Altered intrinsic organisation of brain networks implicated in attentional processes in adult attention-deficit/hyperactivity disorder: a resting state study of attention, default mode and salience network connectivity

Deficits in task-related attentional engagement in attention-deficit/hyperactivity disorder (ADHD) have been hypothesized to be due to altered interrelationships between attention, default mode and salience networks. We examined the intrinsic connectivity during rest within and between these networks. Six minutes resting state scans were obtained. Using a network-based approach, connectivity within and between the dorsal and ventral attention, the default mode and the salience networks was compared between the ADHD and control group. The ADHD group displayed hyperconnectivity between the two attention networks and within the default mode and ventral attention network. The salience network was hypoconnected to the dorsal attention network. There were trends towards hyperconnectivity within the dorsal attention network and between the salience and ventral attention network in ADHD. Connectivity within and between other networks was unrelated to ADHD. Our findings highlight the altered connectivity within and between attention networks, and between them and the salience network in ADHD. One hypothesis to be tested in future studies is that individuals with ADHD are affected by an imbalance between ventral and dorsal attention systems with the former playing a dominant role during task engagement making individuals with ADHD highly susceptible to distraction by salient task-irrelevant stimuli

Psychological resilience is correlated with dynamic changes in functional connectivity within the default mode network during a cognitive task

Resilience is a dynamic process that enables organisms to cope with demanding environments. Resting-state functional MRI (fMRI) studies have demonstrated a negative correlation between resilience and functional connectivities (FCs) within the default mode network (DMN). Considering the on-demand recruitment process of resilience, dynamic changes in FCs during cognitive load increases may reflect essential aspects of resilience. We compared DMN FC changes in resting and task states and their association with resilience. Eighty-nine healthy volunteers completed the Connor–Davidson Resilience Scale (CD-RISC) and an fMRI with an auditory oddball task. The fMRI time series was divided into resting and task periods. We focused on FC changes between the latter half of the resting period and the former half of the task phase (switching), and between the former and latter half of the task phase (sustaining). FCs within the ventral DMN significantly increased during “switching” and decreased during “sustaining”. For FCs between the retrosplenial/posterior cingulate and the parahippocampal cortex, increased FC during switching was negatively correlated with CD-RISC scores. In individuals with higher resilience, ventral DMN connectivities were more stable and homeostatic in the face of cognitive demand. The dynamic profile of DMN FCs may represent a novel biomarker of resilience

Neural correlates of attention-executive dysfunction in lewy body dementia and Alzheimer's disease.

Attentional and executive dysfunction contribute to cognitive impairment in both Lewy body dementia and Alzheimer's disease. Using functional MRI, we examined the neural correlates of three components of attention (alerting, orienting, and executive/conflict function) in 23 patients with Alzheimer's disease, 32 patients with Lewy body dementia (19 with dementia with Lewy bodies and 13 with Parkinson's disease with dementia), and 23 healthy controls using a modified Attention Network Test. Although the functional MRI demonstrated a similar fronto-parieto-occipital network activation in all groups, Alzheimer's disease and Lewy body dementia patients had greater activation of this network for incongruent and more difficult trials, which were also accompanied by slower reaction times. There was no recruitment of additional brain regions or, conversely, regional deficits in brain activation. The default mode network, however, displayed diverging activity patterns in the dementia groups. The Alzheimer's disease group had limited task related deactivations of the default mode network, whereas patients with Lewy body dementia showed heightened deactivation to all trials, which might be an attempt to allocate neural resources to impaired attentional networks. We posit that, despite a common endpoint of attention-executive disturbances in both dementias, the pathophysiological basis of these is very different between these diseases.This work was supported by an Intermediate Clinical Fellowship . Grant Number: (WT088441MA) to John‐Paul Taylor the National Institute for Health Research (NIHR), and Newcastle Biomedical Research Unit (BRU) based at Newcastle upon Tyne Hospitals NHS Trust, Newcastle University

Abnormal Resting-State Functional Connectivity of Insular Subregions and Disrupted Correlation with Working Memory in Adults with Attention Deficit/Hyperactivity Disorder

