Relation of frontal eye field activity to saccade initiation during a countermanding task |
| |
| Authors: | Joshua W. Brown Doug P. Hanes Jeffrey D. Schall Veit Stuphorn |
| |
| Affiliation: | (1) Center for Integrative and Cognitive Neuroscience, Vanderbilt Vision Research Center, Department of Psychology, Vanderbilt University, Nashville, TN 37203, USA;(2) Department of Psychological and Brain Sciences, Indiana University, 1101 E Tenth St., Bloomington, IN 47405, USA;(3) The Zanvyl Krieger Mind/Brain Institute and The Department of Psychological and Brain Sciences, Johns Hopkins University, 362 Krieger Hall, 3400 N. Charles Street, Baltimore, MD 21218, USA |
| |
| Abstract: | The countermanding (or stop signal) task probes the control of the initiation of a movement by measuring subjects’ ability to withhold a movement in various degrees of preparation in response to an infrequent stop signal. Previous research found that saccades are initiated when the activity of movement-related neurons reaches a threshold, and saccades are withheld if the growth of activity is interrupted. To extend and evaluate this relationship of frontal eye field (FEF) activity to saccade initiation, two new analyses were performed. First, we fit a neurometric function that describes the proportion of trials with a stop signal in which neural activity exceeded a criterion discharge rate as a function of stop signal delay, to the inhibition function that describes the probability of producing a saccade as a function of stop signal delay. The activity of movement-related but not visual neurons provided the best correspondence between neurometric and inhibition functions. Second, we determined the criterion discharge rate that optimally discriminated between the distributions of discharge rates measured on trials when saccades were produced or withheld. Differential activity of movement-related but not visual neurons could distinguish whether a saccade occurred. The threshold discharge rates determined for individual neurons through these two methods agreed. To investigate how reliably movement-related activity predicted movement initiation; the analyses were carried out with samples of activity from increasing numbers of trials from the same or from different neurons. The reliability of both measures of initiation threshold improved with number of trials and neurons to an asymptote of between 10 and 20 movement-related neurons. Combining the activity of visual neurons did not improve the reliability of predicting saccade initiation. These results demonstrate how the activity of a population of movement-related but not visual neurons in the FEF contributes to the control of saccade initiation. The results also validate these analytical procedures for identifying signals that control saccade initiation in other brain structures. |
| |
| Keywords: | Frontal cortex Motor control Oculomotor Reaction time Response time Stochastic models Stop signal Saccade latency |
| 本文献已被 PubMed SpringerLink 等数据库收录！ |
|
