The Bernstein Center for Computational Neuroscience Freiburg


Announcement for the next
BCCN Seminar
Dr. Stuart Baker
Department of Child Health, Sir James Spence Institute
Royal Victoria Infirmary
Newcastle upon Tyne, UK

The Function of Beta-band Oscillations in Sensorimotor Integration
date and time to be announced shortly
Lecture Hall (ground floor)
BCCN building
Hansastraße 9A
79104 Freiburg
Abstract:
Electrical recordings from the motor cortex – in both man and monkey – commonly show waves of synchronised oscillations, with a frequency around 20Hz. This ‘beta-band’ activity was first reported >70 years ago, but its function in the control of movement remains elusive. Crucially, the oscillations disappear at the start of movement; they are strongest during periods of rest or steady contraction. This argues against oscillations being important in movement execution. Oscillations are not only present in motor cortex, but also in the electromyogram of contralateral muscles. Synchronisation between cortex and muscle can be measured as cortico-muscular coherence.

In my laboratory, we have recently been accumulating evidence that these oscillations have a sensorimotor, rather than purely motor, role. We have shown that the phase of corticomuscular coherence is better explained by a feedback loop, involving the periphery, rather than purely descending connections from the cortex. Afferent fibres carry the oscillations, and single neurones in somatosensory cortex encode finger position by the amplitude of oscillations in their discharge, as well as by firing rate.

Based on these results, we speculate that beta-band oscillations perform a sensorimotor recalibration following a movement. Akin to radar or sonar, the motor system sends out a known ‘test pulse’ of oscillatory activity to the periphery. By measuring the response to this pulse, the somatosensory cortex can determine the system state (e.g. limb position, contraction strength). The precise nature of how this computation might work, and the unique role it could play in sensorimotor integration, is currently being investigated using experiments in human subjects and awake behaving monkeys, as well as computational modelling.
The talk is open to the public. Guests are cordially invited!
www.bccn.uni-freiburg.de