Physiology and Biophysics

Eberhard E. Fetz Ph.D.

Professor (and Core Staff WNPRC)

Ph.D. Physics
Massachusetts Institute of Technology, 1967

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Cortical Control of Movement; Bidirectional Brain-Computer Interfaces; Neural Modeling

We are investigating the neural mechanisms involved in programming and executing hand movements by recording neural activity in monkeys trained to manually track visual targets. We are particularly interested in studying ''pre-motoneuronal'' cells in motor cortex and spinal cord that produce postspike effects on forelimb muscle activity. By knowing both the response patterns of these cells during movements and their output connections to target muscles we can make important causal inferences about their contribution to movements. We are currently using multichannel electrode arrays to investigate interactions between motor cortex sites during movement.

We are also developing a head-fixed bidirectional brain-computer interface that operates autonomously during free behavior. This device can record activity of cortical neurons and convert this activity to stimuli delivered at sites in motor cortex, spinal cord or muscles. Triggering stimuli from neural activity can produce changes in the strength of synaptic connections. We are currently investigating ways to enhance and prolong this stimulation-induced synaptic plasticity.

In parallel with these physiological studies, we are also using neural network models to show how neural computation could be performed in large populations of cells. Dynamic network models are used to simulate the neural interactions generating behavior like target tracking. These networks transform multiple temporal input patterns to desired output patterns and provide important insights into the neural mechanisms that mediate movement and short-term memory. Another type of population model has simulated the cortical mechanisms mediating neural plasticity produced by activity-dependent stimulation.