Research › QEEG, Methods & Mechanisms
Localization of visually evoked cortical activity in humans.
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Study at a glance
- Area
- QEEG, Methods & Mechanisms
- Study type
- Observational study
- Authors
- Srebro R
- Journal
- The Journal of Physiology
- Year
- 1985
- Protocol
- Laplacian visual evoked potential mapping
Key findings
- Lower visual field stimuli activated occipital cortex on the side opposite the stimulus
- More peripheral stimuli activated more forward (rostral) cortex, with up to 3 cm variation between people
- Upper field stimuli produced weak activity at the occipital pole, almost unmeasurable in some subjects
- Posterior parietal and inferior temporal activity was often evoked, with patterns differing between individuals
A study that used scalp recordings to work out where in the cortex visual stimuli are processed. Checkerboard patterns were flashed at sixteen positions in the visual field while a multi-electrode array measured the Laplacian of the visual evoked potential, a reference-free measure with about 2 cm resolution at the cortex. Lower-field stimuli activated the occipital convexity opposite the stimulus, while upper-field responses were weak. The author suggests the upper field is mostly represented on deeper occipital surfaces that this method cannot reach.