%0 Journal Article %J Neuroimage %D 2021 %T Within-subject reaction time variability: Role of cortical networks and underlying neurophysiological mechanisms. %A Paraskevopoulou, Sivylla E %A Coon, William G %A Peter Brunner %A Miller, Kai J %A Schalk, Gerwin %K Adult %K Algorithms %K Alpha Rhythm %K Cerebral Cortex %K Connectome %K Electrocorticography %K Female %K Gamma Rhythm %K Humans %K Male %K Middle Aged %K Nerve Net %K Psychomotor Performance %K Reaction Time %K Young Adult %X

Variations in reaction time are a ubiquitous characteristic of human behavior. Extensively documented, they have been successfully modeled using parameters of the subject or the task, but the neural basis of behavioral reaction time that varies within the same subject and the same task has been minimally studied. In this paper, we investigate behavioral reaction time variance using 28 datasets of direct cortical recordings in humans who engaged in four different types of simple sensory-motor reaction time tasks. Using a previously described technique that can identify the onset of population-level cortical activity and a novel functional connectivity algorithm described herein, we show that the cumulative latency difference of population-level neural activity across the task-related cortical network can explain up to 41% of the trial-by-trial variance in reaction time. Furthermore, we show that reaction time variance may primarily be due to the latencies in specific brain regions and demonstrate that behavioral latency variance is accumulated across the whole task-related cortical network. Our results suggest that population-level neural activity monotonically increases prior to movement execution, and that trial-by-trial changes in that increase are, in part, accounted for by inhibitory activity indexed by low-frequency oscillations. This pre-movement neural activity explains 19% of the measured variance in neural latencies in our data. Thus, our study provides a mechanistic explanation for a sizable fraction of behavioral reaction time when the subject's task is the same from trial to trial.

%B Neuroimage %V 237 %P 118127 %8 08/2021 %G eng %R 10.1016/j.neuroimage.2021.118127 %0 Conference Paper %B Engineering in Medicine and Biology Society, 2008. %D 2008 %T Three cases of feature correlation in an electrocorticographic BCI. %A Miller, Kai J %A Blakely, Timothy %A Gerwin Schalk %A den Nijs, Marcel %A Rao, Rajesh PN %A Ojemann, Jeffrey G %K Adolescent %K Adult %K Algorithms %K automated pattern recognition %K control systems %K decorrelation %K Electrocardiography %K Electrodes %K Electroencephalography %K evoked motor potentials %K Feedback %K Female %K frequency %K hospitals %K Humans %K Male %K Middle Aged %K Motor Cortex %K Signal Processing %K Statistics as Topic %K Task Performance and Analysis %K Tongue %K User-Computer Interface %X Three human subjects participated in a closed-loop brain computer interface cursor control experiment mediated by implanted subdural electrocorticographic arrays. The paradigm consisted of several stages: baseline recording, hand and tongue motor tasks as the basis for feature selection, two closed-loop one-dimensional feedback experiments with each of these features, and a two-dimensional feedback experiment using both of the features simultaneously. The two selected features were simple channel and frequency band combinations associated with change during hand and tongue movement. Inter-feature correlation and cross-correlation between features during different epochs of each task were quantified for each stage of the experiment. Our anecdotal, three subject, result suggests that while high correlation between horizontal and vertical control signal can initially preclude successful two-dimensional cursor control, a feedback-based learning strategy can be successfully employed by the subject to overcome this limitation and progressively decorrelate these control signals. %B Engineering in Medicine and Biology Society, 2008. %I IEEE %C Vancouver, BC %8 08/2008 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/19163918 %R 10.1109/IEMBS.2008.4650415