS with and without transcranial direct current (tDCS) in healthy adults. MPAS was applied to two right hand muscles important for manual dexterity: APB and FDI. tDCS, a non-invasive brain stimulation technique, was simultaneously applied over left sensorimotor cortex. Both techniques stimulate motor as well as somatosensory pathways. Neurophysiological measures of motor cortex, including SICI (short intra-cortical inhibition), ICF (intracortical facilitation), and input/output (I/O) curve, were assessed with transcranial magnetic stimulation (TMS). Manual dexterity and proprioceptive acuity were also measured. 14 subjects completed 3 sessions of MPAS in combination with sham, anodal (excitatory) and cathodal (inhibitory) tDCS. 13 subjects completed 2 sessions of sham MPAS with sham or anodal tDCS. In combination with MPAS, anodal tDCS significantly increased the plateau of manual dexterity, increased cortical response to TMS, and tended to improve proprioceptive acuity compared to sham tDCS. The neural basis for the observed functional improvements may thus include somatosensory as well as motor cortex. Neither MPAS nor tDCS alone had any measurable effect. These results suggest that adding tDCS as a central intervention to complement peripheral MPAS may be a promising avenue of treatment for patients with impaired manual dexterity.
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Frick, Barbara. "Nachweis von Veränderungen nicht-fokaler Neuroplastizität bei depressiven Patienten mittels transkranieller Gleichstromstimulation (transcranial direct current stimulation, tDCS)". Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-184027.
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Jalali, Roya. "Investigating the neurobiological changes associated with cerebellar transcranial direct current stimulation (TDCS) using magnetic resonance imaging (MRI)". Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7661/.
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Anodal cerebellar transcranial direct current stimulation (tDCS) is known to enhance motor learning and it is suggested to hold promise as a therapeutic intervention. However, the neural mechanisms underpinning the effects of cerebellar tDCS are unknown. In addition, it is unclear whether this effect is robust across varying task parameters as if cerebellar tDCS is to be used clinically it must have a consistent effect across a relatively wide range of behaviours. Therefore, I performed four studies to address these questions. In the first three studies, I investigated the neural changes associated with cerebellar tDCS using magnetic resonance spectroscopy (MRS) and resting state functional magnetic resonance imaging (fMRI). My goal was to understand how cerebellar tDCS affected the metabolites within the cerebellum and functional connectivity between the cerebellum and distant brain areas. In addition, I wanted to understand if individual differences in how cerebellar tDCS influenced visuomotor adaptation could be explained by the effect tDCS had on neurobiology. Therefore, healthy participants underwent 3 sessions in which they received concurrent anodal cerebellar tDCS during visuomotor adaptation, MRS and resting state fMRI. I found that in 21% of participants cerebellar tDCS caused enhanced visuomotor adaptation, a decrease in GABA and increase in functional connectivity between the cerebellum and parietal cortex. This work suggests an ‘all-or-nothing’ type effect of cerebellar tDCS. In my final study, I examined the consistency of the cerebellar tDCS effect on visuomotor adaptation across a wide range of task parameters which were systematically varied. Each experiment examined whether cerebellar tDCS had a positive effect on adaptation when a unique feature of the task was altered. I found cerebellar tDCS to have an inconsistent effect on visuomotor adaptation. I conclude that such inconsistencies could be dependent on the amount of participants in each group that are receptive to cerebellar tDCS and suggest that at the very least it warrants substantially large sample size in cerebellar tDCS studies.
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Nalesnik, Natasza Dominika. "A study of improving cognitive deficits in schizophrenia using transcranial direct current stimulation with adjunct cognitive training". Thesis, King's College London (University of London), 2014. https://kclpure.kcl.ac.uk/portal/en/theses/a-study-of-improving-cognitive-deficits-in-schizophrenia-using-transcranial-direct-current-stimulation-with-adjunct-cognitive-training(7a2adfb0-0d89-4322-803e-8a3a9c13b5d0).html.
