Time-course of "off-line" prefrontal rTMS effects--a PET study

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Brain Stimulation

Background:

• Repetitive transcranial magnetic stimulation (rTMS) is a valuable tool for studying brain-behavior relationships.
• Understanding the duration and remote effects of rTMS is crucial for experimental design.

Purpose of the Study:

• To investigate the duration and extent of neurophysiological effects following low-frequency rTMS.
• To examine the impact of rTMS on regional cerebral blood flow (rCBF) in interconnected brain areas.

Main Methods:

• 12 healthy male subjects received low-frequency rTMS on the right dorsolateral prefrontal cortex (DLPFC).
• 8 H(2)(15)O positron emission tomography (PET) scans were performed to measure rCBF.
• rCBF was assessed immediately after the rTMS train.

Main Results:

• Increased rCBF was observed at the stimulation site (DLPFC) and ipsilateral prefrontal areas, including the ventrolateral prefrontal cortex (VLPFC).
• These rCBF increases returned to baseline levels within approximately 9 minutes.
• The neurophysiological effects of rTMS were predominantly unilateral.

Conclusions:

• The immediate effects of low-frequency rTMS on rCBF in the prefrontal cortex are transient, lasting less than 9 minutes.
• These findings are important for designing cognitive neuroscience experiments using off-line rTMS to probe brain function.