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UCL Institute of Neurology

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Mechanisms of movement generation and inhibition

Principal Investigator: Dr Alexander (Sasha) Kraskov, Wellcome Trust Senior Research Fellow, a.kraskov{at}ucl.ac.uk

*** post-doctoral positions available!! (apply here) ***

Voluntary control of limb movement is a complex process involving interaction of cortical and subcortical brain areas with the spinal sensorimotor circuitry. The primary motor cortex and corticospinal tract undoubtedly play a major role in the control of skilled hand movements, but recent findings show that even M1 corticospinal output neurons can be modulated just by observation of an action, without any sign of movement on the part of the observer. How can these outputs be active without movement? It challenges our understanding of how movements are generated and prompts research to identify cortical signals that distinguish movement execution from action observation and from other states such as motor imagery.
Moreover, recent evidence suggests that the withholding of movement during action observation is an active process and a key part of the operation of the mirror neuron system (MNS). Suppression of self-movement during action observation is characterised by a dramatic change in the pattern of corticospinal discharge. This in turn could result from a number of cortical and subcortical inhibitory mechanisms, including those originating in the prefrontal cortex and subthalamic nucleus (STN). Both structures have been hypothesised to play a crucial role in suppression of unwanted actions. But their role in movement inhibition during action observation remains unknown. Study of the MNS offers a novel route to better understanding of movement suppression, a key part of human behaviour.
The overall aim of my research is to probe motor system activity during action observation to better understand the mechanisms of movement generation and suppression.
To address these research questions we combine neurophysiological, anatomical and imaging techniques in non-human primates. We also use transcranial magnetic stimulation (TMS) in human volunteers to probe human motor system during action observation.

Current projects
- Role of facilitation and suppression mirror neurons in action inhibition
- Hyperdirect pathway from the motor cortex to subthalamic nucleus (in collaboration with Ludvic Zrinzo and Danny Alexander)
- Sensory properties of mirror neurons (in collaboration with Marco Davare)

Current lab members
Dr Stephan Waldert (Senior Research fellow)
Mr Steven Jerjian (BRT funded PhD student)
Miss Tabatha Lawton (Research Technician)

Alumni
Dr Ganesh Vigneswaran
Dr Roland Philipp [ORCID]

Mentor
Prof Roger Lemon

Collaborations
Prof Kazuhiko Seki
Prof Stuart Baker
Prof Daniel Alexander and Dr Ludvic Zrinzo
Dr Marco Davare
Prof Guiseppe Luppino and Dr Stefano Rozzi
Prof Xavier Golay, Dr Mohamed Tachrount, and Dr David Thomas

Publications [Google Scholar]

Current funding
Wellcome Trust, BBSRC, Royal Society