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Background: Schizophrenia exerts an enormous personal, societal and financial cost and is one of the most disabling of illnesses. Even with optimal treatment, individuals with schizophrenia are commonly left with cognitive impairments impacting on key functions such as memory, attention and learning. These functions are recognised to be primarily associated with the prefrontal cortex of the brain, and modulating activity in this brain region forms the basis of different interventional approaches. This thesis examined if combining two interventions, transcranial direct current stimulation (tDCS) and cognitive training (utilising both working memory and implicit learning tasks), would synergistically improve cognitive deficits in individuals with schizophrenia. Furthermore, neurophysiological effects tDCS during working memory were investigated. Methods: This is a single blind, sham-controlled pilot study of 49 individuals with schizophrenia, randomised into real or sham tDCS stimulation groups. They participated in 4 days of cognitive training spread over a period of 6 weeks and underwent functional magnetic resonance imaging (fMRI) at the 2 weeks visit. The CogState neuropsychological battery was used to assess generalisation of learning to non-trained task from baseline to week 2 visit. fMRI was used to assess the mechanism of improved cognitive performance during working memory assessment. Behavioural data analyses were conducted by specification of multilevel regression models and multiple regressions for training and generalisation effects, respectively. fMRI data analyses were conducted with general linear models. Results: tDCS differentially improved some cognitive deficits when applied as an adjunct to cognitive training. Namely, tDCS facilitated performance on a working memory task, and this improvement was maintained for up to four weeks. No effect of stimulation on implicit learning could be discerned. Generalisation of learning was observed on tasks similar to the domain of working memory, i.e. attention and vigilance and working memory indexed by the CogState neuropsychological battery. fMRI data demonstrated that tDCS reduced activation in temporo-parietal cortex in the real stimulation group during working memory assessment. Discussion: Given the current lack of effective therapies for these serious cognitive functioning deficits on both social functioning and self-reported quality of life in schizophrenia, tDCS offers an important and novel approach to modulating brain networks in order to ameliorate these cognitive deficits.
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Garcia, Michael Louis. "The efficacy of use of transcranial direct current stimulation in the treatment of neurological disease & defect". Thesis, Boston University, 2013. https://hdl.handle.net/2144/12106.
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Thesis (M.A.)--Boston UniversityNon-invasive brain stimulation techniques have recently become popular in the treatment of neurological diseases and disorders. Transcranial direct current stimulation [tDCS] is a method of brain stimulation whereby direct electrical current is passed through the intact scalp into the nervous tissue, producing lasting changes in neural activity of the stimulated areas. The polarity, or direction, of current flow in relation to the orientation of neural networks determines whether neuronal activity is enhanced or inhibited. The lasting increases or decreases in neuronal activity produced by tDCS have been used to shape cognitive function in various neurological diseases and disorders, including stroke, Parkinson’s disease, Alzheimer’s disease and depression. Currently, the mechanism of action for the effects caused by tDCS is not well understood. The goal of this thesis is to evaluate the efficacy of tDCS as a therapy for these brain disorders. The vast majority of these studies found strong and largely consistent evidence for the improvement of symptoms following tDCS for periods lasting up to several weeks when applied appropriately. While further refinement is needed to expand the effectiveness of tDCS treatment, the future looks promising.
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Byrne, Elizabeth Mary. "Working memory training and transcranial electrical brain stimulation". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277101.
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Working memory training improves performance on trained and untrained working memory tasks, but there is little consistent evidence that these gains benefit everyday tasks that rely on working memory. Evidence has shown that transcranial electrical stimulation (tES) may be an effective tool for enhancing cognitive training and promoting transfer. In the first study, participants completed Cogmed working memory training with either active or sham transcranial random noise stimulation (tRNS). Training was associated with substantial gains on the training activities and on transfer measures of working memory with common processing and storage demands to the training tasks. tRNS did not enhance gains on trained or untrained activities. The second study systematically investigated the boundary conditions to training transfer by testing whether gains following backward digit recall (BDR) training transferred within- and across-paradigm to untrained backward recall and n-back tasks with varying degrees of overlap with the training activity. A further aim was to test whether transcranial direct current stimulation (tDCS) enhanced training and transfer. Participants were allocated to one of three conditions: (i) BDR training with active tDCS, (ii) BDR training with sham tDCS, or (iii) visual search control training with sham tDCS. The results indicated that training transfer is constrained by paradigm, but not by stimuli domain or stimuli materials. There was no evidence that tDCS enhanced performance on the training or transfer tasks. The results of Study 1 and Study 2 provide no evidence that tES enhances the benefits of working memory training. The absence of transfer between backward recall training and n-back in Study 2 suggested the tasks might tap into distinct aspects of working memory. Consequently, the final study used a latent variable approach to explore the degree of overlap between different forms of backward recall and n-back tasks containing digits, letters, or spatial locations as stimuli. The best-fitting factor model included two distinct but related (r = .68) constructs corresponding to backward recall and n-back. Both categories of task were linked to a separate fluid reasoning construct, providing evidence that both are valid measures of higher-order complex cognition. Overall, the experiments in this thesis suggest that working memory tasks tap into separate processes and that training may be targeting and improving these distinct processes, explaining the absence of cross-paradigm transfer.
