The ability to control one’s behaviour is a fundamental cognitive function subserved by the prefrontal cortex (PFC). Whereas the neural basis of inhibitory control is reasonably well-established, the possible influence of individual differences in personality on cortical activity associated with this ability remains largely unexplored. The present study obtained self-report ratings of Five-Factor Model personality traits from 42 healthy adults while hemodynamic oxygenation in the PFC was recorded during a Go/No-Go task. Results indicated that Neuroticism, Agreeableness and Openness to Experience were associated with attenuated activity in the lateral PFC, a region critical for emotion regulation and behavioural control, whereas Extraversion and Conscientiousness were associated with greater activation in these regions. Activity within the medial PFC, an area linked to task engagement and self-monitoring, shared a positive association with Agreeableness. These findings provide important insights into how neural systems supporting inhibitory control may be affected by individual differences in personality.

The ability to control one’s behaviour is a fundamental cognitive function subserved by the prefrontal cortex (PFC). Whereas the neural basis of inhibitory control is reasonably well-established, the possible influence of individual differences in personality on cortical activity associated with this ability remains largely unexplored. The present study obtained self-report ratings of Five-Factor Model personality traits from 42 healthy adults while hemodynamic oxygenation in the PFC was recorded during a Go/No-Go task. Results indicated that Neuroticism, Agreeableness and Openness to Experience were associated with attenuated activity in the lateral PFC, a region critical for emotion regulation and behavioural control, whereas Extraversion and Conscientiousness were associated with greater activation in these regions. Activity within the medial PFC, an area linked to task engagement and self-monitoring, shared a positive association with Agreeableness. These findings provide important insights into how neural systems supporting inhibitory control may be affected by individual differences in personality.

Background: Generally, older adults perform worse than younger adults in complex working memory span tasks. So far, it is unclear which processes mainly contribute to age-related differences in working memory span. Objective: The aim of the present study was to investigate age effects and the roles of proactive and coactive interference in a recognition-based version of the operation span task. Methods: Younger and older adults performed standard versions and distracter versions of the operation span task. At retrieval, participants had to recognize target words in word lists containing targets as well as proactive and/or coactive interference-related lures. Results: Results show that, overall, younger adults outperformed older adults in the recognition of target words. Furthermore, analyses of error types indicate that, while younger adults were only affected by simultaneously presented distracter words, older adults had difficulties with both proactive and coactive interference. Conclusion: Results suggest that age effects in complex span tasks may not be mainly due to retrieval deficits in old age. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Children with traumatic brain injury (TBI) often experience difficulties with inhibitory control (IC), manifest in both neurocognitive function (poor performance on the stop signal task, SST) and behavior (emergence of de novo attention-deficit/hyperactivity disorder, or secondary ADHD, S-ADHD). IC allows for the regulation of thought and action, and interacts with reward to modify behaviour adaptively as environments change. Children with developmental or primary ADHD (P-ADHD) exhibit poor IC and abnormalities when responding to rewards, yet the extent to which S-ADHD is similar to and different from P-ADHD in terms of these behaviours is not well-characterized. The cancellation and restraint versions of the SST were used to examine the effects of rewards on 2 distinct forms of IC in children and adolescents divided into 4 groups (control, TBI, S-ADHD, and P-ADHD). The SST requires participants to respond to a “go signal” and inhibit their responses when encountering a “stop signal”. Rewards improved performance similarly across groups, ages, and cancellation and restraint IC tasks. Adolescents exhibited better IC and faster and less variable response execution relative to children. Significant IC deficits were found in both tasks in the P-ADHD group, with participants with S-ADHD exhibiting intermediate cancellation performance relative to the other groups. Participants with TBI without S-ADHD were not impaired on either task. The relationship between neurocognitive and behavioral IC was examined by comparing multi-informant ratings of IC across groups, and examining the relationship between ratings and IC performance on the SST. Participants in the control and TBI groups were rated within the typical range, and exhibited fewer problems than either of the ADHD groups, who differed from each other (the P-ADHD group was rated as more inattentive than the S-ADHD group). Moderate to high concordance was found between parent and teacher reports, each of which was poorly concordant with self-reports. The P-ADHD and S-ADHD groups were unaware of their own deficits. Poorer IC predicted parent and teacher classification of participants into ADHD subtypes, although IC did not predict rating concordance. Despite similar clinical presentations, S-ADHD and P-ADHD differ in the phenotypic expression of behaviour and manifestation of IC across contexts.

