The daily practice of bilingual language control has been argued to affect both lexical processing and non-verbal executive control in bilingual speakers. On the one hand, bilingualism may slow down lexical processing in both languages. On the other hand, bilinguals have been said to show cognitive advantages compared to monolinguals, for example on inhibition and switching tasks. However, this ‘bilingual advantage’ is hotly debated, can often not be replicated, and language groups have been poorly matched on background variables in previous studies. Furthermore, I examined the reliability of the literature and found evidence for the existence of a publication bias (Chapter 3). This over-representation of positive studies compared to studies with null or negative findings hinders a reliable interpretation of the actual effects of bilingualism. The current thesis therefore aimed to examine possible effects of bilingualism on both lexical processing and executive control. Specifically, I investigated the effects of an understudied, but important feature of bilingualism: language use. Effects of bilingualism have been argued to be largest in older adults. Chapter 4 presents a study discussing inhibition and possible effects of age across various tasks. I show that inhibitory control and age effects depend on task-specific features, including the type of interference, type of stimuli, and processing speed. Next, I present a study (Chapter 5 and 6) examining the relation between bilingualism and both lexical processing and executive control in older adults. Importantly, bilingual and monolingual groups were matched on background variables including immigrant status. I furthermore compared a group of active to inactive bilinguals to assess effects of language use. On a lexical processing task, bilinguals had a disadvantage compared to monolinguals. This effect was modulated by language use, implying that not only language proficiency but also actual language use are needed to explain lexical effects of bilingualism. However, the non-verbal executive control tasks showed no consistent effects of bilingualism or language use on inhibition or task switching. Thus, this study did not replicate positive effects on executive control in older adults. Between-subject comparisons remain problematic as groups can never be matched perfectly. Furthermore, these designs cannot assess a causal effect of bilingualism. Therefore, I conducted another study using behavioural and EEG measurements to test for causal effects of language switching on task switching (Chapter 7). When young bilinguals completed a language-switching task prior to a verbal task-switching paradigm, they showed larger switching costs than after a monolingual naming task. However, this effect of language switching was not found for non-verbal task switching. Language switching may thus have a negative impact on verbal switching, but these effects did not extend to non-verbal executive control. Together, these studies suggest that bilingualism and language use affect lexical processing, but there was no evidence for effects of bilingualism and language use on non-verbal executive control in younger or older adults. In combination with other failed replications and the biased literature, this questions the reliability of cognitive benefits associated with bilingualism. However, executive control is not a unity and its manifestation depends on task-specific features. This task impurity, together with the degree to which participant groups are matched, may explain the inconsistency with which effects of bilingualism on executive control have been observed.

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Published Article / The aim of the study was to determine the influence of controlled breathing on school principals' stress relief. The research sample consisted of six primary school principals purposefully selected on the basis of years of school principal experience and the voluntary attendance of a stress alleviation workshop. Based on an interpretive paradigm employing a mixed-methods research approach, a structured questionnaire was used to compare participants' levels of stress before and after attendance of a stress alleviation workshop that focused on controlled breathing. By means of in-depth individual interviews the manifestation of the influence of controlled breathing on participants' stress relief was investigated. Data from the structured questionnaires were analysed as frequencies and mean scores. Through qualitative content analysis data from the individual interviews were analysed as emerging categories and themes. It was found that the regular practising of controlled breathing resulted in participants' stress relief with main improvements related to revitalised energy levels, restored clarity of thinking and improved interpersonal relationships. The findings contribute to research on constructive ways of stress relief within the school environment.

What are the effects of non-balanced bilingualism on cognitive performance? And how do proficient, non-native speakers acquire and use lexical, syntactic and semantic information during sentence processing? Whilst there is growing research on these topics, there is no firm consensus on how to answer these questions. In the literature on cognitive effects of bilingualism, this lack of consensus has even resulted in radically opposing views and a heated debate. In this thesis, I seek to provide a balanced treatment of the literature and to address the above-mentioned questions by employing behavioral and neurophysiological paradigms. First, using a structural priming paradigm, I examine how proficient, non-native speakers of different native language backgrounds (Romance and Germanic) acquire lexically-specific syntactic restrictions of non-alternating verbs in English. Results from these experiments suggest that, although non-native speakers partially acquire lexically-specific syntactic restrictions, their knowledge is not native-like. Moreover, transfer from the first language does not seem to play a role in the acquisition of the relevant restrictions. Second, using Event-Related Potentials (ERPs) I examine whether proficient non-native Spanish-English speakers draw on different forms of semantic information such as relatedness and animacy incrementally during sentence comprehension. Results of these experiments suggest that, while relatedness facilitates processing (indexed by N400s) in both native and non-native speakers, effects of animacy are smaller in non-native speakers, relative to native speakers. Third, I employ a series of auditory attentional tasks and measures of lexical access and verbal fluency to assess cognitive functions in non-balanced bilinguals with different levels of language proficiency. Results show a bilingual advantage in inhibitory control and a non-significant trend towards bilingual better performance in attentional switching, and the groups exhibit similar performance on verbal fluency. Results of all the studies are discussed in the context of the existing literature on cognitive performance in bilinguals and accounts of language processing in native and non-native speakers and suggestions for future research are provided.

