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One of the proposed neural mechanisms involved in working memory is coupling between the theta phase and gamma amplitude. For example, evidence from intracranial recordings shows that coupling between hippocampal theta and cortical gamma oscillations increases selectively during working memory tasks. Theta-gamma phase-amplitude coupling can also be measured non-invasively through scalp EEG; however, EEG can only assess coupling within cortical areas, and it is not yet clear if this cortical-only coupling is truly memory-specific, or a more general phenomenon. We tested this directly by measuring cortical coupling during three different conditions: a working memory task, an attention task, and a passive perception condition. We find similar levels of theta-gamma coupling in all three conditions, suggesting that cortical theta-gamma phase-amplitude coupling is not a memory-specific signal, but instead reflects some other attentional or perceptual processes. Implications for understanding the brain dynamics of visual working memory are discussed. [ABSTRACT FROM AUTHOR]

Value-driven attention capture (VDAC) occurs when previously rewarded stimuli capture attention and impair goal-directed behavior. In a working memory (WM) task with VDAC-related distractors, we observe behavioral variability both within and across individuals. Individuals differ in their ability to maintain relevant information and ignore distractions. These cognitive components shift over time with changes in motivation and attention, making it difficult to identify underlying neural mechanisms of individual differences. In this study, we develop the first participant-specific feedforward neural network models of reaction time from neural data during a VDAC WM task. We used short epochs of electroencephalography (EEG) data from 16 participants to develop the feedforward neural network (NN) models of RT aimed at understanding both WM and VDAC. Using general linear models (GLM), we identified 20 EEG features to predict RT across participants ( r = 0.53 ± 0.08 ). The linear model was compared to the NN model, which improved the predicted trial-by-trial RT for all participants ( r = 0.87 ± 0.04 ). We found that right frontal gamma-band activity and fronto-posterior functional connectivity in the alpha, beta, and gamma bands explain individual differences. Our study shows that NN models can link neural activity to highly variable behavior and can identify potential new targets for neuromodulation interventions. [ABSTRACT FROM AUTHOR]

Tasks which require sustained attention over a lengthy period of time have been a focal point of cognitive fatigue research for decades, with these tasks including air traffic control, watchkeeping, baggage inspection, and many others. Recent research into physiological markers of mental fatigue indicate that markers exist which extend across all individuals and all types of vigilance tasks. This suggests that it would be possible to build an EEG model which detects these markers and the subsequent vigilance decrement in any task (i.e., a task-generic model) and in any person (i.e., a cross-participant model). However, thus far, no task-generic EEG cross-participant model has been built or tested. In this research, we explored creation and application of a task-generic EEG cross-participant model for detection of the vigilance decrement in an unseen task and unseen individuals. We utilized three different models to investigate this capability: a multi-layer perceptron neural network (MLPNN) which employed spectral features extracted from the five traditional EEG frequency bands, a temporal convolutional network (TCN), and a TCN autoencoder (TCN-AE), with these two TCN models being time-domain based, i.e., using raw EEG time-series voltage values. The MLPNN and TCN models both achieved accuracy greater than random chance (50%), with the MLPNN performing best with a 7-fold CV balanced accuracy of 64% (95% CI: 0.59, 0.69) and validation accuracies greater than random chance for 9 of the 14 participants. This finding demonstrates that it is possible to classify a vigilance decrement using EEG, even with EEG from an unseen individual and unseen task. [ABSTRACT FROM AUTHOR]

Language-induced asymmetry to single word reading has been well investigated in past research. Less known are the complex processes and related asymmetries occurring when a word is compared with the previous one, according to specific tasks. To this end, we used a paradigm based on 80 sequential word pair comparisons and three blocked tasks: phonological, semantic and orthographical matching judgment. Participants had to decide whether the target word (W2) did or did not match the prime word (W1), presented 2 sec before, according to the task. The event-related potentials (ERPs) evoked by W2 in 20 participants have been analyzed. The first negative wave, the Recognition Potential (RP), peaking at about 120 ms over parietal sites, showed greater amplitude at left sites in all tasks, thus revealing the typical left-lateralization. At frontal sites, only the phonological task showed left lateralization. The following N400 (300–450 ms) showed an interesting interaction: Match trials elicited greater left asymmetry on frontal regions to phonological than to semantic than to visual-perceptual tasks, whereas mismatch trials induced an inverted asymmetry, marked by greater amplitude over right frontal sites, regardless of the task. Concerning the late N400 (450–600 ms), phonological and semantic tasks showed an overlapping pattern, with left lateralization in match and right lateralization in mismatch conditions. Results point to complex task- and time-dependent hemispheric asymmetries in word matching. [ABSTRACT FROM AUTHOR]

The medial olivocochlear (MOC) system is thought to be responsible for modulation of peripheral hearing through descending (efferent) pathways. This study investigated the connection between peripheral hearing function and conscious attention during two different modality tasks, auditory and visual. Peripheral hearing function was evaluated by analyzing the amount of suppression of otoacoustic emissions (OAEs) by contralateral acoustic stimulation (CAS), a well-known effect of the MOC. Simultaneously, attention was evaluated by event-related potentials (ERPs). Although the ERPs showed clear differences in processing of auditory and visual tasks, there were no differences in the levels of OAE suppression. We also analyzed OAEs for the highest magnitude resonant mode signal detected by the matching pursuit method, but again did not find a significant effect of task, and no difference in noise level or number of rejected trials. However, for auditory tasks, the amplitude of the P3 cognitive wave negatively correlated with the level of OAE suppression. We conclude that there seems to be no change in MOC function when performing different modality tasks, although the cortex still remains able to modulate some aspects of MOC activity. [ABSTRACT FROM AUTHOR]