An interactive framework of working memory and inhibitory control has been endorsed for examining cognitive development across the lifespan (Roberts & Pennington, 1996). According to this framework, the interaction between working memory and inhibitory control (WMIC) is necessary for adaptive daily functioning (Roberts & Pennington, 1996) and crucial for the development of executive functioning in childhood (Brocki & Bohlin, 2004). Empirical work from early developmental periods supports the interactive WMIC framework (e.g., Bell, 2001; Diamond, Kirkham, & Amso, 2002) and has identified sources of variability (brain electrical activity, temperament, and language) associated with WMIC functioning in infancy and early childhood (Wolfe & Bell, 2004). Although there is some evidence to suggest the interdependent nature of working memory and inhibitory control in late childhood and adulthood (Diamond, 2002; Luna, Garver, Urban, Lazar, & Sweeney, 2004), work in these later developmental periods has focused primarily on the independent processes of working memory (WM) and inhibitory control (IC) and the interactive WMIC framework has not been directly investigated from late childhood onward. Therefore, the first goal of the current study was to examine the interactive framework in a late childhood sample. The second goal of the study was to examine sources of variability in WMIC functioning in late childhood, with the intention of determining which sources of variability were associated with and contributed unique variance in explaining WMIC performance. Thirty-eight children (19 male) completed four age-appropriate interactive WMIC tasks (the color-word Stroop, the Fruit Stroop, the counting go/no-go and the Wisconsin Card Sort Test) and two language tasks. Both parents and children responded to a temperament questionnaire. Brain electrical activity was collected via EEG recordings during a two-minute baseline and WMIC tasks. The four interactive WMIC tasks were tested for relation of the independent (WM, IC) and combined (WMIC) components within tasks and across tasks. The four WMIC tasks were not correlated with one another. However, the independent (WM, IC) components were correlated both with one another and with the combined WMIC measure within each task, providing some support for an interactive framework in late childhood. The sources of variability associated with the independent (WM, IC) and combined (WMIC) components of each task were identified. These sources were used to explain both collective and unique variance in WMIC functioning for each task. Different sources of variability explained independent (WM, IC) and combined (WMIC) performance across tasks. Unique and shared contributors within and across tasks (the color-word Stroop, the Fruit Stroop, the counting go/no-go and the Wisconsin Card Sort Test) and components (WM, IC, WMIC) are discussed in an effort to determine how sources of variability may be related to WMIC functioning. / Ph. D.

The focus of this project falls largely within the realm of investigating the development of brain-cognition relations from a developmental cognitive neuroscience perspective. There were two main goals of this study. First, this study focused on the regional differences in baseline-to-working memory task brain electrical activity and specifically investigated the hypothesis that there would be an increasing specificity of task EEG power between 3½ and 4½ years of age. The second goal of this study was to investigate the sources of variability in working memory function and to specifically examine the contributions of task-related EEG, the regulatory dimensions of temperament, and linguistic ability to the prediction of working memory performance. This second study objective included an investigation of the relation between working memory and each of these variables (1) separately, (2) in conjunction with age, and (3) collectively to examine any multivariate contributions to the explanation of variance in working memory function in early childhood. The results of this study provided some support to the increasing specificity of baseline-to-task EEG power hypothesis. Specifically, an increase in brain electrical activity was found for four scalp regions at age 4 and only two regions at age 4½. These findings coupled with previous work indicating an increase in task brain electrical activity for only one region at age 4½ suggest that cortical specialization is occurring during the early childhood years. With regard to the investigation of sources of variability working memory function, age, brain electrical activity, temperament, and linguistic functioning were all found to be meaningful variables in the explanation of variance in working memory. However, linguistic functioning " and specifically language receptivity " was found to be the strongest and most meaningful associate of working memory function. Additional findings of interest included the differential associations demonstrated between working memory and temperament for each age group and also an increase in the strength of the relation between working memory and language across the three ages. / Ph. D.