Dual Processing theory proposes that the ability to over ride associative (System 1) in favour of analytical (System 2) processed in deductive reasoning may depend on inhibitory control. The present study applies this association to a spatial reasoning task by adapting a mental rotation task to a multichoice format including System 1 (mirror) and System 2 (rotated image) responses. Fifty undergraduate volunteers from the University of Canterbury responded to a Stroop task as a measure of inhibitory control that was compared with System 1 and System 2 responding from a spatial and a deductive reasoning task. It was expected that people with weaker inhibitory potential would make more System 1 and fewer System 2 responses in both deductive and visual-spatial reasoning tasks. Contrary to expectation System 2 responding dominated for both tasks and correlations between both reasoning tasks and measures of inhibitory control were non-significant. The differing idiosyncratic demands of each task may have obscured any common variables associated with inhibitory control. This research initiated a test for the presence of System 1 and System 2 in spatial reasoning.

Early experience critically shapes cognitive, affective, and behavioral development, and experiences of early life stress (ELS) have been documented to negatively impact developmental trajectories. An increasing need exists for innovative intervention development to ameliorate negative impacts of ELS. Translational neuroscience approaches hold promise for addressing the needs of individuals who have experienced ELS through the development and testing of targeted intervention strategies grounded in neuroscientific knowledge. The current dissertation work employed a translational neuroscience approach to improve inhibitory control (IC) in a group of adolescents (N=20) exposed to a range of ELS via a brief, computerized training paradigm. Baseline analyses of the association between ELS and IC revealed a positive relationship (i.e., increased ELS, increased IC performance), counter to hypotheses. The IC training did not significantly improve IC in the training group compared to the control group over time, contrary to hypotheses and previous work demonstrating the effectiveness of this IC training in young adults. Transfer of training effects to a non-trained IC task and to real-world risk-taking behavior were limited. ELS demonstrated some moderation of neural effects of IC training. The use of neuroimaging in this dissertation work allowed for further investigation of neural mechanisms even in the absence of significant behavioral training, transfer, and moderation effects. Results are discussed in the context of the utility of such IC training approaches for adolescents with ELS exposure and of translational neuroscience approaches more broadly. Future directions for IC training, translational neuroscience intervention approaches, and the incorporation of neuroimaging in this work are explored. This dissertation includes unpublished co-authored material. / 10000-01-01

Inhibitory control, described as the ability to suppress one response in favor of a goal-directed response, is thought to play an important role in the development of emotional regulation as well as various forms of psychopathology, including ADHD. Up until very recently, inhibitory control has been researched within two completely separate fields of study: temperament and neuropsychology. In the temperament/personality literature, inhibitory control is a major component of the overarching temperament/personality factor of Effortful Control/Conscientiousness. In the field of neuropsychology, inhibitory control is considered one aspect of executive function. Further complicating the current understanding of inhibitory control is the complexity of the underlying neural networks implicated in inhibitory control. This study examined inhibitory control in temperament and executive function in children with and without ADHD, and it explored the relationship between inhibitory control and the superior frontal cortex (SFC) and orbital frontal cortex (OFC) volumes. In order to assess subareas of the OFC and SFC, an innovative parcellation method was used. Results suggested that the temperament and executive function measures of inhibitory control did form a single factor as long as they were measured within the same modality, parent-report. In contrast, the performance-based measure of inhibitory control was not correlated with any of the parent-report measures of inhibitory control and was, therefore, analyzed separately in relation to OFC and SFC volumes. Parent-rated inhibitory control was predicted by ADHD status only, but exploratory analyses suggested that left anterior SFC, right and left anterior medial OFC, and gender were related to parent-rated inhibitory control. In contrast, performance-based inhibitory control was predicted by gender and left SFC, specifically posterior left SFC. Taken together, these findings suggest a conceptual overlap between temperament and executive function that brings together two areas of the literature and has implications for the understanding of various forms of psychopathology characterized by deficits in inhibitory control. This study provides evidence for the role of the SFC and the OFC in inhibitory control, depending upon the measurement method, and contributes to the broader understanding of the neural mechanisms of inhibitory control in children.

