The goal of this project was to investigate the relationship between executive attention and specific linguistic and control processes during goal-directed tasks in aphasia. Its central premise was that PWA often possess dissociable impairments in linguistic processes and in the mechanisms that control and efficiently utilize those processes. The motivation for this claim was based on observations that PWA often present with deficits in the online processing of linguistic information, which in some instances have been interpreted as evidence for impaired linguistic operations, but in others has been interpreted as evidence for impaired control of language processing due to more general cognitive constraints. The current work tested claims regarding the Executive Attention model (Engle and Kane, 2004) in aphasia and its relation to varying task sets in linguistic and nonlinguistic tasks. 20 PWA and 23 matched controls were tested on four tasks measuring executive attention in verbal and nonverbal domains using word-picture interference, semantic and perceptual go/no-go, and spatial Stroop designs. Participants were also tested on lexical decision and numerosity judgment tasks with varying speed and accuracy-focused instructions, with performance modeled using the Diffusion Model (Ratcliff, 1978). Overall, the current work found evidence for the predicted domain-general and domain-specific impairments in executive attention at the level of individual PWA. However, these executive attention deficits did not appear to be associated with difficulties adapting to shifting speed-accuracy constraints. In addition, group-level patterns of performance across experiments suggest an additional related executive control deficit in the area of generating and maintaining arbitrary stimulus-response mappings. This study also demonstrated the appropriateness and potential applicability of the diffusion model in aphasia research, and diffusion model analyses found that PWA had difficulty adjusting their nondecision times in response to speed constraints, had lower drift rates in lexical decision, which reflected inefficient processing of lexical information, and had a disproportionately difficult time efficiently processing easy stimuli in lexical and numerosity tasks.

Many theories of decision-making consider pain, monetary loss, and other forms of punishment to be interchangeable quantities that are processed by the same neural system. For example, standard reinforcement learning models utilize a single reinforcement term to represent both monetary losses and pain signals. By contrast, I propose that 1) pain signals present unique computational challenges, 2) these challenges are addressed in humans and other animals by anterior cingulate cortex (ACC), and 3) pain is regulated by cognitive control during goal-directed tasks, using principles of the hierarchical reinforcement learning model of the ACC (HRL-ACC). To show this, I conducted 3 studies. In Study 1, I conducted an electrophysiological study to investigate the effect of task goals on event-related brain potentials (ERPs) during conditions where pain and reward are used. Specifically, I investigated whether feedback stimuli predicting forthcoming pain would elicit the reward positivity, an ERP component that is more positive-going to positive feedback than to negative feedback, when the goal of the task is to find electrical shocks. Contrary to my predictions, a standard reward positivity was not elicited by pain feedback in this task. In Study 2, I conducted three behavioral experiments wherein the subjective costs of mild electrical shocks were equated with monetary losses for each individual participant using a calibration procedure. I hypothesized that decision-making behavior in face of painful events and decision making behavior in the face of monetary losses would be different from each other despite the outcomes (pain vs. monetary loss) being equated for their subjective costs. This prediction was confirmed, demonstrating that the costs associated with pain and monetary losses differ in more than just magnitude. In Study 3, to explain these results, I developed an extension to an existing computational framework, the HRL-ACC model. The present model provides insight into choice behaviour in the pain and monetary loss (ML) conditions by showing that cognitive control levels converge to an average level across trials. In the pain condition, cognitive control fluctuates from trial to trial in a systematic fashion, causing trials with low shock levels to be over-valued and shocks with high-shock levels to be undervalued. By contrast, in the ML condition cognitive wanes across trials because it is not needed and the model displays normative behavior. These findings are in line with psychological approaches to pain treatment and provide neuro-cognitive explanations that underlie their mechanisms. In line with the HRL-ACC theory, I propose that the ACC regulates pain by motivating good performance in the face of physical punishments (but not monetary losses) in order to achieve long-term goals that are produced by ACC. / Graduate / 2021-08-18