Developmental stuttering is a physiological disorder of speech motor control. Unlike acquired conditions, developmental stuttering is responsive to fluency-inducing conditions involving the manipulation or elimination of auditory feedback. It was hypothesized that stutterers experience interference effects from competing sensory feedback during the working memory interval in which contextual information is held on-line in order to prepare subsequent motor responses. Behavior and EEG activity of stutterers and non stutterers were compared during working memory tasks. Participants were 22 male, right-handed stutterers, mean age 28.2 years, age matched with 22 male, right-handed nonstutterers. Behavioral measures included a written verbal fluency task, an auditory delayed match-to-sample key press task, and a written digit span task. As hypothesized, there were no group differences in verbal fluency. Also as hypothesized, stutterers had higher error scores (more false positives) on the auditory delayed match-to-sample key press task. This suggests increased sensitivity to auditory stimuli and difficulty inhibiting response to stimulation. Groups did not differ in digit span, but there was a trend toward significance (p=.07). If stutterers do experience overlapping or excessive sensory stimulation during the working memory phase of speech motor plan assembly, the EEG of stutterers should evidence differences consistent with excessive or inefficient processing of "extra" sensory stimuli. Monopolar recordings were collected from 19 sites in accordance with the international 10-20 system of electrode placement. EEG was recorded during 60 seconds of resting-eyes-closed and resting-eyes-open~ 60 seconds during a silent backwards-subtraction math task; 120 seconds during an auditory delayed match-to-sample key press task. As hypothesized, stutterers exhibited more theta activity than nonstutterers in frontal regions in all conditions, both in the low theta subband (3-5 Hz) and the high theta subband (5.5-7.5 Hz). Also as hypothesized, stutterers produced more alpha activity in the low alpha subband (8-10 Hz) in frontal regions in all conditions. There were no group differences in the high alpha subband (10.5-13 Hz). There were no hemispheric differences in frontal regions. Increased cortical activity and increased sensitivity to stimuli support the proposed hypothesis that stutterers experience excess sensory stimulation while attempting motor plan assembly, suggestive of stuttering as a disorder of attention. / Ph. D.

As of 2016, diagnosis of ADHD in the US is controversial. Diagnosis of ADHD is based on subjective observations, and treatment is usually done through stimulants, which can have negative side-effects in the long term. Evidence shows that the probability of diagnosing a child with ADHD not only depends on the observations of parents, teachers, and behavioral scientists, but also on state-level special education policies. In light of these facts, unbiased, quantitative methods are needed for the diagnosis of ADHD. This problem has been tackled since the 1990s, and has resulted in methods that have not made it past the research stage and methods for which claimed performance could not be reproduced. This work proposes a combination of machine learning algorithms and signal processing techniques applied to EEG data in order to classify subjects with and without ADHD with high accuracy and confidence. More specifically, the K-nearest Neighbor algorithm and Gaussian-Mixture-Model-based Universal Background Models (GMM-UBM), along with autoregressive (AR) model features, are investigated and evaluated for the classification problem at hand. In this effort, classical KNN and GMM-UBM were also modified in order to account for uncertainty in diagnoses. Some of the major findings reported in this work include classification performance as high, if not higher, than those of the highest performing algorithms found in the literature. One of the major findings reported here is that activities that require attention help the discrimination of ADHD and Non-ADHD subjects. Mixing in EEG data from periods of rest or during eyes closed leads to loss of classification performance, to the point of approximating guessing when only resting EEG data is used. / Master of Science

