Distinct roles of two thalamostriatal systems in visually triggered decision-making in common marmosets.

The cortico-basal ganglia circuitry plays important roles in the control of various higher-order functions, such as motor control, cognition, and emotion. The thalamostriatal system is involved in learning and switching of behaviors and recovery from cognitive and motor deficits in rodents. Here, we applied selective neural pathway targeting to investigate roles of two representative thalamostriatal pathways arising from the parafascicular nucleus (Pf) and centre médian nucleus (CM) in common marmosets. Targeting of the Pf projecting to the caudate (Cd) resulted in impaired reversal of learned responses in a visual discrimination task, showing increased perseverative errors during the reversal phase. Targeting the CM innervating the putamen (Pu) disturbed acquisition of the visual discrimination. In contrast, elimination of the Pf-Cd or CM-Pu pathway did not alter performance of motor skill learning. Our results indicate that these two thalamostriatal pathways have distinct roles in learning processes of sensory cue-dependent decision-making in nonhuman primates.