Townsend, BR;
(2006)
Primary motor cortical-cerebellar interactions in the control of precision grip.
Doctoral thesis , UCL (University College London).
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Abstract
The primary motor cortex (Ml) and cerebellum are strongly interconnected structures. For control of the arm and hand, the cerebellum must influence other parts of the motor network with direct access to the spinal cord, since it has no descending projections to the lower cervical cord itself. One important control pathway involves interactions of the cerebellum with Ml. This thesis describes findings from simultaneous recording of neuronal activity in these structures, with the aim of addressing how they interact. Recordings were made from Ml and cerebellar dentate nucleus in macaque monkeys performing a precision grip task. Multiple single units and local field potentials (LFP) were sampled, concurrent with EMG from hand muscles. A variety of approaches were then taken to assess Ml-cerebellar communication. Correlations of neural discharge in Ml and cerebellum with muscle activity were evaluated. Evidence was found for linear encoding of muscle activity in both areas. Different output pathways of Ml to cerebellum were identified and studied at the single neuron level. Neurons in each pathway were interconnected and showed similar activity patterns. Functional connectivity between the two structures was investigated, by compiling spike-triggered averages (SpTAs) of local field potentials, and stimulus-triggered averaging of single units. Finally, firing rates and LFP activity within these structures were monitored across different load conditions during blocked and randomized trial sequences. Ml and cerebellar activity was dissociated between these conditions, highlighting the role of the cerebellum in predictive control of grip force. Coupling of oscillatory LFP activity between these structures was consistently observed across task conditions. It is suggested that SpTA effects and coherent LFPs represent communication across short and broad time scales respectively. Overall, this research demonstrates how simultaneous recordings can provide new insights into the roles of Ml and cerebellum in the control of hand movements.
| Type: | Thesis (Doctoral) |
|---|---|
| Title: | Primary motor cortical-cerebellar interactions in the control of precision grip |
| Identifier: | PQ ETD:593465 |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Thesis digitised by ProQuest. |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1446136 |
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