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Pisella, L., N. Alahyane, A. Blangero, F. Thery, S. Blanc i D. Pelisson. "Right-hemispheric dominance for visual remapping in humans". Philosophical Transactions of the Royal Society B: Biological Sciences 366, nr 1564 (27.02.2011): 572–85. http://dx.doi.org/10.1098/rstb.2010.0258.
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We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms (intuitively related to remapping impairments) are observed in both neglect and constructional apraxia. More specifically, we review findings from the intervening saccade paradigm in humans—and present additional original data—which suggest a specific role of the asymmetrical network at the temporo-parietal junction (TPJ) in the right hemisphere in visual remapping: following damage to the right dorsal posterior parietal cortex (PPC) as well as part of the corpus callosum connecting the PPC to the frontal lobes, patient OK in a double-step saccadic task exhibited an impairment when the second saccade had to be directed rightward . This singular and lateralized deficit cannot result solely from the patient's cortical lesion and, therefore, we propose that it is due to his callosal lesion that may specifically interrupt the interhemispheric transfer of information necessary to execute accurate rightward saccades towards a remapped target location. This suggests a specialized right-hemispheric network for visuo-spatial remapping that subsequently transfers target location information to downstream planning regions, which are symmetrically organized.
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Vesia, Michael, Jachin A. Monteon, Lauren E. Sergio i J. D. Crawford. "Hemispheric Asymmetry in Memory-Guided Pointing During Single-Pulse Transcranial Magnetic Stimulation of Human Parietal Cortex". Journal of Neurophysiology 96, nr 6 (grudzień 2006): 3016–27. http://dx.doi.org/10.1152/jn.00411.2006.
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Dorsal posterior parietal cortex (PPC) has been implicated through single-unit recordings, neuroimaging data, and studies of brain-damaged humans in the spatial guidance of reaching and pointing movements. The present study examines the causal effect of single-pulse transcranial magnetic stimulation (TMS) over the left and right dorsal posterior parietal cortex during a memory-guided “reach-to-touch” movement task in six human subjects. Stimulation of the left parietal hemisphere significantly increased endpoint variability, independent of visual field, with no horizontal bias. In contrast, right parietal stimulation did not increase variability, but instead produced a significantly systematic leftward directional shift in pointing (contralateral to stimulation site) in both visual fields. Furthermore, the same lateralized pattern persisted with left-hand movement, suggesting that these aspects of parietal control of pointing movements are spatially fixed. To test whether the right parietal TMS shift occurs in visual or motor coordinates, we trained subjects to point correctly to optically reversed peripheral targets, viewed through a left–right Dove reversing prism. After prism adaptation, the horizontal pointing direction for a given visual target reversed, but the direction of shift during right parietal TMS did not reverse. Taken together, these data suggest that induction of a focal current reveals a hemispheric asymmetry in the early stages of the putative spatial processing in PPC. These results also suggest that a brief TMS pulse modifies the output of the right PPC in motor coordinates downstream from the adapted visuomotor reversal, rather than modifying the upstream visual coordinates of the memory representation.
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Djukic-Macut, Natasa, Slobodan Malobabic, Natalija Stefanovic, Predrag Mandic, Tatjana Filipovic, Aleksandar Malikovic i Milena Saranovic. "Asymmetries in numerical density of pyramidal neurons in the fifth layer of the human posterior parietal cortex". Vojnosanitetski pregled 69, nr 8 (2012): 681–85. http://dx.doi.org/10.2298/vsp101126016d.
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Background/Aim. Both superior parietal lobule (SPL) of dorsolateral hemispheric surface and precuneus (PEC) of medial surface are the parts of posterior parietal cortex. The aim of this study was to determine the numerical density (NV) of pyramidal neurons in the layer V of SPL and PEC and their potential differences. Methods. From 20 (40 hemispheres) formaline fixed human brains (both sexes; 27- 65 years) tissue blocks from SPL and PEC from the left and right hemisphere were used. According to their size the brains were divided into two groups, the group I with the larger left (15 brains) and the group II with the larger right hemisphere (5 brains). Serial Nissl sections (5 ?m) of the left and right SPL and PEC were used for stereological estimation of NV of the layer V pyramidal neurons. Results. NV of pyramidal neurons in the layer V in the left SPL of brains with larger left hemispheres was significantly higher than in the left SPL of brains with larger right hemisphere. Comparing sides in brains with larger left hemisphere, the left SPL had higher NV than the right one, and then the left PEC, and the right SPL had significantly higher NV than the right PEC. Comparing sides in brains with the larger right hemisphere, the left SPL had significantly higher NV than left PEC, but the right SPL had significantly higher NV than left SPL and the right PEC. Conclusion. Generally, there is an inverse relationship of NV between the medial and lateral areas of the human posterior parietal cortex. The obtained values were different between the brains with larger left and right hemispheres, as well as between the SPL and PEC. In all the comparisons the left SPL had the highest values of NV of pyramidal neurons in the layer V (4771.80 mm-3), except in brains with the larger right hemisphere.
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Hinkley, Leighton B. N., Leah A. Krubitzer, Jeff Padberg i Elizabeth A. Disbrow. "Visual-Manual Exploration and Posterior Parietal Cortex in Humans". Journal of Neurophysiology 102, nr 6 (grudzień 2009): 3433–46. http://dx.doi.org/10.1152/jn.90785.2008.
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Areas of human posterior parietal cortex (PPC) specialized for processing sensorimotor information associated with visually locating an object, reaching to grasp, and manually exploring that object were examined using functional MRI. Cortical activation was observed in response to three tasks: 1) saccadic eye movements, 2) visually guided reaching to grasp, and 3) manual shape discrimination. During saccadic eye movements, cortical fields within the lateral and rostral superior parietal lobe (SPL) and the caudal SPL and parieto-occipital boundary were active. During visually guided reaching to grasp, regions of cortex within the postcentral sulcus (PoCS) and rostral intraparietal sulcus (IPS) were active, as well as the caudal SPL of the left hemisphere and the medial and caudal IPS of the right hemisphere. Cortical regions at the junction of the IPS and PoCS and an area in the medial SPL were active bilaterally during shape manipulation. Only a few regions were most active during a single motor behavior, whereas several areas were highly active during two or more tasks. Hemispheric asymmetries in activation patterns were observed during visually guided reaching to grasp. The gross areal organization of human PPC is likely similar to the pattern previously described in nonhuman primates, including multifunctional regions and asymmetric processing of some manual abilities.
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Rounis, Elisabeth, Kielan Yarrow i John C. Rothwell. "Effects of rTMS Conditioning over the Fronto-parietal Network on Motor versus Visual Attention". Journal of Cognitive Neuroscience 19, nr 3 (marzec 2007): 513–24. http://dx.doi.org/10.1162/jocn.2007.19.3.513.
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Many studies have shown that visuospatial orienting attention depends on a network of frontal and parietal areas in the right hemisphere. Rushworth et al. [Rushworth, M. F., Krams, M., & Passingham, R. E. The attentional role of the left parietal cortex: The distinct lateralization and localization of motor attention in the human brain. Journal of Cognitive Neuroscience, 13, 698–710, 2001] have recently provided evidence for a left-lateralized network of parietal areas involved in motor attention. Using two variants of a cued reaction time (RT) task, we set out to investigate whether high-frequency repetitive transcranial magnetic stimulation (rTMS; 5 Hz) delivered “off-line” in a virtual lesion paradigm over the right or left dorsolateral prefrontal cortex (DLPFC) or the posterior parietal cortex (PPC) would affect performance in a motor versus a visual attention task. Although rTMS over the DLPFC on either side did not affect RT performance on a spatial orienting task, it did lead to an increase in the RTs of invalidly cued trials in a motor attention task when delivered to the left DLPFC. The opposite effect was found when rTMS was delivered to the PPC: In this case, conditioning the right PPC led to increased RTs in invalidly cued trials located in the left hemispace, in the spatial orienting task. rTMS over the PPC on either side did not affect performance in the motor attention task. This double dissociation was evident in the first 10 min after rTMS conditioning. These results enhance our understanding of the networks associated with attention. They provide evidence of a role for the left DLPFC in the mechanisms of motor preparation, and confirm Mesulam's original proposal for a right PPC dominance in spatial attention [Mesulam, M. M. A cortical network for directed attention and unilateral neglect. Annals of Neurology, 10, 309–325, 1981].
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Ambrosini, Ettore, i Antonino Vallesi. "Domain-general Stroop Performance and Hemispheric Asymmetries: A Resting-state EEG Study". Journal of Cognitive Neuroscience 29, nr 5 (maj 2017): 769–79. http://dx.doi.org/10.1162/jocn_a_01076.
