title: Movement related cortical potentials of cued versus self-initiated movements: double dissociated modulation by dorsal premotor cortex versus supplementary motor area rTMS.
abstract: The dorsal premotor cortex (PMd) is thought to play a significant role in movement preparation cued by sensory information rather than in self-initiated movements. The evidence in humans for this contention is still circumstantial. Here we explored the effects of modulation of PMd by excitability decreasing 1 Hz repetitive transcranial magnetic stimulation (rTMS) versus excitability increasing 5 Hz rTMS on two forms of movement related cortical potentials: contingent negative variation (CNV) versus Bereitschaftspotential (BP) reflecting externally cued versus self-triggered movement preparation. Ten healthy right-handed subjects performed visually cued or self-triggered simple sequential finger movements with their right hand. CNV and BP were recorded by 25 EEG electrodes covering the fronto-centro-parietal cortex and divided into an early (1500-500 ms before a go-signal or movement onset) and a late potential (500-0 ms). MRI-navigated 1 Hz rTMS of the left PMd resulted in significant increase of the late CNV over the left central region predominantly contralateral to the prepared right hand movement, while 5 Hz rTMS had no effect on CNV. In contrast, 1 and 5 Hz rTMS did not modify BP. Control experiments of 1 Hz rTMS of the supplementary motor area (SMA) and of low-intensity 1 Hz rTMS of the left primary motor cortex did not change CNV, but 1 Hz SMA-rTMS increased late BP. This double dissociation of effects of PMd-rTMS versus SMA-rTMS on CNV versus BP provides direct evidence that the left PMd in humans is more involved in preparatory processes of externally cued rather than self-initiated movements, contrasting with an opposite role of the SMA.
authors.affiliation: Department of Neurology, Motor Cortex Group, Goethe University, Frankfurt/Main, Germany.
authors.forename: Ming-Kuei
authors.initials: MK
authors.lastname: Lu
authors.forename: Noritoshi
authors.initials: N
authors.lastname: Arai
authors.forename: Chon-Haw
authors.initials: CH
authors.lastname: Tsai
authors.forename: Ulf
authors.initials: U
authors.lastname: Ziemann
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003265:Contingent Negative Variation / Q000502:physiology; D003463:Cues; D004569:Electroencephalography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult