Masayuki Matsumoto

Masayuki Matsumoto studies neural signals associated with reward, learning and decision making. His 2007 study with Okihide Hikosaka compared responses in the lateral habenula and dopaminergic neurons during a rewarded saccade task. Reward-predicting and no-reward-predicting targets produced opposing response patterns in the two populations.^[ref]

A conceptual example explains the reversal control. Initially, suppose a left target predicts reward and a right target predicts no reward. Swap those outcomes while leaving the screen positions unchanged. A response that follows the newly unrewarded side cannot be explained solely by a permanent preference for rightward stimuli. The study observed response reversals when rewarded and unrewarded positions changed.^[ref]

This design separates spatial stimulation from the outcome associated with it. It also illustrates why a neural signal related to an adverse outcome should be described through the task and measured response, rather than treated as a complete measure of an animal's emotion.