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The ability to suppress irrelevant information while executing a task, also known as interference resistance ability, is a function of pFC that is critical for successful goal-directed human behavior. In the study of interference resistance and, more generally, executive functions, two key questions are still open: Does pFC contribute to cognitive control abilities through lateralized but domain-general mechanisms or through hemispheric specialization of domain-specific processes? And what are the underlying causes of interindividual differences in executive control performance? To shed light on these issues, here we employed an interindividual difference approach to investigate whether participants' hemispheric asymmetry in resting-state electrophysiological brain dynamics may reflect their variability in domain-general interference resistance. We recorded participants' resting-state electroencephalographic activity and performed spectral power analyses on the estimated cortical source activity. To measure participants' lateralized brain dynamics at rest, we computed the right–left hemispheric asymmetry score for the β/α power ratio. To measure their domain-general interference resistance ability, verbal and spatial Stroop tasks were used. Robust correlations followed by intersection analyses showed that participants with stronger resting-state-related left-lateralized activity in different pFC regions, namely the mid-posterior superior frontal gyrus, middle and posterior middle frontal gyrus, and inferior frontal junction, were more able to inhibit irrelevant information in both domains. The present results confirm and extend previous findings showing that neurophysiological difference factors may explain interindividual differences in executive functioning. They also provide support for the hypothesis of a left pFC hemispheric specialization for domain-independent phasic cognitive control processes mediating Stroop performance.
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Duecker, Felix, Teresa Schuhmann, Nina Bien, Christianne Jacobs i Alexander T. Sack. "Moving Beyond Attentional Biases: Shifting the Interhemispheric Balance between Left and Right Posterior Parietal Cortex Modulates Attentional Control Processes". Journal of Cognitive Neuroscience 29, nr 7 (lipiec 2017): 1267–78. http://dx.doi.org/10.1162/jocn_a_01119.
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The concept of interhemispheric competition has been very influential in attention research, and the occurrence of biased attention due to an imbalance in posterior parietal cortex (PPC) is well documented. In this context, the vast majority of studies have assessed attentional performance with tasks that did not include an explicit experimental manipulation of attention, and, as a consequence, it remains largely unknown how these findings relate to core attentional constructs such as endogenous and exogenous control and spatial orienting and reorienting. We here addressed this open question by creating an imbalance between left and right PPC with transcranial direct current stimulation, resulting in right-hemispheric dominance, and assessed performance on three experimental paradigms that isolate distinct attentional processes. The comparison between active and sham transcranial direct current stimulations revealed a highly informative pattern of results with differential effects across tasks. Our results demonstrate the functional necessity of PPC for endogenous and exogenous attentional control and, importantly, link the concept of interhemispheric competition to core attentional processes, thus moving beyond the notion of biased attention after noninvasive brain stimulation over PPC.
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de Graaf, Tom A., Alard Roebroeck, Rainer Goebel i Alexander T. Sack. "Brain Network Dynamics Underlying Visuospatial Judgment: An fMRI Connectivity Study". Journal of Cognitive Neuroscience 22, nr 9 (wrzesień 2010): 2012–26. http://dx.doi.org/10.1162/jocn.2009.21345.
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Previous functional imaging research has consistently indicated involvement of bilateral fronto-parietal networks during the execution of visuospatial tasks. Studies with TMS have suggested that the right hemispheric network, but not the left, is functionally relevant for visuospatial judgments. However, very little is still known about the interactions within these fronto-parietal networks underlying visuospatial processing. In the current study, we investigated task modulation of functional connectivity (instantaneous correlations of regional time courses), and task-specific effective connectivity (direction of influences), within the right fronto-parietal network activated during visuospatial judgments. Ten healthy volunteers performed a behaviorally controlled visuospatial judgment task (ANGLE) or a control task (COLOR) in an fMRI experiment. Visuospatial task-specific activations were found in posterior parietal cortex (PPC) and middle/inferior frontal gyrus (MFG). Functional connectivity within this network was task-modulated, with significantly higher connectivity between PPC and MFG during ANGLE than during COLOR. Effective connectivity analysis for directed influence revealed that visuospatial task-specific projections within this network were predominantly in a frontal-to-parietal direction. Moreover, ANGLE-specific influences from thalamic nuclei to PPC were identified. Exploratory effective connectivity analysis revealed that closely neighboring clusters, within visuospatial regions, were differentially involved in the network. These neighboring clusters had opposite effective connectivity patterns to other nodes of the fronto-parietal network. Our data thus reveal that visuospatial judgments are supported by massive fronto-parietal backprojections, thalamo-parietal influence, and multiple stages, or loops, of information flow within the visuospatial network. We speculate on possible functional contributions of the various network nodes and informational loops in a neurocognitive model.
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Saxena, Sadhvi, Zafer Keser, Chris Rorden, Leonardo Bonilha, Julius Fridriksson, Alexandra Walker i Argye Elizabeth Hillis. "Disruptions of the Human Connectome Associated With Hemispatial Neglect". Neurology 98, nr 2 (10.01.2022): e107-e114. http://dx.doi.org/10.1212/wnl.0000000000013050.
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Background and ObjectivesHemispatial neglect is a heterogeneous and complex disorder that can be classified by frame of reference for “left” vs “right,” including viewer-centered neglect (VCN, affecting the contralesional side of the view), stimulus-centered neglect (SCN, affecting the contralesional side of the stimulus, irrespective of its location with respect to the viewer), or both. We investigated the effect of acute stroke lesions on the connectivity of neural networks that underlie VCN or SCN.MethodsA total of 174 patients within 48 hours of acute right hemispheric infarct underwent a detailed hemispatial neglect assessment that included oral reading, scene copy, line cancellation, gap detection, horizontal line bisection tests, and MRI. Each patient's connectivity map was generated. We performed a linear association analysis between network connectivity strength and continuous measures of neglect to identify lesion-induced disconnections associated with the presence or severity of VCN and SCN. Results were corrected for multiple comparisons.ResultsAbout 42% of the participants with right hemisphere stroke had at least one type of neglect. The presence of any type of neglect was associated with lesions to tracts connecting the right inferior parietal cortex, orbitofrontal cortex, and right thalamus to other right-hemispheric structures. VCN only was strongly associated with tracts connecting the right putamen to other brain regions and tracts connecting right frontal regions with other brain regions. The presence of both types of neglect was most strongly associated with tracts connecting the right inferior and superior parietal cortex to other brain regions and those connecting left or right mesial temporal cortex to other brain regions.DiscussionOur study provides new evidence for the specific white matter tracts where disruption can cause hemispatial neglect in a relatively large number of participants and homogeneous time after onset. We obtained MRI and behavioral testing acutely, before the opportunity for rehabilitation or substantial recovery.Classification of EvidenceThis study provides Class II evidence that damage to specific white matter tracts identified on MRI are associated with the presence of neglect following right hemispheric stroke.
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Gitelman, Darren R., Nathaniel M. Alpert, Stephen Kosslyn, Kirk Daffner, Leonard Scinto, William Thompson i M.-Marsel Mesulam. "Functional imaging of human right hemispheric activation for exploratory movements". Annals of Neurology 39, nr 2 (luty 1996): 174–79. http://dx.doi.org/10.1002/ana.410390206.
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Ogawa, Kenji, i Toshio Inui. "Reference Frame of Human Medial Intraparietal Cortex in Visually Guided Movements". Journal of Cognitive Neuroscience 24, nr 1 (styczeń 2012): 171–82. http://dx.doi.org/10.1162/jocn_a_00132.
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Visually guided reaching involves the transformation of a spatial position of a target into a body-centered reference frame. Although involvement of the posterior parietal cortex (PPC) has been proposed in this visuomotor transformation, it is unclear whether human PPC uses visual or body-centered coordinates in visually guided movements. We used a delayed visually guided reaching task, together with an fMRI multivoxel pattern analysis, to reveal the reference frame used in the human PPC. In experiments, a target was first presented either to the left or to the right of a fixation point. After a delay period, subjects moved a cursor to the position where the target had previously been displayed using either a normal or a left–right reversed mouse. The activation patterns of normal sessions were first used to train the classifier to predict movement directions. The activity patterns of the reversed sessions were then used as inputs to the decoder to test whether predicted directions correspond to actual movement directions in either visual or body-centered coordinates. When the target was presented before actual movement, the predicted direction in the medial intraparietal cortex was congruent with the actual movement in the body-centered coordinates, although the averaged signal intensities were not significantly different between two movement directions. Our results indicate that the human medial intraparietal cortex uses body-centered coordinates to encode target position or movement directions, which are crucial for visually guided movements.
