Frontal Theta Modulation in Sequential Working Memory: the Impact of Spatial Regularity and Scenario

Area of Science:

• Cognitive Neuroscience
• Neurophysiology

Background:

• Working memory (WM) relies on extracting spatial regularities to reduce cognitive load.
• Electrophysiological correlates of spatial regularity processing in WM remain largely unknown.
• Frontal-midline theta (FM-theta) is implicated in sequential WM, but its modulation by spatial regularity is unclear.

Purpose of the Study:

• To investigate how spatial regularity influences frontal-midline theta (FM-theta) activity during sequential working memory.
• To differentiate the neural mechanisms underlying spatial regularity processing from general task difficulty.

Main Methods:

• Participants encoded, maintained, and reproduced sequences with varying spatial regularity under different scenario complexities.
• Electroencephalography (EEG) was used to record brain activity.
• Behavioral accuracy and EEG spectral power (4-30 Hz) and connectivity were analyzed.

Main Results:

• Higher sequence regularity and simpler scenarios improved behavioral accuracy.
• Theta power increased, while alpha/beta power decreased with sequence complexity.
• Spatial regularity, not scenario difficulty, modulated fronto-posterior theta connectivity and FM-theta frequency.

Conclusions:

• Frontal-midline theta (FM-theta) exclusively tracks spatial regularity demands in sequential working memory.
• FM-theta's role involves long-range connectivity and frequency modulation, independent of scenario difficulty.
• FM-theta serves as a specific neural marker for spatial regularity processing, offering potential for neuromodulatory interventions.