Attention modulates EEG spectral activity across serial positions.

Area of Science:

• Cognitive Neuroscience
• Neurophysiology

Background:

• Electroencephalographic (EEG) activity is linked to attentional processes, including suppressing irrelevant stimuli and orienting attention.
• Understanding how spectral activity changes during memory encoding under varying attentional demands is crucial.

Purpose of the Study:

• To investigate the evolution of spectral activity during word list learning under full and divided attention.
• To examine how multitasking demands affect attentional components and their neural correlates.

Main Methods:

• Recorded scalp EEG during a delayed free-recall task.
• Participants encoded word lists under full attention or divided attention (with a simultaneous target detection task).
• Analyzed high gamma (50-100 Hz) and alpha (8-12 Hz) frequency bands in relation to serial position and task conditions.

Main Results:

• High gamma activity decreased and alpha activity increased across serial positions during word list presentation.
• Divided attention reduced the change in gamma power across the list.
• Alpha activity showed lower power during target trials compared to distractor trials, irrespective of serial position.

Conclusions:

• Frequency-specific EEG activity reflects distinct attentional processes during memory encoding.
• Gamma frequencies are sensitive to cognitive load and dual-task interference.
• Alpha power differentiates between gradual increases in cognitive load and immediate attentional orienting.