Bimanual Co-ordination

Most of our everyday movements involve usage of both hands in some co-ordinated fashion. This could be for everyday actions such as to unscrew a cap off a bottle, to eat using knife and fork, to tie our shoe-laces, or for more refined movements such as to play a musical instrument. Research has shown very clearly that when one hand moves, this has an impact on movements of the other hand, and control of the two hands in not completely independent. For example, the well known party trick of tapping your head and rubbing your stomach at the same time results in both hands making a mixture of both intended movements.

There has been a large body of behavioural and computational research into the constraints of bimanual movements. Recently, with the more widespread availability of non-invasive brain scanning (such as fMRI) and stimulation (such as TMS) techniques, it has been possible to indirectly observe and probe different brain areas during bimanual movements - perhaps not surprisingly, many different areas play a role in controlling hand function across both hemispheres.

Despite this body of research there is very little direct evidence on what information is used to control the two hands together, and where in the brain this processing takes place; there are several candidate brain areas with a bilateral organisation that could be involved. These include the corticospinal system, the brainstem, the cerebellum as well as the spinal cord.

I am interested in how different areas in the motor system are involved in controlling movements of the upper limbs. To gain a better understanding of this we are using a variety of approaches:

  • The modulation of motor cortical excitability is studied in man during a variety of bimanual and unimanual movements by using TMS and corticomuscular coherence analysis.
  • A further series of experiments looks to characterise how afferent (sensory) stimulation can modulate the excitability of motor circuits controlling the opposite upper limb.
  • Finally, the bilateral contributions of descending motor systems (such as cortico- and reticulo-spinal) to spinal cord circuits is being investigated through a series of acute and chronic behavioural experiments

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