Dissertations / Theses on the topic 'Brainstem'
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1
Toward, Marie Ann. "Understanding brainstem microvessels in hypertension." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492621.
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Hypertension is associated with autonomic nervous system dysfunction. Elevated sympathetic outflow and alterations in the baroreceptor reflex sensitivity may play an important role in the initiation and maintenance of high blood pressure. Previous work from this laboratory has demonstrated that endothelial derived genes are differentially expressed in key brainstem nuclei in hypertensive rats. In addition, angiotensin II acting at the nucleus tractus solitarii has been shown to attenuate the baroreflex through a vascular-neuronal signalling mechanism involving the release of nitric oxide. This evidence has led to the hypothesis that alterations in brainstem microvascular gene expression are causative to hypertension in animals and man.
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Tijssen, Hendrikus N. "Novel methods for brainstem FMRI." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:ed8e4c4f-5152-44e4-936f-ccf6092d904b.
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The brainstem plays a crucial role in a great number of vital functions such as respiratory regulation, visual reflexes, and the perception of pain. The small size and close proximity of the nuclei requires high-resolution functional magnetic resonance imaging (FMRI). However, brainstem FMRI using conventional gradient-echo echo-planar imaging (GRE-EPI) techniques is challenging due to the increased signal dropout and geometric distortions in the brainstem. The primary aim of the work presented in this thesis was to investigate alternative methods for brainstem FMRI in order to overcome some of the challenges associated with single-shot GRE-EPI techniques. Towards this goal 3D segmented sequences were explored, which have the advantage that the size of the geometric distortions is not proportional to the resolution at which is scanned. In particular, two sequences were investigated: balanced steady-state free-precession (bSSFP) and spoiled gradient echo (SPGR). First, a set of experiments was conducted, in which each experiment aimed to isolate a limited range of sequence properties in order to characterize and assess the potential of the candidate sequences. It was found that bSSFP has better noise characteristics compared to GRE-EPI when applied with a 2D acquisition, but when 3D readouts were used the signal instabilities increased dramatically. Based on these findings, experiments that investigate the influence of multishot acquisitions on signal instabilities caused by physiological noise were performed. The signal instabilities were found to mainly originate from regions of CSF and blood and were highly correlated to the cardiac cycle. Several correction methods were explored and one method was identified to be implemented in vivo. A novel method that allows real-time cardiac synchronization of the k-space acquisition was developed. The developed methods used a custom parallel imaging reconstruction to allow for acquisition with a fixed volume frame rate, which is desirable for FMRI purposes. The method was found to reduce the signal instabilities in 3D SPGR and bSSFP significantly. A comprehensive assessment of two currently available retrospective correction techniques was conducted and their practicalities were compared. Recommendations are made to improve the robustness of the investigated correction methods. A novel optimization method was implemented, which was developed to determine the optimal regressor set for retrospective corrections. The method can be applied to image based as well as k-space based methods.
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Motts, Susan D. "Cholinergic circuitry in auditory brainstem." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1290120470.
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Chen, Zhixiong. "Brainstem Mechanisms Underlying Ingestion and Rejection." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1041523002.
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Marciszewski, Kasia. "Does Migraine Stem From the Brainstem?" Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21241.
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The exact neural mechanisms underlying migraine have been strongly debated for decades. It is well accepted the trigeminovascular system plays a role in migraine, however the precise neurobiological mechanism by which migraine attacks are initiated is presently unknown. Existing literature has demonstrated that even between attacks, the migraine brain differs from that of controls and has led to the current theory of migraine as a “cycling” brain disorder. This suggests that the changes observed in migraine are not fixed, but rather dynamic in nature, and that function, sensitivity and even anatomy of the brainstem may fluctuate throughout the migraine cycle. However, while the brainstem has been heavily implicated in migraine pathogenesis, it has been poorly studied by neural imaging investigations. Likewise, the spontaneous and episodic nature of migraines has made it difficult to study the migraine cycle in its entirety. As such, this thesis aimed to explore brainstem anatomy, functional connectivity, and sensitivity to noxious stimuli, in migraineurs across the entire migraine cycle. The investigations performed in this thesis, consistently revealed key brainstem pain-processing regions, such as the spinal trigeminal nucleus and periaqueductal grey matter, as having altered anatomy, functional connectivity, and sensitivity across the migraine cycle. Most intriguingly, these changes were most dramatically altered in the 24 hours immediately prior to migraine onset. This suggests the observed changes in these brainstem regions may underlie the processes causing migraine initiation. Furthermore, these changes were dynamic in nature, supporting the notion of a “cycling” migraine brain. This opens new avenues for migraine research which will hopefully lead to better prophylactic treatments, capable of controlling these fluctuations that underlie the disorder.
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Al-Rawas, Sami Farah Salim. "Brainstem cardio-respriratory functions in Rett syndrome." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405417.
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Mather, Nicole K. "The development of the major brainstem decussations." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365330.
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Khorsandi, Mehdi. "Brainstem Gangliosides in Suddden Infant Death Syndrome." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc504326/.
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Recent studies have shown that the Sudden Infant Death Syndrome (SIDS) is related to abnormal control of respiration (Ischemic degeneration of the brainstem may play an important role in altered respiratory control leading to death). In our studies we have examined brainstem ganglioside compositions in samples derived from SIDS victims and appropriate controls. Gangliosides are acidic glycosphingolipids that contain sialic acid. The high concentration of gangliosides in the central nervous system (CNS) implies that these lipids play an important role in CNS function. Some studies have indicated that gangliosides may function as receptor site determinants or modifiers, and in neural transmission. In our studies we used the Tettamanti, et al methodology to extract gangliosides, and High Performance Thin Layer Chromatography (HPTLC) and laser densitometry techniques for ganglioside analysis. The results of these analyses are being employed to establish lipid profile patterns to determine if there are significant variations in these lipid patterns between SIDS and control groups.
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Carey, Marc Brandon. "Brainstem auditory evoked potentials in anuran amphibians." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4267.
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In this study, I looked at the effects of sound level, temperature and dehydration/hypernatremia on the brainstem auditory evoked potential (BAEP) of four species of anuran amphibians (Rana pipiens, Rana catesbeiana, Bufo americanus and Bufo terrestris). The BAEP was used because it allowed me to monitor both the peripheral and central aspects of auditory nervous function simultaneously and over a long period of time.
10
Felder, Shannon N. "Survey of Auditory Brainstem Response Referral Criteria." Scholar Commons, 2000. https://scholarcommons.usf.edu/etd/1545.
