Repetitive Transcranial Magnetic Stimulation Affects behavior by Biasing Endogenous Cortical Oscillations
Massihullah Hamidi1, Heleen A Slagter, Giulio Tononi
1Medical Scientist Training Program, University of Wisconsin - Madison Madison, WI, USA.
Frontiers in Integrative Neuroscience
|July 10, 2009
Summary
Repetitive transcranial magnetic stimulation (rTMS) effects on behavior depend on individual brain activity. rTMS can enhance cognitive tasks by modulating alpha-band oscillations, challenging the idea that it only disrupts brain function.
Area of Science:
- Neuroscience
- Cognitive Science
- Neuroimaging
Background:
- Repetitive transcranial magnetic stimulation (rTMS) is often assumed to disrupt neural activity, potentially impairing cognitive performance.
- Recent findings suggest rTMS can also enhance behavior, questioning the 'noise injection' hypothesis.
Purpose of the Study:
- To investigate the neurophysiological mechanisms underlying rTMS effects on visual working memory.
- To explore the relationship between rTMS-induced changes in brain activity and behavioral outcomes.
Main Methods:
- Simultaneous electroencephalography (EEG) and rTMS were used during a visual working memory task.
- rTMS was delivered to the superior parietal lobule (SPL) or a control area during the delay period.
- Participants performed location and object working memory tasks.
Main Results:
- Individual differences in rTMS effects on task accuracy were predicted by changes in EEG alpha-band power.
- Decreased alpha-band power correlated with improved performance, while increased power correlated with impairment.
- rTMS-induced changes in alpha-gamma phase synchrony predicted behavioral changes.
Conclusions:
- Alpha-band oscillations play an active role in cognitive processes, not just reflecting a lack of activity.
- The complex behavioral effects of rTMS may arise from biasing endogenous network oscillations.
- These findings provide new insights into the neural mechanisms of rTMS and cognitive function.
