Sustained activity in the medial wall during working memory delays

Area of Science:

• Neuroscience
• Cognitive Neuroscience

Background:

• Medial wall areas are implicated in cognitive functions, but their specific roles in working memory remain unclear.
• Previous research has primarily focused on motor and eye movement areas, leaving gaps in understanding their contribution to memory-based tasks.

Purpose of the Study:

• To investigate the role of medial wall areas in human working memory using functional magnetic resonance imaging (fMRI).
• To identify specific medial wall regions exhibiting sustained activity during working memory delays.
• To differentiate memory-related activity from motor preparation signals.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to measure brain activity.
• Medial motor areas (SMA, CMA) and eye movement areas (SEF) were functionally defined.
• Sustained activity during spatial and face working memory tasks was analyzed in relation to these landmarks.

Main Results:

• Two distinct areas, the pre-supplementary motor area (pre-SMA) and the caudal anterior cingulate cortex (caudal-AC), showed sustained activity during both spatial and face working memory delays.
• These identified areas (pre-SMA and caudal-AC) were located anterior to the SMA, CMA, and SEF.
• Activity in pre-SMA and caudal-AC during memory delays was distinct from activity during simple motor response preparation.

Conclusions:

• Sustained activity in pre-SMA and caudal-AC during working memory delays reflects a state of preparedness for response selection based on online information.
• These findings suggest that these medial wall areas play a crucial role in cognitive control and information maintenance within working memory.
• The study differentiates cognitive functions of pre-SMA and caudal-AC from purely motor preparation roles.