Prestimulus alpha power signals attention to retrieval

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• The human brain operates in distinct modes, including encoding (storing new information) and retrieval (searching for old information).
• A 'ready-to-encode' mode, indicated by prestimulus brain activity, predicts memory performance.
• It remains unclear if a similar 'ready-to-retrieve' mode exists.

Purpose of the Study:

• To investigate if prestimulus brain oscillations are linked to internal attention during memory retrieval.
• To determine if a 'ready-to-retrieve' brain state can be identified.

Main Methods:

• Participants studied vocabulary word pairs, followed by cues to either restudy or retrieve.
• Prestimulus brain activity, specifically alpha power, was measured using electroencephalography (EEG).
• Beamformer analysis localized the source of the observed effects, and correlation analysis examined relationships between brain activity and memory performance.

Main Results:

• Task cues to prepare for retrieval, compared to restudy, significantly decreased prestimulus alpha power before word stimuli onset.
• This prestimulus alpha power decrease was localized to the right secondary visual cortex (Brodmann area 18).
• The prestimulus alpha power effect positively correlated with stimulus-induced alpha/beta power, predicting better memory performance.

Conclusions:

• Prestimulus alpha power decreases signal internal attention to retrieval, analogous to the 'ready-to-encode' state.
• This 'ready-to-retrieve' state enhances the processing of episodic memories.
• Findings suggest potential applications for brain-computer interfaces in optimizing learning strategies through online monitoring of alpha oscillations.