Cognitive reappraisal (CR) involves changing one’s mental states in response to an emotionally eliciting event in order to down regulate the potential emotional impact. In this study, 50 children who were 9-10 years old were instructed to engage in CR during a sad film. Children were then exposed to a disappointing situation and asked to self-report on their CR after the disappointment task. As hypothesized, there was variability in level of CR use during the disappointment task. Contrary to hypothesis, children’s CR was not related to parent CR. Nor was the association between parent CR and child CR moderated by child baseline frontal EEG asymmetry, as hypothesized. Post-hoc analyses revealed that parent CR moderated the association between child baseline frontal EEG asymmetry and task-related frontal EEG asymmetry, such that children presenting with left frontal asymmetry at baseline and who had parents with higher CR showed left frontal asymmetry during the disappointment task. This was conceptualized as physiological regulation during an emotion event. Post-hoc analyses also revealed that children’s CR after the disappointment task was predicted by task-related frontal EEG asymmetry, as well as self-reports of ER strategies. I conclude that task-specific CR can be assessed in preadolescents but that much research is needed to determine the correlates of child use of CR during emotional situations. / M.S. / Changing the way one thinks of an emotional event is considered highly adaptive, this strategy is referred to as cognitive reappraisal (CR). 50 children between the ages of 9 and 10 and their parents participated in this study. Children were asked to engage in CR while watching a sad film. Then, they were exposed to a disappointing event. After the disappointment, children were asked to complete a self-report questionnaire which gathered information on their CR during the disappointment task. Parents also completed an adult version of this questionnaire. Children’s responses were varied, but their CR was not related to their parent’s CR. Children’s brain activity was also not related to either parent’s nor children’s CR. Parent’s own CR was linked to children’s brain activity during rest and during the disappointment task, making brain activity more extreme for children with greater activation in the frontal left hemisphere of the brain during rest, the area involved with greater regulation. Additionally, children’s CR was predicted by their self-reported emotion regulation and their brain activity during the disappointment task. Our results indicate that wen parents are capable of changing the way they think about an emotional event, using CR, their children are benefitting in ways that are not easily observable, such as through brain activity.

Inhibitory Control (IC), a vital facet of childhood development, involves the ability to suppress a dominant response, as well as the ability to suppress irrelevant thoughts and behaviors. This ability emerges during the first year of life and develops rapidly during the preschool years. A variety of tasks have been developed to measure IC in this age group and, recently, research has demonstrated important differences in task performance according to various distinctions among these tasks. One under-researched distinction is that of whether an IC task requires the child to give a verbal or a motoric response. Therefore, the purpose of this study was to examine, in 4-year-old children, the differences and similarities among IC tasks requiring either a verbal or a motoric response. Differences were explored with respect to the contributions to verbal and motoric IC performance of language, intelligence, temperament, and frontal encephalography, as well as with respect to social and school readiness outcomes. IC was best described by a two-component model, distinguishing verbal and motoric IC. Both baseline and task electrophysiology contributed to task performance in the verbal Yes-No task as well as the motoric IC composite. Language and intelligence, too, were associated with both verbal and motoric IC, although nonverbal intelligence was less strongly correlated with verbal IC than it was with motoric IC. All laboratory measures of IC related to parent report of children’s IC as well as to other parent-reported temperament scales and factors. Children’s verbal and motoric IC were associated, too, with children’s social development, surprisingly showing the most consistent associations with social inhibition. Asocial behavior positively correlated more strongly with motoric IC than with verbal IC. Children’s laboratory IC positively correlated with their school readiness, even when controlling for their intelligence although children’s emergent literacy more positively related to their motoric, rather than verbal, IC. An interaction of intelligence and IC contributed to social variables, but not to school readiness. This research supports the important distinction between verbal and motoric IC, and demonstrates the utility of including an array of measures of both in early childhood research. / Ph. D.

Previous literature has suggested an apparent P300 sensitivity to self-relevant stimuli. To further explore this relationship, we asked participants to submit 10 photos, each of a particular category (e.g. footwear, plants), to be used as either targets or distractors in a given condition of an oddball task. Furthermore, we attempted to see whether the effect of self-relevance on the P300 could be induced in a participant by allowing them to study a set of unique photos which would then be used as targets. Our analysis suggested that P300 amplitude elicited in response to self-relevant stimuli used as targets was statistically significantly greater than all other conditions’ targets. This effect was not correlated with the participant sentiment toward their own photos as assessed by the Revised Personal Involvement Inventory. In light of this, we suggest a generalized effect of self-relevance on the P300. Limitations and future directions are discussed.

