Neural Dynamics of the Basal Ganglia During Perceptual, Cognitive, and Motor Learning and Gating

Abstract

This article summarizes neural models that simulate how the basal ganglia contribute to associative and reinforcement learning, and to movement gating, in multiple brain systems. The first model proposes how the substantia nigra pars compacta (SNc) generates widespread dopaminergic learning signals in response to unexpected rewarding cues, including a circuit for adaptively timed learning using metabotropic glutamate receptor (mGluR)-mediated Ca2+ spikes that occur with different delays in striosomal cells. Similar circuits for spectral timing occur in cerebellum and hippocampus. The TELOS model shows how the substantia nigra pars reticulata (SNr) learns to selectively gate saccadic eye movements or cognitive plans, and how spatially invariant object categories can activate spatially variant representations to control specific actions. The VITE model proposes how basal ganglia gating controls selection and variable speeds of arm movements. The cARTWORD model explains how prefrontally controlled basal ganglia gates can explain phonemic restoration, notably how future context can influence how past sounds are consciously heard. The MOTIVATOR model clarifies how the basal ganglia and amygdala coordinate their complementary functions to control learning and performance of motivated acts. The lisTELOS model proposes how sequences of saccades can be learned and performed from an Item-Order-Rank spatial working memory under the control of three parallel basal ganglia loops. Basal ganglia gating in the regulation of working memory storage, visual imagery, useful field of view, thinking, planning, and Where’s Waldo searching are also discussed, as is how its breakdown can lead to hallucinations.