Does white matter matter? Spatio-temporal dynamics of task switching in aging

Area of Science:

• Neuroscience
• Cognitive Aging
• Neuroimaging

Background:

• Aging is associated with declines in executive functions, such as task switching.
• These cognitive changes may stem from age-related alterations in brain structure and function, particularly in neural connections.

Purpose of the Study:

• To investigate age-related functional and structural brain changes during task switching between spatial and verbal tasks.
• To explore the relationship between anterior corpus callosum (CC) size, brain activity, and task-switching performance in older adults.

Main Methods:

• Measured anterior corpus callosum (CC) size (structural measure) and used event-related optical signal (EROS) (functional measure).
• Assessed behavioral performance in task switching between spatial and verbal tasks in younger and older adults.

Main Results:

• Older adults exhibited greater task-switching difficulties, particularly for spatial tasks, and this was associated with smaller anterior CC size.
• EROS data revealed general switching activity in the left middle frontal gyrus and task-specific activity in the inferior frontal gyrus, lateralized by task type.
• In older adults, the lateralization of switch-to-spatial activity was dependent on CC size, with larger CCs associated with right-hemisphere activity and smaller CCs with left-hemisphere activity.

Conclusions:

• Task switching involves both general and task-specific neural processes.
• Age-related white matter changes, indicated by reduced CC size, may contribute to impaired task switching, supporting the cortical disconnection hypothesis of aging.