Neurophysiology of implicit timing in serial choice reaction-time performance



Praamstra P, Kourtis D, Kwok HF & Oostenveld R (2006) Neurophysiology of implicit timing in serial choice reaction-time performance. Journal of Neuroscience, 26 (20), pp. 5448-5455.

Neural representations of time for the judgment of temporal durations are reflected in electroencephalographic (EEG) slow brain potentials, as established in time production and perception tasks. Here, we investigated whether anticipatory processes in reaction-time procedures are governed by similar mechanisms of interval timing. We used a choice reaction task with two different, temporally regular stimulus presentation regimes, both with occasional deviant interstimulus intervals. Temporal preparation was shown in the form of adjustments in time course of slow brain potentials, such that they reached their maximum amplitude just before a new trial, independent of the duration of the interstimulus interval. Preparation was focused on a brief time window, demonstrated by a drop in amplitude of slow potentials as the standard interval had elapsed in deviant interstimulus intervals. Implicit timing influencing perceptual processing was shown in reduced visual-evoked responses to delayed stimuli after a deviant interstimulus interval and in a reduction of EEG α power over the visual cortex at the time when the standard interval had elapsed. In contrast to explicit timing tasks, the slow brain potential manifestations of implicit timing originated in the lateral instead of the medial premotor cortex. Together, the results show that temporal regularities set up a narrow time window of motor and sensory attention, demonstrating the operation of interval timing in reaction time performance. The divergence in slow brain potential distribution between implicit and explicit timing tasks suggests that interval timing for different behaviors relies on qualitatively similar mechanisms implemented in distinct cortical substrates. Copyright © 2006 Society for Neuroscience.

Motor preparation; premotor cortex; electroencephalography; contingent negative variation; reaction time; timing;

Journal of Neuroscience: Volume 26, Issue 20

Publication date17/05/2006
Date accepted by journal12/04/2006
PublisherSociety for Neuroscience

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Dr Dimitrios Kourtis

Dr Dimitrios Kourtis

Lecturer, Psychology