Obsessive-compulsive disorder (OCD) is associated with diminished quality of life and cognitive control dysfunction. Conflict adaptation is a reflection of cognitive control, and consists of the ability to detect conflict in previous trials and adjust performance on current trials. Conflict adaptation is thought to rely on interplay between the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC) for detecting conflict and signaling for increases in control, respectively. We hypothesized that individuals with OCD would show reduced conflict adaptation effects in response times, error rates, ACC activation, and dlPFC activation when compared with healthy control subjects. We also expected diminished conflict adaptation to be associated with poorer quality of life in those with OCD. Nineteen individuals with OCD and twenty psychiatrically-healthy controls completed a Stroop task while response times, error rates, and fMRI data were recorded. 2-Group (OCD, control) x 2-Previous Trial Congruency (congruent, incongruent), x 2-Current Trial Congruency (congruent, incongruent) ANOVAs were conducted for both behavioral and fMRI data. Indices of conflict adaptation were correlated with quality of life scores. There was a significant response time conflict adaptation effect collapsed across groups; however, there were no between-groups interactions or main effects. No error rate conflict adaptation was observed at any level of the analysis. On fMRI analyses, the dlPFC showed increased activation on incongruent relative to congruent trials collapsed across groups; however, no ACC activation differences were observed between current incongruent and congruent trials. Conflict adaptation-related activation was noted in the ACC collapsed across groups. The between-groups ANOVA revealed a significant cluster in the ACC with control participants showing greater ACC, medial prefrontal cortex, and left orbitofrontal cortex conflict adaptation activation-related activation relative to individuals with OCD. No between-groups differences were seen in the dlPFC. Conflict adaptation was not significantly related to quality of life. Individuals with OCD may use different neural processes to achieve similar behavioral results to those of healthy controls. Alternative explanations of conflict adaptation effects such as temporal learning theory are also discussed. Our hypothesized model for the ACC and dlPFC functioning as the evaluative and regulative components of cognitive control was only partly supported. ACC and dlPFC activation appeared to highlight different roles, but these roles may be independent rather than existing in a feedback loop. Although quality of life is significantly diminished in individuals with OCD, this loss of quality of life does not appear to be mediated by conflict adaptation differences.

Theories embedded within evolutionary neurobiology offer useful frameworks within which to understand cognitive impairment in schizophrenia (SCZ). The current research invokes the Dual Trends Theory (DTT), an evolutionary model that posits that neural architecture develops along two separate pathways: the dorsal ‘archicortical’ trend and the ventral ‘paleocortical’ trend. Although various lines of research converge to suggest that SCZ is associated with dorsal trend impairment in the context of relative ventral trend sparing, one persistent inconsistency exists. Specifically, individuals with SCZ routinely show impairment on tasks of action inhibition (AI; the ability to inhibit a pre-planned movement), a function routinely shown to be mediated by the inferior frontal gyrus, a key structure of the ventral trend. Here we argue that conventional tasks of AI conflate AI per se with response conflict (CON) demands, a function shown to be mediated by the anterior cingulate cortex, a key structure of the dorsal trend. We define CON as any aspect of a task that increases the difficulty of deciphering or interpreting the meaning of task stimuli (e.g., greater perceptual similarity between imperative task stimuli). The current research administered novel AI tasks in order to independently examine increases in CON and increases in the prepotency to respond to a pre-planned movement (PREP; considered a more fundamental measure of AI). Consistent with study hypotheses, individuals with Schizoprenia-spectrum disorders (specifically schizotypy) failed to show compensatory response time (RT) slowing when confronted with increasing CON demands yet showed proportional RTs, relative to healthy control participants, as PREP demands increased. These findings were interpreted as reflecting impairment in their ability to detect and/or decipher CON. More broadly, these findings suggest that cognitive abnormalities in SCZ may represent disproportionately impaired dorsal trend circuitry.