Blast-related mild traumatic brain injury (mTBI) is a common injury among Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans due to the frequent use of improvised explosive devices (IEDs). A significant minority of veterans with blast-related mTBI complain of postconcussion symptoms (PCS) and cognitive difficulties, even years after the injury. Studies have suggested that these behavioral sequelae are primarily linked to mental health disorders such as posttraumatic stress disorder (PTSD). However, mTBI is associated with neural changes and the impact of these changes on behavioral sequelae is unclear. As such, this dissertation had three goals. First, this dissertation assessed whether the severity of PCS in blast-exposed individuals is associated with the extent of mTBI-related neural injury. Results revealed that individuals with mTBI with loss of consciousness (LOC) had significantly more white matter abnormalities than no-TBI controls and that these white matter abnormalities were spatially variable across individuals. Importantly, the extent of white matter abnormality was associated with physical PCS severity and mediated the relationship between mTBI with LOC and physical PCS. Second, this dissertation examined whether these white matter abnormalities were also associated with overall cognitive impairment. In light of the observed variability in white matter injury, a measure of overall cognitive status that takes into account heterogeneity of cognitive impairment was used. Results showed that the extent of white matter abnormality was associated with cognitive status and mediated the relationship between mTBI with LOC and cognitive impairment. Third, this dissertation examined performance and brain function in the context of an experimental measure of cognitive control known to be sensitive to residual effects of mTBI. Results revealed that although behavioral performance was similar across groups, the mTBI group had enhanced functional connectivity between brain networks important for task performance, suggesting a potential compensatory mechanism in mTBI. Together, the findings of this dissertation suggest that mTBI is associated with structural and functional connectivity alterations years after the injury. Further, this dissertation suggests that whereas structural connectivity changes may have negative behavioral consequences, changes in functional connectivity may serve as a compensatory mechanism for successful performance.

No description available.

No description available.

Thesis advisor: Ellen Winner / Cognitive control, the ability to limit attention to goal-relevant information, subserves higher-order cognitive functions such as reasoning, attention, planning and organization. Counterintuitively, deficits in these functions have proven advantageous in certain contexts: low cognitive control means less filtering of attention, and such unfiltered attention leads to novel solutions in insight problem solving contexts. Insight is the clear and often sudden discernment of a solution to a problem by means that are not obvious, and it plays an indispensable role in creative thinking. This study examined whether insight problem solving is a compensatory advantage for children of low socioeconomic status because of their known deficits in cognitive control. One hundred and forty-eight children ages 4 to 11 years old, each completed two insight problem solving tasks (the Box Problem and the Pencil Problem) and a cognitive control task (the Flanker/Reverse Flanker). In addition, their parents completed a sociodemographic questionnaire, which was used as a measure of their socioeconomic status and child rearing values of obedience versus independence. No association was found between children’s socioeconomic status and their ability to use insight to solve a problem. Results did show that older children exhibited less cognitive flexibility than did to younger children, and that diminished cognitive flexibility correlated with older children’s ability to solve the Box Problem; however, this effect did not hold when age, sex, race, socioeconomic status, and parental report of obedience versus independence, were accounted for. Ultimately, age was the only significant predictor of children’s insight problem solving ability, such that older children were significantly more likely to solve the Box Problem and to arrive at a solution more quickly for the Pencil Problem compared to younger children. Findings from this study are explained using evidence from research on children’s tool innovation showing that young children are poor at inventing tools, and that older children’s ability to use objects for atypical functions may be the result of their greater exposure to and experience with tools. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

The anterior cingulate has been implicated in a number of cognitive processes that are at risk following traumatic brain injury (TBI), such as executive function and emotional processing. While the cingulate is believed to play a role in the above-mentioned cognitive processes, the relative roles of gray and white matter in functional outcomes post-TBI are not fully understood. The current study investigated various quantifiable brain properties (e.g., cortical thickness and volume, volume of underlying white matter, and white matter integrity) of the caudal anterior cingulate (CAC) gyrus and their relationships with behavioral measures of cognitive control following pediatric TBI. Parent ratings at three months post-injury indicated that TBI children demonstrated greater difficulty inhibiting inappropriate behavior and effectively transitioning between tasks. Reductions of CAC white matter integrity were observed in TBI participants, in the absence of significant morphometric group differences in this region. Neither CAC morphometrics nor fractional anisotropy (FA) were associated with experimental measures of cognitive control. The current findings indicate that DTI metrics may be more sensitive to brain changes in the region of the CAC following TBI. While strong relationships were not observed between CAC properties and measures of cognitive control, it is possible that study limitations may have obscured potential findings.