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Takahashi, H., N. Yahata, M. Matsuura, K. Asai, Y. Okubo, H. Tanaka i M. Koeda. "Neural Responses to Human Voice and Hemisphere Dominance for Lexical-semantic Processing". Methods of Information in Medicine 46, nr 02 (2007): 247–50. http://dx.doi.org/10.1055/s-0038-1625416.
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Summary Objectives : In our previous functional magnetic resonance imaging (fMRI) study, we determined that there was distinct left hemispheric dominance for lexical- semantic processing without the influence of human voice perception in right-handed healthy subjects. However, the degree of right-handedness in the right-handed subjects ranged from 52 to 100 according to the Edinburgh Handedness Inventory (EHI) score. In the present study, we aimed to clarify the correlation between the degree of right-handedness and language dominance in the fronto-temporo-parietal cortices by examining cerebral activation for lexical-semantic processing. Methods : Twenty-seven normal right-handed healthy subjects were scanned by fMRI while listening to sentences (SEN), reverse sentences (rSEN), and identifiable non-vocal sounds (SND). Fronto-temporo-parietal activation was observed in the left hemisphere under the SEN - rSEN contrast, which included lexical- semantic processing without the influence of human voice perception. Laterality Indexwas calculated as LI = (L - R)/(L + R) X 100, L: left, R: right. Results : Laterality Index in the fronto-temporo-parietal cortices did not correlate with the degree of right-handedness in EHI score. Conclusions : The present study indicated that the degree of right-handedness from 52 to 100 in EHI score had no effect on the degree of left hemispheric dominance for lexical-semantic processing in right-handed healthy subjects.
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Ross, B., A. T. Herdman i C. Pantev. "Right Hemispheric Laterality of Human 40 Hz Auditory Steady-state Responses". Cerebral Cortex 15, nr 12 (16.03.2005): 2029–39. http://dx.doi.org/10.1093/cercor/bhi078.
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Putnam, Mary Colvin, Megan S. Steven, Karl W. Doron, Adam C. Riggall i Michael S. Gazzaniga. "Cortical Projection Topography of the Human Splenium: Hemispheric Asymmetry and Individual Differences". Journal of Cognitive Neuroscience 22, nr 8 (sierpień 2010): 1662–69. http://dx.doi.org/10.1162/jocn.2009.21290.
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The corpus callosum is the largest white matter pathway in the human brain. The most posterior portion, known as the splenium, is critical for interhemispheric communication between visual areas. The current study employed diffusion tensor imaging to delineate the complete cortical projection topography of the human splenium. Homotopic and heterotopic connections were revealed between the splenium and the posterior visual areas, including the occipital and the posterior parietal cortices. In nearly one third of participants, there were homotopic connections between the primary visual cortices, suggesting interindividual differences in splenial connectivity. There were also more instances of connections with the right hemisphere, indicating a hemispheric asymmetry in interhemispheric connectivity within the splenium. Combined, these findings demonstrate unique aspects of human interhemispheric connectivity and provide anatomical bases for hemispheric asymmetries in visual processing and a long-described hemispheric asymmetry in speed of interhemispheric communication for visual information.
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Wang, Bin, Lan Yang, Wenjie Yan, Weichao An, Jie Xiang i Dandan Li. "Brain asymmetry: a novel perspective on hemispheric network". Brain Science Advances 9, nr 2 (czerwiec 2023): 56–77. http://dx.doi.org/10.26599/bsa.2023.9050014.
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Brain asymmetry, involving structural and functional differences between the two hemispheres, is a major organizational principle of the human brain. The structural and functional connectivity within each hemisphere defines the hemispheric network or connectome. Elucidating left-right differences of the hemispheric network provides opportunities for brain asymmetry exploration. This review examines the asymmetry in the hemispheric white matter and functional network to assess health and brain disorders. In this article, the brain asymmetry in structural and functional connectivity including network topologies of healthy individuals, involving brain cognitive systems and the development trend, is highlighted. Moreover, the abnormal asymmetry of the hemispheric network related to cognition changes in brain disorders, such as Alzheimer’s disease, schizophrenia, autism spectrum disorder, attention deficit hyperactivity disorder, and bipolar disorder, is presented. This review suggests that the hemispheric network is highly conserved for measuring human brain asymmetries and has potential in the study of the cognitive system and brain disorders.
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Mouri, Kiminori, i Yoichi Ando. "On the sound environment for the right and left human hemispheric tasks". Journal of the Acoustical Society of America 100, nr 4 (październik 1996): 2787. http://dx.doi.org/10.1121/1.416472.
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Maravita, A., L. Posteraro, M. Husain, P. Vuilleumier, S. Schwartz i J. Driver. "Looking at human eyes affects contralesional stimulus processing after right hemispheric stroke". Neurology 69, nr 16 (15.10.2007): 1619–21. http://dx.doi.org/10.1212/01.wnl.0000277696.34724.76.
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Villar González, Pamela, Onur Güntürkün i Sebastian Ocklenburg. "Lateralization of Auditory Processing of Silbo Gomero". Symmetry 12, nr 7 (17.07.2020): 1183. http://dx.doi.org/10.3390/sym12071183.
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Left-hemispheric language dominance is a well-known characteristic of the human language system. However, it has been shown that leftward language lateralization decreases dramatically when people communicate using whistles. Whistled languages present a transformation of a spoken language into whistles, facilitating communication over great distances. In order to investigate the laterality of Silbo Gomero, a form of whistled Spanish, we used a vocal and a whistled dichotic listening task in a sample of 75 healthy Spanish speakers. Both individuals that were able to whistle and to understand Silbo Gomero and a non-whistling control group showed a clear right-ear advantage for vocal dichotic listening. For whistled dichotic listening, the control group did not show any hemispheric asymmetries. In contrast, the whistlers’ group showed a right-ear advantage for whistled stimuli. This right-ear advantage was, however, smaller compared to the right-ear advantage found for vocal dichotic listening. In line with a previous study on language lateralization of whistled Turkish, these findings suggest that whistled language processing is associated with a decrease in left and a relative increase in right hemispheric processing. This shows that bihemispheric processing of whistled language stimuli occurs independent of language.
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Giljov, Andrey, Karina Karenina i Yegor Malashichev. "Facing each other: mammal mothers and infants prefer the position favouring right hemisphere processing". Biology Letters 14, nr 1 (styczeń 2018): 20170707. http://dx.doi.org/10.1098/rsbl.2017.0707.
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The right hemisphere plays a crucial role in social processing. Human mothers show a robust left cradling/holding bias providing greater right-hemispheric involvement in the exchange of social information between mother and infant. Here, we demonstrate that a similar bias is evident in face-to-face spatial interactions in marine and terrestrial non-primate mammals. Walruses and Indian flying foxes showed a significant population-level preference for the position which facilitates the use of the left visual field in both mother and infant. This behavioural lateralization may have emerged owing to benefits conferred by the enhanced right-hemispheric social processing providing the mother and infant an optimal perception of each other.
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Chen, Aihong, Yue Deng, Xiaobing Zuo i Suting Zhong. "Alteration in Asymmetry of White Matter Network of Parkinson’s Disease". Contrast Media & Molecular Imaging 2022 (4.07.2022): 1–8. http://dx.doi.org/10.1155/2022/8493729.
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Parkinson’s disease (PD) is manifest clinically by an asymmetrical presentation of motor dysfunction. A large number of previous neuroimaging research studies have stated the alteration in the hemispheric asymmetry of morphological features in PD disease. Diffusion Magnetic Resonance Imaging (MRI), which is noninvasive, has been widely used to quantify the white matter network in the human brain of both healthy subjects and patients. Besides, graph theory analysis is widely used to quantify the topological architecture of the human brain network. Lately, researchers have discovered that the topological architecture of the white matter network significantly differs in PD compared with healthy controls (HC). Nevertheless, the asymmetry of the topological architecture of the white matter network for PD patients remains unclear. To clarify this, the diffusion-weighted images and tractography technique were used to reconstruct the hemispherical white matter networks for 22 bilateral PD patients and 18 HC subjects. Network-based statistical analysis and graph theory analysis approaches were employed to estimate the asymmetry at both the connectivity level and the hemispheric topological level for PD patients. We found that the PD group showed atypically right-higher-than-left asymmetry in hemispheric brain global and local efficiencies. The detected right-higher-than-left asymmetry was driven by the atypically topological changes in the left hemispheric brain in the PD group. Findings from these studies might provide new insights into the asymmetric features of hemispheric disconnectivity and emphasize that the topological asymmetry of the hemispheric brain could be used as a biomarker to identify PD individuals.