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The primary objective of the project was to survey recognized “experts” in the field of neurodiagnostic audiology and practicing audiologists regarding their referral criteria and referral patterns for administering an auditory brainstem response test (ABR). For purposes of this study, “expert” was defined as any recognized audiologist with at least two or more publications and/or seminars in the field of auditory evoked potentials. Responses of experts and practicing audiologists were compared and contrasted to establish: a) if there was a standard referral pattern; b) what, if any, were the apparent critical components of referral patterns; and, c) whether or not current practice reflected the utilization of such critical components.
The survey was designed to establish whether the respondent was practicing, in what type of practice setting, and how often ABRs were performed. Specificity and sensitivity of ABR outcomes was also requested. The survey was administered verbally, via telephone, to 3 experts and was sent via e-mail to 178 randomly selected audiologists in the United States. Of the latter 53 returned, 38 reported conducting ABRs. Thus, data analysis was reported on 38 respondents.
The survey results did not reveal a consistent standard referral pattern. Critical components for referral were hypothesized based on the “expert” majority response. These include ABR referral based on the presence of: (1) asymmetric sensorineural hearing loss; (2) unilateral tinnitus; (3) positive reflex decay; and, (4) word recognition rollover. The majority of “non-expert” practitioners surveyed reported that these symptoms warranted consideration for referral, thus reflecting utilization of apparent critical components.
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Brand, Antje. "Precise Temporal Processing in the Gerbil Auditory Brainstem." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-8842.
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Makeham, John Murray. "Functional neuroanatomy of tachykinins in brainstem autonomic regulation." University of Sydney, 1997. http://hdl.handle.net/2123/1960.
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Doctor of Philosophy (PhD)Little is known about the role that tachykinins, such as substance P and its receptor, the neurokinin-1 receptor, play in the generation of sympathetic nerve activity and the integration within the ventrolateral medulla (VLM) of many vital autonomic reflexes such as the baroreflex, chemoreflex, somato-sympathetic reflex, and the regulation of cerebral blood flow. The studies described in this thesis investigate these autonomic functions and the role of tachykinins through physiological (response to hypercapnoea, chapter 3), anatomical (neurokinin-1 receptor immunohistochemistry, chapter 4) and microinjection (neurokinin-1 receptor activation and blockade, chapters 5 and 6) experiments. In the first series of experiments (chapter 3) the effects of chemoreceptor activation with hyperoxic hypercapnoea (5%, 10% or 15% CO2 in O2) on splanchnic sympathetic nerve activity and sympathetic reflexes such as the baroreflex and somato-sympathetic reflex were examined in anaesthetized rats. Hypercapnoea resulted in sympatho-excitation in all groups and a small increase in arterial blood pressure in the 10 % CO2 group. Phrenic nerve amplitude and phrenic frequency were also increased, with the frequency adapting back to baseline during the CO2 exposure. Hypercapnoea selectively attenuated (5% CO2) or abolished (10% and 15% CO2) the somato-sympathetic reflex while leaving the baroreflex unaffected. This selective inhibition of the somato-sympathetic reflex while leaving the baroreflex unaffected was also seen following neurokinin-1 receptor activation in the rostral ventrolateral medulla (RVLM) (see below). Microinjection of substance P analogues into the RVLM results in a pressor response, however the anatomical basis for this response is unknown. In the second series of experiments (chapter 4), the distribution of the neurokinin-1 receptor in the RVLM was investigated in relation to catecholaminergic (putative sympatho-excitatory “C1”) and bulbospinal neurons. The neurokinin-1 receptor was demonstrated on a small percentage (5.3%) of C1 neurons, and a small percentage (4.7%) of RVLM C1 neurons also receive close appositions from neurokinin-1 receptor immunoreactive terminals. This provides a mechanism for the pressor response seen with RVLM microinjection of substance P analogues. Neurokinin-1 receptor immunoreactivity was also seen a region overlapping the preBötzinger complex (the putative respiratory rhythm generation region), however at this level a large percentage of these neurons are bulbospinal, contradicting previous work suggesting that the neurokinin-1 receptor is an exclusive anatomical marker for the propriobulbar rhythm generating neurons of the preBötzinger complex. The third series of experiments (chapter 5) investigated the effects of neurokinin-1 receptor activation and blockade in the RVLM on splanchnic sympathetic nerve activity, arterial blood pressure, and autonomic reflexes such as the baroreflex, somato-sympathetic reflex, and sympathetic chemoreflex. Activation of RVLM neurokinin-1 receptors resulted in sympatho-excitation, a pressor response, and abolition of phrenic nerve activity, all of which were blocked by RVLM pre-treatment with a neurokinin-1 receptor antagonist. As seen with hypercapnoea, RVLM neurokinin-1 receptor activation significantly attenuated the somato-sympathetic reflex but did not affect the sympathetic baroreflex. Further, blockade of RVLM neurokinin-1 receptors significantly attenuated the sympathetic chemoreflex, suggesting a role for RVLM substance P release in this pathway. The fourth series of experiments (chapter 6) investigated the role of neurokinin-1 receptors in the RVLM, caudal ventrolateral medulla (CVLM), and nucleus tractus solitarius (NTS) on regional cerebral blood flow (rCBF) and tail blood flow (TBF). Activation of RVLM neurokinin-1 receptors increased rCBF associated with a decrease in cerebral vascular resistance (CVR). Activation of CVLM neurokinin-1 receptors decreased rCBF, however no change in CVR was seen. In the NTS, activation of neurokinin-1 receptors resulted in a biphasic response in both arterial blood pressure and rCBF, but no significant change in CVR. These findings suggest that in the RVLM substance P and the neurokinin-1 receptor play a role in the regulation of cerebral blood flow, and that changes in rCBF evoked in the CVLM and NTS are most likely secondary to changes in arterial blood pressure. Substance P and neurokinin-1 receptors in the RVLM, CVLM and NTS do not appear to play a role in the brainstem regulation of tail blood flow. In the final chapter (chapter 7), a model is proposed for the role of tachykinins in the brainstem integration of the sympathetic baroreflex, sympathetic chemoreflex, cerebral vascular tone, and the sympatho-excitation seen following hypercapnoea. A further model for the somato-sympathetic reflex is proposed, providing a mechanism for the selective inhibition of this reflex seen with hypercapnoea (chapter 3) and RVLM neurokinin-1 receptor activation (chapter 5). In summary, the ventral medulla is essential for the generation of basal sympathetic tone and the integration of many vital autonomic reflexes such as the baroreflex, chemoreflex, somato-sympathetic reflex, and the regulation of cerebral blood flow. The tachykinin substance P, and its receptor, the neurokinin-1 receptor, have a role to play in many of these vital autonomic functions. This role is predominantly neuromodulatory.
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Peng, Qunming. "Brainstem a neocortical simulator interface for robotic studies /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1438917.
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Zhang, Rui. "Classification of auditory brainstem response using minimal data." Thesis, University of Ulster, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436792.
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Stephenson, Mark Ray. "Human auditory brainstem response to dichotic click stimuli /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267546983858.