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Ashworth-Beaumont, Jim. "The effect of anodal transcranial direct current stimulation on spatial motor skill learning in healthy and spinal cord injured humans". Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/7376.
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Anodal transcranial direct current stimulation (tDCS) is an intervention which is thought to enhance motor learning in healthy and stroke-injured states, when applied adjunctively during skill learning. We set out to investigate whether anodal tDCS might enhance functional rehabilitation from incomplete tetraplegic SCI. To address current limitations in the measurement of task-dependent skill, a novel integrated skill training and measurement task, the Motor Skill Rehabilitation Task (MSRT) was designed and developed. Measures of performance from this task delivered the functional measure of spatial motor skill learning, Task Productivity Rate (TPR). TPR was analysed and validated as a univariate dependent outcome, which is of potential importance to the future development of clinical measures measuring goal-directed motor skills. The MSRT was included alongside conventional behavioural measures in a repeated-measures RCT pilot study, the first to investigate the effect of anodal tDCS on rehabilitation of motor skill from chronic spinal cord injury. Adjunctive application of anodal tDCS had a statistically significant benefit upon retention of skill in the incomplete spinal cord injured population, but only when the independent factor of sensory acuity was included in the analysis. Differences between the development of task-dependent skill and generic dexterity over time suggested that spatial skill development was subject to an interaction of short-term and lasting effects. A larger study in healthy persons further investigated these phenomena, also applying Transcranial Magnetic Stimulation (TMS)–evoked measurements to investigate intervention-dependent effects upon the excitability of projections between the primary motor cortex and muscles involved in the prehension task. The findings revealed that active tDCS did not enhance skill learning at 7 days beyond the training period, but did significantly alter the development of motor skill following a period of learning and subsequent skill consolidation which was associated with underlying perturbation of motor control strategy. Significant and divergent patterns of cortical plasticity were evoked in projections to muscles necessary for reaching and grasping. The main findings of this thesis do not support anodal tDCS as an effective adjunctive means of enhancing spatial motor skill in rehabilitation from incomplete tetraplegic SCI. If applied in patient populations, the clinical benefits of anodal tDCS may be contingent both on the nature of the sensorimotor deficit affecting upper limb function and the spatial demands of the behavioural task. The findings of this project serve to inform further research in relation to the effect of anodal tDCS on the brain and behavioural outcomes, the potential for efficacy in target patient groups and the sensitivity of outcome measures to spatial and temporal dimensions of practical motor skills.
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Amadi, Ugwechi. "Transcranial stimulation to enhance cortical plasticity in the healthy and stroke-affected motor system". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:bb27ac6f-a79d-459a-b5a0-e9a209ac7132.
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This thesis investigated transcranial direct current stimulation (tDCS) as applied to the motor system, and its ability to modulate underlying cortical processes and resultant motor behaviours. Functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) were employed to assess the extent to which tDCS induces quantifiable changes in neural structure and function in controls and stroke patients. Modifications in the connectivity of intrinsic functional networks following tDCS application were examined using resting state fMRI. Polarity-specific changes were found: cathodal (inhibitory) tDCS increased the strength of the default mode network and increased functional coupling between major nodes within the motor network. No significant effects were found following anodal (excitatory) tDCS. Although anodal tDCS elicited only subtle changes in resting activity, it is known to produce robust modifications of behaviour. Single and paired-pulse TMS were used to investigate the neurophysiological underpinnings of these changes. Consistent with the theory of homeostatic plasticity, anodal tDCS applied prior to task performance increased GABAA-mediated cortical inhibition and worsened behaviour. The specificity of these changes suggests a central role for the mechanism of surround inhibition. A longitudinal clinical trial in chronic stroke patients was conducted to determine the utility of tDCS as an adjunct in motor rehabilitation. Serial MRI scans revealed that, when combined with motor training, anodal tDCS increased functional activity and grey matter in primarily ipsilesional motor areas. These brain changes were correlated with behavioural improvements in the stroke-affected upper limb. The laterality of connectivity at baseline, as measured by resting state activity and corticospinal tract integrity, was predictive of response to the rehabilitation program, particularly in those stroke patients who received tDCS. Asymmetry favouring the contralesional hemisphere predicted greater behavioural gains. Such results underscore the importance of re-normalisation of structure and functional activity toward the lesioned hemisphere in stroke rehabilitation.
