Parallel basal ganglia mechanisms for choosing good objects


April 29, 2014 - 1:00pm
NW 243
About the Speaker
Okihide Hikosaka (NIH)

The basal ganglia are equipped with inhibitory and disinhibitory mechanisms that enable a subject to choose valuable objects and actions. Notably, a value can be determined flexibly by recent experience or stably by prolonged experience. We discovered that the head and tail of the monkey caudate nucleus selectively and differentially process flexible and stable values of visual objects. These signals are sent to the superior colliculus through different parts of the substantia nigra so that the animal looks preferentially at high-valued objects, but in different manners. Thus, relying on short-term value memories, the caudate head circuit allows the animal’s gaze to move expectantly to recently valued objects. Relying on long-term value memories, the caudate tail circuit allows the animal’s gaze to move automatically to previously valued objects. Such flexible-stable parallel mechanisms for object values create a highly adaptable system for decision making.