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Makeham, John M. "Functional neuroanatomy of tachykinins in brainstem autonomic regulation." Connect to full text, 2006. http://hdl.handle.net/2123/1960.
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Thesis (Ph. D.)--University of Sydney, 2007.Title from title screen (viewed 1 November 2007). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Physiology, Faculty of Medicine. Degree awarded 2007 ; thesis submitted 2006. Bibliography: leaves 239-284. Also issued in print.
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Bee, Lucy Ann. "Brainstem control of spinal sensory processing in the rat." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444107/.
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Brainstem structures engage descending facilitatory and inhibitory neurones to potentiate or suppress the onward passage of sensory inputs from spinal loci to the brain. The final output for this bidirectional control is the rostral ventromedial medulla (RVM), which shapes sensory processing via relays between the spinal cord and brain, ultimately influencing pain perception via On and Off cells. I aimed to determine the predominant nature of this supraspinal control in the normal anaesthetised state and to see how descending influences may change with pathophysiology. By injecting a local anaesthetic into the RVM of normal rats and measuring the evoked responses of dorsal horn neurones to various stimuli, I demonstrated a dominant facilitation of spinal neuronal responses to high-threshold stimuli. Following nerve injury, reductions in spinal cord activity induced by intra-RVM lignocaine further encompassed responses to low-threshold stimuli, and the proportion of neurones influenced in this manner increased. The increase in descending facilitatory influences in the neuropathic state is suggestive of nerve injury induced plasticity. I additionally employed targeted ablation techniques using the neurotoxin saporin to show that mu-opioid receptor expressing cells in the RVM underlie spinal facilitation. This pathway involves spinal 5HT3 receptors, since typical responses to spinal ondansetron, a 5HT3 receptor antagonist, require the integrity of RVM MOR cells. Importantly, I showed that these neurones are critical for maintaining behavioural hypersensitivities following nerve injury, and are necessary for the full inhibitory efficacy of spinal pregabalin in the neuropathic state. These results define a pathway that could be pivotal for linking the sensory and affective components of pain. Understanding this connection, and how one component influences the other, may help explain the variable valence of suffering that is experienced by patients in response to the same nervous system injuries, and explain differences in treatment outcomes in an otherwise consistent population.
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Webster, Deirdre M. S. "Avian brainstem and descending spinal projections associated with locomotion." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29316.
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Electrical microstimulation studies in the decerebrate bird have previously identified brainstem regions that play a role in the initiation of locomotion. This thesis was designed to identify the neuroanatomical connections of these physiologically defined locomotor regions. The experiments were conducted on the Pekin duck, Anas platyrhynchos; Canada goose, Branta canadensis; Sulphur-crested cockatoo, Cacatua galerita; and Eastern rosella, Platycercus eximius.
A variety of retrograde tracer chemicals (e.g. wheat germ agglutinin-horseradish peroxidase and fluorescent tracer True Blue) were injected into either the cervical or lumbar spinal cord alone or in conjunction with a more rostral subtotal lesion of the spinal cord to determine (1) the origins of spinal projections to the spinal cord, and (2) the funicular organization of these pathways at the lumbar level. The distribution of retrogradely labelled neurones was similar in all avian species examined. There were no direct telencephalic projections to the spinal cord. Descending brainstem-spinal spinal pathways from previously identified "locomotor sites" in the ventromedial medulla (nucleus reticularis medullaris centralis and nucleus reticularis, gigantocellularis) projected to the lumbar level via the ventrolateral funiculus, whereas dorsolateral "locomotor sites" (nucleus reticularis parvocellularis, nucleus and descending tract of the trigeminal nerve) only projected as far as the cervical spinal cord. The afferent projections to these identified brainstem locomotor regions were determined by discrete injections of retrograde fluorescent tracers into the ventromedial or dorsolateral pontomedullary locomotor sites. Afferent input originated principally from the pontomedullary reticular formation and the mesencephalon.
The similarity of avian spinal and brainstem connections to those previously described for mammals indicates considerable conservation of the origins and organization of descending locomotor pathways between mammalian and non-mammalian species.Science, Faculty of
Zoology, Department of
Graduate
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Torgerson, Cory S. "Respiratory chemoreception and rhythm generation in the tadpole brainstem." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34705.pdf.
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Straaten, Henrica Lucia Maria van. "Automated auditory brainstem response hearing screening in NICU graduates." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/57978.
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Anwar, Fallatah. "Enhancement of Speech Auditory Brainstem Responses Using Adaptive Filters." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23272.
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Several adaptive filters were investigated to enhance speech auditory brainstem responses (speech ABR). The objective was to shorten the long recording time currently needed by the standard coherent averaging method to obtain acceptable performance, which has limited the clinical adoption of speech ABR. Five algorithms were implemented: Wiener Filter (WF), Steepest Descent (SD), Adaptive Noise Cancellation (ANC) based on Least-Mean-Square error (LMS) and normalized LMS error (nLMS), and a multi-adaptive cascade combination of SD and LMS. The performance of the adaptive filters was assessed on speech ABR data gathered from several subjects and compared with coherent averaging using the overall Signal-to-Noise Ratio (SNR), the local SNR around the fundamental frequency and the first formant, and Mean-Square-Error (MSE) in the time and frequency domains. The adaptive filters could reduce the time needed, by at least one order of magnitude, for obtaining comparable signal quality as that obtained with coherent averaging.
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Jeggo, Ross David. "5-HT modulation [receptors] of brainstem cardio-respiratory neurones." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409105.
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Schafe, Glenn E. "Neuroanatomical substrates of conditioned taste aversion : forebrain-brainstem interactions /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9068.
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Alwan, Abdulrahman. "Implementation of Wavelet-Kalman Filtering Technique for Auditory Brainstem Response." Thesis, Linköpings universitet, Informationskodning, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-85116.
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Auditory brainstem response (ABR) evaluation has been one of the most reliable methods for evaluating hearing loss. Clinically available methods for ABR tests require averaging for a large number of sweeps (~1000-2000) in order to obtain a meaningful ABR signal, which is time consuming. This study proposes a faster new method for ABR filtering based on wavelet-Kalman filter that is able to produce a meaningful ABR signal with less than 500 sweeps. The method is validated against ABR data acquired from 7 normal hearing subjects with different stimulus intensity levels, the lowest being 30 dB NHL. The proposed method was able to filter and produce a readable ABR signal using 400 sweeps; other ABR signal criteria were also presented to validate the performance of the proposed method.
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Samimi, Hamed. "Automatic Recognition of Speech-Evoked Brainstem Responses to English Vowels." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32975.
