Speaker
Description
Where in the brain is a decision made? Previous studies showed that activity in prefrontal areas reflects information pertinent to the ongoing decision, suggesting that decision-making is part of the frontal lobe’s executive functions. However, decision-related neural modulation is also shown in sensorimotor areas. Does this imply that these areas are all causally involved in the decision processes? Here, we investigated the causal role of dorsal premotor (PMd) and parietal reach region (PRR) using a multi-attribute decision task. Two male monkeys were presented with reach targets whose reward value was indicated by two attributes - its brightness (”bottom-up” feature) and its orientation (“top-down” feature). We predicted that the latency of choice-predictive activities in PMd and PRR would reflect their causal role, especially when the attributes are in conflict. The population analysis of early tuned cells showed 1) both PMd and PRR predicted choices before action execution, 2) PMd often preceded PRR, and 3) conflict resolution between equally-valued choices was primarily driven by biases in baseline activity in PMd, but not PRR. The neural space analysis on the entire population showed 4) directional tuning in PRR preceded PMd when the choice was based on the bottom-up feature, whereas the opposite was true when the choice was based on the top-down feature. Our results suggest that value-based decisions are made at the individual attribute levels in a distributed decision network that includes PMd and PRR, as opposed to at an abstract, fully integrated value space exclusively in the prefrontal cortex.