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Chen, Xianming, Yonghui Liang, Yihong Deng, Jianzhong Li, Shiyan Chen, Cuixia Wang i Ping Luo. "Age-Associated Reduction of Asymmetry in Human Central Auditory Function: A 1H-Magnetic Resonance Spectroscopy Study". Neural Plasticity 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/735290.
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The aim of this study was to investigate the effects of age on hemispheric asymmetry in the auditory cortex after pure tone stimulation. Ten young and 8 older healthy volunteers took part in this study. Two-dimensional multivoxel 1H-magnetic resonance spectroscopy scans were performed before and after stimulation. The ratios of N-acetylaspartate (NAA), glutamate/glutamine (Glx), andγ-amino butyric acid (GABA) to creatine (Cr) were determined and compared between the two groups. The distribution of metabolites between the left and right auditory cortex was also determined. Before stimulation, left and right side NAA/Cr and right side GABA/Cr were significantly lower, whereas right side Glx/Cr was significantly higher in the older group compared with the young group. After stimulation, left and right side NAA/Cr and GABA/Cr were significantly lower, whereas left side Glx/Cr was significantly higher in the older group compared with the young group. There was obvious asymmetry in right side Glx/Cr and left side GABA/Cr after stimulation in young group, but not in older group. In summary, there is marked hemispheric asymmetry in auditory cortical metabolites following pure tone stimulation in young, but not older adults. This reduced asymmetry in older adults may at least in part underlie the speech perception difficulties/presbycusis experienced by aging adults.
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Brancucci, Alfredo, Giuliana Lucci, Andrea Mazzatenta i Luca Tommasi. "Asymmetries of the human social brain in the visual, auditory and chemical modalities". Philosophical Transactions of the Royal Society B: Biological Sciences 364, nr 1519 (4.12.2008): 895–914. http://dx.doi.org/10.1098/rstb.2008.0279.
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Structural and functional asymmetries are present in many regions of the human brain responsible for motor control, sensory and cognitive functions and communication. Here, we focus on hemispheric asymmetries underlying the domain of social perception, broadly conceived as the analysis of information about other individuals based on acoustic, visual and chemical signals. By means of these cues the brain establishes the border between ‘self’ and ‘other’, and interprets the surrounding social world in terms of the physical and behavioural characteristics of conspecifics essential for impression formation and for creating bonds and relationships. We show that, considered from the standpoint of single- and multi-modal sensory analysis, the neural substrates of the perception of voices, faces, gestures, smells and pheromones, as evidenced by modern neuroimaging techniques, are characterized by a general pattern of right-hemispheric functional asymmetry that might benefit from other aspects of hemispheric lateralization rather than constituting a true specialization for social information.
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Carswell, C. Melody, i Christopher D. Wickens. "Lateral Task Segregation and the Task-Hemispheric Integrity Effect". Human Factors: The Journal of the Human Factors and Ergonomics Society 27, nr 6 (grudzień 1985): 695–700. http://dx.doi.org/10.1177/001872088502700608.
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The task-hemispheric integrity effect refers to the high time-sharing efficiency obtained for the concurrent performance of a verbal and spatial task when the spatial task is displayed to the left of the operator's midline and is controlled by the left hand and the verbal components are located to the operator's right. Results of two experiments are reported, each designed to test the contribution of lateral display or control separation to the task-hemispheric integrity advantage. Reduction of display separation greatly reduced the effects associated with such hemispheric compatibility. Allocating both controls to the same hand eliminated these effects altogether. The constraints imposed by these data on the application of the task-hemispheric integrity principle of S-C-R compatibility are discussed.
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Perlmutter, Joel S., William J. Powers, Peter Herscovitch, Peter T. Fox i Marcus E. Raichle. "Regional Asymmetries of Cerebral Blood Flow, Blood Volume, and Oxygen Utilization and Extraction in Normal Subjects". Journal of Cerebral Blood Flow & Metabolism 7, nr 1 (luty 1987): 64–67. http://dx.doi.org/10.1038/jcbfm.1987.9.
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Positron emission tomography (PET) and 15O-labeled radiotracers were used to measure regional CBF, cerebral blood volume (CBV), CMRO2, and oxygen extraction in 32 right-handed subjects at rest. Mean left hemispheric CBF (46.2 ± 6.8 ml/100 g/min) and CMRO2 (2.60 ± 0.59 ml/100 g/min) were significantly lower than right hemispheric values (47.4 ± 7.2 and 2.66 ± 0.61 ml/100 g/min, respectively; p < 0.0001 for both), whereas left and right hemispheric CBV and oxygen extraction were not significantly different. We further investigated these asymmetries by comparing left- and right-sided values for specific cortical and subcortical regions. We found that left-sided CBF and CMRO2 were significantly lower than right-sided values for sensorimotor, occipital, and superior temporal regions, whereas only left-sided CBF values were lower for anterior cingulum. CBV was asymmetric for the anterior cingulate and midfrontal regions, and oxygen extraction was asymmetric for the sensorimotor area. No asymmetries were observed in inferior parietal cortex, thalamus, putamen, or pallidum. Knowledge of these normal physiological asymmetries is essential for proper interpretation of PET studies of physiology and pathology. Furthermore, the ability to detect asymmetries with PET may lead to a better understanding of the lateralization of specific functions in the human brain.
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Vesia, Michael, Xiaogang Yan, Denise Y. Henriques, Lauren E. Sergio i J. D. Crawford. "Transcranial Magnetic Stimulation Over Human Dorsal–Lateral Posterior Parietal Cortex Disrupts Integration of Hand Position Signals Into the Reach Plan". Journal of Neurophysiology 100, nr 4 (październik 2008): 2005–14. http://dx.doi.org/10.1152/jn.90519.2008.
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Posterior parietal cortex (PPC) has been implicated in the integration of visual and proprioceptive information for the planning of action. We previously reported that single-pulse transcranial magnetic stimulation (TMS) over dorsal–lateral PPC perturbs the early stages of spatial processing for memory-guided reaching. However, our data did not distinguish whether TMS disrupted the reach goal or the internal estimate of initial hand position needed to calculate the reach vector. To test between these hypotheses, we investigated reaching in six healthy humans during left and right parietal TMS while varying visual feedback of the movement. We reasoned that if TMS were disrupting the internal representation of hand position, visual feedback from the hand might still recalibrate this signal. We tested four viewing conditions: 1) final vision of hand position; 2) full vision of hand position; 3) initial and final vision of hand position; and 4) middle and final vision of hand position. During the final vision condition, left parietal stimulation significantly increased endpoint variability, whereas right parietal stimulation produced a significant leftward shift in both visual fields. However, these errors significantly decreased with visual feedback of the hand during both planning and control stages of the reach movement. These new findings demonstrate that 1) visual feedback of hand position during the planning and early execution of the reach can recalibrate the perturbed signal and, importantly, and 2) TMS over dorsal–lateral PPC does not disrupt the internal representation of the visual goal, but rather the reach vector, or more likely the sense of initial hand position that is used to calculate this vector.
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Kirimoto, Hikari, Tatsunori Watanabe, Nami Kubo, Shota Date, Toru Sunagawa, Tatsuya Mima, Katsuya Ogata, Hisato Nakazono, Shozo Tobimatsu i Antonio Oliviero. "Influence of Static Magnetic Field Stimulation on the Accuracy of Tachystoscopically Presented Line Bisection". Brain Sciences 10, nr 12 (18.12.2020): 1006. http://dx.doi.org/10.3390/brainsci10121006.
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Transcranial static magnetic stimulation (tSMS) has been known to reduce human cortical excitability. Here, we investigated whether tSMS would modulate visuo-spatial cognition in healthy humans. Subjects performed a visuo-spatial task requiring judgements about the symmetry of pre-bisected lines. Visual stimuli consisted of symmetrically or asymmetrically transected lines, tachystoscopically presented for 150 ms on a computer monitor. Task performance was examined before, immediately after, and 10 min after tSMS/sham stimulation of 20 min over the posterior parietal cortex (PPC: P4 from the international 10–20 system) or superior temporal gyrus (STG: C6). Nine out of 16 subjects misjudged pre-bisected lines by consistently underestimating the length of the right-side segment (judging lines to be exactly pre-bisected when the transector was located to the left of the midpoint, or judging the left-side segment to be longer when the transector was located at the midpoint). In these subjects showing a leftward bias, tSMS over the right STG reduced the magnitude of the leftward bias. This did not occur with tSMS over the right PPC or sham stimulation. In the remaining right-biased subjects, no intervention effect was observed with any stimulation. Our findings indicate that application of tSMS over the right STG modulates visuo-spatial cognition in healthy adults.
