55 results found
Nigmatullina Y, Hellyer PM, Nachev P, et al., 2014, The neuroanatomical correlates of vestibular adaptation in ballet dancers, Joint Congress of European Neurology, Publisher: SPRINGER HEIDELBERG, Pages: S190-S191, ISSN: 0340-5354
Nigmatullina Y, Hellyer PM, Nachev P, et al., 2014, The neuroanatomical correlates of vestibular adaptation in ballet dancers, Joint Congress of European Neurology, Publisher: WILEY-BLACKWELL, Pages: 278-278, ISSN: 1351-5101
Kwok H-T, Baxter D, DeFelice J, et al., 2014, The neuropathology of blast traumatic brain injury in a porcine polytrauma model, BRAIN INJURY, Vol: 28, Pages: 779-780, ISSN: 0269-9052
Carhart-Harris RL, Leech R, Hellyer PJ, et al., 2014, The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs, FRONTIERS IN HUMAN NEUROSCIENCE, Vol: 8, ISSN: 1662-5161
Ham TE, Bonnelle V, Hellyer P, et al., 2014, The neural basis of impaired self-awareness after traumatic brain injury, BRAIN, Vol: 137, Pages: 586-597, ISSN: 0006-8950
Hellyer PJ, Shanahan MP, Scott G, et al., 2014, The control of global brain dynamics: Opposing actions of frontoparietal control and default mode networks on attention, Journal of Neuroscience, Vol: 34, Pages: 451-461, ISSN: 1529-2401
Baxter D, Sharp DJ, Feeney C, et al., 2013, Pituitary Dysfunction after Blast Traumatic Brain Injury: The UK BIOSAP Study, ANNALS OF NEUROLOGY, Vol: 74, Pages: 527-536, ISSN: 0364-5134
Nigmatullina Y, Hellyer PJ, Nachev P, et al., 2013, The Neuroanatomical Correlates of Training-Related Perceptuo-Reflex Uncoupling in Dancers, Cerebral Cortex, Vol: 25, Pages: 554-562
Sensory input evokes low-order reflexes and higher-order perceptual responses. Vestibular stimulation elicits vestibular-ocular reflex (VOR) and self-motion perception (e.g., vertigo) whose response durations are normally equal. Adaptation to repeated whole-body rotations, for example, ballet training, is known to reduce vestibular responses. We investigated the neuroanatomical correlates of vestibular perceptuo-reflex adaptation in ballet dancers and controls. Dancers' vestibular-reflex and perceptual responses to whole-body yaw-plane step rotations were: (1) Briefer and (2) uncorrelated (controls' reflex and perception were correlated). Voxel-based morphometry showed a selective gray matter (GM) reduction in dancers' vestibular cerebellum correlating with ballet experience. Dancers' vestibular cerebellar GM density reduction was related to shorter perceptual responses (i.e. positively correlated) but longer VOR duration (negatively correlated). Contrastingly, controls' vestibular cerebellar GM density negatively correlated with perception and VOR. Diffusion-tensor imaging showed that cerebral cortex white matter (WM) microstructure correlated with vestibular perception but only in controls. In summary, dancers display vestibular perceptuo-reflex dissociation with the neuronatomical correlate localized to the vestibular cerebellum. Controls' robust vestibular perception correlated with a cortical WM network conspicuously absent in dancers. Since primary vestibular afferents synapse in the vestibular cerebellum, we speculate that a cerebellar gating of perceptual signals to cortical regions mediates the training-related attenuation of vestibular perception and perceptuo-reflex uncoupling.
