Brain Networks Communicate Through Theta Oscillations to Encode High Load in a Visuospatial Working Memory Task: An...

Area of Science:

• Neuroscience
• Cognitive Science
• Brain Imaging

Background:

• Visuospatial working memory (VSWM) encoding is crucial for cognitive tasks, yet its neural underpinnings remain unclear.
• Understanding VSWM encoding mechanisms is vital for explaining memory capacity limitations.
• Dense-array electroencephalography (EEG) offers high temporal and spatial resolution for studying brain dynamics during cognitive tasks.

Purpose of the Study:

• To investigate the neural mechanisms of VSWM encoding using high-density EEG.
• To differentiate the functional brain connectivity during VSWM encoding from other memory processes.
• To examine how memory load affects brain connectivity during VSWM encoding.

Main Methods:

• Utilized 128-channel EEG to record brain activity during a VSWM task.
• Computed lagged linear coherence (LagR) across seven frequency bands (delta, theta, alpha, beta, gamma) between 84 regions of interest (ROIs).
• Analyzed changes in LagR with varying memory loads (low vs. high) and correlated connectivity with error rates.

Main Results:

• Theta band LagR significantly varied in 13 brain connections with memory load during VSWM encoding.
• Increased theta band LagR was observed in twelve connections at high memory load, notably between the right cuneus and right middle temporal gyrus.
• Decreased theta LagR between left and right precentral gyri at high load may relate to sustained attention, while altered connectivity between fusiform and lingual gyri predicted performance errors.

Conclusions:

• Identified specific neural connections, particularly in the theta band, critical for VSWM encoding.
• Demonstrated that encoding is a rate-limiting process influencing working memory capacity.
• Provided insights into the dynamic functional brain connectivity supporting visuospatial memory formation.