Neurological and psychiatric disorders reveal that the basal ganglia subserve diverse functional domains, including movement, reward, and cognitive disorders (e.g., Parkinson's disease, addiction, schizophrenia). Monkey anatomical studies show that the striatum, the input structure of the basal ganglia, receives projections from nearly the entire cerebral cortex with a broad topography of motor, limbic, and association zones. However, until recently, non-invasive methods have not been available to conduct the complete mapping of the cortex to the striatum in humans. The development of functional connectivity magnetic resonance imaging (fcMRI) now allows the identification of functional connections in humans. The present dissertation reports two studies that first create a complete map of corticostriatal connectivity and then more closely examine striatal connectivity with association networks underlying cognition.

Theories embedded within evolutionary neurobiology offer useful frameworks within which to understand cognitive impairment in schizophrenia (SCZ). The current research invokes the Dual Trends Theory (DTT), an evolutionary model that posits that neural architecture develops along two separate pathways: the dorsal ‘archicortical’ trend and the ventral ‘paleocortical’ trend. Although various lines of research converge to suggest that SCZ is associated with dorsal trend impairment in the context of relative ventral trend sparing, one persistent inconsistency exists. Specifically, individuals with SCZ routinely show impairment on tasks of action inhibition (AI; the ability to inhibit a pre-planned movement), a function routinely shown to be mediated by the inferior frontal gyrus, a key structure of the ventral trend. Here we argue that conventional tasks of AI conflate AI per se with response conflict (CON) demands, a function shown to be mediated by the anterior cingulate cortex, a key structure of the dorsal trend. We define CON as any aspect of a task that increases the difficulty of deciphering or interpreting the meaning of task stimuli (e.g., greater perceptual similarity between imperative task stimuli). The current research administered novel AI tasks in order to independently examine increases in CON and increases in the prepotency to respond to a pre-planned movement (PREP; considered a more fundamental measure of AI). Consistent with study hypotheses, individuals with Schizoprenia-spectrum disorders (specifically schizotypy) failed to show compensatory response time (RT) slowing when confronted with increasing CON demands yet showed proportional RTs, relative to healthy control participants, as PREP demands increased. These findings were interpreted as reflecting impairment in their ability to detect and/or decipher CON. More broadly, these findings suggest that cognitive abnormalities in SCZ may represent disproportionately impaired dorsal trend circuitry.

With the growing prevalence of bilingualism in modern society, it has become increasingly important to understand how the ability to speak more than one language affects cognitive function across the lifespan. Although bilingualism has been associated with disadvantages in measures of language use, bilinguals appear to demonstrate superior executive functioning compared to monolinguals. This “bilingual advantage” has been found for several aspects of cognitive control, including attention, inhibition and conflict resolution. Based on the overlap between cognitive networks and brain regions affected by aging, it has been further proposed that cognitive control—and by extension, bilingualism—confers protective effects against cognitive decline associated with natural aging. Here, we review the behavioral performance of bilinguals on linguistic and cognitive control measures, as well as evaluating information on the neural correlates of bilingualism and its relation to cognitive control and cognitive decline. An assessment of the present literature suggests that, compared to monolingual performance, the bilingual advantage in cognitive control carries over to a reasonable protective effect against cognitive decline. However, the lack of integrated research in the field demonstrates a need for further exploration of the specific facets of bilingualism, its potential significance for neurodegenerative diseases (e.g., Alzheimer’s disease), and the role of bilingualism in cognitive reserve.

The construct of cognitive control is often invoked to provide a mechanism responsible for information-processing in ill-defined situations. However, the dual-mechanism theory of cognitive control distinguishes between proactive and reactive varieties, and provides a more concrete framework for explaining behavior across various conditions. Importantly, although proactive and reactive control have been theorized to apply to differential performance observed in various clinical and aging populations, no empirical work has been conducted examining how this theory may apply to individual differences in working memory capacity within a young, healthy population. The current research directly assessed proactive versus reactive control by administering three versions of the AX version of the continuous performance test to individuals varying in working memory capacity. Across the task versions, specific trial type frequencies were manipulated to examine whether this variable interacted with WMC to cause individuals to engage in one control type over the other. In addition, the current work investigated whether individuals can change their mode of control on a trial-to-trial basis, something that had not previously been examined. Individuals low in working memory capacity exhibited specific performance deficits relative to the individuals high in working memory capacity. The results extend the application of the dual-mechanism theory to individual differences in working memory capacity and provide a theoretical framework to explain previous findings in the working memory capacity literature.

