Colloquium: Veit Stuphorn

Please join us for the CogSci colloquium next Monday.

Monday, September 14
4:00 p.m.
PY 101

Veit Stuphorn, Johns Hopkins University, will present, "Should I go? Medial frontal cortex and the decision whether or not to act."

Abstract:
Cognitive control of behavior depends on neural mechanisms for initiating and inhibiting movements. Motor-related regions in medial frontal cortex, in particular supplementary and pre-supplementary motor areas (SMA, pre-SMA), are widely considered to play a central role in movement initiation and inhibition. To test this hypothesis, we recorded from neurons in SMA and pre-SMA of monkeys performing a countermanding task. Temporal analysis of neural activity and behavior in this task allowed us to test whether neuronal activity is sufficient to control movement initiation or inhibition. Surprisingly, almost all movement-related neurons in SMA and pre-SMA failed to exhibit time-locked activity changes predictive of movement execution. These cells were therefore not sufficient to initiate movements. Furthermore, the activity of most these cells was contingent on the expectation of reward and therefore was also not necessary for movement initiation. We found a small number of neurons that were more active during successful response cancelation. However, only a minority of these putative inhibitory cells responded early enough to be able to influence the cancelation of the movement. This set of findings suggests that the movement-related activity in pre-SMA and SMA is neither sufficient nor necessary to control movement initiation. These results are remarkably similar to recent findings in the supplementary eye field (SEF), despite a number of mechanical differences in the two effector systems. This suggests that the functional organization of the frontal motor system follows broadly parallel principles. In general, the activity in the medial frontal cortex might represent the motivation to generate a particular action if it is necessary to obtain a reward. This signal would serve as a link between reward representation and action execution and could guide action selection during deliberate voluntary decision making.