Mapping neural activity during naturalistic visual and memory search

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Vision

Background:

• Hybrid search, crucial for everyday tasks like landmark navigation, involves searching for items stored in memory.
• While behavioral aspects are known, the neural mechanisms of hybrid search are not well understood.

Purpose of the Study:

• To investigate the neural dynamics of hybrid search using magnetoencephalography (MEG) and eye-tracking.
• To explore oscillatory and evoked brain responses during naturalistic visual search with memory components.

Main Methods:

• Concurrent MEG and eye movement recordings during a free-viewing hybrid search task.
• Time-frequency analysis, source reconstruction, and deconvolution methods were applied.

Main Results:

• Alpha-band power decreased with memory load during encoding/retention.
• Frontoparietal beta-band activity increased with memory load during search.
• Distinct evoked responses, including a V1-localized lambda response and a right inferior parietal P3m component, differentiated target from distractor fixations.

Conclusions:

• Hybrid search involves specific oscillatory (alpha, beta) and evoked (lambda, P3m) neural signatures.
• Alpha-band modulation relates to perceptual/mnemonic load, while beta-band reflects cognitive control.
• These findings elucidate the dynamic interplay of memory, attention, and visual processing in active vision.