The effect of cortical repetitive transcranial magnetic stimulation on cognitive event-related potentials recorded in the subthalamic nucleus

Experimental Brain Research (Impact Factor: 2.17). 06/2010; 203(2):317-327. DOI: 10.1007/s00221-010-2232-4

ABSTRACT We studied whether the cognitive event-related potentials (ERP) in the subthalamic nucleus (STN) are modified by the modulation
of the inferior frontal cortex (IFC) and the dorsolateral prefrontal cortex (DLPFC) with repetitive transcranial magnetic
stimulation (rTMS). Eighteen patients with Parkinson’s disease who had been implanted with a deep brain stimulation (DBS)
electrode were included in the study. The ERPs were recorded from the DBS electrode before and after the rTMS (1Hz, 600 pulses)
over either the right IFC (10 patients) or the right DLPFC (8 patients). The ERPs were generated by auditory stimuli. rTMS
over the right IFC led to a shortening of ERP latencies from 277±14ms (SD) to 252±19ms in the standard protocol and
from 296±17ms to 270±20ms in the protocol modified by a higher load of executive functions (both P<0.01). The application of rTMS over the DLPFC and the sham stimulation over the IFC showed no significant changes. The
shortening of ERP latency after rTMS over the right IFC reflected the increase in the speed of the cognitive process. The
rTMS modulation of activity of the DLPFC did not influence the ERP. Connections (the IFC-STN hyperdirect pathway) with the
cortex that bypass the BG-thalamocortical circuitries could explain the position of the STN in the processing of executive

KeywordsInferior frontal cortex-Subthalamic nucleus-Executive functions-ERP-P3-Hyperdirect pathway

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