Bilateral parieto-frontal network for verbal working memory: an interference approach using repetitive transcranial magnetic stimulation (rTMS).
Verbal working memory has been attributed to a left-dominant neuronal network, including parietal, temporal and prefrontal cortical areas. The current study was designed to evaluate the contribution of these brain regions to verbal working memory processes and to assess possible hemispheric asymmetry. The effect of repetitive transcranial stimulation (rTMS) on performance in a verbal working memory task both during, and after an rTMS train (110% of individual motor threshold, 4 Hz) over nine different scalp locations was studied [bilateral middle frontal gyrus (MFG), bilateral supramarginal gyrus (SMG), bilateral inferior parietal cortex (IP) and three different midline control sites]. Significant performance deterioration was observed during rTMS over the left and right MFG and left and right IP. There was no consistent interference effect across subjects over the left or right SMG and the three different midline control sites. The interference effect with the given stimulation parameters did not last beyond the rTMS train itself. The data provide evidence for a symmetrical, bilateral parieto-frontal verbal working memory network. The data are discussed with respect to the competing ideas of a parieto-frontal central executive network vs. a network that processes the inherent semantic and object features of the visually presented verbal stimuli in parallel.
Mottaghy
Felix M
FM
Department of Nuclear Medicine (KME), Research Center Jülich, 52426 Jülich, Germany. f.m.mottaghy@fz-juelich.de
Döring
Tobias
T
Müller-Gärtner
Hans-Wilhelm
HW
Töpper
Rudolf
R
Krause
Bernd J
BJ
D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology*; D009483:Neuropsychological Tests; D015588:Observer Variation; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D014705:Verbal Behavior / Q000502:physiology*