The devil is in the detail: brain dynamics in preparation for a global-local task

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• Visual scene analysis often requires processing information at different scales or "grain" sizes.
• Attention control mechanisms are crucial for directing cognitive resources to the relevant level of analysis.
• The dorsal attention network (DAN) and visual processing network (VPN) are key brain networks involved in attention and visual processing.

Purpose of the Study:

• To investigate the involvement of the DAN and VPN in preparing for visual analysis at different grain sizes.
• To examine the neural correlates of processing local (small features) versus global (large features) information in visual scenes.
• To determine if attention preparation for visual analysis is lateralized or asymmetric.

Main Methods:

• Utilized event-related optical signals (EROS) for high temporal and spatial resolution brain activity measurement.
• Employed a hierarchical visual stimulus to elicit local and global processing conditions.
• Analyzed behavioral data to assess performance in local versus global conditions.
• Examined brain activation patterns within the DAN and VPN.

Main Results:

• Behavioral data showed that processing small features (local) was more difficult than processing large features (global).
• Cues predicting local trials led to increased DAN activation, particularly in the left hemisphere with a frontal-to-parietal progression.
• Higher DAN activation in the left parietal regions predicted better performance.
• An interaction between analysis level and hemisphere was observed in the VPN, with local processing engaging ventral VPN and global processing engaging dorsal VPN.

Conclusions:

• Preparation for analyzing different visual feature sizes is an asymmetric process, requiring more effort for small features due to lower salience.
• The dorsal attention network (DAN) is involved in preparing for visual analysis at different scales, consistent with its role in general attention control.
• Hemispheric asymmetries and distinct sub-regions within the visual processing network (VPN) are engaged depending on whether local or global visual information is prioritized.