Biopsychology Colloquium

Prof. Mark Laubach, Biological and Biomedical Sciences Department, Yale University

Tuesday, November 03, 2009, 12:00 pm – 1:00 pm
4448 East Hall

Event Information

Abstract

The frontal cortex and basal ganglia are necessary for flexibly assigning reward values to external stimuli and for guiding actions based on expected outcomes. We have used multi-site, multi-electrode recording methods to study neural activity related to the changes in reward values in the striatum. Using a flexible go/no-go task, we reported that neurons in the dorsomedial, but not the ventral, striatum are activated when the reward value of a stimulus is changed from unrewarded to rewarded (Kimchi and Laubach, JN, 2009a). More recently, we
found activations in both dorsomedial and ventral striatum following negative changes in reward value, when a stimulus becomes unrewarded (Kimchi and Laubach, In Preparation). This difference in the spatial extent of reward-related activity may result from selective activations of different parts of medial and orbital frontal cortex that project to the dorsomedial and ventral striatum.

Most neurons that are sensitive to changes in reward value fire during the initiation of action sequences associated with reward collection.This is an interesting point in the task, as it is when we find major changes in task-related activity during the initial acquisition of the go/no-go task (Kimchi and Laubach, JN, 2009b) and during instrumental learning using a simple operant procedure (Kimchi et al., JNP, 2009).We also found that the level of task-related activity corresponded to the tendency of animals to collect rewards independent of the stimulus and was influenced by actions made on the preceding trial. Together, our studies suggest that the striatum dynamically represents changes in stimulus-reward contingencies and biases animals to engage in food-seeking behavior.

For More Information

Website URL: http://info.med.yale.edu/bbs/faculty/lau_ma.html