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The objective of this study is to investigate automatic recognition of speech-evoked
auditory brainstem responses (speech-evoked ABR) to the five English vowels (/a/, /ae/, /ao (ɔ)/, /i/ and /u/). We used different automatic speech recognition methods to
discriminate between the responses to the vowels. The best recognition result was
obtained by applying principal component analysis (PCA) on the amplitudes of the first ten harmonic components of the envelope following response (based on spectral components at fundamental frequency and its harmonics) and of the frequency following response (based on spectral components in first formant region) and combining these two feature sets. With this combined feature set used as input to an artificial neural network, a recognition accuracy of 83.8% was achieved. This study could be extended to more complex stimuli to improve assessment of the auditory system for speech communication in hearing impaired individuals, and potentially help in the objective fitting of hearing aids.
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Kumar, Natasha N. "Studies on Cholinergic and Enkephalinergic Systems in Brainstem Cardiorespiratory Control." University of Sydney, 2007. http://hdl.handle.net/2123/2014.
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Doctor of Philosophy(PhD)This thesis addresses the neurochemistry and function of specific nuclei in the autonomic nervous system that are crucial mediators of cardiorespiratory regulation. The primary aim is to build on previous knowledge about muscarinic cholinergic mechanisms within cardiorespiratory nuclei located in the ventrolateral medulla oblongata. The general focus is characterisation of gene expression patterns of specific muscarinic receptor subtypes in central nuclei involved in blood pressure control and respiratory control in normal rats. The findings were subsequently extended by characterisation of muscarinic receptor gene expression patterns in 1) a rat model of abnormal blood pressure control (hypertension) (Chapter 3) 2) a rat model of cholinergic sensitivity (Chapter 5) 3) the rat ventral respiratory group (Chapter 6) The results of a series of related investigations that ensued from the initial aims more finely characterise the neurocircuitry of the ventrolateral medulla, from a specifically cholinoceptive approach. All five muscarinic receptor subtypes are globally expressed in the ventrolateral medulla but only the M2R mRNA was significantly elevated in the VLM of hypertensive animals compared to their normotensive controls and in the VLM of animals displaying cholinergic hypersensitivity compared to their resistant controls. Surprisingly, M2R mRNA is absent in catecholaminergic cell groups but abundant in certain respiratory nuclei. Two smaller projects involving gene expression of other neurotransmitter / neuromodulators expressed in cardiorespiratory nuclei were also completed during my candidature. Firstly, the neurochemical characterisation of enkephalinergic neurons in the RVLM, and their relationship with bulbospinal, catecholaminergic neurons in hypertensive compared to normotensive animals was carried out (Chapter 4). A substantial proportion of sympathoexcitatory neurons located in the RVLM were enkephalinergic in nature. However, there was no significant difference in preproenkephalin expression in the RVLM in hypertensive compared to normotensive animals. Secondly, the identification and distribution of components of the renin-angiotensin aldosterone system (RAAS) within the brainstem, and differences in gene expression levels between hypertensive and normotensive animals was also investigated. The RAAS data was not included in this thesis, since the topic digresses substantially from other chapters and since it is published (Kumar et al., 2006). The mRNA expression aldosterone synthase, mineralocorticoid receptor (MR1), 12-lipoxygenase (12-LO), serum- and glucocorticoid- inducible kinase and K-ras) were found to be present at all rostrocaudal levels of the ventrolateral medulla. Expression of MR1 mRNA was lower in the RVLM of SHR compared with WKY rats and 12-LO mRNA levels were lower in the CVLM in SHR compared with WKY rats. Otherwise, there was no difference in gene expression level, or the method of detection was not sensitive enough to detect differences in low copy transcripts between hypertensive and normotensive animals.
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Machaalani, Rita. "Brainstem pathology in SIDS and in a comparative piglet model." University of Sydney. Medicine, 2003. http://hdl.handle.net/2123/605.
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This thesis tests the hypothesis that increased neuronal cell death in SIDS infants is related to the ability of risk factors, such as prone sleeping, to expose infants to intermittent hypercapnic hypoxia (IHH). Based on the hypothesis that the NMDA system is linked to neuronal death, by way of excitotoxicity, correlations were also sought between cell death and changes in NMDA receptor (NR1) expression in brainstem nuclei controlling cardiorespiratory function. The first aim of this study was to verify that increased neuronal cell death occurs in SIDS infants. To verify a piglet model of SIDS risk factors, brainstem changes were examined in piglets exposed to IHH, and comparisons were made to changes seen in SIDS infants. The NMDA receptor was characterised in controls for both the human infant and the piglet groups. Comparisons of neuronal changes were made with SIDS infants, and piglets exposed to IHH. Non-radioactive in-situ hybridisation and immunohistochemistry were performed on formalin fixed and paraffin embedded brainstem tissue to identify markers of cell death (caspase-3, active caspase-3, and TUNEL), and to examine NR1 mRNA and protein expressions. Staining was quantified using computerised image analysis software. Eight nuclei from the brainstem medulla (caudal in piglets, and mid in infants), and two nuclei from the rostral pons (infants) were studied. The first dataset included human infants aged 1-6 months with a diagnosis of SIDS (n=15) or non-SIDS (n=10). The second dataset comprised developing piglets aged 13-14 days, with controls (n=6), against those exposed to IHH for 2 (n=6) or 4 (n=5) days. Increased neuronal cell death was not verified in the SIDS infants, but abnormalities in NR1 expression were present in selected nuclei of the medulla. Piglets exposed to IHH had increased neuronal cell death and changes in NR1 in selected nuclei of the medulla. There was also a positive correlation between increased cell death and high NR1 levels. Preliminary data showed that SIDS infants who usually slept prone had some differences in NR1 compared to those who did not usually sleep prone. From these findings, it was concluded that IHH may underlie the abnormalities in NMDA receptor expression that are present in the brainstem of SIDS infants. Although IHH can induce an increase in neuronal cell death, its significance in the aetiology of SIDS is not known. In piglets, IHH induced cell death correlated with high NMDA expression in some brainstem nuclei, supporting the hypothesis that excitotoxicity may be involved in the mechanism for cell death. Moreover, this thesis presents for the first time, �preliminary pathological proof� of an association between prone sleeping and abnormal NMDA receptor expression in SIDS infants.
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Wood, Lori Laraine. "Multiple brainstem auditory steady-state response interactions for different stimuli." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/15532.
