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Cerebellar transcranial magnetic stimulation impairs verbal working memory
John E Desmond1, S H Annabel Chen, Perry B Shieh
1Department of Neurology, Johns Hopkins University, Baltimore, MD, USA. dr.jdesmond@gmail.com
Annals of Neurology
|September 24, 2005
Summary
Disrupting the right superior cerebellum using transcranial magnetic stimulation (TMS) slowed verbal working memory reaction times, suggesting the cerebellum
Area of Science:
- Neuroscience
- Cognitive Psychology
Background:
- Previous research suggests the cerebellum plays a role in verbal working memory.
- Event-related fMRI studies show superior cerebellar activation during verbal memory encoding.
Purpose of the Study:
- To investigate the causal role of the right superior cerebellum in verbal working memory.
- To determine if disrupting this region impairs performance on a verbal working memory task.
Main Methods:
- Functional magnetic resonance imaging (fMRI)-guided transcranial magnetic stimulation (TMS) was used to disrupt the right superior cerebellum (hemispheric lobule VI/Crus I).
- Single-pulse TMS was applied during the encoding phase of a verbal working memory task.
- Sham TMS and a motor control task were included to control for non-specific effects.
Main Results:
- TMS disruption of the right superior cerebellum did not affect accuracy but significantly increased reaction times (RTs) on correct trials.
- The increase in RT was greater for the verbal working memory task compared to the motor control task.
- Sham TMS did not influence RTs, ruling out distraction from the TMS click.
Conclusions:
- Cerebellar disruption specifically impacts verbal working memory performance, as evidenced by increased reaction times.
- These findings support the involvement of cerebrocerebellar circuits in verbal working memory processes.
- The right superior cerebellum is causally implicated in the encoding phase of verbal working memory.