Assessment of Unconsciousness for Memory Consolidation Using EEG Signals

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.

Neurophysiological Response Based on Auditory Sense for Brain Modulation Using Monaural Beat

“…The 64 channels, using Ag/AgCI electrodes, were placed according to the 10-20 international system. EEG pre-processing was performed with the EEGLAB toolbox for MATLAB following [17], [18] and consisted of downsampled to 250 Hz, band pass filtered between 0.5 Hz to 50 Hz, and channel interpolation using the Gaussian distributions kurtosis.…”

“…Additionally, we divided brain regions into five groups as follows: frontal, central, temporal, parietal, and occipital regions (Fig. 1-c) [18]. To identify brain symmetry, each region was divided into left and right, excluding the center electrodes (FPz, AFz, Fz, FCz, Cz, CPz, Pz, POz, Oz, and Iz).…”

Differential EEG Characteristics during Working Memory Encoding and Re-encoding

“…The word-pair memory task consisted of learning and recall sessions was previously covered by Shin et al [12]. All participants were asked to memorize 54 semantically related word pairs [13].…”

“…To identify the characteristics of the conditions according to the frequency of interest, we divided it into delta (2-4Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), and gamma (30-100 Hz) bands. We also were grouped into five brain regions (frontal, central, temporal, parietal, and occipital regions) to compare differences between brain regions [12].…”

Decoding 3D Representation of Visual Imagery EEG using Attention-based Dual-Stream Convolutional Neural Network

“…Brain-computer interface (BCI) is a promising technology to control the peripheral devices using intrinsic brain activity. BCI has been developed to rehabilitate neurological impairment patients [1], [2], estimate one's mental state [3]- [5], and detect some diseases early [6], [7]. Electroencephalogram (EEG) is one of the most actively used non-invasive BCI modalities.…”