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Chapman, Ryan Michael. "The effect of transcranial direct current stimulation on the behavioral and neurophysiological performance of healthy subjects during reaching". Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2455.
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It is well established that cathodal transcranial direct current stimulation (tDCS) can decrease the excitability of the primary motor cortex (M1) in humans. Despite the cortical inhibition caused by cathodal tDCS, it remains unknown how this intervention alters unrestrained dynamic reaching movements qualitatively. Accordingly, we designed this study to examine how cathodal tDCS impacts unrestrained dynamic reaching as measured by qualitative kinematic features and electromyography (EMG). Ten young, healthy adult subjects were recruited to participate in a two day protocol involving repetitively reaching to two different targets (large and small) both before and following cathodal tDCS applied over the contralateral M1 during one session and before and following sham tDCS over the same brain region during another session. We discovered that cathodal tDCS was not able to alter the kinematic features of reaching in these subjects but did degrade the EMG performance, specifically by increasing the amount of co-contraction between muscle pairs. Because co-contraction is an indicator of relatively unskilled performance, these results seem to indicate that cathodal tDCS of M1 preferentially disrupts the learning or execution of highly coordinated muscle firing patterns during dynamic reaching. This work adds to the growing body of knowledge about how tDCS applied over M1 affects our movements. Moreover, it leads us to believe that tDCS can be utilized to assist in rehabilitation of patient populations who suffer from neurological dysfunctions but EMG assessments may need to be included in order to more effectively assess the patient performance.
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O'Connell, Neil Edward. "Non-invasive brain stimulation as a novel approach to the treatment of chronic non-specific low back pain". Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/7237.
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Chronic non-specific low back pain (CNSLBP) is a widespread but poorly understood condition that places a substantial burden on the sufferer, health services and the wider economy. Existing approaches to management do not demonstrate impressive levels of effectiveness. There is growing evidence that CNSLBP is associated with significant alterations in central nervous system (CNS) structure and function, suggesting a possible role for the brain in the aetiology of the condition, and presenting a case for novel therapies which aim to treat CNSLBP by affecting brain function. One such potential therapeutic approach is non-invasive brain stimulation (NIBS). Following a literature review discussing the epidemiology and management of low back pain, the evidence for altered CNS function and the potential role of brain stimulation in CNSLBP and chronic pain generally this thesis includes 3 original scientific studies: (i) A Cochrane systematic review of the effectiveness of NIBS techniques for the treatment of chronic pain; (ii) A randomised double-blind exploratory study of transcranial direct current stimulation of the motor cortex in the treatment of CNSLBP; (iii) Is blinding to the stimulation condition maintained in trials comparing 2mA tDCS with sham stimulation? A randomised cross-over study. Results: There is limited existing evidence that some forms of NIBS may have a beneficial effect on chronic pain, though caution is warranted. Exploratory data from study 2 is not suggestive that tDCS to the motor cortex is effective for treating CNSLBP. Commonly used sham controls in trials of tDCS do not ensure adequate blinding, and so introduce a potential source of bias to the existing evidence base. Conclusion: Further research is required to establish the value of NIBS as a treatment for chronic pain and CNSLBP. Future research in tDCS will need to develop and employ fully validated sham controls to ensure adequate blinding. NIBS cannot currently be recommended for the treatment of CNSLBP.
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Slepian, Peter Maxwell. "The Effect of Transcranial Direct Current Stimulation of the Prefrontal Cortex on Emotional Modulation of Pain and Nociception". Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1562019976550469.
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Mungee, Aditya [Verfasser]. "Modifying emotional memory in healthy human subjects through transcranial direct current stimulation of the prefrontal cortex / Aditya Mungee". Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2018. http://d-nb.info/1170876498/34.