Hellyer PJ, Leech R, Ham TE, et al., 2013, Individual prediction of white matter injury following traumatic brain injury, Annals of Neurology, ISSN: 1531-8249
Nigmatullina Y, Hellyer PJ, Nachev P, et al., 2012, Attenuation of self-motion perception relates to reduced cortical connectivity, Neuroscience 2012
Hellyer PJ, Sharp DJ, Ham TE, et al., 2012, White and grey matter damage after traumatic brain injury: An integrated approach to explaining cognitive function, Neuroscience 2012
Sharp DJ, Leech R, Ham TE, et al., 2012, Traumatic axonal injury after exposure to blast: A comparison of white matter damage in blast and non-blast traumatic brain injury (Blast Injury Outcome Study in Armed forces Personnel - BIOSAP), Neuroscience 2012
Jilka S, Ham T, Pickering A, et al., 2012, To switch or not to switch: Posterior cingulate cortex response during task switching, Neuroscience 2012
Josephs O, Leech R, Brownsett S, et al., 2012, Filling in Black Holes in fMRI: Dual Gradient Echo EPI with Optimized Z-Shim, Organisation for Human Brain Mapping
Hellyer PJ, Shanahan MP, Scott G, et al., 2012, Global network dynamics during task based activity in the brain., Organisation for Human Brain Mapping
Hellyer PJ, Shanahan MP, Scott G, et al., 2012, Global network dynamics during task based activity in the brain., British Association of Cognitive Neuroscience
Baxter D, Hellyer P, Ham T, et al., 2012, White matter damage and cognitive impairment. A study comparing military blast induced brain injury with civilian diffuse axonal injury and uninjured brains, Publisher: INFORMA HEALTHCARE, Pages: 628-629, ISSN: 0269-9052
Sharp DJ, Hellyer PJ, Ham T, et al., 2011, Predicting cognitive impairment after traumatic brain injury using machine learning applied to diffusion tensor imaging., Neuroscience 2011
Scott G, Hellyer PJ, Shanahan M, et al., 2011, From structural networks to functional networks via coupled oscillators, Neuroscience 2011
Hellyer PJ, Woodhead ZVJ, Leech R, et al., 2011, An investigation of twenty/20 vision in reading, Neuroscience 2011
Ham T, Bonnelle V, Barber T, et al., 2011, THE NEURAL BASIS OF IMPAIRED SELF-AWARENESS AFTER TRAUMATIC BRAIN INJURY, 10th International Neurotrauma Symposium (INTS), Publisher: MARY ANN LIEBERT INC, Pages: A7-A8, ISSN: 0897-7151
One functional anatomical model of reading, drawing on human neuropsychological and neuroimaging data, proposes that a region in left ventral occipitotemporal cortex (vOT) becomes, through experience, specialized for written word perception. We tested this hypothesis by presenting numbers in orthographical and digital form with two task demands, phonological and numerical. We observed a main effect of task on left vOT activity but not stimulus type, with increased activity during the phonological task that was also associated with increased activity in the left inferior frontal gyrus, a region implicated in speech production. Region-of-interest analysis confirmed that there was equal activity for orthographical and digital written forms in the left vOT during the phonological task, despite greater visual complexity of the orthographical forms. This evidence is incompatible with a predominantly feedforward model of written word recognition that proposes that the left vOT is a specialized cortical module for word recognition in literate subjects. Rather, the physiological data presented here fits better with interactive computational models of reading that propose that written word recognition emerges from bidirectional interactions between three processes: visual, phonological, and semantic. Further, the present study is in accord with others that indicate that the left vOT is a route through which nonlinguistic stimuli, perhaps high contrast two-dimensional objects in particular, gain access to a predominantly left-lateralized language and semantic system.
Daws RE, Scott G, Soreq E, et al., Concurrent optimisation of brain states and behavioural strategies when learning complex tasks
<jats:title>Abstract</jats:title><jats:p>We designed two novel fMRI paradigms to investigate how people self-optimise performance when managing competing demands. We hypothesised that the brain adopts distinct functional states to support different tasks, that switching between them involves a costly process of collapse and reconfiguration of the functional connectome, and that this process is optimised with practice. Accordingly, self-ordered switches (SOS) were associated with transient states of low-connectivity and high-activation. Individuals progressively improved their performance with practice. This learning behaviour was reflected by an ongoing redeployment of the neural resources supporting switching and routine behaviour. Furthermore, those who developed more structured behaviours also scored more points, showed a greater deepening of switching-dysconnectivity and a greater tuning of activity within dorsal frontoparietal cortex to switching events with practice. These results demonstrate that a fundamental property of human neurocognitive systems is concurrent self-optimisation to maximise behavioural outcomes and minimise the use of neural resources.</jats:p>
Hellyer PJ, Clopath C, Kehagia AA, et al., Balanced activation in a simple embodied neural simulation
In recent years, there have been many computational simulations ofspontaneous neural dynamics. Here, we explore a model of spontaneous neuraldynamics and allow it to control a virtual agent moving in a simpleenvironment. This setup generates interesting brain-environment feedbackinteractions that rapidly destabilize neural and behavioral dynamics andsuggest the need for homeostatic mechanisms. We investigate roles for bothlocal homeostatic plasticity (local inhibition adjusting over time to balanceexcitatory input) as well as macroscopic task negative activity (thatcompensates for task positive, sensory input) in regulating both neuralactivity and resulting behavior (trajectories through the environment). Ourresults suggest complementary functional roles for both local homeostaticplasticity and balanced activity across brain regions in maintaining neural andbehavioral dynamics. These findings suggest important functional roles forhomeostatic systems in maintaining neural and behavioral dynamics and suggest anovel functional role for frequently reported macroscopic task-negativepatterns of activity (e.g., the default mode network).
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