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Timing of early activity in the visual cortex as revealed by simultaneous MEG and ERG recordings.
- Source :
-
NeuroImage [Neuroimage] 2006 Mar; Vol. 30 (1), pp. 239-44. Date of Electronic Publication: 2005 Nov 28. - Publication Year :
- 2006
-
Abstract
- To clarify the latency of the earliest cortical activity in visual processing, electroretinograms (ERGs) and visual evoked magnetic fields (VEFs) following flash stimulation were recorded simultaneously in six human subjects. Flash stimuli were applied to the right eye and ERGs were recorded from a skin electrode placed on the lower lid. ERGs showed two major deflections in all subjects: an eyelid-negativity around 20 ms and a positivity around 60 ms corresponding to an a- and b-waves, respectively. The mean onset and peak latency of the earliest component of VEFs (37 M) was 30.2 and 36.9 ms, respectively. There was a linear correlation between the peak latency of the a-wave and the onset latency of the 37 M (r=0.90, P=0.011). When a single equivalent current dipole analysis was applied to the 37 M, four out of six subjects showed highly reliable results. The generator of the 37 M was estimated to be located in the striate cortex in all four subjects. Since post-receptoral activities in the retina are expected to start around the peak of the a-wave (20 ms), the early cortical activity, which appears 10 ms later than the a-wave peak, is considered to be the earliest cortical activity following flash stimulation.
- Subjects :
- Adult
Brain Mapping
Dominance, Cerebral physiology
Electroretinography statistics & numerical data
Humans
Male
Photic Stimulation
Reaction Time physiology
Reference Values
Statistics as Topic
Time Factors
Electroencephalography statistics & numerical data
Evoked Potentials, Visual physiology
Magnetoencephalography statistics & numerical data
Signal Processing, Computer-Assisted
Visual Cortex physiology
Visual Perception physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1053-8119
- Volume :
- 30
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- NeuroImage
- Publication Type :
- Academic Journal
- Accession number :
- 16310379
- Full Text :
- https://doi.org/10.1016/j.neuroimage.2005.09.003