The research on bilingual language processing explores two main avenues of relevance to the present study: lexico-semantic access and cognitive control. Lexico-semantic access research investigates the manner in which bilingual individuals retrieve single words from their lexical system. Healthy bilingual individuals can manipulate their lexico-semantic access to accommodate settings in which code- or language-switching is expected. Alternatively, they can manipulate their lexico-semantic access to speak only their first (L1) or second (L2) languages. Cognitive control, also known as executive functioning, is closely related to lexico-semantic access. Specifically, bilingual individuals maintain and switch between their languages through a mechanism known as cognitive control. Both cognitive control and lexico-semantic access are important for language processing in healthy bilingual individuals as well as bilingual persons with aphasia (BPWA). However, the extent to which BPWA utilize each of these processes in the production of single words is still unknown. The present study used a method of verbal fluency in the form of a novel modified category generation task to assess the relative contributions of lexico-semantic access and cognitive control in bilingual healthy controls and BPWA.

Orientadora: Profa. Dra. Maria Teresa Carthery-Goulart / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Neurociência e Cognição, 2017. / Vantagens cognitivas do bilinguismo têm sido questionadas. Variáveis confundentes (i.e., idade, nível socioeconômico, imigração, etc.) e as múltiplas variáveis da experiência bilíngue poderiam explicar os diferentes achados da literatura. Neste estudo controlamos as variáveis confundentes e caracterizamos uma amostra bilíngue quanto à proficiência, balanceamento, idade e forma de aquisição, grau de imersão, frequência e padrão de uso da segunda língua (L2). Utilizamos o Paradigma Numérico de Stroop e avaliamos sob o ponto de vista comportamental e eletrofisiológico a influência do bilinguismo tardio, proficiente, não balanceado, sem imersão e receptivo em tarefas de controle inibitório (efeitos de interferência e Stroop) e flexibilidade mental (efeito de alternância ou custo local), dois aspectos centrais do controle cognitivo/funções executivas. Não encontramos vantagens quanto ao controle inibitório ou flexibilidade mental, observando apenas que bilíngues apresentaram no teste de Stroop, menores tempos de reação que monolíngues. Quanto à eletrofisiologia analisamos as componentes N200, N400 e P300, relacionadas de modo geral ao controle inibitório, processamento de conflitos e utilização de recursos atencionais, respectivamente. Não encontramos diferenças significantes entre os grupos. Nossos achados corroboram os de estudos realizados com adultos de outras nacionalidades e falantes de outras línguas. Discutimos as peculiaridades de nossa amostra como possível fator responsável pela ausência das vantagens. Esses bilíngues, apesar de altamente proficientes, vivem em contexto no qual predomina a L1. Assim, a frequência de alternância entre as línguas é rara e o uso da L2 é dominantemente receptivo (leitura e compreensão oral), sendo diferentes da maioria dos bilíngues adultos jovens descritos nos estudos em que se encontraram vantagens no controle cognitivo. Nossos resultados apontam: (1) a necessidade de que as pesquisas caracterizem de forma mais detalhada a amostra bilíngue no sentido de determinar como diferentes populações podem produzir diferentes resultados, (2) a possível importância da frequência de alternância entre as línguas no fortalecimento das funções executivas e (3) a necessidade de novos estudos que avaliem como o uso receptivo da L2 pode afetar a experiência bilíngue. / Cognitive advantages of bilingualism have been questioned. Confounding variables (i.e., age, socioeconomic level, immigration, etc.) and the multiple variables of bilingual experience could explain the different findings in the literature. In this study we controlled the confounding variables and characterized the bilingual sample regarding proficiency, balance, age and context of acquisition, immersion degree, frequency and pattern of L2 use. We used the Numerical Stroop Paradigm for evaluating the influence of late, proficient, non balanced, without immersion and receptive bilingualism in tasks of inhibitory control (interference and Stroop effects) and mental flexibility (local switching cost), two central aspects of cognitive control / executive functions. We did not find any advantages in inhibitory control or mental flexibility,only observing that bilinguals were faster than monolinguals in the Stroop test. Regarding electrophysiology, we analyzed N200, N400 and P300 components, related generally to inhibitory control, conflict processing and use of attentional resources, respectively. We did not find significant differences between groups. Our findings corroborate those of studies conducted with adults of other nationalities and speakers of other languages. We discuss the peculiarities of our sample as a possible factor responsible for the absence of advantages. These bilinguals, although highly proficient, live in a context in which L1 predominates. Thus, the frequency of language alternation is rare and the use of L2 is predominantly receptive (reading and listening comprehension), being different from most of the young adult bilinguals described in the studies that found advantages in cognitive control. Our results point out: (1) the need for studies to characterize the bilingual sample as broadly as possible to determine how different populations can produce different results; (2) the possible importance of frequency of switching between languages and (3) the need for further studies that assess how receptive L2 use may affect bilingual experience.

