Document Detail

Detection of a weak somatosensory stimulus: role of the prestimulus mu rhythm and its top-down modulation.
MedLine Citation:
PMID:  19400673     Owner:  NLM     Status:  MEDLINE    
The ongoing neural activity in human primary somatosensory cortex (SI) is characterized by field potential oscillations in the 7-13 Hz range known as the mu rhythm. Recent work has shown that the magnitude of the mu oscillation immediately preceding the onset of a weak stimulus has a significant impact on its detection. The neural mechanisms mediating this impact remain not well understood. In particular, whether and how somatosensory mu rhythm is modulated by executive areas prior to stimulus onset for improved behavioral performance has not been investigated. We addressed these issues by recording 128-channel scalp electroencephalogram from normal volunteers performing a somatosensory perception experiment in which they reported the detection of a near-threshold electrical stimulus ( approximately 50% detection rate) delivered to the right index finger. Three results were found. First, consistent with numerous previous reports, the N1 component ( approximately 140 msec) of the somatosensory-evoked potential was significantly enhanced for perceived stimulus compared to unperceived stimulus. Second, the prestimulus mu power and the evoked N1 amplitude exhibited an inverted-U relationship, suggesting that an intermediate level of prestimulus mu oscillatory activity is conducive to stimulus processing and perception. Third, a Granger causality analysis revealed that the prestimulus causal influence in the mu band from prefrontal cortex to SI was significantly higher for perceived stimulus than for unperceived stimulus, indicating that frontal executive structures, via ongoing mu oscillations, exert cognitive control over posterior sensory cortices to facilitate somatosensory processing.
Yan Zhang; Mingzhou Ding
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of cognitive neuroscience     Volume:  22     ISSN:  1530-8898     ISO Abbreviation:  J Cogn Neurosci     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-18     Completed Date:  2010-03-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8910747     Medline TA:  J Cogn Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  307-22     Citation Subset:  IM    
University of Florida, Gainesville, FL 32611, USA.
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MeSH Terms
Brain Mapping*
Electric Stimulation
Electroencephalography / methods
Evoked Potentials, Somatosensory / physiology*
Psychomotor Performance / physiology
Sensory Thresholds / physiology*
Signal Detection, Psychological / physiology*
Somatosensory Cortex / physiology*
Spectrum Analysis / methods
Young Adult

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