Motor selection dynamics in FEF explain the reaction time variance of saccades to single targets

• Main Authors: Christopher K Hauser, Dantong Zhu, Terrence R Stanford, Emilio Salinas
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2018-04-01
• Series: eLife
• Subjects: attention; decision making; reward; monkey; saccadic eye movements; frontal eye field
• Online Access: https://elifesciences.org/articles/33456

In studies of voluntary movement, a most elemental quantity is the reaction time (RT) between the onset of a visual stimulus and a saccade toward it. However, this RT demonstrates extremely high variability which, in spite of extensive research, remains unexplained. It is well established that, when a visual target appears, oculomotor activity gradually builds up until a critical level is reached, at which point a saccade is triggered. Here, based on computational work and single-neuron recordings from monkey frontal eye field (FEF), we show that this rise-to-threshold process starts from a dynamic initial state that already contains other incipient, internally driven motor plans, which compete with the target-driven activity to varying degrees. The ensuing conflict resolution process, which manifests in subtle covariations between baseline activity, build-up rate, and threshold, consists of fundamentally deterministic interactions, and explains the observed RT distributions while invoking only a small amount of intrinsic randomness.