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Preparatory modulations relative to the timing of upcoming stimuli may involve activation or suppression mechanisms. Here, we assessed the interplay between these mechanisms with transcranial magnetic stimulation (TMS) of the motor cortex. Single- or paired-pulse TMS with 3- or 15-ms interstimulus intervals was delivered during the interval between the warning and the imperative stimuli (i.e., the foreperiod) of a choice reaction time task. Temporal uncertainty was manipulated through between-block variation of the foreperiod duration (500 or 2500. ms). The shortening of reaction time for the short foreperiod was accompanied with a decrease in amplitude of the single-pulse motor evoked potential (MEP), indicating corticospinal suppression. The co-occurring increase in amplitude of both paired-pulse MEPs (3 and 15. ms) expressed relative to single-pulse MEPs reveals released short intracortical inhibition (SICI) and enhanced intracortical facilitation (ICF). These results suggest that temporal preparation is associated with both corticospinal suppression and cortical activation. © 2010 Elsevier B.V.

Item Type:	Refereed Article
Research Division:	Psychology
Research Group:	Cognitive and computational psychology
Research Field:	Sensory processes, perception and performance
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in psychology
UTAS Author:	Tandonnet, C (Dr Christophe Tandonnet)
UTAS Author:	Garry, MI (Associate Professor Michael Garry)
UTAS Author:	Summers, JJ (Professor Jeffery Summers)
ID Code:	66258
Year Published:	2010
Web of Science® Times Cited:	26
Deposited By:	Psychology
Deposited On:	2011-01-11
Last Modified:	2015-02-06
Downloads:	0