The Effects of Behavioral Context on Motor Performance and Neural ActivityPavlovsky, Nicholas (2020) The Effects of Behavioral Context on Motor Performance and Neural Activity. Doctoral Dissertation, University of Pittsburgh. (Unpublished)
AbstractContext greatly influences our behavior. How you react to a ball flying toward you is completely different if you are playing baseball or dodgeball. What neural mechanisms endow our behavior with context sensitivity? It is well known that contextual signals influence neural activity in many different brain areas, but we do not know how the brain can distinguish context information from the signals needed for successful motor behavior. In this thesis, I show two examples of context-dependent processing in monkeys: the first is behavioral, the second is neurophysiological. First, I present an example of behavioral context that is known to drastically change performance: “choking under pressure”. Everybody – from competitors in a spelling bee to NFL kickers – knows how “nerves” can affect performance. Are animals also susceptible to this behavioral quirk? I trained two monkeys to perform a difficult reaching task while cueing the amount of reward given for successful task completion. As potential rewards increased, the animals’ performance improved. But, when the reward was exceptionally high, their performance paradoxically declined. Simply put, the monkeys choked under pressure. I observed this effect across multiple sessions and in two separate tasks. This work establishes an animal model of choking under pressure, allowing us to further explore the neural mechanisms of this phenomenon. In a second study, I examined whether task instructions affected neural activity in the dorsal premotor cortex (PMd). Two monkeys performed a delayed reaching task with no constraints on their gaze behavior. I recorded neural activity and the animals’ eye position, and I found almost no relationship between eye position and neural activity. This is in stark contrast to previous studies that reported eye position signals in PMd. Those previous studies, however, instructed the monkeys to fixate their gaze while reaching. Our results demonstrate that task requirements influence the tuning properties of neurons involved in motor control, and it shows that context affects neural processing, even in areas that control movements. Taken together, these studies show that context influences behavioral performance in monkeys, as it does in humans, and they begin to reveal the neural underpinnings of context-dependent sensory-motor processing. Share
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