The present study evaluated direct and indirect associations between aerobic fitness, executive control, and emotion regulation among a sample of children aged 8-12 years. To evaluate these associations, the study employed a cross-sectional design and full-information maximum likelihood (FIML) structural equation modeling. Although the hypothesized factor analytic model failed to converge, an alternative exploratory model allowed for the evaluation of associations between primary study variables. Results supported a moderate direct association between childhood aerobic fitness and executive control, a strong direct negative association between executive control and emotion regulation, and a moderate indirect association between aerobic fitness and emotion regulation through executive control. These findings provide preliminary evidence that executive control functions as a mediator between aerobic fitness and emotion regulation and may help explain the means by which aerobic exercise exerts its influence on emotional wellbeing among preadolescent children.

Posttraumatic Stress Disorder (PTSD) is an anxiety disorder characterised by disturbed arousal, altered attention, and fear processing, and a reduction in the ability to perform cognitive tasks. Predominant neurophysiological models of PTSD have been focused on alterations in fear-related regulation, and few incorporate broader changes in generic executive control which may underlie many of the clinical symptoms and cognitive deficits in PTSD. This thesis aimed to investigate the neurophysiology of executive inhibitory control in PTSD using a Go/NoGo response inhibition task and converging functional imaging, structural imaging and electrophysiological measures. The first series of studies aimed to elucidate a normative neural network model of inhibitory control, and are consistent with normative control involving the activation of a mainly right-lateralised ventral lateral prefrontal cortex (VLPFC) network. Inhibitory control-related activation was found to be affected by levels of anxiety and changes in underlying neural structure; alterations in frontal cortical maturation and volume were related to additional activation of bilateral frontal cortical regions and the dorsal striatum, with anxiety increasing the demand on inhibitory control-related activation. In contrast to healthy participants, PTSD was associated with reduced inhibitory control as indexed by inhibitory behaviour, diminished activation of the right VLPFC, and slowed inhibition-related information processsing. PTSD participants relied on the greater activation of a left fronto-striatal inhibition network to support control, with the activation affected by levels of PTSD severity and comorbid anxiety. This left fronto-striatal activation in PTSD was related to underlying increases in fronto-striatal neural structure. Further, the ability to efficiently engage a left fronto-striatal network in PTSD during inhibitory control predicted better response to cognitive behavior for PTSD, consistent with the proposal that an improved ability to flexibly engage control systems may facilitate the resolution of PTSD symptoms. Taken together, this program of research extends current neurophysiological model of PTSD to show that PTSD involves a fundamental disturbance in the function and structure of key fronto-striatal response control networks associated with inhibitory control.

The present study seeks to explore if the bilingual advantage and disadvantage of children who are natively bilingual in English and Spanish extends to children who gain exposure to and eventually become bilingual in these languages beginning at ages 5 and 6. Specifically, the study compares executive control, vocabulary, and verbal fluency for three groups of children: a) native Spanish-English bilinguals, b) late bilinguals that have completed at least 5 years of a 50-50 dual language immersion program in English and Spanish in school, and c) English monolinguals that have not had second language instruction. The proposed study seeks a better understanding of the unique cognitive skill sets of native and late bilingual and monolingual children, and to inform educational policy related to bilingual students. / text

Many studies of ‘executive control’ have focused on the prefrontal cortex (PFC), which contains the neuronal functional properties, modulatory neurotransmitters, and network connections with sensory and motor regions to make this large brain area a candidate region to provide all the necessary elements to voluntarily control behavior. However, like the motor and premotor cortex, the PFC is integrated with the basal ganglia (BG) in such a similar fashion, that it is impossible not to consider that the PFC might depend on the BG to implement executive control effectively. This thesis draws on knowledge of PFC and BG function, and combines studies that require the instantaneous top-down control over motor behavior with a neurological patient group with primarily BG dysfunction (Parkinson’s disease), to provide for a new understanding of prefrontal-BG networks sub-serving executive control. The tasks performed by subjects consist of antisaccades (generate a voluntary eye-movement away from a visual stimulus) and those dealing with task switching (change behavior after an alternate was previously required). Numerous neural and functional imaging studies have identified key areas of the prefrontal cortex and BG that are critical to antisaccade generation, and studies in task switching have implicated similar neural mechanisms that are involved in overriding one behavior with another. By combining task switching with antisaccades, this thesis specifically examines the neural mechanisms related to suddenly changing behavior, under conditions where one behavior is easier to perform than the other. The methods utilize on-line eye-tracking in healthy young adults and older adults with, and without, Parkinson’s disease, to develop theories of a role of the BG in executive control, and to search for specific neural correlates of executive control signals in the PFC, premotor cortex and BG using functional magnetic resonance imaging (fMRI). Together, the conclusions drawn from this thesis point to an important role of the BG in overriding more automatic behavior with behavior that is more difficult to perform. This thesis also suggests that this overriding mechanism occurs through the boosting of cortical executive control signals via net excitatory feedback from the BG. / Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2010-09-09 12:17:46.904

