Assessment of Unconsciousness for Memory Consolidation Using EEG Signals

TL;DR

This study investigates how unconscious states during sleep affect memory consolidation by analyzing EEG signals, revealing specific brain activity patterns linked to memory performance during unconsciousness.

Contribution

It introduces a novel approach to assess unconsciousness in memory consolidation using EEG signals during sleep, focusing on neural correlates of unconscious memory processing.

Findings

Spindle power correlates positively with location memory performance.

Negative correlations between delta, alpha, spindle connectivity and memory tasks.

Brain activity changes during unconsciousness relate to subsequent memory recall.

Abstract

The assessment of consciousness and unconsciousness is a challenging issue in modern neuroscience. Consciousness is closely related to memory consolidation in that memory is a critical component of conscious experience. So far, many studies have been reported on memory consolidation during consciousness, but there is little research on memory consolidation during unconsciousness. Therefore, we aim to assess the unconsciousness in terms of memory consolidation using electroencephalogram signals. In particular, we used unconscious state during a nap; because sleep is the only state in which consciousness disappears under normal physiological conditions. Seven participants performed two memory tasks (word-pairs and visuo-spatial) before and after the nap to assess the memory consolidation during unconsciousness. As a result, spindle power in central, parietal, occipital regions during unconsciousness was positively correlated with the performance of location memory. With the memory performance, there was also a negative correlation between delta connectivity and word-pairs memory, alpha connectivity and location memory, and spindle connectivity and word-pairs memory. We additionally observed the significant relationship between unconsciousness and brain changes during memory recall before and after the nap. These findings could help present new insights into the assessment of unconsciousness by exploring the relationship with memory consolidation.