Localization of cortical phase and amplitude dynamics during visual working memory encoding and retention

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Brain Activity

Background:

• Human brain oscillation amplitudes change with visual working memory (VWM) task load.
• The specific brain regions and dynamics of these modulations remain unclear.
• Understanding these processes is crucial for clarifying their functional significance in VWM.

Purpose of the Study:

• To investigate the dynamics and cortical origins of brain activity modulations during VWM.
• To elucidate the functional significance of these modulations for VWM performance.
• To identify neural correlates of individual differences in VWM capacity.

Main Methods:

• Utilized magnetoencephalography (MEG) and electroencephalography (EEG).
• Employed minimum norm estimate-based source modeling for analyzing brain activity.
• Studied ongoing brain activity during a parametric VWM task across multiple frequency bands.

Main Results:

• Memory load-dependent neuronal activity spread from occipital to frontoparietal regions during encoding.
• During VWM retention, theta/alpha, high-alpha, beta, gamma, and high-gamma amplitudes were suppressed, but strengthened in frontoparietal regions.
• Occipital and occipitotemporal regions showed strengthened beta, gamma, and high-gamma amplitudes with increasing memory load.
• Individual VWM capacity correlated with N1 evoked response and frontoparietal high-alpha/high-gamma oscillations.

Conclusions:

• Both early visual processing and late retention period activities impact VWM behavioral outcomes.
• Beta and gamma oscillations likely support object representation maintenance in VWM.
• Alpha, beta, and gamma oscillations collectively contribute to attentional and executive processing in VWM.