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The Journal of Neuroscience, September 20, 2006, 26(38):9629-9638; doi:10.1523/JNEUROSCI.2657-06.2006
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Behavioral/Systems/Cognitive
Acute Changes in Frontoparietal Activity after Repetitive Transcranial Magnetic Stimulation over the Dorsolateral Prefrontal Cortex in a Cued Reaction Time Task
Elisabeth Rounis,1 Klaas E. Stephan,2 Lucy Lee,2 Hartwig R. Siebner,3 A. Pesenti,6 Karl J. Friston,2 John C. Rothwell,1 andRichard S. J. Frackowiak2,4,5 1Sobell Department of Motor Neuroscience and Movement Disorders and 2Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom, 3Department of Neurology, Christian-Albrechts-University, D-24105 Kiel, Germany, 4Departement d'Etudes Cognitives, Ecole Normale Superieure, 75005 Paris, France, 5Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Santa Lucia, 00179 Rome, Italy, and 6Department of Neurological, Motor, and Sensorial Sciences, IRCCS San Raffaele, 00163 Rome, Italy
Correspondence should be addressed to Elisabeth Rounis, Sobell Department of Motor Neuroscience and Movement Disorders, 8-11 Queen Square, London WC1N 3BG, UK. Email: e.rounis{at}ion.ucl.ac.uk
Lesion and functional imaging studies in humans have suggested that the dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC), and intraparietal sulcus (IPS) are involved in orienting attention. A functional magnetic resonance imaging study supplemented by a behavioral experiment examined the effects of 5 Hz repetitive transcranial magnetic stimulation (rTMS) conditioning to the right and left DLPFC on reaction times and synaptic activity as indexed by changes in the blood oxygenation level-dependent (BOLD) signal during a cued choice reaction time task. Orienting precues were either correct (valid) or incorrect (invalid) with respect to the subsequent move cue. The effects of real and sham rTMS were compared for each site of stimulation. Invalid trials showed a significant increase in response times and increases in the BOLD signal in right frontal and parietal regions when compared with valid trials. Conditioning left DLPFC with rTMS led to decreased BOLD signal during performance of this reorienting task in areas including left VLPFC and left IPS. Comparing invalid to valid trials after right DLPFC conditioning revealed decreased BOLD signal in right VLPFC. Data from the behavioral study showed that right DLPFC rTMS selectively increases response times in invalid trials. This effect was only present in the first 10 min after rTMS conditioning. No effect was found in either validly or invalidly cued trials with left DLPFC conditioning. These results suggest that 5 Hz rTMS over right DLPFC exerts remote effects on the activity of areas that functionally interact with the DLPFC during attentional processes, particularly when the reorienting of attention is more demanding as in invalid trials.
Key words: attention; functional imaging; dorsolateral prefrontal cortex; Posner task; reorienting; repetitive transcranial magnetic stimulation
Received Jan. 27, 2006; revised Aug. 4, 2006; accepted Aug. 7, 2006.
Correspondence should be addressed to Elisabeth Rounis, Sobell Department of Motor Neuroscience and Movement Disorders, 8-11 Queen Square, London WC1N 3BG, UK. Email: e.rounis{at}ion.ucl.ac.uk
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[Abstract] [Full Text] [PDF]
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