Electroencephalography

Epilepsy is a multifaceted neurological disorder characterized by superfluous and recurrent seizure activity. Electroencephalogram (EEG) signals are indispensable tools for epilepsy diagnosis that reflect real-time insights of brain activity. Recently, epilepsy researchers have increasingly utilized Deep Learning (DL) architectures for early and timely diagnosis. This research focuses on resolving the challenges, such as data diversity, scarcity, limited labels, and privacy, by proposing potential contributions for epilepsy detection, prediction, and forecasting tasks without impacting the accuracy of the outcome. The proposed design of diversity-enhanced data augmentation initially averts data scarcity and inter-patient variability constraints for multiclass epilepsy detection. The potential features are extracted using a graph theory-based approach by analyzing the inherently dynamic characteristics of augmented EEG data. It utilizes a novel temporal weight fluctuation method to recognize the drastic temporal fluctuations and data patterns realized in EEG signals. Designing the Siamese neural network-based few-shot learning strategy offers a robust framework for multiclass epilepsy detection.

Infants have an innate desire to form social bonds and jealousy protests are an attempt to regain exclusive maternal attention from a social usurper. The current study examined neurophysiological and bio-hormonal processes related to jealousy responses during the first year and a half of life. Prior to and after the first year of life, infants express jealousy protest behavior when faced with a social threat. Resting-state frontal EEG coherence indicated a developmental shift from bilateral connectivity in younger infants to increased frontal specialization in older infants in relation to jealousy responses. Furthermore, 6- to 9-month-old infants exhibited more frontal neuroconnectivity in the right hemisphere (i.e., an area related to negative emotions) of the brain compared to left when faced with social threat. Lastly, social threat activated HPA reactivity in infants higher in temperamental distress. This study provides further evidence for the emerging links between physiological and socioemotional responses in infancy due to loss of exclusive maternal attention.

Prior research on neurophysiology of infants of depressed mothers commonly has focused on EEG power and asymmetry. Whether infants of depressed mothers show differences in coherence is undetermined. This study examined the development of EEG alpha coherence in infants of mothers with various degrees of depression. Also investigated was the normative development of alpha coherence in infancy. The relationship between maternal depression and infant coherence was analyzed at different infant ages, from 1-12-months-old. There were significant effects of maternal depression on infant coherence between frontal-occipital regions, frontal-parietal regions, and central-parietal regions, in 1-month-olds. There were also significant maternal depression effects in central-parietal coherence in 1-3-month-olds and 3-6-month-olds. Differences were in the right hemisphere and were generally characterized by lower coherence in infants whose mothers had higher depression. Infants whose mothers had lower depression demonstrated age-related decreases in coherence, but infants of more highly depressed mothers did not show age-related differences.

When practiced over long periods of time (>16 weeks), mindfulness positively impacts inhibitory processing, in that as mindfulness exposure and experience increases, inhibitory processing is enhanced. Similarly, long-term mindfulness practice diminishes the impact of emotionally-valanced scenes. However recently, more work is underway on how brief mindfulness inductions impact these same outcomes. Across two online pilot studies (behavioral outcomes only) and one in-person experiment (behavioral and neuronal outcomes), how a brief focused-breathing induction impacts response inhibition and the perception of affective words was explored. Findings demonstrate that a 30-minute mindfulness induction produced a diminished Simon Effect, as well as faster processing of neutral and positive words (faster LPP latencies) and less-effortful processing of negative words (reduced LPP amplitudes). How brief mindfulness inductions may impact resting frontal alpha asymmetry were also explored.

Temperament and its development have been associated with the alpha band of EEG coherence in previous research that focused on adolescent and adult populations, results suggest that this measure stands as a reliable indicator of emotional states. In the current study, five data sets from previously conducted studies were analyzed to determine if resting state alpha coherence measures differ in various brain regions and are associated with variation in levels of temperament. Additionally, we aimed to determine if, as age increases, a synchronous result in coherence may be seen (specifically, from posterior to anterior), in accordance with neurophysiological development. Regression analyses suggested that the negative affectivity temperamental qualities did not significantly associate with coherence. Repeated-measures analyses yielded significant results in favor of the electrocortical development hypothesis and, through exploratory analysis, more reactive temperament scores depicting positive affectivity, emotional/self-regulation, and activity level displayed in infants who had higher coherence in posterior regions. The study was suggestive of high coherence values associating with highly reactive temperamental attributes in posterior regions in the 3- to 12-month-old participants and higher coherence values displaying in posterior regions compared to anterior regions consistently across age groups.

