Source dipole analysis reveals a new brain response to visual symmetry

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Neuroscience

Background:

• Visual regularity, particularly symmetry, engages extrastriate cortex networks.
• Previous electroencephalography (EEG) studies show symmetry responses scale with visual symmetry proportion.
• This response is enhanced during active regularity discrimination tasks, but its neural origins and timing remain unclear.

Purpose of the Study:

• To investigate the neural origins and time course of enhanced symmetry processing during regularity discrimination.
• To differentiate between early sensory and later cognitive contributions to symmetry perception.

Main Methods:

• Employed source dipole analysis on electroencephalography (EEG) data.
• Analyzed brain activity during visual symmetry discrimination tasks.

Main Results:

• Confirmed bilateral extrastriate cortex dipoles generate the parametric symmetry response.
• Observed enhanced activity in these extrastriate regions during regularity discrimination.
• Identified a novel, later symmetry response originating in the posterior cingulate cortex, specifically during discrimination.

Conclusions:

• The extrastriate response reflects general visual symmetry processing, enhanced by attention.
• The posterior cingulate response uniquely signals strong, task-relevant regularity, indicating a distinct cognitive role.
• These findings clarify the neural circuitry underlying both perceptual and cognitive aspects of symmetry discrimination.