Dept.: Professor, Department of Physiology & Biophysics, Core Staff, Regional Primate Research Center; Adjunct, Department of Bioengineering
Neuroscience Focus Group:
Neural control of movement; 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 ”premotoneuronal” 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. Recordings of spinal interneurons in behaving monkeys have revealed that spinal neurons share many properties of cortical neurons, including preparation for instructed movements.
We are currently developing an implantable ‘brain-computer interface’ to record activity of cortical neurons in monkeys and convert this activity to stimuli delivered at sites in motor cortex, spinal cord or muscles. An implanted array of microelectrodes records neural activity; and a computer chip discriminates action potentials and controls the stimulus parameters. We will study the behavioral adaptation of monkeys to the long-term presence of these artificial feedback loops. The recurrent connection also generates lasting plastic changes through time-dependent plasticity.
In parallel with these physiological studies, we are also using neural network simulations to show how neural computation could be performed in large populations of cells. Dynamic recurrent neural network modeling has provided important insights into the neural mechanisms that could mediate movement and short-term memory.