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Auditory steady-state responses (ASSRs) have been shown to be accurate in predicting thresholds of individuals with hearing loss. Although new stimuli are being proposed and clinically implemented, there are no data to indicate whether response interactions would be adversely affected by their use. This study investigated the effects of three different stimuli (AM, AM/FM and AM²) at two different intensities (60 dB HL and 80 dB HL) on response amplitudes and interactions in normal-hearing adults. Stimuli were generated by the Rotman MultiMASTER research system and presented via air conduction through EAR-3A insert earphones. Carrier frequencies of 0.5, 1, 2, and 4 kHz were 80-Hz modulated in three conditions: individually (monotic single; MS), simultaneously in one ear (monotic multiple; MM), and simultaneously in both ears (dichotic multiple; DM). It was predicted that stimuli with broader spectra would result in greater amplitudes. This was demonstrated in the MS condition by the AM/FM stimulus, which evoked responses significantly larger than those to both AM and AM² stimuli at all frequencies except 0.5 kHz at 60 and 80 dB HL. In the multiple (MM and DM) conditions, response amplitudes to AM² were significantly larger than AM and AM/FM response amplitudes at both intensities. It was also predicted that more interactions would be found when using stimuli with broader spectra, even at moderate intensities. This was illustrated by the drop in amplitude by the AM/FM stimulus in the multiple conditions versus in the single condition, even at 60 dB HL. Relative efficiency values in the multiple conditions were never less than that found in the single condition at 60 dB HL; at 80 dB HL, the majority (83%) of comparisons were more efficient in the multiple conditions than the single condition. Based on these results, the optimal stimulus to use appears to be dependent on the chosen condition. In the single condition, AM/FM stimuli result in the largest response amplitudes, however, in the multiple condition, AM² stimuli provide the best combination of amplitude values and testing efficiency.
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Bergeron, André 1967. "Multiple-step gaze shifts reveal gaze position error in brainstem." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82831.
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The superior colliculus (SC) is a structure that is implicated in the control of visual orienting behaviors. The SC contains a motor map which encodes saccade vectors topographically. Small saccades are encoded rostrally, larger ones caudally. More recently, it was shown that the rostral part of the SC contains a specialized "fixation zone". A group of cells located in the rostral SC have been called SC fixation neurons (SCFNs). SCFNs via projections to "omni-pause" neurons (OPNs) seem to play an important role during fixation behavior by holding gaze on target for a certain period of time through inhibition of the gaze saccade generator. By comparison, the caudal SC generates saccadic commands via its direct connections to the gaze saccade generator. When the head is unrestrained, large gaze shifts are generally made with the contribution of eye and head (gaze = eye-in-head + head-in-space). For a gaze shift executed in one step, gaze, eye, and head trajectories are very stereotyped; each part of the trajectory is correlated in time to another. Consequently, it is difficult to relate brainstem cells activity to a specific trajectory. A differentiation between the trajectories can be obtained by the use of multiple-step gaze-shifts that cats often use naturally. Multiple-step gaze shifts are gaze displacements that are composed of a variable number of gaze saccades separated by periods of steady fixation. The main goal of this thesis was to relate cell activity of both SC cells and OPNs with specific features of the multiple-step gaze shifts. The study of SC cells during multiple-step gaze shifts revealed that neither SCFNs nor cells on the SC motor map encode the complex motor sequence of steps and plateaus in multiple step gaze shifts. They are concerned with keeping track of the difference between current gaze position and the final intended gaze destination independently of how the gaze displacement is achieved. This finding challenges
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Balfour, Robert Henry. "Metabolic regulation of the electrical activity of identified brainstem neurones." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436317.
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Habbal, Karim. "Anatomical Localization of Membrane Progesterone Receptors in Brainstem Respiratory Areas." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29227/29227.pdf.
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La progestérone est un stimulant respiratoire, mais l’implication des différents types de récepteurs de progesterone dans ces effets n’est pas connue. La progesterone possède 2 types de récepteurs: des récepteurs nucléaires (nPR) et des récepteurs membranaires (mPR). nPR est exprimé dans le noyau du tractus solitatrius (NTS), un des noyaux du tronc cérébral impliquées dans le contrôle respiratoire. En revanche on ne sait pas si les mPR sont exprimés dans ce noyaux. Nous avons effectués des marquages immunohistochimiques sur des coupes de tronc cérébral de souris adultes (mâles). Une coloration dense a été trouvé pour les récepteurs mPRα et mPRβ dans les NTS caudal et rostral, le noyau vague et le noyau hypoglosse. mPRα est exprimé dans les corps cellulaires, tandis que mPRβ se trouve dans les fibres neuronales. Des experiences de double marquage en immunofluorescence montrent une co-localisation de mPRα et mPRβ dans des neurones exprimant la tyrosine hydroxylase, enzyme de synthèse des catécholamines dans le NTS. De plus, la 3β-hydroxystéroïde déshydrogénase, impliquée dans la synthèse de progestérone, est également exprimé dans le NTS. Ces résultats suggèrent que mPRα et mPRβ peuvent jouer un rôle dans le contrôle respiratoire et que la synthèse de progestérone locale peut moduler la fonction respiratoire.Progesterone is a potent respiratory stimulant, but the implication of progesterone receptor subtypes on this effect are not known. Progesterone has two main types of receptors, the "classical" nuclear receptor, and the recently identified membrane progesterone receptors. While it has been shown that the nuclear progesterone receptor is expressed in the nucleus tractus solitatrius, a brainstem nuclei involved in respiratory control, much less is known relatively to the expression of membrane progesterone receptors in this area. Accordingly, we used immunohistochemistry to determine the localization of membrane progesterone receptors (mPR) in respiratory-related areas in the brainstem of adult male mice. Serial slices were incubated with antibodies against alpha and beta mPR (mPRα and mPRβ). A prominent staining for mPRα, and mPRβ appeared in caudal and rostral parts of the nucleus tractus solitarius (NTS), X and XII nuclei, but while mPRα stained cell bodies, mPRβ stained fibers. With double fluorescence labeling and confocal microscopy we showed that mPRα is co-localized in catecholaminergic neurons (TH+) in NTS. mPRβ is expressed in TH+ fibers in these regions. Furthermore, 3β- hydroxysteroid dehydrogenase (3β-HSD), which is involved in progesterone synthesis, was also densily expressed in these regions. These results suggest that mPRα and mPRβ may play a role in respiratory control, and that local progesterone synthesis may modulate respiratory function.
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Ragi, Elias. "Analysis of the brainstem auditory evoked potentials in neurological disease." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:466085f6-6206-4253-974f-b0436baa2230.
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Many phenomena in the BAEP are difficult to explain on the basis of the accepted hypothesis of its origin (after Jewett, 1970). The alternative mechanism of origin to which these phenomena point is summation of oscillations. Therefore, simulation of the BAEP by a mathematical model consisting of the addition of four sine waves was tested. The model did simulate a normal BAEP as well variations in the waveform produced by reversing click polarity. This simulation gives further clues to the origin of the BAEP. The four sine waves begin simultaneously; corresponding BAEP oscillations must, therefore, originate from a single structure. These oscillations begin in less than half a millisecond after the click. This suggests that the structure from which they arise is outside the brainstem. This alternative mechanism indicates that wave latencies do not reflect nervous conduction between discrete nuclei, and interpretation of BAEP abnormality need to be reconsidered. It also implies that mathematical frequency analysis is more appropriate, but this could be applied only when these methods have been perfected. Meanwhile, through visual analysis and recognition of oscillations, abnormality can be detected and described in terms that may have physiological significance.
