Target processing in overt serial visual search involves the dorsal attention network: A fixation-based event-related...

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Neuroimaging

Background:

• Serial visual search involves sequential attention shifts.
• Previous fMRI studies often neglected overt attention (eye movements).
• The neural processing differences between target and distractor fixations remain unclear.

Purpose of the Study:

• To investigate neural differences between target and distractor processing during visual search with eye movements.
• To examine the role of the dorsal attention system and visual cortex in target identification.
• To explore the influence of search difficulty (number of targets) on brain activation.

Main Methods:

• Functional magnetic resonance imaging (fMRI) during a multiple target visual search task.
• Analysis focused on brain activity during eye fixations on targets versus distractors.
• Twenty healthy young adults participated in the experiment with a 20-item display.

Main Results:

• Target fixations, compared to distractor fixations, elicited widespread activation in the dorsal attention system and visual cortex.
• Later-identified targets showed stronger activation in the left inferior frontal gyrus and left supramarginal gyrus than earlier targets.
• Increased number of targets correlated with heightened activation in visual and verbal working memory areas.

Conclusions:

• Overt attention, reflected by eye movements, plays a crucial role in visual search.
• Distinct neural mechanisms differentiate target from distractor processing, involving attention and visual networks.
• Search difficulty modulates activity in higher-order cognitive control and memory regions.