Distinct neural manifolds and critical roles of primate caudate nucleus in multimodal decision-making

Perceptual decision-making is an important cognitive function involving distributed networks spanning cortico-subcortical levels, yet most studies only include single modality stimulus and reveal largely similar signals related with animal choice across areas, making it puzzling about individual’s unique roles. Using a multimodal paradigm, here we showed dorsal medial striatum, namely caudate nucleus (CN) in primate, dramatically differs from association cortex in a reduced low-dimensional subspace. Specifically, bimodal neural state evolved towards nonvisual (vestibular) in CN, rather than towards visual as in frontal/parietal cortices. The distinct CN trajectories pattern may readily explain behaviors including close-to-vestibular but not visual reaction time under bimodal condition, or vestibular-overweighting during cue-conflict context. Further causal-link experiments including applying GABA-A-receptor agonist, and D1-receptor antagonist confirmed CN’s essential role of dopaminergic input. Electrical-microstimulation also verified CN’s sufficient contributions. Our results indicate beyond relay-station in cortico-striatal circuitry, CN plays distinct and critical roles in complex tasks with multimodal inputs.