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Tedesco, Triccas Lisa. "The effect of combining transcranial direct current stimulation with robot therapy for the impaired upper limb in stroke". Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366455/.
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Neurological rehabilitation technologies such as Robot Therapy (RT) and noninvasive brain stimulation (NIBS) can promote motor recovery after stroke. The novelty of this research was to explore the feasibility and the effect of the combination method of NIBS called transcranial Direct Current Stimulation (tDCS) with uni-lateral and three-dimensional RT for the impaired upper limb (UL) in people with sub-acute and chronic stroke. This thesis involved three studies: (a) systematic review with meta-analyses (b) a pilot double-blinded randomised controlled trial with a feasibility component and (c) a reliability study of the measurement of Motor Evoked Potential (MEP) response using Transcranial Magnetic Stimulation in healthy adults. The first study involved a review of seven papers exploring the combination of tDCS with rehabilitation programmes for the UL in stroke. For the second study, stroke participants underwent 18 x one hour sessions of RT (Armeo®) over eight weeks during which they received 20 minutes real tDCS or sham tDCS. Outcome measures were applied at baseline, post-intervention and at three-month follow-up. The qualitative component explored the views and experiences of the participants of RT and NIBS using semi-structured interviews. The third study involved age-matched healthy adults exploring intrarater and test-retest reliability of the TMS assessment. Results of the three studies were the following: Seven papers were reviewed and a small effect size was found favouring real tDCS and rehabilitation programmes for the UL in stroke. 22 participants (12 sub-acute and 10 chronic) completed the pilot RCT. Participants adhered well to the treatment. One participant dropped out of the trial due to painful sensations and skin problems. The sub-acute and chronic groups showed a clinically significant improvement of 15.5% and 8.8% respectively in UL impairments at post-intervention from baseline. There was no difference in the effects of sham and anodal tDCS on UL impairments. Participants found the treatment beneficial and gave suggestions how to improve future research. In summary, the TMS assessment showed excellent reliability for measurement of resting motor threshold but poor to moderate reliability for MEP amplitude. In conclusion, it was indicated that RT may be of benefit in sub-acute and chronic stroke however, adding tDCS may not result in an additive effect on UL impairments and dexterity. The present study provided a power calculation for a larger RCT to be carried out in the future.
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Bueno-Lopez, Ana [Verfasser]. "Effects of slow oscillatory transcranial direct current stimulation (so-tDCS) on sleep-dependent memory consolidation / Ana Bueno-Lopez". Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2020. http://d-nb.info/1223928128/34.
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Kan, Benjamin. "Effect of transcranial direct current stimulation (tDCS) on maximal voluntary isometric strength and endurance of the elbow flexors". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/375.
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The present study investigated the effects of transcranial direct current stimulation (tDCS) on maximal voluntary contraction strength (MVC) and the time to failure (TTF) of an isometric muscle endurance test of the elbow flexors. Prior to the main study, the test-retest reliability of MVC and TTF measures was investigated using 10 men (33.2 ± 9.4 y) for the measurements separated by 60 min (within-day) and one week (between-day). Coefficient of variation (CV), Intraclass correlation (ICC, R), a paired t-test and the Bland-Altman plots revealed that TTF at 30% MVC task was reliable, and was able to detect a possible effect of tDCS on TTF, if the magnitude of effect was greater than 11%. Based on the reliability study results, it was hypothesised that tDCS would increase TTF from the first test to the second test separated by 60 min, when a tDCS treatment was administered immediately before the second test. Fifteen men (27.7 ± 8.4 y) were tested for MVC and TTF at 30%-MVC before and immediately after tDCS or sham intervention (10 min) in three separate sessions. In two sessions direct current (2 mA) was delivered through saline-soaked sponge electrodes, with the anode placed on the scalp overlying the right motor cortical representation of the left arm and the cathode secured over the right shoulder. One session was a sham intervention (current delivery for the first 30s). The order of the intervention sessions was randomised and counterbalanced amongst the subjects and subjects who were blinded to intervention type. Changes in MVC strength and TTF from pre to post intervention were compared between the interventions by a two-way repeated measures ANOVA. No significant differences were evident for the two tDCS sessions. MVC strength (baseline: 66.0 ± 11.4 Nm) decreased by 5.9 ± 4.2 % (P
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Scheffler, Grit. "The potential of transcranial direct current stimulation to facilitate motor learning in children and young people with hemiplegic cerebral palsy". Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201982.
