Autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) have been difficult to differentiate in clinical settings, as these two disorders are phenotypically similar and both exhibit atypical attention and executive functioning. Mischaracterizations between these two disorders can lead to inappropriate medication regimes, significant delays in special services, and personal distress to families and caregivers. There is evidence that ASD and ADHD are biologically different for attentional and executive functioning mechanisms, as only half of individuals with co-occurring ASD and ADHD respond to stimulant medication. Further, neurobehavioral work has supported these biological differences for ASD and ADHD, with both shared and distinct functional connectivity. In specific, two brain networks have been implicated in these disorders: the salience network (SN) and frontoparietal network (FPN). The SN is a network anchored by bilateral anterior insula and the dorsal anterior cingulate cortex and has been implicated in “bottom-up” attentional processes for both internal and external events. The FPN is anchored by lateral prefrontal cortex areas and the parietal lobe and plays a roll in “top-down” executive processes. Functional connectivity subgroups differentiated ASD from ADHD with between SN-FPN connectivity patterns, but not by within-SN or within-FPN connectivity patterns. Further, subgroup differences in ASD+ADHD comorbidity vs. ASD only were found for within-FPN connectivity. / Master of Science / Autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) have been difficult to differentiate in clinical settings, as these two disorders are similar and both exhibit attention and executive functioning difficulties. ASD and ADHD have shared and distinct functional brain network connectivity related to attention and executive functioning. Two brain networks have been implicated in these disorders: the salience network (SN) and frontoparietal network (FPN). The SN is a network that has been implicated in “bottom-up” attentional processes for both internal and external events. The FPN plays a roll in “top-down” executive processes. This study found that functional connectivity patterns between the SN and FPN differentiated ASD from ADHD. Further, connectivity patterns in children with co-occurring ASD and ADHD were characterized by within-FPN connectivity.

Goal-directed episodic simulation, the imaginative construction of a hypothetical personal event or series of events focused on a specific goal, is essential to our everyday lives. We often imagine how we could solve a problem or achieve a goal in the future, or how we could have avoided a misstep in the past, but many of the behavioral and neural mechanisms underlying such goal-directed simulations have yet to be explored. The three papers of this dissertation investigated the neural correlates of three types of future episodic simulations in Papers 1 and 2 and examined a fourth such simulation directed at past events as an adaptive, constructive process in Paper 3. Some research has associated default network activity with internally-focused, but not with goal-directed cognition. Papers 1 and 2 of this dissertation showed that regions of the default network could form functional networks with regions of the frontoparietal control network while participants imagined solving specific problems or going through a sequence of steps necessary to achieve a personal goal. When participants imagined events they associated with actually attaining a goal, default network regions flexibly coupled with reward-processing regions, providing evidence that the default network can join forces with other networks or components thereof to support goal-directed episodic simulations. Using two distinct paradigms with both young and older adults, Paper 3 focused on episodic counterfactual simulations of how past events could have turned out differently and tested whether counterfactual simulations could affect participants' memory of the original events. Our results revealed that episodic counterfactual simulations can act as a type of internally generated misinformation by causing source confusion between the original event and the imagined counterfactual outcome, especially in older adults. The findings of the three papers in this dissertation lay the groundwork for further research on the behavioral and neural mechanisms of goal-directed episodic simulations, as well as their adaptive functions and possible downsides. / Psychology

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Physiological indicators like heart rate (HR) and its variability (HRV) from ECG (electrocardiograms), and frontal lobe alpha power asymmetry (AA) and frontoparietal connectivity from EEG (electroencephalograms), can elucidate the role of the nervous system and other visceral organs and their effects on behavioral measures of cognitive and emotional self-regulation. Knowledge of the intergenerational transmission of cardiac and cerebral physiology can provide insight as to the developmental patterns of the organization and stabilization of these physiological processes in children and their mothers. The current study addresses a key question: Is there a developmental shift from 3-9 years of age in the overall pattern of EEG and ECG similarity between children and their mothers? The hypothesis was that there would be increasing child-mother similarity with age. EEG and ECG physiology was examined during a resting-state baseline period, during completion of cognitive tasks, and as baseline-to-task changes in EEG AA and frontoparietal coherence, and ECG HR and HRV in children and their mothers. A socioeconomically diverse longitudinal sample of 171 mothers with their children at ages 3, 6, and 9 years completed questionnaires and laboratory visits. Results indicated that there was some evidence to suggest the presence of mother-child similarity. Twenty of the seventy-two estimated intraclass correlations were significant. Furthermore, of the 20 significant correlations overall, none were present at child age 3 years, 6 were significant at child age 6 years, and 14 were significant at child age 9 years. Thus, overall, there was evidence that by age 6 years, child-mother similarity in physiological indicators of SR had begun to emerge. Additionally, consistent with the study hypothesis, there was some evidence of a pattern of increasing similarity for certain physiological indicators. Of the 72 estimated age-difference Fisher tests for increasing similarity, 17 were significant and in the hypothesized direction. The greatest number were seen during the task condition for ages 6 and 9, and particularly for the frontoparietal EEG variables. Findings are interpreted in light of social learning and behavioral genetics theories.