The Influences of Posture and Motivation on Neural Population Activity in Motor CortexMarino, Patrick (2023) The Influences of Posture and Motivation on Neural Population Activity in Motor Cortex. Doctoral Dissertation, University of Pittsburgh. (Unpublished)
AbstractThe brain integrates disparate information to plan and execute even our simplest movements. The details of a reach to your phone will depend on the phone’s location, your arm’s initial posture, and even on who is calling. How does the brain combine these sources of information to produce precise, coordinated movements? Primary motor cortex (M1) is likely an important hub, as it receives inputs carrying the relevant information and sends outputs to the spinal cord for controlling movement. In this work, I investigate how two important signals for movement control, body posture and expected reward, interact with movement goal signals to shape neural population activity in motor cortex. I first use a brain-computer interface to decouple posture and goal signals and show that these signals modulate separate dimensions of M1 activity. I then show that this finding generalizes to overt movements, and that the neural representation of posture is conserved across tasks. Finally, I show that posture and goal signals combine in a largely additive manner across a wide range of behaviors. Together, these findings suggest that posture signals are sequestered from goal signals in a stable “posture subspace” in M1 activity. The separation of posture and goal signals into distinct subspaces might underlie the brain’s ability to simultaneously control movement and perceive the state of the body, and to flexibly combine this information to perform movements from any initial posture. Next, in collaboration with colleagues, I develop a novel behavioral paradigm for studying the effect of motivation on motor control. This paradigm uses reward sizes to affect motivation, and includes a setting in which extreme rewards induce ‘choking under pressure,’ or worse than expected performance, in laboratory animals. We show that, like posture signals, motivation signals modulate separate neural dimensions from goal signals. However, motivation signals interacted more strongly with goal signals: increases in expected reward cause an increase, then decrease, in neural information about upcoming movements. This result suggests that failures of movement preparation may underlie choking under pressure. Together, these studies suggest organizing principles by which motor cortex combines behaviorally relevant information to guide movements and have implications for the calibration and control of neural prosthetics. Share
Details
MetricsMonthly Views for the past 3 yearsPlum AnalyticsActions (login required)
|
![[img]](http://d-scholarship.pitt.edu/style/images/fileicons/application_pdf.png)
![[feed]](/images/feed-icon-32x32.png){kind=icon}