O esquecimento intencional pode cumprir uma função estratégica no sistema cognitivo, que permite aos indivíduos não pensar sobre acontecimentos indesejados do passado, tais como eventos traumáticos, dolorosos e violentos, dos quais se prefere não recordar. Enquanto esquecer involuntariamente é uma falha da lembrança, por outro lado, esquecer intencionalmente parece ser uma função estratégica da memória. A presente dissertação teve por objetivo investigar os mecanismos neurocognitivos que contribuem para o esquecimento de memórias. A dissertação se organizou em dois estudos. O primeiro estudo consiste em uma revisão sistemática de artigos empíricos publicados nos últimos dez anos sobre a supressão de memórias indesejadas. O segundo estudo é um ensaio empírico, no qual foi executado um experimento adaptado do paradigma Think/No-Think com a utilização de marcadores eletrofisiológicos de eletroencefalograma. Participaram do experimento 22 sujeitos, alocados aleatoriamente em dois grupos com estratégias distintas de esquecimento: Supressão de memória e substituição de pensamentos. Durante toda a tarefa experimental, os participantes tiveram dados de EEG continuamente gravados. Os resultados decorrentes do ensaio empírico estão de acordo com os achados da literatura, indicando que a positividade parietal em torno de 400-800ms após a apresentação do estímulo é um marcador de lembrança consciente durante a recuperação de memória. Apenas na estratégia de supressão de memória houve uma redução da positividade centro-parietal durante o esquecimento, entre 450 e 700ms após apresentação do estímulo. Além disso, uma maior deflexão no componente N2 durante a supressão é um preditor de esquecimento induzido. Os achados indicam que é possível mapear o sistema neurocognitivo subjacente à supressão de memórias. / Intentional forgetting can be characterized as a strategic function of the cognitive system that allows us not to think about unwanted memories from our past, as for example emotional events or traumatic experiences that we would prefer not to remember. While forgetting involuntarily is a failure of recollection, on the other hand, forgetting intentionally seems to be a strategic function of memory. The aim of this dissertation was to investigate the neurocognitive mechanisms that contribute to forgetting memories. The dissertation was organized in two studies. The first study consists of a systematic review of empirical articles published in the last ten years on the suppression of unwanted memories. The second study is an empirical essay, in which an experiment adapted from the Think/No-Think paradigm was performed, with the use of electrophysiological markers of electroencephalogram. Twenty-two subjects participated in the experiment, randomly assigned to two groups with distinct strategies of forgetting: Memory suppression and thought substitution. Throughout the experimental task, participants had continuously recorded EEG data. The results of the empirical essay are in agreement with the literature findings, indicating that the parietal positivity around 400-800 ms after the presentation of the stimulus is a marker of conscious memory during memory recovery. Only direct memory suppression reduced centro-parietal positivity during forgetting, between 450 and 700 ms post-stimulus. Also, a greater deflection in the N2 component during suppression is an induced forgetting predictor. The findings indicate that it is possible to map the neurocognitive system underlying memory suppression.

O esquecimento intencional pode cumprir uma função estratégica no sistema cognitivo, que permite aos indivíduos não pensar sobre acontecimentos indesejados do passado, tais como eventos traumáticos, dolorosos e violentos, dos quais se prefere não recordar. Enquanto esquecer involuntariamente é uma falha da lembrança, por outro lado, esquecer intencionalmente parece ser uma função estratégica da memória. A presente dissertação teve por objetivo investigar os mecanismos neurocognitivos que contribuem para o esquecimento de memórias. A dissertação se organizou em dois estudos. O primeiro estudo consiste em uma revisão sistemática de artigos empíricos publicados nos últimos dez anos sobre a supressão de memórias indesejadas. O segundo estudo é um ensaio empírico, no qual foi executado um experimento adaptado do paradigma Think/No-Think com a utilização de marcadores eletrofisiológicos de eletroencefalograma. Participaram do experimento 22 sujeitos, alocados aleatoriamente em dois grupos com estratégias distintas de esquecimento: Supressão de memória e substituição de pensamentos. Durante toda a tarefa experimental, os participantes tiveram dados de EEG continuamente gravados. Os resultados decorrentes do ensaio empírico estão de acordo com os achados da literatura, indicando que a positividade parietal em torno de 400-800ms após a apresentação do estímulo é um marcador de lembrança consciente durante a recuperação de memória. Apenas na estratégia de supressão de memória houve uma redução da positividade centro-parietal durante o esquecimento, entre 450 e 700ms após apresentação do estímulo. Além disso, uma maior deflexão no componente N2 durante a supressão é um preditor de esquecimento induzido. Os achados indicam que é possível mapear o sistema neurocognitivo subjacente à supressão de memórias. / Intentional forgetting can be characterized as a strategic function of the cognitive system that allows us not to think about unwanted memories from our past, as for example emotional events or traumatic experiences that we would prefer not to remember. While forgetting involuntarily is a failure of recollection, on the other hand, forgetting intentionally seems to be a strategic function of memory. The aim of this dissertation was to investigate the neurocognitive mechanisms that contribute to forgetting memories. The dissertation was organized in two studies. The first study consists of a systematic review of empirical articles published in the last ten years on the suppression of unwanted memories. The second study is an empirical essay, in which an experiment adapted from the Think/No-Think paradigm was performed, with the use of electrophysiological markers of electroencephalogram. Twenty-two subjects participated in the experiment, randomly assigned to two groups with distinct strategies of forgetting: Memory suppression and thought substitution. Throughout the experimental task, participants had continuously recorded EEG data. The results of the empirical essay are in agreement with the literature findings, indicating that the parietal positivity around 400-800 ms after the presentation of the stimulus is a marker of conscious memory during memory recovery. Only direct memory suppression reduced centro-parietal positivity during forgetting, between 450 and 700 ms post-stimulus. Also, a greater deflection in the N2 component during suppression is an induced forgetting predictor. The findings indicate that it is possible to map the neurocognitive system underlying memory suppression.

