Contributions of rodent medial prefrontal cortex to response variability
Tervo D.G.R, Vollmer A.S., Behnam R., Karpova A.Y. (Howard Hughes Medical Institute)
Being able to combine exploitation of more profitable options with behavioral variability is important in dynamic environments and in competitive social interactions. We have investigated how animals balance the two requirements by implementing a modified version of the task designed to simulate a competitive setting (Lee et al., 2004).
Rats played a game against a competitive agent simulated by a computer.
Animals selected one of two reward ports and were rewarded only when the competitor made the same selection. The competitor used the history of the animal's choices and rewards to determine the conditional probability of the animal making a left choice on the next trial given the immediate history.
If the calculated probability was different from the required one (0.1, 0.25, 0.5, 0.75 and 0.9 in different sessions), the opponent preferentially selected the side opposite from the animal's bias; if not, the opponent made a random selection. This task required the ability to combine variable partitioning of responses between two options with unpredictable sequencing of behavioral choices. In all sessions, the sequence of behavioral choices was optimal with respect to the required partitioning between the two options and approached maximal entropy within that constraint. Furthermore, when faced with an emulated opponent that used a flawed prediction algorithm to compete with the animal, which punished all patterns except for one, the majority of rats found and exploited the flaw within one or two sessions.
These behavioral results suggest that animals use local history of choices and rewards to dynamically adjust their behavior in this task.
Finally, we found that temporally precise, channelrhodopsin-based stimulation of dmPFC during initiation of a fraction of trials led to a specific enrichment of decisions in a manner consistent with a perturbation of the conditional probability of the rats' choices.
Время: 28.04.2011 в 18:00
Место: ауд. 106 9 корпуса.
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