There is evidence that language ability is related to a number of cognitive processes, including memory. As children become more proficient language-users, they develop the ability to use language as a memory attribute. This study used EEG coherence to investigate the extent to which verbal encoding strategies account for individual differences in two short-term recognition memory tasks in 50 3-year-olds. Children with better expressive and receptive language performed better on the picture memory task (which contains stimuli that can easily be labeled) but not the abstract memory task, indicating that language may support memory processes for some types of stimuli more than for others. Analyses of EEG coherence at the hypothesized electrode pairs (F7-T3 and F8-T4) at baseline and encoding were not significant, indicating that verbal encoding does not account for individual differences in short-term memory performance. When these electrode pairs were examined at baseline and retrieval for the picture memory task, EEG coherence analyses indicated that it may be the use of language as a retrieval cue rather than an encoding strategy that explains individual differences in short-term recognition memory. / Ph. D.

The present study examined source memory development in a sample of 4 and 6 year children. Patterns of brain electrical (EEG) activity were examined in order to provide a neural basis for the role of prefrontal cortex functioning during source monitoring. Children were taught a series of novel facts from two difference sources (either an experimenter or puppet) and their memory for both item and source information was later tested. Results demonstrated that, after controlling for language, patterns of frontal brain activity predicted 6 year item recall performance, and trends toward significance were observed for temporal brain activity predicting 6 year source recall performance. No associations between frontal or temporal EEG activity and episodic memory judgments were observed among 4-year-old children. Future investigations should examine how source memory, and on a more general level contextual memory binding, influence the development of episodic memory in early childhood. / Master of Science

The analysis and understanding of physiological and brain signals is critical in order to decode user’s behavioral/neural outcome measures in different domain scenarios. Personal Health-Care agents have been proposed recently in order to monitor and acquire reliable data from daily activities to enhance control participants’ wellbeing, and the quality of life of multiple non-neurotypical participants in clinical lab-controlled studies. The inclusion of new wearable devices with increased and more compact memory requirements,and the possibility to include long-size datasets on the cloud and network-based applications agile the implementation of new improved computational health-care agents. These new enhanced agents are able to provide services including real time health-care,medical monitoring, and multiple biological outcome measures-based alarms for medicaldoctor diagnosis. In this dissertation we will focus on multiple Signal Processing (SP), Machine Learning (ML), Saliency Relevance Maps (SRM) techniques and classifiers with the purpose to enhance the Personal Health-care agents in a multimodal clinical environment. Therefore, we propose the evaluation of current state-of-the-art methods to evaluate the incidence of successful hypertension detection, categorical and emotion stimuli decoding using biosignals. To evaluate the performance of ML, SP, and SRM techniques proposed in this study, wedivide this thesis document in two main implementations: 1) Four different initial pipelines where we evaluate the SP, and ML methodologies included here for an enhanced a) Hypertension detection based on Blood-Volume-Pulse signal (BVP) and Photoplethysmography (PPG) wearable sensors, b) Heart-Rate (HR) and Inter-beat-interval (IBI) prediction using light adaptive filtering for physical exercise/real environments, c) Object Category stimuli decoding using EEG features and features subspace transformations, and d) Emotion recognition using EEG features from recognized datasets. And 2) A complete performance and robust SRM evaluation of a neural-based Emotion Decoding/Recognition pipeline using EEG features from Autism Spectrum Disorder (ASD) groups. This pipeline is presented as a novel assistive system for lab-controlled Face Emotion Recognition (FER) intervention ASD subjects. In this pipeline we include a Deep ConvNet asthe Deep classifier to extract the correct neural information and decode emotions successfully.