Document Detail

On the processing of spatial frequencies as revealed by evoked-potential source modeling.
MedLine Citation:
PMID:  10825719     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES AND METHODS: Visually evoked potentials (VEPs) are known to be sensitive to spatial frequency, especially in the time range between 50 and 100 ms post-stimulus. In two experiments we localized the cortical activity elicited by stimuli of varying spatial frequency in scalp-recorded brain potentials, using multi-electrode recordings and dipole-source analysis. RESULTS: Low spatial frequencies (<1 c/d) activated relatively lateral occipital areas, the orientation of the neural ensembles involved being predominantly perpendicular to the scalp surface. In contrast, high spatial frequencies (>4 c/d) induced activation of more medial occipital areas with the predominant orientation of the sources being much more parallel to the scalp surface. Furthermore, at about 100 ms latency the lateral-occipital response to low spatial frequencies was stronger in the right hemisphere; no such asymmetry was found for the responses to the high spatial frequencies. These findings were consistent across varying recording conditions, individual subjects, subject populations, stimulus characteristics (grating orientation, grating vs. checkerboard), and task conditions (active vs. passive). CONCLUSION: The results indicate that there are differences in sensitivity to specific spatial frequencies between primary and secondary visual areas, as well as between the right and the left hemispheres.
J L Kenemans; J M Baas; G R Mangun; M Lijffijt; M N Verbaten
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology     Volume:  111     ISSN:  1388-2457     ISO Abbreviation:  Clin Neurophysiol     Publication Date:  2000 Jun 
Date Detail:
Created Date:  2000-07-14     Completed Date:  2000-07-14     Revised Date:  2008-09-10    
Medline Journal Info:
Nlm Unique ID:  100883319     Medline TA:  Clin Neurophysiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  1113-23     Citation Subset:  IM    
Department of Psychopharmacology, Faculty of Pharmacy, Rudolf Magnus Institute for Neurosciences, University of Utrecht, PO Box 80082, 3508 TB, Utrecht, The Netherlands.
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MeSH Terms
Analysis of Variance
Brain Mapping*
Evoked Potentials, Visual / physiology*
Fixation, Ocular
Occipital Lobe / physiology*
Photic Stimulation
Reaction Time
Scalp / innervation
Space Perception
Visual Fields
Grant Support

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