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Early gamma-band activity as a function of threat processing in the extrastriate visual cortex
Cognitive Neuroscience
|February 14, 2012
Summary
Threat perception rapidly engages the visual cortex. Gamma band activity in the visual cortex is reduced when viewing angry faces, suggesting a role in processing threat cues.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Visual Processing
Background:
- Emotional stimuli elicit greater visual cortex activity than neutral stimuli.
- Threat-related information is processed rapidly, suggesting early visual cortex modulation.
- Gamma band oscillations (40–100 Hz) are linked to threat processing.
Purpose of the Study:
- To investigate gamma band activity during the perception of threat-related versus neutral facial expressions.
- To determine the timing and location of visual cortex modulation by threat cues.
- To explore the role of gamma activity in the affective modulation of visual processing.
Main Methods:
- Magnetoencephalography (MEG) was employed to measure brain activity.
- Participants viewed task-irrelevant, threat-related (angry) and neutral facial expressions.
- Gamma band activity was analyzed in the extrastriate visual cortex (BA 18).
Main Results:
- A bilateral reduction in gamma band activity was observed for angry faces compared to neutral faces.
- This reduction occurred within 50–250 ms after stimulus onset.
- The effect was localized to the extrastriate visual cortex (BA 18).
Conclusions:
- Gamma activity in the visual cortex is involved in the affective modulation of visual processing.
- This modulation is particularly relevant for the perception of threat cues.
- Early-stage visual processing is influenced by the emotional content of stimuli, especially threats.