A fundamental question of human existence is how much control we have on our behaviour. This dissertation aims to add to our understanding of cognitive control by characterising how a particular failure of performance, Goal Neglect (GN), is affected by different forms of complexity manipulations. In Chapter 2, I develop a new task to test GN and unlike previous studies, I manipulate complexity qualitatively by altering the instructional cues - the cues instructing the participant to shift to a different rule set. GN was sensitive to this kind of complexity manipulation and this is linked to a failure in recognizing the significance of the instructional cues. In Chapter 3, I propose a new entropy-like measure to quantify the temporal clustering of GN and use this to test the differential temporal patterns that are predicted by two theoretical models of GN. The results suggest that both models are likely to be operant, but with their relative dominance being different across time: GN early on in the task appears to be mostly driven by failures which are “task model” like, whilst GN which manifests later on is better aligned with the “monitoring” account. Chapter 2 also revealed that GN can be sensitive to manipulations of complexity during task performance, which motivated the question of whether previously published studies suggesting the contrary, were perhaps due to insufficient complexity. Hence, in Chapter 4, using the new GN task, I investigate this further. Overall, the results were mixed and indicated that complexity does not appear to affect GN unless the complexity manipulation is more closely associated to the critical event. Throughout this dissertation, I refer to models and empirical evidence from the Prospective Memory (PM) literature given the apparent similarity between PM and GN experimental paradigms. In Chapter 5, I take this further and investigate how PM failures and GN are different, if at all, with the broader aim to integrate what are otherwise isolated domains. I found a mixture of null findings which suggest that it is not entirely clear if GN and PMf reflect different capacities. Nonetheless, while investigating the differences between GN and PMf, a much more interesting question emerged with respect to what structural features of a task predict different signatures of GN-like and PMf-like errors. The key finding to this theory-neutral approach was a general rule about task structure: a combination of extended practice and low frequency of critical events predict both a larger amount of errors and with more of these occurring late in the task. Overall, this research has shed further light on task conditions that may result in different error signatures and that may reflect different cognitive resources.

abstract: A converging operations approach using response time distribution modeling was adopted to better characterize the cognitive control dynamics underlying ongoing task cost and cue detection in event based prospective memory (PM). In Experiment 1, individual differences analyses revealed that working memory capacity uniquely predicted nonfocal cue detection, while proactive control and inhibition predicted variation in ongoing task cost of the ex-Gaussian parameter associated with continuous monitoring strategies (mu). In Experiments 2A and 2B, quasi-experimental techniques aimed at identifying the role of proactive control abilities in PM monitoring and cue detection suggested that low ability participants may have PM deficits during demanding tasks due to inefficient monitoring strategies, but that emphasizing importance of the intention can increase reliance on more efficacious monitoring strategies that boosts performance (Experiment 2A). Furthermore, high proactive control ability participants are able to efficiently regulate their monitoring strategies under scenarios that do not require costly monitoring for successful cue detection (Experiment 2B). In Experiments 3A and 3B, it was found that proactive control benefited cue detection in interference-rich environments, but the neural correlates of cue detection or intention execution did not differ when engaged in proactive versus reactive control. The results from the current set of studies highlight the importance of response time distribution modeling in understanding PM cost. Additionally, these results have important implications for extant theories of PM and have considerable applied ramifications concerning the cognitive control processes that should be targeted to improve PM abilities. / Dissertation/Thesis / Doctoral Dissertation Psychology 2015