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Xiang Qian, Xu, G. V. Korobeynikov, D. M. Mishchuk i L. G. Korobeynikova. "Features of individual cognitive style of qualified badminton players". Health, sport, rehabilitation 6, nr 4 (20.12.2020): 39–46. http://dx.doi.org/10.34142/hsr.2020.06.04.04.
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Aim: to determine of peculiarities of personal cognitive styles in qualified badminton players.
Material and methods. The studies were carried out using the hardware-software computer complex "Multipsychometer-05". The modified Stroop test was selected. The indicators of the test "Field dependence" were determined: field independence, left hemispheric dominance, functional asymmetry, and the effectiveness of the test. The obtained results of the study were analyzed for the entire sample of badminton players, as well as separately for men and women.
Results. According to the results of scientific research on the field dependence of qualified badminton players, it was found that all athletes in our sample demonstrate a slight bias towards field dependence; dominated by right hemisphere dominance; in functional asymmetry and efficiency, qualified badminton players demonstrate an average level. The analysis of test indicators, taking into account gender dimorphism, showed that among men 72% demonstrate a predominance of right hemispheric dominance of varying degrees, 28% have left hemispheric dominance. As for women, 54% demonstrate a predominance of right hemispheric dominance of varying degrees, and 37% demonstrate left hemispheric dominance of varying degrees.
Conclusions. Men show a tendency towards better test performance and have more pronounced functional asymmetry. The cognitive style of skilled badminton players determines the strategy of selection and processing of information, problem solving, learning and other types of cognitive activities. Because human cognitive-activity styles are genetically determined and demonstrate a pronounced stability of cognitive-stylistic characteristics in ontogenesis, they can be used as prognostic and diagnostic criteria.
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Vikingstad, Eric M., Yue Cao, Ajith J. Thomas, Alex F. Johnson, Ghaus M. Malik i Kenneth M. A. Welch. "Language Hemispheric Dominance in Patients with Congenital Lesions of Eloquent Brain". Neurosurgery 47, nr 3 (1.09.2000): 562–70. http://dx.doi.org/10.1097/00006123-200009000-00004.
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ABSTRACT OBJECTIVE In 90% of normal subjects, the left hemisphere is dominant for language function. We investigated whether congenital lesions of the left perisylvian regions altered cortical language representation in right-handed individuals. METHODS Using functional magnetic resonance imaging, we studied language hemispheric dominance in five right-handed adult patients with congenitally acquired arteriovenous malformations (AVMs) originating from left hemispheric cortical language regions. The AVMs had not caused neurological symptoms during early development, but patients presented as adults with migraine, seizure, or minor hemorrhage. Results obtained from the AVM patients were contrasted to those from right-handed brain-injured stroke patients recovering from aphasia and to those from right-handed normal subjects. RESULTS During silent picture naming and verb generation tasks, cortical language networks lateralized primarily to the right hemisphere in the AVM group, compared with the left hemisphere in the normal group. This right hemisphere-shifted language network in the AVM group exceeded the shifts toward right hemispheric dominance found in the stroke group. CONCLUSION Patients with AVMs affecting the left perisylvian regions recruited the right hemisphere into language processing networks during early development, presumably in response to congenitally aberrant circulation. This early right hemisphere recruitment in the AVM patients exceeded the similar process in the brains of stroke patients whose left cortical language networks were damaged in adulthood. Our data provide evidence of effective plasticity in the developing human brain compared with the mature brain response to injury. Knowledge of cortical language representation should assist presurgical planning in patients with developmental anomalies affecting apparently language-dominant brain regions.
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Frak, Victor, D. Bourbonnais, I. Croteau i H. Cohen. "Interlimb Transfer of Grasp Orientation is Asymmetrical". Scientific World JOURNAL 6 (2006): 1805–9. http://dx.doi.org/10.1100/tsw.2006.291.
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One the most fundamental aspects of the human motor system is the hemispheric asymmetry seen in behavioral specialization. Hemispheric dominance can be inferred by a contralateral hand preference in grasping. Few studies have considered grasp orientation in the context of manual lateralization and none has looked at grasp orientation with natural prehension. Thirty right-handed adults performed precision grasps of a cylinder using the thumb and index fingers, and the opposition axis (OA) was defined as the line connecting these two contact points on the cylinder. Subjects made ten consecutive grasps with one hand (primary hand movements) followed by ten grasps with the other hand (trailing movements). Differences between primary and trailing grasps revealed that each hemisphere is capable of programming the orientation of the OA and that primary movements with the right hand significantly influenced OA orientation of the trailing left hand. These results extend the hemispheric dominance of the left hemisphere to the final positions of fingers during prehension.
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Lochy, Aliette, Adélaïde de Heering i Bruno Rossion. "The non-linear development of the right hemispheric specialization for human face perception". Neuropsychologia 126 (marzec 2019): 10–19. http://dx.doi.org/10.1016/j.neuropsychologia.2017.06.029.
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Rinaldi, Luca, Andrea Ciricugno, Lotfi B. Merabet, Tomaso Vecchi i Zaira Cattaneo. "The Effect of Blindness on Spatial Asymmetries". Brain Sciences 10, nr 10 (23.09.2020): 662. http://dx.doi.org/10.3390/brainsci10100662.
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The human cerebral cortex is asymmetrically organized with hemispheric lateralization pervading nearly all neural systems of the brain. Whether the lack of normal visual development affects hemispheric specialization subserving the deployment of visuospatial attention asymmetries is controversial. In principle, indeed, the lack of early visual experience may affect the lateralization of spatial functions, and the blind may rely on a different sensory input compared to the sighted. In this review article, we thus present a current state-of-the-art synthesis of empirical evidence concerning the effects of visual deprivation on the lateralization of various spatial processes (i.e., including line bisection, mirror symmetry, and localization tasks). Overall, the evidence reviewed indicates that spatial processes are supported by a right hemispheric network in the blind, hence, analogously to the sighted. Such a right-hemisphere dominance, however, seems more accentuated in the blind as compared to the sighted as indexed by the greater leftward bias shown in different spatial tasks. This is possibly the result of the more pronounced involvement of the right parietal cortex during spatial tasks in blind individuals compared to the sighted, as well as of the additional recruitment of the right occipital cortex, which would reflect the cross-modal plastic phenomena that largely characterize the blind brain.
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Ruff, Christian C., Felix Blankenburg, Otto Bjoertomt, Sven Bestmann, Nikolaus Weiskopf i Jon Driver. "Hemispheric Differences in Frontal and Parietal Influences on Human Occipital Cortex: Direct Confirmation with Concurrent TMS–fMRI". Journal of Cognitive Neuroscience 21, nr 6 (czerwiec 2009): 1146–61. http://dx.doi.org/10.1162/jocn.2009.21097.
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We used concurrent TMS–fMRI to test directly for hemispheric differences in causal influences of the right or left fronto-parietal cortex on activity (BOLD signal) in the human occipital cortex. Clinical data and some behavioral TMS studies have been taken to suggest right-hemisphere specialization for top–down modulation of vision in humans, based on deficits such as spatial neglect or extinction in lesioned patients, or findings that TMS to right (vs. left) fronto-parietal structures can elicit stronger effects on visual performance. But prior to the recent advent of concurrent TMS and neuroimaging, it was not possible to directly examine the causal impact of one (stimulated) brain region upon others in humans. Here we stimulated the frontal or intraparietal cortex in the left or right hemisphere with TMS, inside an MR scanner, while measuring with fMRI any resulting BOLD signal changes in visual areas V1–V4 and V5/MT+. For both frontal and parietal stimulation, we found clear differences between effects of right- versus left-hemisphere TMS on activity in the visual cortex, with all differences significant in direct statistical comparisons. Frontal TMS over either hemisphere elicited similar BOLD decreases for central visual field representations in V1–V4, but only right frontal TMS led to BOLD increases for peripheral field representations in these regions. Hemispheric differences for effects of parietal TMS were even more marked: Right parietal TMS led to strong BOLD changes in V1–V4 and V5/MT+, but left parietal TMS did not. These data directly confirm that the human frontal and parietal cortex show right-hemisphere specialization for causal influences on the visual cortex.
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Gainotti, Guido. "The Difficult Integration between Human and Animal Studies on Emotional Lateralization: A Perspective Article". Brain Sciences 11, nr 8 (23.07.2021): 975. http://dx.doi.org/10.3390/brainsci11080975.
