How push–pull neural geometry shapes dexterous movement ”

How push–pull neural geometry shapes dexterous movement
Firas Mawase, Technion

Abstract: Hand dexterity is fundamental to skilled movement, yet how the motor cortex coordinates the activity of individual muscles to produce selective finger movements remains incompletely understood. In this seminar, I will explore the neural mechanisms underlying finger individuation, focusing on how motor cortical population dynamics and the activity of identified corticomotoneuronal (CM) cells contribute to movement preparation and execution. Using simultaneous recordings of motor cortical neurons and forearm muscles in behaving non-human primates, we examine the relationship between neural activity and muscle recruitment during individuated finger movements. At the population level, neural activity is organized along dimensions that distinguish individual finger movements and their directions, with substantial structure emerging before movement onset, potentially reflecting the preparation of specific motor actions. At the level of CM cells, our recent findings reveal a push–pull organization in which facilitative and suppressive influences combine to shape selective muscle recruitment. This organization suggests a mechanism through which heterogeneous CM activity is integrated to sculpt the motor commands required to initiate dexterous movements. I will discuss these findings in the broader context of human finger control, drawing on our studies of motor impairments following stroke and computational models of neural injury and recovery. Together, these results provide a multiscale perspective on how the nervous system prepares and generates dexterous movements and how these mechanisms may be disrupted following brain injury.