Keynote Addresses

Join us at the Society for the Neural Control of Movement Annual Meeting to hear from our Distinguished Career Award Winner and the Early Career Award Winner deliver keynote presentations.

Abstract

“Shining Light in the Dark Basement: The Basal Ganglia in Action”

The basal ganglia have long been known by clinicians to be important in the genesis of extrapyramidal motor disorders, but these deep-lying structures of the forebrain were relatively neglected by basic scientists, due to their physical inaccessibility. A revolution in our understanding of these structures now is on-going. Dopamine-containing neurons, discovered by Schultz and Romo to signal unexpected rewards and reward-related cues (reward prediction errors), now are being found to become active just before movements, as either drivers or motivation-related modulators of movement initiation. The direct and indirect basal ganglia pathways, proposed as go/no-go systems for movement control, are seen as co-active regulators of movement, likely aligning with the pioneering hypothesis put forward by Mink and Thach. Frequency-specific oscillatory activities in basal ganglia networks are now seen as hallmarks of dysfunction (and increasingly, of function) of basal ganglia circuits. Yet the question of why we move or do not move has remained a mystery. We work on this mystery in our laboratory. We have identified major circuits leading from prefrontal cortical regions related in human to mood and affect to specialized zones in the striatum called striosomes (striatal bodies) and then to the dopamine-containing neurons of the substantia nigra and to the lateral habenula, which itself can modulate the dopamine and serotonin systems. We are finding that these circuits are differentially activated in relation to cost-benefit decisions about whether to act or not—whether to approach or to avoid offers—when the offers combine rewarding and aversive options. These experiments capitalize on modified versions of approach-avoidance tasks initially designed to study anxiety and depression in humans. By manipulating these striosome-related circuits, we can strikingly modify the amounts of approach and avoidance behavior. We have found that these circuits are also related to repetitive, stereotyped movements, hallmarks of some neuropsychiatric disorders and of the results of exposure to chronic stress. The functions of these circuits could have powerful effects on the control of action in health and disease.

Abstract

“Somatosensory feedback for real-world hand control”

Real world control requires actively using sensory information from the skin and muscles to guide reaching, grasping, and object manipulation.  In this talk, I will provide an overview of several ongoing projects that leverage (slightly) more realistic paradigms and experimental manipulations to reveal new insights into these processes.  First, I will describe how tactile inputs from the skin can evoke rapid feedback responses that contribute to the online control of object manipulation.  Second, I will show that the tactile acuity in the context of such motor control tasks exceeds that for perceptual judgments by nearly an order of magnitude.  Third, I will show that, in the context of hand control, spinal stretch reflexes show remarkable sophistication – integrating information across the elbow and wrist joints to operate at the level of the global task goal, to keep the hand on target, regardless of how individual muscles are stretched.