Sustained alpha oscillations serve attentional prioritization in working memory, not maintenance

Area of Science:

• Cognitive Neuroscience
• Neuroscience
• Psychology

Background:

• Working memory (WM) theories debate the necessity of sustained neural activity for information retention.
• Ongoing alpha-band neural activity during WM maintenance challenges activity-silent models.
• The specific function of alpha oscillations in WM—attentional prioritization versus general maintenance—remains unclear.

Purpose of the Study:

• To investigate the role of alpha oscillations in working memory maintenance and attentional prioritization.
• To differentiate between alpha activity as a general maintenance mechanism versus a reflection of attentional focus.

Main Methods:

• A visual working memory task with two memory items, one prioritized for earlier recall.
• Inclusion of short (1s) and long (3s) delay intervals to assess sustained effects.
• Time-resolved decoding analyses and impulse-based decoding to track neural representations and readout.

Main Results:

• Both memory items were initially decodable, but only the prioritized item maintained decodability throughout the delay.
• Sustained alpha power selectively tracked the prioritized item, especially during longer delays.
• Impulse decoding revealed increased readout for the deprioritized item only when it became immediately relevant.

Conclusions:

• Sustained alpha-band activity in working memory primarily serves attentional prioritization.
• Unattended or deprioritized items transition to an activity-quiescent state, supporting synaptic storage models.
• Findings challenge the notion of alpha oscillations as a universal maintenance mechanism in working memory.