Posttraumatic Stress Disorder (PTSD) is an anxiety disorder characterised by disturbed arousal, altered attention, and fear processing, and a reduction in the ability to perform cognitive tasks. Predominant neurophysiological models of PTSD have been focused on alterations in fear-related regulation, and few incorporate broader changes in generic executive control which may underlie many of the clinical symptoms and cognitive deficits in PTSD. This thesis aimed to investigate the neurophysiology of executive inhibitory control in PTSD using a Go/NoGo response inhibition task and converging functional imaging, structural imaging and electrophysiological measures. The first series of studies aimed to elucidate a normative neural network model of inhibitory control, and are consistent with normative control involving the activation of a mainly right-lateralised ventral lateral prefrontal cortex (VLPFC) network. Inhibitory control-related activation was found to be affected by levels of anxiety and changes in underlying neural structure; alterations in frontal cortical maturation and volume were related to additional activation of bilateral frontal cortical regions and the dorsal striatum, with anxiety increasing the demand on inhibitory control-related activation. In contrast to healthy participants, PTSD was associated with reduced inhibitory control as indexed by inhibitory behaviour, diminished activation of the right VLPFC, and slowed inhibition-related information processsing. PTSD participants relied on the greater activation of a left fronto-striatal inhibition network to support control, with the activation affected by levels of PTSD severity and comorbid anxiety. This left fronto-striatal activation in PTSD was related to underlying increases in fronto-striatal neural structure. Further, the ability to efficiently engage a left fronto-striatal network in PTSD during inhibitory control predicted better response to cognitive behavior for PTSD, consistent with the proposal that an improved ability to flexibly engage control systems may facilitate the resolution of PTSD symptoms. Taken together, this program of research extends current neurophysiological model of PTSD to show that PTSD involves a fundamental disturbance in the function and structure of key fronto-striatal response control networks associated with inhibitory control.

Empathy is an essential prerequisite for the development and maintenance of close interpersonal relationships. Given that older adults are particularly vulnerable to the negative consequences of loneliness and social isolation, it is surprising that few studies have assessed empathy in this group. The current programme of research addressed this gap in the literature by testing competing predictions derived from Socioemotional Selectivity Theory and the Ageing-Brain Model for age-related sparing and impairment of empathy, respectively. Study 1 compared young (N = 80) and older (N = 49) adults?? self-reported levels of cognitive and affective empathy, and engagement in social activities. It was found that although affective empathy is spared, cognitive empathy is subject to age-related decline, and this decline mediates reductions in social participation. These data therefore affirmed the importance of further investigation into the nature, causes and potential consequences of age-related differences in empathy. Since disinhibition is one mechanism contributing to difficulty taking the perspective of another, and is known to increase with age, in Study 2, behavioural measures sensitive to inhibitory failure and to cognitive empathy were administered to young (N = 36) and older (N = 33) adults. One of the measures of cognitive empathy directly manipulated inhibitory demands, involving either high or low levels of self-perspective inhibition. The results indicated that older adults were selectively impaired on the high-inhibition condition, with cognitive disinhibition mediating this association. Study 2 therefore provided important evidence relating to one potential mechanism that contributes to age-related difficulties in perspective-taking. Studies 3 and 4 provided the first behavioural assessments of age-related differences in affective empathy by using electromyography to index facial expression mimicry. Study 3 found that young (N = 35) and older (N = 35) adults?? demonstrate comparable mimicry of anger, but older adults?? initial (i.e., implicit) reactions were associated with reduced anger recognition. Thus, to test the possibility that despite explicit recognition difficulties, implicit processing of facial expressions may be preserved in older adulthood, Study 4 compared young (N = 46) and older (N = 40) adults?? mimicry responses to subliminally presented angry and happy facial expressions. As predicted, the two groups demonstrated commensurate subconscious mimicry of these expressions. Taken together, these studies indicate that separate components of empathy are differentially affected by healthy adult ageing. Implications for competing perspectives of socioemotional functioning in older adulthood are discussed.