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Even if for many years hemispheric asymmetries have been considered as a uniquely human feature, an increasing number of studies have described hemispheric asymmetries for various behavioral functions in several nonhuman species. An aspect of animal lateralization that has attracted particular attention has concerned the hemispheric asymmetries for emotions, but human and animal studies on this subject have been developed as independent lines of investigation, without attempts for their integration. In this perspective article, after an illustration of factors that have hampered the integration between human and animal studies on emotional lateralization, I will pass to analyze components and stages of the processing of emotions to distinguish those which point to a continuum between humans and many animal species, from those which suggest a similarity only between humans and great apes. The right lateralization of sympathetic functions (involved in brain and bodily activities necessary in emergency situations) seems consistent across many animal species, whereas asymmetries in emotional communication and in structures involved in emotional experience, similar to those observed in humans, have been documented only in primates.
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Meng, Ming, Tharian Cherian, Gaurav Singal i Pawan Sinha. "Lateralization of face processing in the human brain". Proceedings of the Royal Society B: Biological Sciences 279, nr 1735 (4.01.2012): 2052–61. http://dx.doi.org/10.1098/rspb.2011.1784.
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Are visual face processing mechanisms the same in the left and right cerebral hemispheres? The possibility of such ‘duplicated processing’ seems puzzling in terms of neural resource usage, and we currently lack a precise characterization of the lateral differences in face processing. To address this need, we have undertaken a three-pronged approach. Using functional magnetic resonance imaging, we assessed cortical sensitivity to facial semblance, the modulatory effects of context and temporal response dynamics. Results on all three fronts revealed systematic hemispheric differences. We found that: (i) activation patterns in the left fusiform gyrus correlate with image-level face-semblance, while those in the right correlate with categorical face/non-face judgements. (ii) Context exerts significant excitatory/inhibitory influence in the left, but has limited effect on the right. (iii) Face-selectivity persists in the right even after activity on the left has returned to baseline. These results provide important clues regarding the functional architecture of face processing, suggesting that the left hemisphere is involved in processing ‘low-level’ face semblance, and perhaps is a precursor to categorical ‘deep’ analyses on the right.
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Schwartz, Theodore H., Michael M. Haglund, Ettore Lettich i George A. Ojemann. "Asymmetry of Neuronal Activity During Extracellular Microelectrode Recording from Left and Right Human Temporal Lobe Neocortex During Rhyming and Line-Matching". Journal of Cognitive Neuroscience 12, nr 5 (wrzesień 2000): 803–12. http://dx.doi.org/10.1162/089892900562615.
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Recordings of neuronal activity in humans have identified few correlates of the known hemispheric asymmetries of functional lateralization. Here, we examine single-unit activity recorded from both hemispheres during two delayed match-to-sample tasks that show strong hemispheric lateralization based on lesion effects; a line-matching (LM) task related to the right hemisphere, and a rhyming (RHY) task related to the left. Nineteen neuronal populations were recorded with extracellular microelectrodes from the left temporal neocortex of 11 awake patients, and 18 from the right in 9 patients during anterior temporal lobectomy for complex partial seizures under local anesthesia. All subjects were left hemisphere dominant for language. Twelve (32%) populations exhibited statistically significant changes in activity at p < .05. Although changes in firing frequency were recorded from both hemispheres during both tasks, the RHY task elicited changes in activity several hundred milliseconds earlier on the left side than on the right. The LM task, on the other hand, induced changes earlier on the right side than on the left. Both hemispheres contained units active during verbal responses regardless of which behavior elicited the response. Our results indicate that cerebral dominance is reflected in earlier neuronal activity in the anterior temporal lobe during tasks lateralized to that hemisphere.
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Albanese, M. C., E. G. Duerden, V. Bohotin, P. Rainville i G. H. Duncan. "Differential Effects of Cognitive Demand on Human Cortical Activation Associated With Vibrotactile Stimulation". Journal of Neurophysiology 102, nr 3 (wrzesień 2009): 1623–31. http://dx.doi.org/10.1152/jn.91295.2008.
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This event-related functional MRI study examines the neural correlates of vibrotactile sensation within the context of different psychophysical demands. Nine subjects received vibrotactile stimuli on the right volar forearm during detection, localization, and passive tasks. In the detection task, subjects indicated the offset (end) of each stimulus by pressing a response key with their left hand. In the localization task, subjects identified the location of the stimulus (“distal?” or “proximal?”) by pressing the appropriate response key 4 s after the end of the stimulus. In the passive task, subjects received the same vibrotactile stimuli, but no response was required. Analysis of stimulus-evoked activity compared with the resting baseline period revealed significant bilateral secondary somatosensory cortex activation for all three tasks. However, only in the offset-detection and localization tasks was stimulus-evoked activation observed in other expected areas of tactile processing, such as contralateral primary somatosensory cortex neighboring the posterior parietal cortex (SI/PPC) and in bilateral anterior insular cortex (aIC). During the localization task, we identified vibrotactile-evoked activation in the right aIC, which was maintained after the termination of the stimulus. Results suggest that vibrotactile-related activation within SI/PPC and aIC is enhanced by the increased levels of attention and cognitive demands required by the detection and localization tasks. Activation of aIC not only during vibrotactile stimulation, but also during the poststimulus delay in the localization trials, is consistent with the growing literature linking this area with the perception and short-term memory of tactile information.
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Ogawa, Kenji, i Toshio Inui. "Lateralization of the Posterior Parietal Cortex for Internal Monitoring of Self- versus Externally Generated Movements". Journal of Cognitive Neuroscience 19, nr 11 (listopad 2007): 1827–35. http://dx.doi.org/10.1162/jocn.2007.19.11.1827.
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Internal monitoring or state estimation of movements is essential for human motor control to compensate for inherent delays and noise in sensorimotor loops. Two types of internal estimation of movements exist: self-generated movements, and externally generated movements. We used functional magnetic resonance imaging to investigate differences in brain activity for internal monitoring of self- versus externally generated movements during visual occlusion. Participants tracked a sinusoidally moving target with a mouse cursor. On some trials, vision of either target (externally generated) or cursor (self-generated) movement was transiently occluded, during which subjects continued tracking by estimating current position of either the invisible target or cursor on screen. Analysis revealed that both occlusion conditions were associated with increased activity in the presupplementary motor area and decreased activity in the right lateral occipital cortex compared to a control condition with no occlusion. Moreover, the right and left posterior parietal cortex (PPC) showed greater activation during occlusion of target and cursor movements, respectively. This study suggests lateralization of the PPC for internal monitoring of internally versus externally generated movements, fully consistent with previously reported clinical findings.
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Shu, Ni, Yaou Liu, Yunyun Duan i Kuncheng Li. "Hemispheric Asymmetry of Human Brain Anatomical Network Revealed by Diffusion Tensor Tractography". BioMed Research International 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/908917.
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The topological architecture of the cerebral anatomical network reflects the structural organization of the human brain. Recently, topological measures based on graph theory have provided new approaches for quantifying large-scale anatomical networks. However, few studies have investigated the hemispheric asymmetries of the human brain from the perspective of the network model, and little is known about the asymmetries of the connection patterns of brain regions, which may reflect the functional integration and interaction between different regions. Here, we utilized diffusion tensor imaging to construct binary anatomical networks for 72 right-handed healthy adult subjects. We established the existence of structural connections between any pair of the 90 cortical and subcortical regions using deterministic tractography. To investigate the hemispheric asymmetries of the brain, statistical analyses were performed to reveal the brain regions with significant differences between bilateral topological properties, such as degree of connectivity, characteristic path length, and betweenness centrality. Furthermore, local structural connections were also investigated to examine the local asymmetries of some specific white matter tracts. From the perspective of both the global and local connection patterns, we identified the brain regions with hemispheric asymmetries. Combined with the previous studies, we suggested that the topological asymmetries in the anatomical network may reflect the functional lateralization of the human brain.
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Behne, Nicole, Beate Wendt, Henning Scheich i André Brechmann. "Contralateral White Noise Selectively Changes Left Human Auditory Cortex Activity in a Lexical Decision Task". Journal of Neurophysiology 95, nr 4 (kwiecień 2006): 2630–37. http://dx.doi.org/10.1152/jn.01201.2005.
