Distinctive Interaction Between Cognitive Networks and the Visual Cortex in Early Blind Individuals

Area of Science:

• Neuroscience
• Cognitive Science
• Neuroimaging

Background:

• In early blind individuals, nonperceptual cognitive tasks activate the visual cortex, unlike in sighted individuals where activation is limited to association areas.
• This phenomenon suggests the visual cortex in the blind is integrated into typical task-dependent neural networks.

Purpose of the Study:

• To test the hypothesis that visual cortex activation in early blind individuals results from its integration into task-dependent networks.
• To investigate the functional connectivity of segmented visual cortex areas during resting state in relation to specific cognitive tasks.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to study blind and sighted subjects.
• Tasks included speech comprehension, long-term memory, and executive control (verbal and nonverbal), alongside resting-state data collection.
• Resting-state functional connectivity was assessed for segmented visual cortex areas identified by task sensitivity.

Main Results:

• All tasks activated the visual cortex in blind subjects relative to sighted subjects, allowing for task-sensitive segmentation.
• Language tasks showed connectivity to frontal and temporal language areas.
• Executive control tasks connected to the right dorsal frontoparietal network, and memory tasks linked to mesial frontoparietal episodic memory regions.

Conclusions:

• The study demonstrates the selective integration of distinct visual cortex regions into specific brain-scale networks in early blind individuals.
• These integrated visual cortex areas exhibit unique localization, lateralization, and functional roles corresponding to language, executive, and memory functions.
• This provides evidence for cross-modal plasticity and functional reorganization of the visual cortex following early-onset blindness.