ObjectivesExecutive function (EF) deficits are major impairments in adults with attention deficit/hyperactivity disorder (ADHD). Previous studies have shown that the insula is involved in cognitive and EFs. However, the insula is highly heterogeneous in function, and few studies have focused on functional networks which related to specific insular subregions in adults with ADHD. We explored the functional networks of the insular subregions [anterior insula (AI), mid-insula (MI), and posterior insula (PI)]. Furthermore, their correlations with self-ratings of ecological EFs, including inhibition, shifting, and working memory were investigated.MethodsResting-state functional magnetic resonance imaging data in 28 adults with ADHD and 30 matched healthy controls (HCs) were analyzed. The seed-based resting-state functional connectivity (RSFC) of the insular subregions was evaluated. We also investigated their associations with the Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) inhibition, working memory, and shifting factor scores.ResultsCompared with HCs, adults with ADHD showed altered RSFC of the AI, with the precuneus, precentral gyrus, and inferior temporal gyrus extended to the middle temporal gyrus, lingual gyrus, and superior occipital gyrus, respectively. There were no significant differences in RSFC of the MI and PI between the two groups. Within the HC group, working memory scores were associated with the RSFC of AI with precuneus and temporal gyrus. However, there was no correlation between these variables in the ADHD group.ConclusionThe study evaluated RSFC patterns of the insular subregions in adults with ADHD for the first time. Altered RSFC of the AI which is a crucial region of salience network (SN) and part of regions in default mode network (DMN), were detected in adults with ADHD in both results with and without global signal regression (GSR), suggesting that disrupted SN-DMN functional connectivity may be involved in EF impairments in adults with ADHD, especially with respect to working memory. Deficits of the AI which is involved in salient stimuli allocation, might be associated with the pathophysiology of ADHD. The inconsistent results of MI and PI between analyses with and without GSR need further exploration

Autonomic and central nervous system correlates of cognitive control training for attentional disorders

Deficits in cognitive control and attentional processing are commonly observed in people with Attention-Deficit/Hyperactivity Disorder (ADHD) and Specific Learning Difficulties (SpLDs) such as Dyslexia. Poorer performance in the pro/antisaccade task have been observed in these individuals, which suggests impaired visual attention and inhibitory control mechanisms. Atypical cognitive processing is also related to a state of autonomic hypoarousal in conditions such as ADHD. In this thesis, I examined whether the computer-based gaze-control RECOGNeyes training program using the pro/antisaccade task could improve cognitive control of visual attention by targeting the visual attention network and whether such improvements correlate with increased arousal. A group of 35 volunteers with SpLDs and/or ADHD completed the pro/antisaccade task before and after two weeks of training their visual attention using RECOGNeyes. Magnetoencephalography (MEG), pupillometry and electrocardiography were recorded, while they performed the pro/antisaccade task. Our task performance measures, reaction time (RT) and accuracy, and reading indices improved after RECOGNeyes training. Our findings demonstrate for the first time that autonomic measures of sympathetic pupil dilation and parasympathetic cardiac deceleration both correlate with faster saccadic RTs together (which was stronger for antisaccade trials than prosaccade trials) and account for separate variance in RT. Additionally, distinct MEG oscillatory profiles were uncovered in different frequency bands within regions of the visual attention network during the pro/antisaccade task. Slow-wave oscillations of delta and theta bands show anteriorising effects, suggested to mediate timing responses and bottom-up communication from the posterior to anterior network regions. Alpha-oscillations are proposed to have top-down preparatory inhibitory effects, particularly from the bilateral frontal eye field, and alpha-suppression in the right parietal eye field. Beta amplitude presents an additional “anticipatory” event-related desynchronisation (ERD) prior to target onset that is stronger on day 2 and antisaccade trials, which could relate to generalised inhibitory control mechanisms. This thesis supports the existence of complex central and autonomic processes underlying attention and arousal that are not yet fully understood and warrant further investigation. By increasing our understanding of the integrated attentional processes and inhibitory control, this could help the development of targeted treatment solutions, such as RECOGNeyes, for ADHD and SpLDs, to improve outcomes in these individuals

Functional organisation of behavioural inhibitory control mechanisms in cortico-basal ganglia circuitry: implications for stimulant use disorder.

