Neural mechanism of flexible decision making

Behavioral switching is a fundamental ability for humans to behave appropriately in response to context. Here, we use a perceptual decision-making framework to explain how sensory-motor associations switch flexibly according to context. Monkeys were trained to switch between a direction discrimination task and a depth discrimination task depending on the color of the fixation point. We examined neural activity in the middle temporal (MT) and lateral intraparietal (LIP) regions while the monkeys performed the switching task. Sensory representations in the MT region were task independent, but outputs from MT were interpreted to elicit task-releted build-up activity in LIP neurons. Systemic administration of ketamine, an NMDA receptor antagonist, impaired information selection and initiation of evidence accumulation. These results suggest that task switching occurs through task-dependent communication between sensory and decision related cortical areas and that context-dependent flexibility may be impaired in neuropsychiatric disorders.