Prestimulus amygdala spectral activity is associated with visual face awareness

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neurophysiology

Background:

• Alpha cortical oscillations are known to suppress sensory processing and affect conscious perception.
• The role of oscillatory neural activity in the amygdala, crucial for salience detection, on stimulus awareness remains unclear.

Purpose of the Study:

• To investigate whether oscillatory activity in the human amygdala impacts face detection and visual awareness.
• To explore the potential role of amygdala oscillations in perceptual gating mechanisms.

Main Methods:

• Intracranial electroencephalography (EEG) was recorded from 9 human amygdalae.
• A continuous flash suppression task was used to assess face detection.
• Spectral analysis focused on prestimulus power and phase coherence, particularly in the alpha band.

Main Results:

• Increased alpha band power and phase coherence were observed in the amygdala when faces were undetected compared to detected.
• These findings mirror previous observations in cortical regions using scalp-EEG.
• Decreases in alpha and gamma bands preceded face detection, with prestimulus alpha power negatively correlating with detection rates.

Conclusions:

• Prestimulus oscillations in the human amygdala, especially in the alpha band, contribute to perceptual gating of visual stimuli.
• This study provides novel insights into the subcortical mechanisms underlying visual awareness and the amygdala's role within these processes.