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Simon, Horst Hubertus. "Development of the efferent system in the segmented chick brainstem." Thesis, King's College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307096.
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Farrell, Gary. "Objective estimation of endolymphatic hydrops using auditory brainstem response measures." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293124.
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Lv, Jing. "Objective detection of auditory brainstem responses using a bootstrap technique." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438664.
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Roh, Jinsook. "Modules in the brainstem and spinal cord underlying motor behaviors." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/42929.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 89-95).
Previous studies using reduced or intact animal preparations suggested that coordinated movements can be generated by appropriate combinations of muscle synergies controlled by the nervous system. However, which areas of the central nervous system are responsible for structuring and combining muscle synergies remains an open question. In my thesis, I have addressed the question whether the brainstem and spinal cord are involved in structuring and combining muscle synergies in order to execute a range of natural movements. The strategy to investigate this question was to analyze the electromyogram (EMG) data recorded from the leg muscles during frog motor behaviors before and after neuronal transection. In my two sets of experiments, EMGs were recorded before and after transection at the level of the caudal end of the third ventricle and at the level of the caudal end of the pons in two groups of frogs. When the section was at the level of rostral midbrain, movements such as jumps, swims, kicks, and walks could be performed by the animals. In contrast, when the transection was at the level of rostral medulla, only a partial repertoire of natural movements could be evoked. Systematic analysis of muscle synergies in these preparations found two different types of synergies: (1) synergies shared by intact animals and animals with transection, and (2) synergies specific to individual motor behaviors. In addition, almost all synergies utilized in the execution of natural motor behaviors remain invariant after transection at the level of the caudal end of the third ventricle or at the level of the caudal end of the pons. The results suggest the following:
(cont.) (1) the neural network within the brainstem and spinal cord are necessary and sufficient in combining muscle synergies in the organization of natural movements, and (2) the neural circuitries within the medulla and spinal cord are sufficient to structure the repertoire of muscle synergies in natural motor behaviors. Overall, the major findings of this study indicate how the neural divisions in the CNS are functionally differentiated for structuring and combining modules in execution of natural movements.
by Jinsook Roh.
Ph.D.
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Hsieh, Yee-Hsee. "BRAINSTEM GABAA RECEPTOR SHAPE THE RESPONSE AND ADAPTATION TO HYPOXIA." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1184267396.
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Zaitoun, Maha Mustafa Ahmad. "The auditory brainstem response (ABR): an objective or subjective measure?" Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15846.
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Objectives: This thesis describes three studies investigating the consistency and reliability of ABR testing procedures, the extent of inter-and intra-rater variability and performance, the impact of additional case information on ABR testing results. Methods: The participants for all studies were audiologists who conduct ABR testing. Study 1 consisted of a 69-item survey regarding ABR testing protocols that was completed online. In studies 2 and 3, a test set of infant ABR traces was obtained from a large public peadiatric audiology clinic in Sydney, Australia. In Study 2, 61 audiologists estimated hearing threshold for 15 ABR cases that were each presented twice in order to estimate inter and intra-reader variability. In study 3, 14 audiologists were asked to estimate the hearing threshold for 16 infants twice in two sessions at least 5 months apart; with and without provision of standard clinical information. Results: Audiologists vary in how they conduct ABR testing and there are differences in the training period audiologists undertake before starting ABR testing. Audiologists show good levels of agreement when assessing repeated ABR traces, however, optimum performance was not achieved. No significant differences were found for sensitivity, specificity or accuracy when clinical history information was provided compared to when it was not provided. Conclusions: There is a need for greater emphasis on the importance of following evidence-based guidelines for ABR testing whenever it is possible. Audiologists’ experience and ABR training periods significantly predicts accuracy of ABR reading. Good levels of agreement were found between and within audiologists. ABR traces are interpreted with the same accuracy regardless of whether patients ‘history information is available or not. The data provided should contribute to an improvement in the service of infants hearing diagnostics and help reduce audiologists’ variability.
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Kumar, Natasha N. "Studies on Cholinergic and Enkephalinergic Systems in Brainstem Cardiorespiratory Control." Thesis, University of Sydney, 2016. http://hdl.handle.net/2123/2014.
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This thesis addresses the neurochemistry and function of specific nuclei in the autonomic nervous system that are crucial mediators of cardiorespiratory regulation. The primary aim is to build on previous knowledge about muscarinic cholinergic mechanisms within cardiorespiratory nuclei located in the ventrolateral medulla oblongata. The general focus is characterisation of gene expression patterns of specific muscarinic receptor subtypes in central nuclei involved in blood pressure control and respiratory control in normal rats. The findings were subsequently extended by characterisation of muscarinic receptor gene expression patterns in 1) a rat model of abnormal blood pressure control (hypertension) (Chapter 3) 2) a rat model of cholinergic sensitivity (Chapter 5) 3) the rat ventral respiratory group (Chapter 6) The results of a series of related investigations that ensued from the initial aims more finely characterise the neurocircuitry of the ventrolateral medulla, from a specifically cholinoceptive approach. All five muscarinic receptor subtypes are globally expressed in the ventrolateral medulla but only the M2R mRNA was significantly elevated in the VLM of hypertensive animals compared to their normotensive controls and in the VLM of animals displaying cholinergic hypersensitivity compared to their resistant controls. Surprisingly, M2R mRNA is absent in catecholaminergic cell groups but abundant in certain respiratory nuclei. Two smaller projects involving gene expression of other neurotransmitter / neuromodulators expressed in cardiorespiratory nuclei were also completed during my candidature. Firstly, the neurochemical characterisation of enkephalinergic neurons in the RVLM, and their relationship with bulbospinal, catecholaminergic neurons in hypertensive compared to normotensive animals was carried out (Chapter 4). A substantial proportion of sympathoexcitatory neurons located in the RVLM were enkephalinergic in nature. However, there was no significant difference in preproenkephalin expression in the RVLM in hypertensive compared to normotensive animals. Secondly, the identification and distribution of components of the renin-angiotensin aldosterone system (RAAS) within the brainstem, and differences in gene expression levels between hypertensive and normotensive animals was also investigated. The RAAS data was not included in this thesis, since the topic digresses substantially from other chapters and since it is published (Kumar et al., 2006). The mRNA expression aldosterone synthase, mineralocorticoid receptor (MR1), 12-lipoxygenase (12-LO), serum- and glucocorticoid- inducible kinase and K-ras) were found to be present at all rostrocaudal levels of the ventrolateral medulla. Expression of MR1 mRNA was lower in the RVLM of SHR compared with WKY rats and 12-LO mRNA levels were lower in the CVLM in SHR compared with WKY rats. Otherwise, there was no difference in gene expression level, or the method of detection was not sensitive enough to detect differences in low copy transcripts between hypertensive and normotensive animals.
