Altered functional connectivity underpins cognitive changes in chronic spinal cord injury

Area of Science:

• Neuroscience
• Cognitive Science
• Rehabilitation Medicine

Background:

• Spinal cord injury (SCI) increases the risk of cognitive impairment, particularly affecting executive functions.
• Neural mechanisms underlying cognitive deficits post-SCI remain largely unknown.
• Executive functions are crucial for daily living and are often compromised after SCI.

Purpose of the Study:

• To investigate the neural correlates of executive functions in individuals with spinal cord injury (SCI).
• To compare brain activity and functional connectivity during an executive function task between SCI patients and controls.
• To explore the relationship between cognitive performance and brain network alterations in SCI.

Main Methods:

• Prospective observational study involving 26 individuals with chronic SCI and 26 matched controls.
• Functional magnetic resonance imaging (fMRI) was used during a phonemic verbal fluency task (proxy for executive functions).
• Analysis included task performance, brain activity (BOLD signal), and seed-based functional connectivity using general linear models.

Main Results:

• Individuals with SCI performed significantly worse on the verbal fluency task (15% fewer correct words).
• Lower brain activity was observed in the right putamen in the SCI group.
• Reduced functional connectivity was found between the left insula and superior frontal gyrus in SCI individuals.
• In SCI patients, verbal fluency performance negatively correlated with connectivity between the insula/postcentral gyrus and putamen/precentral gyrus.

Conclusions:

• Altered brain activity and functional connectivity in regions associated with executive functions are present in individuals with SCI.
• The insula's altered connectivity may contribute to executive function deficits post-SCI.
• Disrupted sensorimotor network connectivity appears to interfere with cognitive functions like verbal fluency in SCI.