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Transcranial direct current stimulation (tDCS) is a non-invasive stimulation technique that modulates brain function by increasing or decreasing cortical excitability (Nitsche & Paulus, 2001). In chronic stroke patients tDCS has been shown to improve function of the affected arm when combined with rehabilitative motor training (e.g. Lindenberg et al., 2010) and thus has the potential to accelerate motor learning. Its potential as a treatment for upper limb function in hemiplegic cerebral palsy (CP) had not been explored, which was the principle aim of this doctorate. After literature reviews on CP and tDCS (Chapter 1) feasibility work in healthy subjects was conducted to develop and validate the experimental procedures (Chapters 2 to 5). Chapter 2 examined whether tDCS improved motor performance of the non-preferred hand in healthy right-handed adults. The sophisticated kinematic outcome measures detected changes in performance due to learning, but no effect of tDCS was found. In Chapter 3, a novel motor learning task was developed and validated in healthy children and adolescents. This task was added to the study protocol and using a revised study design tDCS was found again to have no benefit on either motor performance or motor learning in healthy adults (Chapter 4). Tolerability, perception and acceptance of electrical stimulation were explored in Chapters 5 and 6, with the former showing that tDCS was well tolerated by healthy adults. Using a qualitative research methodology Chapter 6 established that teenagers with CP and their parents had concerns over the application of electricity on the scalp and how little is currently known of tDCS effects in CP. In Chapter 7, tDCS was applied to a teenager with hemiplegic CP with no clear beneficial effects. Finally, the contribution of this doctoral work with regard to the use of tDCS for the rehabilitation of motor function in CP is discussed in Chapter 8.
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Gidyk, Darryl C. "Modulation of compensation and recovery in a rat model of motor cortex stroke : implications of transcranial direct current stimulation". Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience, c2011, 2011. http://hdl.handle.net/10133/3236.
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The present thesis examines the effects of transcranial direct current stimulation and
forelimb rehabilitation on motor recovery after stroke in rats. Post-stroke motor outcomes were
quantified using an innovative battery of behavioural tests and high resolution, in vivo
electrophysiology was employed to examine coherence of neural activity between hemispheres.
It was shown that rats that received brain stimulation concurrently with forelimb rehabilitation
displayed functional recovery, whereas rats that received rehabilitation alone partially regained
motor function, but the improvements were not due to restitution of original movement
patterns. Results from electrophysiological recordings showed that rats that received brain
stimulation and rehabilitation regained pre-stroke levels of interhemispheric coherence, but rats
that received rehabilitation alone did not. The present thesis suggests that transcranial direct
current stimulation may be a viable adjunct therapy to increase the efficacy of physical
rehabilitation with regard to post-stroke motor outcomes. Interhemishperic coherence between
homotopic neuronal populations may represent a biomarker of genuine motor recovery after
stroke.ix, 75 leaves : col. ill. ; 29 cm
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MELO, Lorena Figueiredo de. "Efeitos das estimulações cerebelares não invasivas no aprendizado motor e equilíbrio de indivíduos saudáveis". Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18609.