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In a previous study, we hypothesized that the approach of presenting information-bearing stimuli to one ear and noise to the other ear may be a general strategy to determine hemispheric specialization in auditory cortex (AC). In that study, we confirmed the dominant role of the right AC in directional categorization of frequency modulations by showing that fMRI activation of right but not left AC was sharply emphasized when masking noise was presented to the contralateral ear. Here, we tested this hypothesis using a lexical decision task supposed to be mainly processed in the left hemisphere. Subjects had to distinguish between pseudowords and natural words presented monaurally to the left or right ear either with or without white noise to the other ear. According to our hypothesis, we expected a strong effect of contralateral noise on fMRI activity in left AC. For the control conditions without noise, we found that activation in both auditory cortices was stronger on contralateral than on ipsilateral word stimulation consistent with a more influential contralateral than ipsilateral auditory pathway. Additional presentation of contralateral noise did not significantly change activation in right AC, whereas it led to a significant increase of activation in left AC compared with the condition without noise. This is consistent with a left hemispheric specialization for lexical decisions. Thus our results support the hypothesis that activation by ipsilateral information-bearing stimuli is upregulated mainly in the hemisphere specialized for a given task when noise is presented to the more influential contralateral ear.
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Kumar, Neeraj, Amit Jaiswal, Dipanjan Roy i Arpan Banerjee. "Effective networks mediate right hemispheric dominance of human 40 Hz auditory steady-state response." Neuropsychologia 184 (czerwiec 2023): 108559. http://dx.doi.org/10.1016/j.neuropsychologia.2023.108559.
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Thomason, Moriah E., Elizabeth Race, Brittany Burrows, Susan Whitfield-Gabrieli, Gary H. Glover i John D. E. Gabrieli. "Development of Spatial and Verbal Working Memory Capacity in the Human Brain". Journal of Cognitive Neuroscience 21, nr 2 (luty 2009): 316–32. http://dx.doi.org/10.1162/jocn.2008.21028.
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A core aspect of working memory (WM) is the capacity to maintain goal-relevant information in mind, but little is known about how this capacity develops in the human brain. We compared brain activation, via fMRI, between children (ages 7–12 years) and adults (ages 20–29 years) performing tests of verbal and spatial WM with varying amounts (loads) of information to be maintained in WM. Children made disproportionately more errors than adults as WM load increased. Children and adults exhibited similar hemispheric asymmetry in activation, greater on the right for spatial WM and on the left for verbal WM. Children, however, failed to exhibit the same degree of increasing activation across WM loads as was exhibited by adults in multiple frontal and parietal cortical regions. Thus, children exhibited adult-like hemispheric specialization, but appeared immature in their ability to marshal the neural resources necessary to maintain large amounts of verbal or spatial information in WM.
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Serino, Andrea, Elisa Canzoneri i Alessio Avenanti. "Fronto-parietal Areas Necessary for a Multisensory Representation of Peripersonal Space in Humans: An rTMS Study". Journal of Cognitive Neuroscience 23, nr 10 (październik 2011): 2956–67. http://dx.doi.org/10.1162/jocn_a_00006.
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A network of brain regions including the ventral premotor cortex (vPMc) and the posterior parietal cortex (PPc) is consistently recruited during processing of multisensory stimuli within peripersonal space (PPS). However, to date, information on the causal role of these fronto-parietal areas in multisensory PPS representation is lacking. Using low-frequency repetitive TMS (rTMS; 1 Hz), we induced transient virtual lesions to the left vPMc, PPc, and visual cortex (V1, control site) and tested whether rTMS affected audio–tactile interaction in the PPS around the hand. Subjects performed a timed response task to a tactile stimulus on their right (contralateral to rTMS) hand while concurrent task-irrelevant sounds were presented either close to the hand or 1 m far from the hand. When no rTMS was delivered, a sound close to the hand reduced RT-to-tactile targets as compared with when a far sound was presented. This space-dependent, auditory modulation of tactile perception was specific to a hand-centered reference frame. Such a specific form of multisensory interaction near the hand can be taken as a behavioral hallmark of PPS representation. Crucially, virtual lesions to vPMc and PPc, but not to V1, eliminated the speeding effect due to near sounds, showing a disruption of audio–tactile interactions around the hand. These findings indicate that multisensory interaction around the hand depends on the functions of vPMc and PPc, thus pointing to the necessity of this human fronto-parietal network in multisensory representation of PPS.
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Gosavi, Shilpa N. "Morphological Evaluation and Inter-hemispheric Differences of Human Sylvain Sulcus: A Cadaveric Study". Bharati Vidyapeeth Medical Journal 3, nr 1 (31.03.2023): 9–12. http://dx.doi.org/10.56136/bvmj/2022_00110.
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Background: The current literature specifies variations in the morphology of the lateral sulcus in the human brain, and it is highly confined to the point of its posterior termination. The present study was conducted to evaluate morphometric characteristics of lateral sulcus as well as to find out associated interhemispheric differences among adult brain samples. Methodology: Across-sectional study was carried out at the Department of Anatomy of one of the medical colleges in Pune city of Maharashtra. In the study, 54 formalin-fixed intact adult brains, irrespective of gender, were examined. The lateral sulcus was inspected for each segment, surface, and termination from the given samples. The data was entered into Microsoft Office Excel Sheet. The data analysis was done using Statistical Package for Social Sciences (SPSS) version 25 software. Results: The most frequently occurred termination types, viz. oblique and straight. The U-shaped configuration was observed to be the commonest pattern. The diagonal sulcus was noted in 32 (59.25%) hemispheres, while the triangularis sulcus was identified in 45 (83.33%) hemispheres. The mean of the total length of the lateral sulcus on the left side was greater than on the right side. The left lateral sulcus was significantly longer than the right, and both were positively correlated. Conclusion: The findings of present study conform to the literature regarding the morphology of lateral sulcus and associated inter-hemispheric differences related to it
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Morimoto, Hiroki M., Satoshi Hirose, Junichi Chikazoe, Koji Jimura, Tomoki Asari, Ken-ichiro Yamashita, Yasushi Miyashita i Seiki Konishi. "On Verbal/Nonverbal Modality Dependence of Left and Right Inferior Prefrontal Activation during Performance of Flanker Interference Task". Journal of Cognitive Neuroscience 20, nr 11 (listopad 2008): 2006–14. http://dx.doi.org/10.1162/jocn.2008.20138.
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One of the most prevailing views on the functional localization of human cognition is the hemispheric specialization, wherein the left and right hemispheres are implicated primarily in verbal and nonverbal functions, respectively. Cognitive control is known to involve the lateral prefrontal cortex. However, it remains unclear whether the hemispheric specialization in the lateral prefrontal cortex can be observed in cognitive control per se, independent of sensory aspects of stimulus materials. In this functional magnetic resonance imaging study, we tested whether the verbal/nonverbal hemispheric specialization applies to the lateral prefrontal activation by investigating interference suppression, the ability to filter out irrelevant information in the environment. The flanker task was employed using a compound stimulus that contained a target and a flanker. The flanked stimulus was either a color word flanked by a colored patch or a colored patch flanked by a color word, which allowed us to manipulate the modality of the presented flanker stimulus from which interference originates, keeping the total stimulus modality balanced. The inferior frontal gyrus (IFG) showed prominent Modality-by-Hemisphere interaction in interference suppression, the left IFG being activated when a word flanker (plus a patch target) was presented and the right IFG being activated when a patch flanker (plus a word target) was presented. These results suggest that the verbal/nonverbal hemispheric specialization in the IFG can be explained by cognitive control processes per se, independent of sensory aspects of presented materials.
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Jonas, Jacques, Corentin Jacques, Joan Liu-Shuang, Hélène Brissart, Sophie Colnat-Coulbois, Louis Maillard i Bruno Rossion. "A face-selective ventral occipito-temporal map of the human brain with intracerebral potentials". Proceedings of the National Academy of Sciences 113, nr 28 (27.06.2016): E4088—E4097. http://dx.doi.org/10.1073/pnas.1522033113.
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Human neuroimaging studies have identified a network of distinct face-selective regions in the ventral occipito-temporal cortex (VOTC), with a right hemispheric dominance. To date, there is no evidence for this hemispheric and regional specialization with direct measures of brain activity. To address this gap in knowledge, we recorded local neurophysiological activity from 1,678 contact electrodes implanted in the VOTC of a large group of epileptic patients (n = 28). They were presented with natural images of objects at a rapid fixed rate (six images per second: 6 Hz), with faces interleaved as every fifth stimulus (i.e., 1.2 Hz). High signal-to-noise ratio face-selective responses were objectively (i.e., exactly at the face stimulation frequency) identified and quantified throughout the whole VOTC. Face-selective responses were widely distributed across the whole VOTC, but also spatially clustered in specific regions. Among these regions, the lateral section of the right middle fusiform gyrus showed the largest face-selective response by far, offering, to our knowledge, the first supporting evidence of two decades of neuroimaging observations with direct neural measures. In addition, three distinct regions with a high proportion of face-selective responses were disclosed in the right ventral anterior temporal lobe, a region that is undersampled in neuroimaging because of magnetic susceptibility artifacts. A high proportion of contacts responding only to faces (i.e., “face-exclusive” responses) were found in these regions, suggesting that they contain populations of neurons involved in dedicated face-processing functions. Overall, these observations provide a comprehensive mapping of visual category selectivity in the whole human VOTC with direct neural measures.