Cocaine users display impaired inhibitory control. The influence of cocaine-related stimuli on inhibitory control has not been assessed. The Attentional Bias-Behavioral Activation (ABBA) task uses cocaine and neutral images as cues to determine if drug-related images impair inhibitory control in cocaine users. This dissertation was designed to assess the influence of cocaine images on inhibitory control in cocaine users through the conduct of studies designed to address four aims. The first aim was to demonstrate that cocaine users display impaired inhibitory control following cocaine images compared to neutral images on the ABBA task. This was accomplished through the conduct of two experiments. The first experiment piloted the ABBA task and cocaine users completed the cocaine go (n = 15) or neutral go condition (n = 15) of the task. The second experiment consisted of two studies designed to develop a within-subjects methodology for using the ABBA task. In the first study, cocaine users completed either the cocaine go (n = 20) or neutral go (n = 20) condition of the ABBA task and all participants also completed the Cued Go/No-Go task, with geometric shapes as cues. In the second study, cocaine users (n = 18) completed the cocaine go condition of the ABBA task and a modified version of the ABBA task with all neutral images as cues to further refine a possible within-subjects methodology. The second aim was to demonstrate that inhibitory failures occur most often when cues are presented for short compared to longer durations of time. Data collected during other protocols (n = 91) were combined to investigate the influence of stimulus onset asynchrony (SOA; i.e., the amount of time a cue is presented before a target indicated a response should be executed or withheld) on inhibitory control following cocaine-related and neutral cues on the ABBA task. The third aim was to demonstrate impaired inhibitory control following cocaine images on the ABBA task is specific to cocaine users. Cocaine users (data collected in the second experiment of the first aim) and non-using control participants (n = 16) completed the cocaine go and all neutral conditions of the ABBA task and the Cued Go/No-Go task. The fourth aim was to demonstrate the feasibility and acceptability of inhibitory control training to cocaine-related stimuli with cocaine users. A small pilot clinical trial was conducted and cocaine users were randomly assigned to complete inhibitory control training to cocaine images or geometric shapes. Cocaine images impaired inhibitory control on the ABBA task, as demonstrated by an increased proportion of inhibitory failures in the cocaine go condition compared to the neutral go condition in Experiments 1, 2, and 4. The proportion of inhibitory failures following cocaine images in Experiment 4 was increased at short (i.e., 100, 200) compared to long SOAs. Cocaine images also impaired inhibitory control compared to the Cued Go/No-Go Task in Experiment 2, however there were no differences in the proportion of inhibitory failures between the cocaine go and all neutral conditions of the ABBA task. There were no differences between cocaine users and controls in Experiment 3 for the proportion of inhibitory failures on the ABBA or Cued Go/No-Go tasks, but controls responded faster indicating a speed/accuracy trade off occurred in the control group. Inhibitory control training as an approach to improve treatment outcomes is feasible, as indicated by attendance and accuracy on the training task, and participants rated the overall procedure as satisfactory in Experiment 5. A better understanding of inhibitory control in the presence of cocaine related cues could be crucial to better understand how drug cues contribute to the risk for relapse and the continued use of drugs because both occur in the presence of drug cues.