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Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns
Published on: May 12, 2019
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Stimulus Dependence of Gamma Oscillations in Human Visual Cortex
D Hermes1, K J Miller2, B A Wandell3
1Department of Psychology, New York University, New York, NY, USA Department of Psychology, Stanford University, Stanford, CA, USA.
Cerebral Cortex (New York, N.Y. : 1991)
|May 24, 2014
Summary
Gamma oscillations in visual cortex are not always necessary for seeing, as broadband signals also support visual recognition. These findings clarify the role of different neural signals in visual processing.
Area of Science:
- Neuroscience
- Visual Cortex Research
- Electrophysiology
Background:
- Gamma band oscillations (30-80 Hz) in visual cortex are linked to perception and attention.
- A broadband signal (80-200 Hz) is also observed in human electrocorticography (ECoG) data.
- The conditions eliciting gamma oscillations and their necessity for visual encoding are unclear.
Purpose of the Study:
- To investigate the conditions under which gamma oscillations occur in the human visual cortex.
- To determine the relationship between gamma oscillations and broadband signals.
- To assess the necessity of gamma oscillations for visual perception and recognition.
Main Methods:
- Utilized human electrocorticography (ECoG) recordings from the visual cortex (V1/V2/V3).
- Presented various visual stimuli, including luminance gratings, noise patterns, and natural images.
- Analyzed spectral changes in ECoG responses, focusing on gamma band oscillations and broadband signals.
Main Results:
- Robust gamma oscillations were elicited by luminance gratings but not by noise or many natural images.
- Gamma oscillations were found to be absent for many visual stimuli that are nonetheless perceived.
- All visual stimuli consistently induced broadband spectral changes in ECoG responses.
Conclusions:
- Gamma oscillations are not a ubiquitous or necessary component of visual encoding in the human visual cortex.
- Broadband spectral changes in ECoG responses reflect asynchronous neural signals supporting visual perception.
- Information transmission for recognition can occur via broadband signals even without pronounced gamma oscillations.