The neural and psychological mechanisms of inhibitory control processes were investigated, focusing on the cortico-basal ganglia circuits in rats and humans. These included behavioural flexibility, ‘waiting’ and ‘stopping’ impulsivity and involved serial spatial reversal learning task in rodents, and in humans, premature responses in the Monetary Incentive Delay (MID) task and the stop-signal reaction time task. Chapter 2 and Chapter 3 focus on individual differences in behavioural flexibility in rats while Chapter 4, Chapter 5 and Chapter 6 consider how inhibitory control mechanisms are affected by the psychostimulant drug cocaine in both rats and humans. As reported in Chapter 2, systemic modulation of monoaminergic transmission by monoamine oxidase A (MAO-A) inhibitors enhanced reversal learning performance, selectively by decreasing the lose-shift probability, thereby implicating a role for dopamine, serotonin and noradrenaline in facilitating learning from negative feedback. Resting state functional magnetic resonance imaging (fMRI) revealed enhanced functional connectivity of the orbitofrontal and motor cortices as a correlate of flexible reversal learning performance, consistent with elevated levels of monoamines in these region (Chapter 3). Having clarified the mechanisms underlying behavioural flexibility in rats, Chapter 4 reports that escalation of intravenous cocaine self-administration induces behavioural inflexibility in rats even after a relatively short period of cocaine intake. Computational models, including a reinforced and Bayesian learner, revealed a lack of exploitation of the learned response-outcome relationships in cocaine-exposed rats. Chapter 5 focused on impulse control in human volunteers, identifying the striatal and cingulo-opercular networks as substrates of impulsive, premature responding in healthy 4 volunteers, stimulant-dependent individuals and their unaffected siblings. Loss of impulse control was elicited by different incentives for drug-free participants as opposed to drug users. Drug cues elicited striatal activation and increased premature responses in the stimulant-dependent group compared with the control group. In contrast, the ventral striatum was linked to incentive specific activation to reward anticipation. Task-based fMRI demonstrated that interactions between dorsal striatum and cingulo-opercular “cold cognition” networks underlie failures of impulse control in the control, at-risk and stimulant-dependent groups. However, whereas the cingulo-opercular networks were associated with premature responding in all groups, the reward system was activated specifically by the drug incentive cues in the stimulant group, and by monetary incentive cues in the drug-free groups. Chapter 6 presents evidence that corticostriatal functional and effective connectivity in an overlapping network that includes the anterior cingulate and inferior frontal cortices as well as motor cortex, the subthalamic nucleus and dorsal striatum, is critical to stopping impulse control in both control and cocaine individuals. No stopping efficiency impairments were observed in the cocaine-dependent group. Nevertheless, lower structural corticostriatal connectivity measured using diffusion MRI was associated with response execution impairments in cocaine participants performing a stop-signal reaction time task. Further, response execution was rescued by the selective noradrenaline reuptake inhibitor atomoxetine, which also increased corticostriatal effective connectivity. Finally, increased impulsivity and behavioural inflexibility seen in stimulant use disorder in Chapter 5 and Chapter 4, respectively, were not observed in the endophenotype at risk for developing stimulant abuse but were rather a consequence of stimulant abuse. These results further clarify the monoaminergic substrates of behavioural flexibility and specify the neural and computational impairments in inhibitory control induced by stimulant dependence.Pinsent Darwin Studentship from the Dept of Physiology, Development and Neuroscienc

The Effect of Circadian Rhythms on BOLD Dynamics and Effective Connectivity

Masteroppgave i psykologiMAPSYK360INTL-KMDINTL-MNMAPS-PSYKINTL-PSYKINTL-MEDINTL-JUSINTL-SVINTL-H

The interplay between automatic and controlled processes: experimental contributions to dual-process theories of cognition

Since its beginnings, psychological science has frequently used dichotomous categories to describe behavior and mental phenomena. The most traditional dual models have impactfully equipped both the scientific and folkloristic psychological vocabularies of such dichotomies (e.g., conscious vs. unconscious, logic vs. creative, rational vs. emotional). However, while offering an affordable account of how the human cognitive system works, these models appear too simplistic. Substantially, they are grounded upon the findings obtained in decades of results in almost all the psychological fields, from perception to social processes, which have been later merged into a broad systemic theory of human cognition. However, this dual-system theory, which proposed to unify all cognitive dualities into System 1 (automatic, unconscious, fast, effortless, intuitive, and so on) and System 2 (controlled, conscious, slow, effortful, rational, and so on) entities, lacks a systematic investigation of its basic assumptions: for instance, that the features are aligned within and complementary between the two systems. These properties are essential for the tenets of the theory since a systemic theory should postulate the interdependence and interrelation of the elements constituting a system. In this view, the central thread linking all the experimental contributions in the present work is that the dual-system theory should resist when investigating cognitive performance either at low- and at high-level of complexity (complexity defined as the variety of mechanisms implicated in the phenomena of interest). Through seven studies conducted in three research lines, addressing temporal attention, task-switching, and decision-making, the interaction between automatic and controlled features in each process has shown to be the rule rather than the exception. Thus, the results presented in this work support the idea that the dual-system theory current formulation has a weak explanatory power, suggesting that decomposition approaches aimed at disentangling the contribution of qualitatively and quantitatively different mechanisms in each cognitive process are needed to advance or put aside dual-process theories