<p dir="ltr">Metacontrol describes outsourcing cognitive control to environmental cues, allowing for efficient instantiation of appropriate cognitive control. While recent years have seen many studies characterizing metacontrol in behavioral terms, relatively little effort has been made to characterize the neural mechanisms underlying metacontrol. Thus, the current dissertation project aimed to investigate the neural systems and interactive features of metacontrol, more specifically, proactive and reactive metacontrol that exert context-appropriate control states in preparatory and just-in-time manners, respectively. Specifically, Study 1 employed a functional magnetic resonance imaging technique and identified brain regions activated under proactive and reactive metacontrol operations. Importantly, the study revealed that the two metacontrol modes were supported by distinct neural systems. Building on the premise that distinct neural systems supporting the two metacontrol modes would enable the concurrent operation of both modes, Study 2 tested whether a preparatory metacontrol mode, proactive metacontrol, can coexist with a just-in-time metacontrol mode, reactive metacontrol. Using electroencephalography, Study 2 revealed that the two metacontrol modes can operate in parallel. Lastly, extending Study 2, Study 3 investigated how proactive metacontrol interacts with reactive metacontrol. Study 3 observed that high preparatory control states during proactive metacontrol benefit reactive metacontrol. Specifically, reactive metacontrol was observed only when penalties were at stake, which promoted heightened preparatory control states. In summary, Study 1 demonstrated that the two metacontrol modes are not only operationally distinctive but also characterized by separate neural systems underlying them. This aligns with the observation from Study 2 showing that the parallel operation of two metacontrol modes is feasible. Lastly, Study 3 suggests that despite the two metacontrol modes being supported by distinct neural systems (as shown in Study 1), they are not entirely independent and can interact with each other. Collectively, these findings reveal the relationship between the two metacontrol modes and elucidate their intricate interactions, thereby deepening our understanding of the neurocognitive mechanisms underlying metacontrol.</p>

Widespread availability of digital tools has changed the daily lives of college students. Yet, the intricacies underlying these digital ecosystems and their relationship to psychological functioning, particularly among these younger ‘digital native’ age cohorts, are still unclear. A growing body of work points to associations between digital media behaviors and the capacity for top-down self-regulatory control over thoughts, emotions, and behavior. Behavioral scientists often subdivide this skillset into separate psychological constructs with different labels (e.g., cognitive control, executive functioning, emotion regulation), and use a varied array of tasks and surveys to index its subcomponents. The general finding from across behavioral studies is that groups (and individuals) with weaker executive functioning (EF) skills also tend to exhibit heavier and more problematic digital media habits (e.g., excessive, or addiction-like use). This is presumably because the inability to reliably exert control makes one more prone to impulsive engagement with digital media (e.g., frequent phone-checking), greater attentional distractibility in response to media-associated cues (e.g., notifications), and more difficulty with sustaining goal-relevant behaviors in the presence of digital media. However, there has also been empirical work suggesting null and even positive or nonlinear relationships between digital media use and EF. The current study aimed to address these seemingly opposing sets of findings by examining how, and to what extent, individual differences in one’s self- and mobile-reported smartphone habits relate with specific facets of higher-order cognition. In our examination of the interplay between these factors, we found consistent patterns emerge between subjective measures of everyday and problematic smartphone use and common non-social executive functioning skills. Furthermore, we also found evidence indicating an overlapping pattern of findings highlighting the relationships between one’s cognizance toward their actual mobile usage habits and specific facets of socially oriented self-regulation. / Psychology

The representation of incoming information, goals and the flexible processing of these are required for cognitive control. Efficient mechanisms are needed to decide when it is important that novel information enters working memory (WM) and when these WM ‘gates’ have to be closed. Compared to neural foundations of maintaining information in WM, considerably less is known about what neural mechanisms underlie the representational dynamics during WM gating. Using different EEG analysis methods, we trace the path of mental representations along the human cortex during WM gate opening and closing. We show temporally nested representational dynamics during WM gate opening and closing depending on multiple independent neural activity profiles. These activity profiles are attributable to a ventral stream-prefrontal cortex processing cascade. The representational dynamics start in the ventral stream during WM gate opening and WM gate closing before prefrontal cortical regions are modulated. A regional specific activity profile is shown within the prefrontal cortex depending on whether WM gates are opened or closed, matching overarching concepts of prefrontal cortex functions. The study closes an essential conceptual gap detailing the neural dynamics underlying how mental representations drive the WM gate to open or close to enable WM functions such as updating and maintenance.