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CAPES
A presente dissertação apresenta dois estudos com o intuito de avançar no conhecimento das repercussões das estimulações cerebelares no aprendizado motor e equilíbrio de indivíduos saudáveis. O estudo 1 se propôs a investigar os efeitos polaridade-dependentes da estimulação transcraniana por corrente contínua cerebelar (ETCCc) no equilíbrio de indivíduos saudáveis. O estudo 2, verificou os efeitos da ETCCc e da estimulação magnética transcraniana repetitiva cerebelar (EMTr-c) no aprendizado motor de saudáveis. No primeiro estudo, 15 voluntárias saudáveis e destras foram submetidas a três sessões de ETCCc (anódica, catódica e sham) no hemisfério cerebelar direito em ordem contrabalanceada. Em cada sessão, o equilíbrio estático e dinâmico foi avaliado pela ferramenta Biodex Balance System antes e após cada estimulação, através dos testes Athlete Single Leg Stability e Limits of Stability. Os resultados apontaram para uma piora no equilíbrio estático após a ETCCc catódica, avaliado pelo Athlete Single Leg Stability do membro inferior esquerdo em comparação com os valores basais (p=0,01) e com a ETCCc sham (p=0,04). Dessa forma, é possível afirmar que a ETCCc catódica foi capaz de interferir no equilíbrio estático de indivíduos saudáveis. O segundo estudo foi realizado com 18 voluntários destros, submetidos a seis sessões em ordem contrabalanceada. As sessões consistiram na aplicação dos seguintes protocolos sobre o hemisfério cerebelar esquerdo: (i) ETCCc anódica; (ii) ETCCc catódica; (iii) ETCCc sham; (iv) EMTr-c 10 Hz; (v) EMTr-c 1 Hz e (vi) EMTr-c sham. O aprendizado motor online (durante a estimulação) e offline (após a estimulação) foi avaliado através do teste de reação serial (aquisição e evocação) e teste de escrita (duração total e precisão do movimento), respectivamente. Foi observado que para o aprendizado motor online, as EMTr-c 1 Hz (p=0,018) e 10 Hz (p=0,010) e ETCCc catódica (p=0,001) foram capazes de alterar a aquisição, enquanto que todas as estimulações (p<0,05), com exceção da anódica (p=0,126), foram capazes de interferir na evocação da sequência aprendida. Em relação ao aprendizado motor offline, houve redução da duração total da escrita para todas as condições de estimulação (p<0,05). Para a precisão do movimento, houve melhora apenas para as condições: ETCCc anódica (p=0,003), EMTr-c 1 Hz (p=0,006) e 10 Hz (p=0,014). Portanto, a EMTr-c parece melhorar o aprendizado motor independente da frequência de estimulação e do momento da execução da tarefa (online ou offline). Por outro lado, o efeito da ETCCc mostra-se polaridade-dependente, visto que apenas a ETCCc anódica melhorou o aprendizado offline e a catódica apresentou melhores resultados para o aprendizado online.
This dissertation comprises two studies in order to understand the effects of cerebellar stimulations on motor learning and postural balance of healthy individuals. The first experiment (study 1) aimed to investigate the polarity-dependent effects of cerebellar transcranial direct current stimulation (ctDCS) on postural balance in healthy volunteers. The second experiment (study 2) aimed to evaluate ctDCS and cerebellar repetitive transcranial magnetic stimulation (c-rTMS) effects on motor learning in healthy individuals. In the first study, 15 righ-handed healthy volunteers were submitted to three ctDCS sessions (anodal, cathodal and sham) in a counterbalanced order. In each session, static and dynamic balance were evaluated by the Biodex Balance System before and after each stimulation through the Athlete Single Leg Stability and Limits of Stability tests. It was found a worsening static balance after cathodal ctDCS, assessed by Left Athlete Single Leg Stability test when compared to baseline (p=0.01) and sham stimulation (p=0.04). Thus, it is reasonable to assume that cathodal ctDCS was able to interfere on static balance in healthy individuals. The second experiment (study 2) was performed with 18 righthanded volunteers submitted to six session in a counterbalanced order. In each session, the left cerebellar hemisphere was modulated by the following protocols: (i) Anodal ctDCS; (ii) Cathodal ctDCS; (iii) Sham ctDCS; (iv) 10 Hz c-rTMS; (v) 1 Hz crTMS and (vi) Sham c-rTMS. Motor learning was evaluated during (online) or after (offline) stimulation protocols by the serial reaction test (acquisition and evoking phases) and handwriting test (duration and movement precision), respectively. It was observed that for online motor learning, 1 Hz c-rTMS (p=0.018) and 10 Hz (p=0.010) and also cathodal ctDCS (p=0.001), were able to interfere on acquisition phase. All stimulations (p<0.05) except for anodal ctDCS (p=0.126) were able to interfere when the learned sequence was evoked. Regarding offline motor learning, results revealed a reduction of duration for all stimulation conditions. However, for movement precision it was found an improvement for anodal ctDCS (p=0.003), 1 Hz c-rTMS (p=0.006) and 10 Hz c-rTMS (p=0.014). Therefore, c-rTMS seems to improve motor learning independently of stimulation frequency and time (online or offline). On the other hand, ctDCS effects were polarity-dependent since anodal ctDCS was capable to modulate offline learning, while cathodal ctDCS showed better results for online motor learning performance.