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Kruja, Jera, Altin Kuqo, Serla Grabova, Arben Rroji i Gentian Vyshka. "Right Hemispheric Leukoencephalopathy as an Incidental Finding Following a Lightning Strike". Open Access Macedonian Journal of Medical Sciences 4, nr 4 (13.12.2016): 692–94. http://dx.doi.org/10.3889/oamjms.2016.141.
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BACKGROUND: Lightning injuries may produce a variety of medical conditions, and specific neurological complications have been identified, with the character of immediate aftershock effects or even long-term consequences.AIM: The authors describe the incidental finding following a routine unenhanced brain MRI performed to a young female patient, suffering from a headache.CASE REPORT: Diffuse white matter changes with the character of a leukoencephalopathy were seen, which strictly interested only the right cerebral hemisphere. The parents referred that she suffered from an indoor lightning strike at age of seven months, although she survived with almost no external burns or signs, and recovered uneventfully at that time. A discussion over the effects of electrocution and lightning strike on the human body in general, and over the nervous system, is made. Particular attention must be shown when making the differential diagnosis of leukoencephalopathies with a strictly one-hemisphere extension since several other conditions might resemble each other under the radiological aspect, here including brain viral infections, genetic disorders, and so on.CONCLUSION: The particularity of the long-term aftershock effects of the lightning strike on the central nervous system raise again the necessity of collecting data and duly reporting every electrical accident, lightning events included.
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García-Quintero, Ximena, Angélica Claros-Hulbert, María Elena Tello-Cajiao, Jhon Edwar Bolaños-Lopez, María Isabel Cuervo-Suárez, Martha Gabriela García Durán, Wendy Gómez-García, Michael McNeil i Justin N. Baker. "Using EmPalPed—An Educational Toolkit on Essential Messages in Palliative Care and Pain Management in Children—As a Strategy to Promote Pediatric Palliative Care". Children 9, nr 6 (6.06.2022): 838. http://dx.doi.org/10.3390/children9060838.
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Background: Most children needing palliative care (PC) live in low- and middle-income countries. In Colombia, pediatric palliative care (PPC) knowledge among healthcare professionals (HCPs) is lacking as PPC is not included in the educational curricula of healthcare programs. Therefore, specific training that improves knowledge of HCPs and access to PC for children and their families is needed. To address this gap, we organized and conducted the Essential Messages in Palliative Care and Pain Management in Children (EmPalPed), an educational toolkit to increase awareness and promote essential knowledge in PPC for low- and middle-income countries. Methodology: The EmPalPed toolkit consisted of a 5-h virtual workshop with small working groups of HCPs caring for children with life-threatening conditions such as cancer. The toolkit was organized along five key domains: (1) PC as it relates to the concept of quality of life (QoL), (2) effective communication, (3) addressing pain management as a top priority, (4) providing end-of-life care, and (5) access to high-quality PC as a fundamental human right. The workshop activities included different educational strategies and tools (e.g., a pocket guide for pain assessment and management, a PPC booklet, a quick guide for communicating bad news, role playing, and discussions of clinical cases). Results: A total of 145 HCPs from 22 centers were trained. The post-test analysis for HCPs showed that attitude and knowledge about communication (p < 0.001), pain assessment (p < 0.001), first-line opioid of choice in children (p < 0.001), and palliative sedation (p < 0.001) had positive and statistically significant changes from the pre-test analysis. Discussion: This study supported the notion that the EmPalPed educational toolkit is an effective mechanism for raising awareness regarding PPC as well as providing training in many of the key aspects of PPC. The EmPalPed training approach should be studied beyond this setting, and the impact should be measured longitudinally.
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Rossion, Bruno, Laurence Dricot, Anne Devolder, Jean-Michel Bodart, Marc Crommelinck, Beatrice de Gelder i Richard Zoontjes. "Hemispheric Asymmetries for Whole-Based and Part-Based Face Processing in the Human Fusiform Gyrus". Journal of Cognitive Neuroscience 12, nr 5 (wrzesień 2000): 793–802. http://dx.doi.org/10.1162/089892900562606.
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Behavioral studies indicate a right hemisphere advantage for processing a face as a whole and a left hemisphere superiority for processing based on face features. The present PET study identifies the anatomical localization of these effects in well-defined regions of the middle fusiform gyri of both hemispheres. The right middle fusiform gyrus, previously described as a face-specific region, was found to be more activated when matching whole faces than face parts whereas this pattern of activity was reversed in the left homologous region. These lateralized differences appeared to be specific to faces since control objects processed either as wholes or parts did not induce any change of activity within these regions. This double dissociation between two modes of face processing brings new evidence regarding the lateralized localization of face individualization mechanisms in the human brain.
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Zhao, Chenxi, Liyuan Yang, Sheng Xie, Zhixin Zhang, Hui Pan i Gaolang Gong. "Hemispheric Module-Specific Influence of the X Chromosome on White Matter Connectivity: Evidence from Girls with Turner Syndrome". Cerebral Cortex 29, nr 11 (7.01.2019): 4580–94. http://dx.doi.org/10.1093/cercor/bhy335.
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AbstractTurner syndrome (TS) is caused by the congenital absence of all or part of one of the X chromosomes in females, offering a valuable human “knockout model” to study the functioning patterns of the X chromosome in the human brain. Little is known about whether and how the loss of the X chromosome influences the brain structural wiring patterns in human. We acquired a multimodal MRI dataset and cognitive assessments from 22 girls with TS and 21 age-matched control girls to address these questions. Hemispheric white matter (WM) networks and modules were derived using refined diffusion MRI tractography. Statistical comparisons revealed a reduced topological efficiency of both hemispheric networks and bilateral parietal modules in TS girls. Specifically, the efficiency of right parietal module significantly mediated the effect of the X chromosome on working memory performance, indicating that X chromosome loss impairs working memory performance by disrupting this module. Additionally, TS girls showed structural and functional connectivity decoupling across specific within- and between-modular connections, predominantly in the right hemisphere. These findings provide novel insights into the functional pathways in the brain that are regulated by the X chromosome and highlight a module-specific genetic contribution to WM connectivity in the human brain.
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Meola, Antonio, Ayhan Comert, Fang-Cheng Yeh, Sananthan Sivakanthan i Juan C. Fernandez-Miranda. "The nondecussating pathway of the dentatorubrothalamic tract in humans: human connectome-based tractographic study and microdissection validation". Journal of Neurosurgery 124, nr 5 (maj 2016): 1406–12. http://dx.doi.org/10.3171/2015.4.jns142741.
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OBJECT The dentatorubrothalamic tract (DRTT) is the major efferent cerebellar pathway arising from the dentate nucleus (DN) and decussating to the contralateral red nucleus (RN) and thalamus. Surprisingly, hemispheric cerebellar output influences bilateral limb movements. In animals, uncrossed projections from the DN to the ipsilateral RN and thalamus may explain this phenomenon. The aim of this study was to clarify the anatomy of the dentatorubrothalamic connections in humans. METHODS The authors applied advanced deterministic fiber tractography to a template of 488 subjects from the Human Connectome Project (Q1–Q3 release, WU-Minn HCP consortium) and validated the results with microsurgical dissection of cadaveric brains prepared according to Klingler’s method. RESULTS The authors identified the “classic” decussating DRTT and a corresponding nondecussating path (the nondecussating DRTT, nd-DRTT). Within each of these 2 tracts some fibers stop at the level of the RN, forming the dentatorubro tract and the nondecussating dentatorubro tract. The left nd-DRTT encompasses 21.7% of the tracts and 24.9% of the volume of the left superior cerebellar peduncle, and the right nd-DRTT encompasses 20.2% of the tracts and 28.4% of the volume of the right superior cerebellar peduncle. CONCLUSIONS The connections of the DN with the RN and thalamus are bilateral, not ipsilateral only. This affords a potential anatomical substrate for bilateral limb motor effects originating in a single cerebellar hemisphere under physiological conditions, and for bilateral limb motor impairment in hemispheric cerebellar lesions such as ischemic stroke and hemorrhage, and after resection of hemispheric tumors and arteriovenous malformations. Furthermore, when a lesion is located on the course of the dentatorubrothalamic system, a careful preoperative tractographic analysis of the relationship of the DRTT, nd-DRTT, and the lesion should be performed in order to tailor the surgical approach properly and spare all bundles.