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Khoder, Suzana. "Role of the prefrontal-brainstem pathway in mediating avoidance behavior." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0256.
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Les mammifères, comme par exemple les rongeurs, soumis à des expériences aversives présentent des réponses comportementales de peur caractéristiques notamment une réponse d'immobilisation (freezing) ou d'évitement. Alors que le rôle du cortex préfrontal dorso-médian (CPFdm) dans l’acquisition ainsi que l’expression du freezing a déjà été expérimentalement établi, son implication dans l’encodage des réponses d’évitement de peur ainsi que l’interaction entre les circuits neuronaux préfrontaux impliqués dans le freezing et/ou l’évitement restent mal compris. Afin de répondre à ces questions, nous avons développé au laboratoire un paradigme expérimental permettant à une souris d’acquérir et d’exprimer le freezing ou l’évitement lors de la présentation d'un même stimulus aversif et ceci en fonction du contexte environnant. Ainsi, nous avons pu déterminer si les mêmes circuits neuronaux dans le cortex préfrontal dorso-médian encodent les deux réponses de peur, le freezing et l’évitement. Nous avons mis en oeuvre au cours de ce travail des approches comportementales, de traçage neuroanatomique, d'immunohistochimie, d'enregistrements extracellulaires in vivo et intracellulaires in vitro ainsi que des approches optogénétiques. Nos résultats indiquent que (i) le CPFdm et les régions dorsales de la substance grise périaqueducale sont activés pendant le comportement d'évitement, (ii) une sous population de neurones du CPFdm encode le comportement d'évitement mais pas le freezing, (iii) cette population neuronale projette sur le dl/lPAG, (iv) l'activation et l'inhibition optogénétique de cette projection induit et bloque l'apprentissage de l'évitement, respectivement et (v) l'apprentissage de l'évitement est associé à la mise en place d'une plasticité des afférences préfrontales sur le dl/lPAG. Dans leur ensemble ces résultats démontrent pour la première fois que la plasticité dépendante de l'activité des neurones du CPFdm projettant sur le dl/lPAG contrôle l'apprentissage de l'évitement de peurMammals, including rodents show a broad range of defensive behaviors as a mean of coping with threatful stimuli including freezing and avoidance behaviors. Several studies emphasized the role of the dorsal medial prefrontal cortex (dmPFC) in encoding the acquisition as well as the expression of freezing behavior. However the role of this structure in processing avoidance behavior and the contribution of distinct prefrontal circuits to both freezing and avoidance responses are largely unknown. To further investigate the role of dmPFC circuits in encoding passive and active fear-coping strategies, we developed in the laboratory a novel behavioral paradigm in which a mouse has the possibility to either passively freeze to an aversive stimulus or to actively avoid it as a function of contextual contingencies. Using this behavioral paradigm we investigated whether the same circuits mediate freezing and avoidance behaviors or if distinct neuronal circuits are involved. To address this question, we used a combination of behavioral, neuronal tracing, immunochemistry, single unit and patch clamp recordings and optogenetic approaches. Our results indicate that (i) dmPFC and dorsolateral and lateral periaqueductal grey (dl/lPAG) sub-regions are activated during avoidance behavior, (ii) a subpopulation of dmPFC neurons encode avoidance but not freezing behavior, (iii) this neuronal population project to the dl/lPAG, (iv) the optogenetic activation or inhibition of this pathway promoted and blocked the acquisition of conditioned avoidance and (v) avoidance learning was associated with the development of plasticity at dmPFC to dl/lPAG synapses. Together, these data demonstrate for the first time that activity-dependent plasticity in a subpopulation of dmPFC cells projecting to the dl/lPAG pathway controls avoidance learning
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SERPIERI, VALENTINA. "Genetic and functional characterization of cerebellar and brainstem congenital defects." Doctoral thesis, Università degli studi di Pavia, 2021. http://hdl.handle.net/11571/1436278.
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Ordway, Gregory A. "Growing Evidence of Dysfunctional Brainstem Glia in Major Depression and Suicide." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etsu-works/8630.
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Jaiswal, Stuti J. "The Consequences of Developmental Nicotine Exposure on Neonatal Central Respiratory Control." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293608.
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Developmental nicotine exposure (DNE) exerts negative consequences on the CNS via the activation of nAChRs that are available early and widely throughout development (refs). In this work, we examined how DNE changed excitatory and inhibitory neurotransmission in brainstem regions involved in central breathing control. Previous work using the brainstem-spinal cord preparation had shown that DNE augmented the respiratory-related response to AMPA, muscimol (a GABAA agonist), and glycine (Luo et al., 2004; Luo et al., 2007; Pilarski and Fregosi, 2009a). These studies used a split-bath preparation in which a drug (AMPA, muscimol, or glycine) was applied to medulla, and the frequency of the respiratory response (in the form of spontaneous, rhythmic bursting activity) was recorded from cervical nerve 4 (C4), which provides output to the diaphragm. Although these studies showed that DNE AMPA, GABA(A), and glycine neurotransmission in the medulla, the regions mediating the effect and the mechanism of DNE's action remained unclear. In this study we tested the hypothesis that the observed changes in respiratory burst frequency were mediated through the preBötzinger complex (preBötC), and the mechanism of enhanced activity involved an upregulation of neurotransmitter receptors. Additionally, we were interested in studying the effect of DNE on breathing-related motor pools, and therefore studied DNE's effect on excitatory and inhibitory neurotransmission in the XIIMN. We approached these questions and aims using a combination of techniques, including extracellular recordings from whole nerve output in rhythmic brainstem slices, immunohistochemistry, and Western blotting. We found enhanced AMPA, GABA(A), and glycine neurotransmission in the XIIMN and preBötC, and varying changes in neurotransmitter receptor expression in both groups. Additionally, we found a decrease in motoneuron soma size in XII motoneurons that stained positively for the glycine receptor. Overall, this study shows that DNE alters inhibitory and excitatory neurotransmission in both the preBötC and XIIMN, and that these changes may be mediated through a combination of change in cell size and receptor expression.
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Felder, Shannon N. "Survey of auditory brainstem response referral criteria / by Shannon N. Felder." University of South Florida, 2001. http://purl.fcla.edu/fcla/etd/SFE0000016.
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Professional research project (Au.D.)--University of South Florida, 2000.Title from PDF of title page.
Document formatted into pages; contains 48 pages.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
ABSTRACT: The primary objective of the project was to survey recognized "experts" in the field of neurodiagnostic audiology and practicing audiologists regarding their referral criteria and referral patterns for administering an auditory brainstem response test (ABR). For purposes of this study, "expert" was defined as any recognized audiologist with at least two or more publications and/or seminarsin the field of auditory evoked potentials.
