Neural control of voluntary movement initiation.

@article{citeulike:89637, abstract = {When humans respond to sensory stimulation, their reaction times tend to be long and variable relative to neural transduction and transmission times. The neural processes responsible for the duration and variability of reaction times are not understood. Single-cell recordings in a motor area of the cerebral cortex in behaving rhesus monkeys (Macaca mulatta) were used to evaluate two alternative mathematical models of the processes that underlie reaction times. Movements were initiated if and only if the neural activity reached a specific and constant threshold activation level. Stochastic variability in the rate at which neural activity grew toward that threshold resulted in the distribution of reaction times. This finding elucidates a specific link between motor behavior and activation of neurons in the cerebral cortex.}, address = {Department of Psychology, Wilson Hall, Vanderbilt University, Nashville, TN 37240, USA. schalljd@ctrvax.vanderbilt.edu}, author = {Hanes, D. P. and Schall, J. D. }, citeulike-article-id = {89637}, comment = {* Single unit recording study of monkey FEF neurons in a countermanding saccade task intended to distinguish between two alternative mathematical models of reaction time duration and variability * Specifically, the authors compare variable rate and variable threshold models of reaction time: in the variable rate model, the trigger activation threshold is constant and variability in the growth rate of the activation function accounts for RT variability; in the variable threshold model, the activation function is constant and it is the activiation threshold that varies * the authors report from 25 of 118 FEF neurons that show movement related activity, typically increasing spiking ~100ms before saccade initiation and peaking shortly after initiation * using FEF activity 10-20 ms before saccade initiation as an index of the trigger threshold activation, there is no change in threshold activation level across different reaction times, consistent with the variable rate model (and inconsistent with the variable threshold model) * the rate of growth of FEF activity from baseline to 15 ms before saccade initiation is a decreasing function of reaction time, also consistent with the variable rate model * furthermore, during signal-inhibit trials of the countermanding task, FEF neurons were less likely to reach trigger threshold during trials where the monkey withheld a saccade than trials where a saccade where executed * finally, to determine if variation in neural activation functions could account for the variability of behavioral RTs, the authors compared RT distributions from individual FEF cells with predictions from linear accumulator with fixed threshold models derived from the parameters of each neuron; 9 of 22 distributions were indistinguishable while 17 of 22 cells showed identical mean RTs }, issn = {0036-8075}, journal = {Science}, keywords = {decisionmaking, fef, monkey, neurophysiology, \_note, reaction\_time, saccade}, month = {October}, number = {5286}, pages = {427--430}, posted-at = {2005-02-07 23:54:48}, priority = {0}, title = {Neural control of voluntary movement initiation.}, url = {http://view.ncbi.nlm.nih.gov/pubmed/8832893}, volume = {274}, year = {1996} }

TY - JOUR ID - citeulike:89637 L3 - citeulike-article-id:89637 TI - Neural control of voluntary movement initiation. JF - Science VL - 274 IS - 5286 SP - 427 EP - 430 AD - Department of Psychology, Wilson Hall, Vanderbilt University, Nashville, TN 37240, USA. schalljd@ctrvax.vanderbilt.edu SN - 0036-8075 N2 - When humans respond to sensory stimulation, their reaction times tend to be long and variable relative to neural transduction and transmission times. The neural processes responsible for the duration and variability of reaction times are not understood. Single-cell recordings in a motor area of the cerebral cortex in behaving rhesus monkeys (Macaca mulatta) were used to evaluate two alternative mathematical models of the processes that underlie reaction times. Movements were initiated if and only if the neural activity reached a specific and constant threshold activation level. Stochastic variability in the rate at which neural activity grew toward that threshold resulted in the distribution of reaction times. This finding elucidates a specific link between motor behavior and activation of neurons in the cerebral cortex. KW - decisionmaking KW - fef KW - monkey KW - neurophysiology KW - _note KW - reaction_time KW - saccade N1 - * Single unit recording study of monkey FEF neurons in a countermanding saccade task intended to distinguish between two alternative mathematical models of reaction time duration and variability * Specifically, the authors compare variable rate and variable threshold models of reaction time: in the variable rate model, the trigger activation threshold is constant and variability in the growth rate of the activation function accounts for RT variability; in the variable threshold model, the activation function is constant and it is the activiation threshold that varies * the authors report from 25 of 118 FEF neurons that show movement related activity, typically increasing spiking ~100ms before saccade initiation and peaking shortly after initiation * using FEF activity 10-20 ms before saccade initiation as an index of the trigger threshold activation, there is no change in threshold activation level across different reaction times, consistent with the variable rate model (and inconsistent with the variable threshold model) * the rate of growth of FEF activity from baseline to 15 ms before saccade initiation is a decreasing function of reaction time, also consistent with the variable rate model * furthermore, during signal-inhibit trials of the countermanding task, FEF neurons were less likely to reach trigger threshold during trials where the monkey withheld a saccade than trials where a saccade where executed * finally, to determine if variation in neural activation functions could account for the variability of behavioral RTs, the authors compared RT distributions from individual FEF cells with predictions from linear accumulator with fixed threshold models derived from the parameters of each neuron; 9 of 22 distributions were indistinguishable while 17 of 22 cells showed identical mean RTs AU - Hanes, DP AU - Schall, JD PY - 1996/10/18/ UR - http://view.ncbi.nlm.nih.gov/pubmed/8832893 ER -