= Okihide Hikosaka
{c}
<Okihide Hikosaka> investigates how <neural circuits> connect sensory information, expected <reward> and <saccades>. With <Masayuki Matsumoto>, he studied the <lateral habenula> and <dopaminergic neurons> while monkeys performed visually guided <saccades>. A 2007 experiment reversed which target position predicted <reward>; neural responses changed along with the reward contingency.<Lateral habenula as a source of negative reward signals in dopamine neurons by Masayuki Matsumoto and Okihide Hikosaka>[Abstract; rhesus-monkey saccade task and reward-location reversal]{ref}
The reversal distinguishes a response to a fixed location from a response associated with its learned outcome. Habenular excitation on unrewarded trials preceded inhibition of <dopaminergic neurons>, and weak <electrical stimulation> of the <lateral habenula> inhibited those <neurons>.<Lateral habenula as a source of negative reward signals in dopamine neurons by Masayuki Matsumoto and Okihide Hikosaka>[Abstract; response timing and stimulation]{ref} Recording and intervention address complementary questions: when does activity occur, and can changing the candidate circuit influence another population? The stimulation result alone does not identify every intervening <synapse> or establish a direct monosynaptic connection.
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