Responses of experts and practicing audiologists were compared and contrasted to establish: a) if there was a standard referral pattern; b) what, if any, were the apparent critical components of referral patterns; and, c) whether or not current practice reflected the utilization of such critical components. The survey was designed to establish whether the respondent was practicing, in what type of practice setting, and how often ABRs were performed. Specificity and sensitivity of ABR outcomes was also requested.
The survey was administered verbally, via telephone, to 3 experts and was sent via e-mail to 178 randomly selected audiologists in the United States. Of the latter 53 returned, 38 reported conducting ABRs. Thus, data analysis was reported on 38 respondents. The survey results did not reveal a consistent standard referral pattern. Critical components for referral were hypothesized based on the "expert" majority response. These include ABR referral based on the presence of: (1) asymmetric sensorineural hearing loss; (2) unilateral tinnitus; (3) positive reflex decay; and, (4) word recognition rollover. The majority of "non-expert" practitioners surveyed reported that these symptoms warranted consideration for referral, thus reflecting utilization of apparent critical components.
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Mode of access: World Wide Web.
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Lary, Sana A. "Auditory brainstem responses in normal and abnormal preterm and fullterm infants." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38080.
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Oquendo, Javier. "Elemental Analysis of Brainstem in Victims of Sudden Infant Death Syndrome." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc500370/.
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A brainstem-related abnormality in respiratory control appears to be one of the most compelling mechanisms for sudden infant death syndrome (SIDS). The elements calcium, copper, iron, potassium, magnesium, sodium, phosphorus, sulfur, and zinc were analyzed by inductively coupled plasma atomic emission spectroscopy in the brainstem of 30 infants who died from SIDS and 10 infants who died from other causes (control). No differences were found between SIDS and control for any element except for more calcium in the SIDS group. A multivariate analysis of the data failed to group the majority of SIDS and control subjects in different clusters. Further research is required to determine the biological significance of the higher calcium found in the SIDS group.,
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Wollman, Lila Buls, and Lila Buls Wollman. "Plasticity of Brainstem Motor Systems in Response to Developmental Nicotine Exposure." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626307.
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Developmental nicotine exposure (DNE) is known to cause abnormal development of multiple brain regions and results in impaired control of breathing and altered behaviors that rely on proper coordination of the muscles of the tongue. The adverse effects of nicotine are presumably caused by its actions on nicotinic acetylcholine receptors (nAChRs), which modulate fast-synaptic transmission and play a prominent role during brain development. Previous work has shown that DNE alters nAChR function in multiple brainstem regions (Pilarski et al., 2012, Wollman et al, 2016). Moreover, DNE causes multiple changes to XIIMNs, which innervate the muscles of the tongue (Powell et al., 2016, Powell et al., 2015, Pilarski et al., 2011). These changes likely reflect both altered development as a primary outcome of the chronic presence of nicotine, as well as, homeostatic adjustments made in an attempt to maintain normal motoneuron output. With the experiments described here, we tested the hypothesis that DNE alters the development of fast-synaptic transmission to XIIMNs, which, along with intrinsic properties of these neurons, is a main determinant of motor output to the muscles of the tongue. Additionally, we tested the hypothesis that DNE alters the function of nAChRs located on multiple brainstem neurons, including those that modulate fast-synaptic transmission to XIIMNs. For these experiments, we used whole cell patch clamp recordings from XIIMNs in a transverse slice of the medulla, and extracellular recordings from the 4th cervical ventral root in the brainstem spinal cord, split bath preparation. All preparations were obtained from control or DNE neonatal rats in the first week of life. Overall, the results of these experiments show that DNE alters fast-synaptic transmission to XIIMNs, which likely reflects appropriate homeostatic adjustments aimed at maintaining normal motor output at rest. However, these results also show that nAChR function is significantly altered by DNE, indicating fast-synaptic transmission may not be appropriately modulated in response to increased release of acetylcholine (ACh), the endogenous neurotransmitter for nAChRs.
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Mirabile, I. "Prion pathology in the brainstem : clinical target areas in prion disease." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1346475/.
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Prion diseases are fatal transmissible neurodegenerative disorders characterized by spongiform changes, neuronal loss, reactive astrocytosis, and deposition of disease associated prion protein (PrP). Our aim was to investigate "clinical target areas" for prion disease, responsible for disease onset, progression, and the clinical phenotype, using PrP overexpressing MloxP and PrP depleted NFH-Cre/MloxP transgenic mouse lines. Upon infection with different prion strains NFH-Cre/MloxP mice have significantly longer survival than MloxP mice (first set of experiments: Me7, ~29 weeks vs. ~17 weeks; Mouse-adapted BSE , ~33 weeks vs. ~20 weeks; second set of experiments: RML, ~35 weeks vs.12 weeks; Me7 ~29 weeks, vs. ~17 weeks; MRC2 ~31 weeks vs. ~22 week). As we found that the first pathological changes in the brains of Me7 and Mouse–adapted BSE infected mice are localized in the brainstem, and clinical signs of prion disease point to brainstem failure, we quantitatively scored spongiosis, abnormal PrP accumulation and astrogliosis at early and late stage of disease in specific brainstem nuclei of RML and Me7 infected MloxP and NFH-Cre/MloxP mice. The first target areas showing abnormal PrP accumulation and gliosis in both prion infections are the locus coeruleus (LC), the nucleus of the solitary tract (NTS) and the pre-Bötzinger complex (PBC). We then studied the pathology progression, scoring prion pathology in these and other brainstem nuclei of infected MloxP and NFH-Cre/MloxP mice in the course of the disease. We show that neural degeneration in the LC, NTS, and PBC correlate with clinical signs characteristic of terminally ill mice. We therefore propose that these areas are potential clinical target areas of prion disease. We also studied the spatial and temporal characteristics of Cre-mediated recombination. With immunohistochemistry in reporter mice, we estimated that in the LC, NTS, and PBC, Cre-mediated recombination is 60% or lower, and this can explain why mice proceed to terminal stage of the disease. In NFH-Cre/MloxP mice we found that recombination is a progressive event and in the hippocampus it is complete by 5 weeks post-natally, differently from previous data. Finally, we produced anti PrP RNAi –encoding lentivirus which could be used as focal therapy in the clinical target areas we propose.
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Lightfoot, Guy Richard. "The effects of click repetition rate on the auditory brainstem response." Thesis, Liverpool John Moores University, 1991. http://researchonline.ljmu.ac.uk/5012/.
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Ordway, Gregory A. "Growing Evidence of Dysfunctional Brainstem Glia in Major Depression and Suicide." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etsu-works/8668.
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