Population-Level Activity Dissociates Preparatory Overt from Covert Attention.

Area of Science:

• Cognitive Neuroscience
• Neuroscience
• Visual Attention

Background:

• Neural signatures of preparing overt eye movements and covert spatial attention are thought to overlap significantly, recruiting similar brain areas.
• While single-cell studies show some dissociation, it's proposed that many visuo-oculomotor cells are involved in both processes, leading to functional overlap.
• Understanding the neural basis of selective visual processing is crucial for cognitive function.

Purpose of the Study:

• To directly test the proposal that neural signatures of preparatory overt and covert attention largely overlap at the population level.
• To investigate whether population-level neural activity dissociates preparatory overt from covert attention using electroencephalography (EEG).
• To identify specific neural processes contributing to the differences between overt and covert attention.

Main Methods:

• Combined human EEG recordings with sensitive decoding techniques to analyze neural activity.
• Utilized inverted encoding modeling to assess the spatial tuning of neural populations.
• Employed cross-decoding analyses to determine if additional neural processes are recruited during overt attention.

Main Results:

• Neural decoding reliably distinguished between overt and covert attention shifts well before saccade initiation.
• Inverted encoding modeling revealed earlier and sharper spatially-tuned neural activity during preparatory overt attention compared to covert attention.
• Cross-decoding indicated that preparatory overt attention recruits at least one additional, early-emerging frontal neural process, likely related to motor preparation or predictive remapping.

Conclusions:

• The neural signatures of overt and covert attention, while overlapping, diverge rapidly at the population level.
• Preparatory overt attention employs an additional spatially selective neural process not present in covert attention, leading to population-level dissociation.
• These findings demonstrate that population-level neural activity, not just single-cell activity, can dissociate preparatory overt from covert attention.