Visual working memory (VWM) is a core cognitive system that supports our ability to maintain and manipulate visual information temporarily when sensory information is no longer present in the environment. VWM and mental rotation, a form of mental imagery, require the ability to generate internal images in the absence of stimuli. Both cognitive processes share visual buffer and are associated with representing and manipulating visual information, however, little is known about the intersection between VWM and mental rotation. In the current work, mental rotation was adopted to study updated mnemonic contents in VWM. In this dissertation, I asked whether the brain mechanisms that support VWM and mental rotation overlap. Participants were asked to remember the orientation of grating or to remember and manipulate, that is mentally rotate, the orientation of grating. Behavioral results showed that mental rotation induced lower fidelity representations of orientation. This confirmed that additional usage in visual buffer to manipulate the visual representation provoked by mental rotation involved negative influence in memory fidelity. In the second study, EEG recording was conducted while participants performed the same task. Visual representations were reconstructed from brain oscillations using the inverted encoding model (IEM). It was found that orientation information from the reconstruction was represented in the amplitude of alpha oscillations (8 – 12 Hz) for both maintained and updated mnemonic contents. Together, this work provides evidence that memory manipulation driven by mental rotation has a decisive effect on the fidelity of visual representations in VWM. Additionally this dissertation demonstrates that the updated memory representations as well as the maintained memory representations are carried in EEG oscillations.

The perception and interpretation of faces provides individuals with a wealth of knowledge that enables them to navigate their social environments more successfully. The present study examined the temporal dynamics of valence information from emotional facial expressions using electroencephalogram (EEG) in conjunction with multi-variate pattern analysis (MVPA). In multiple different classifying conditions, it was demonstrated that when decoding for a positively- vs. a negatively- vs. a neutrally-valenced expression, above chance level decoding accuracy occurs sooner when compared to instances of decoding for a negatively- vs. a negatively- vs. a neutrally-valenced expression. Additionally, results showed that classification accuracy as measured by percentage of correct responses was higher in the classification condition with the positively-valenced expression versus the one with two negatively-valenced
expressions. Together, these finding suggest that neural processing of facial expression may occur hierarchical manner, in that categorization between between-valence (positive vs. negative) facial expressions precedes categorization among within-valence.

Infants have an innate desire to form social bonds and jealousy protests are observed when an infant is trying to regain attention lost by a caregiver to a social competitor. The current study examined jealousy responses during the first year of life, between 6- to 9-months of age and 12- to 18-months of age, in response to loss of exclusive maternal attention, in addition to exploring implications for mother-infant attachment, EEG asymmetry, and cortisol reactivity and regulation. At both age groups, infants demonstrated increased approach behaviors when infants are faced with a social rival, in addition, left-frontal EEG asymmetry was associated with maternal-directed approach behaviors during the social rival condition. In the 6- to 9-month sample, left-frontal EEG asymmetry also demonstrated an association with infants regulatory abilities, measured by salivary cortisol. This study provides further evidence for the emerging links between social and emotional responses in infancy due to loss of exclusive maternal attention.

The present study aimed at quantifying the topographic distribution of spectral power as measured with electroencephalogram (EEG) in patients with opioid use disorder (OUD) across five broad band frequencies (δ, θ, α, β, and γ). Through comparative groups of healthy controls, patients with methamphetamine use disorder, and patients with alcohol use disorder, it was determined that OUD EEG spectral power was globally increased in the δ frequency, and more region-specific in others (frontal lobes in θ and β frequencies). α frequency was reduced in occipital lobes in OUD. The observed changes are discussed in terms of the microcircuit-level changes in the cortex. Based on these findings, EEG may prove to be a valuable tool for diagnostic and prognostic evaluation of OUD.

Racial bias remains a prevalent issue in society. Clues to the cognitive basis for such biases have been found in EEG studies of the ‘Other Race Effect’ (ORE) in relation to the P100 and N170 event related potentials (ERPs). Previous research in this area has focused on adults, and only one such study has looked at implicit racial biases (He et al., 2009), while only a few have looked at experience with own- and other-race persons (Herzmann et al., 2011; Stahl et al., 2008; Walker et al., 2008). The present study is the first to examine how race might modulate ERP responses in children, and the first to relate these responses with both implicit racial biases and race contact experience. We examined EEG responses in 5- to 10-year-old children and adults, and whether such responses were associated with implicit racial biases and own- and other-race experience. Results showed that both children and adults displayed larger P100 and N170 responses to other-race faces, greater implicit racial biases related to larger N170 responses to other- than own-race faces, and greater other-race experience related to larger P100 responses to other- than own-race faces. In terms of age differences, we found that compared with adults, children displayed larger and more delayed P100 and N170 responses, and that in children but not in adults, greater experience with own- and other-races were associated with more delayed N170 responses to other- than own-race faces. These findings suggest that age, experience with own- and other-race persons, and implicit racial biases all influence early ERP responses to own- and other-race individuals.