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A neural basis for real-world visual search in human occipitotemporal cortex
Marius V Peelen1, Sabine Kastner
1Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto, Italy. marius.peelen@unitn.it
Summary
Humans prepare to find objects by activating brain regions that match the target category, aiding visual search in natural scenes. Higher visual cortex activity predicts success, while early visual cortex activity hinders it.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Visual Perception
Background:
- Mammals excel at detecting objects in complex natural environments, crucial for survival.
- Understanding the neural basis of object detection in natural scenes is a key research question.
Purpose of the Study:
- Investigate the role of top-down preparatory processes in detecting familiar object categories within real-world environments.
- Examine how the brain prepares to search for objects when precise visual details are unknown.
Main Methods:
- Utilized human brain imaging (fMRI) to measure brain activity during preparation for object detection.
- Participants prepared to detect people or cars in natural scenes, with stimuli new to them.
- Analyzed multivoxel activity patterns in visual cortex and medial prefrontal cortex.
Main Results:
- Preparatory activity in object-selective cortex (OSC) mirrored responses to actual objects and predicted detection performance.
- Early visual cortex (V1) preparatory activity negatively correlated with search performance, suggesting different search strategies.
- Medial prefrontal cortex showed category-selective preparatory activity, indicating a top-down source.
Conclusions:
- Higher-level visual cortex activity selectively mediates visual search in naturalistic settings.
- Top-down preparation, originating from regions like the medial prefrontal cortex, is crucial for efficient object detection.
- Dissociation between OSC and V1 activity highlights distinct roles in abstract versus imagery-based search preparation.
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