Visual stimuli modulate frontal oscillatory rhythms in a cortically blind patient: Evidence for top-down visual...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Processing

Background:

• Investigating neuronal processing of visual stimuli in individuals with cortical blindness is crucial for understanding brain plasticity and alternative pathways.
• Cortical blindness, resulting from damage to the visual cortex, presents unique challenges for studying residual visual function.

Observation:

• Electrophysiological correlates of face processing were examined in a cortically blind patient (TN) and healthy controls using electroencephalography (EEG).
• Intact and scrambled faces were presented, and time-frequency transforms analyzed oscillatory brain activity, particularly in theta and alpha frequency bands.

Findings:

• TN exhibited post-stimulus oscillatory modulations (theta and alpha synchronization) in frontal scalp sites for both intact and scrambled faces.
• These frontal oscillatory rhythms differed significantly from those observed in control participants.
• Increased theta band activity was noted for incorrect responses, suggesting a link between neural oscillations and response accuracy.

Implications:

• Despite visual cortex destruction, oscillatory brain rhythms persist and shift to anterior regions, indicating an alternative pathway for residual visual function.
• The findings support the existence of a top-down cognitive control process in blindsight.
• This research sheds light on the brain's remarkable ability to adapt and reroute visual information processing.