The Involvement of Corticostriatal Loops in Learning Across Tasks, Species, and Methodologies

The basal ganglia contribute to a variety of forms of learning. The first goal of this chapter is to review the different tasks (instrumental conditioning, visual discrimination, arbitrary visuomotor learning, rule learning, categorization, and decision making) that have been used to study basal-ganglia-dependent learning in rodents, monkeys, and humans. These tasks have several features in common: in each, the subject is first presented with a stimulus within a behavioral context, is then required to respond with an appropriate behavior, and finally receives a reward or positive feedback for correct behavior. The second goal of this chapter is to examine how these different features (stimulus, response, and reward) involve the independent corticostriatal loops that connect the basal ganglia with cerebral cortex. The visual corticostriatal loop is involved in aspects of visual stimulus processing; the motor corticostriatal loop is involved in response selection; and the executive and motivation corticostriatal loops are involved in processing feedback and reward. The chapter concludes with a discussion of how the corticostriatal loops interact during learning.