Agreeableness, Extraversion, Stressor and Physiological Stress Response

Based on the theoretical analysis, with first-hand data collection and using multiple regression models, this study explored the relationship between agreeableness, extraversion, stressor and stress response and figured out interactive effect of agreeableness, extraversion, and stressor on stress response. We draw on the following conclusions: (1) the interaction term of stressor (work) and agreeableness can negatively predict physiological stress response; (2) the interaction term of stressor (health) and agreeableness can negatively predict physiological stress response; (3) the interaction term of stressor (family) and agreeableness can negatively predict physiological stress response; (4) the interaction term of stressor (social) and agreeableness can negatively predict physiological stress response; (5) the interaction term of stressor (work) and extraversion can negatively predict physiological stress response; (6) the interaction term of stressor (health) and extraversion can negatively predict physiological stress response; (7) the interaction term of stressor (family) and extraversion can negatively predict physiological stress response; (8) the interaction term of stressor (social) and extraversion can negatively predict physiological stress response

How does stress induce headache? An experimental study

Psychological stress triggers headaches, but how this happens is unclear. To explore this, 38 episodic migraine sufferers, 28 with tension-type headache (T-TH) and 20 controls rated nausea, negative affect, task-expectancies and headache at 5-minute intervals during an unpredictable and uncontrollable 25-minute mental arithmetic task with a non-contingent failure rate. Blood pressure and pulse rate were measured every 3 minutes and salivary cortisol was sampled before and after the task. Trigeminal activation was measured by nociceptive blink reflex measures during each of the three experimental phases. Multiple regression analyses indicated that negative affect (NA) was the strongest predictor of headache intensity during the task. Increases in stress-headache were unrelated to consistent changes in cardiovascular activity but were related to declines in cortisol and increased post-task trigeminal activity. In repeated measures ANOVAs, participants who developed headache had higher nausea, NA and self-efficacy expectancies than those with no-or-low headache (p <.05 to p <.001). In further multiple regression analyses to identify which aspects of the stress process contributed to the high NA preceding headache, discouragement, anxiety, irritation and tension mediated the relationship between headache intensity during the stressful task and primary and secondary appraisal processes (stressor exposure and stressor reactivity). Avoidant coping, perceived inability to decrease pain, and outcome expectancy independently predicted headache intensity during the stressful task. Anxiety mediated the relationship between headache intensity and the coping tactics of wishful thinking, self-criticism, pain catastrophizing and praying/hoping. Attachment anxiety and the personality traits of openness, agreeableness and conscientiousness moderated the relationship between stress appraisals and headache. Results were discussed using the model of stress-headache as allostatic load. Findings suggest that headache developed when participants overextended themselves during a stressful task, adopting an information processing style which impeded emotional adjustment to changing situational demands. Learning to modify perceptions of threat and adopting a more flexible, less outcome-dependent processing style which avoids response conflict might help to prevent headache from spiralling upward

THE RELATIONSHIP BETWEEN THE DEFAULT MODE RESTING STATE NEURAL NETWORK, RESPIRATORY SINUS ARRHYTHMIA, AND SELF-FOCUSED COGNITION: AN EMPIRICAL ANALYSIS

Functional activity within the default mode resting state neural network (RSNN) and the resting respiratory sinus arrhythmia (RSA) may represent an integrated neural and peripheral cardiovascular index of the baseline, resting state in humans. Research also indicates that the integrated physiological baseline potentially formed by the default mode RSNN and resting RSA may be associated with self-focused cognition. We hypothesize that measures of default mode RSNN (namely functional connectivity strength), resting RSA, and self-focused cognition are, indeed, correlated and aim to demonstrate these relationships. Measures of default mode RSNN functional connectivity strength were derived using functional magnetic resonance imaging, measures of resting RSA were obtained via electrocardiogram, and self-focused cognition was assessed using survey methods. Although our results were largely unsupportive of our hypothesis, we present several possibly methodological confounds that may have impacted our findings, and we describe directions for future research

Associations between personality and whole‐brain functional connectivity at rest: Evidence across the adult lifespan

Introduction: Personality is associated with cognitive, emotional, and social functioning, and can play a role in age‐related cognitive decline and dementia risk; however, little is known about the brain dynamics underlying personality characteristics, and whether they are moderated by age. Methods: We investigated the associations between personality and resting‐state functional MRI data from 365 individuals across the adult lifespan (20–80 years). Participants completed the 50‐item International Personality Item Pool and a resting‐state imaging protocol on a 3T MRI scanner. Within‐network connectivity values were computed based on predefined networks. Regression analyzes were conducted in order to investigate personality–connectivity associations, as well as moderation by age. All models controlled for potential confounders (such as age, sex, education, IQ, and the other personality traits). Results: We found that openness was positively associated with connectivity in the default‐mode network, neuroticism was negatively associated with both the ventral and dorsal attention networks, and agreeableness was negatively associated with the dorsal attention network. In addition, age moderated the association between conscientiousness and the frontoparietal network, indicating that this association become stronger in older age. Conclusions: Our findings demonstrate that personality is associated with brain connectivity, which may contribute to identifying personality profiles that play a role in protection against or risk for age‐related brain changes and dementia

Primate Ventromedial Prefrontal Cortex and the Physiological and Behavioural Dysfunction Characteristic of Mood and Anxiety Disorders

The heterogeneity intrinsic to the ventromedial prefrontal cortex (vmPFC) is evidenced in both its anatomy and implicated function: vmPFC subregions have roles in positive affect, negative affect and autonomic/endocrine regulation. Whether different subregions serve fundamentally different functions, or whether they perform similar computations on different inputs, remains unclear. Nevertheless, the role of the vmPFC in psychopathology is widely appreciated – in mood and anxiety disorders, over-activity within constituent regions of the vmPFC is consistently implicated in symptomatology, together with its normalisation following successful treatment. However, the precise locus of change varies between studies. The work presented in this thesis investigates the causal contributions of over-activity within two key subregions of the vmPFC – the subgenual anterior cingulate cortex (sgACC, area 25) and perigenual anterior cingulate cortex (pgACC, area 32) – in discrete dimensions of behaviour and physiology affected in psychiatric disorders. Specifically, the impact of over-activity is assessed on (i) baseline physiological function; (ii) the regulation of anticipatory, motivational and consummatory aspects of reward-related behaviour; and (iii) negative affect including fear learning, stress recovery and the intolerance of uncertainty. To provide further insight into the mechanism of action of antidepressants, the efficacy of selected treatments is tested on changes induced by over-activity of these regions. Beyond the direct relevance of the results presented here to psychiatric disorders and their treatment, the thesis aims to emphasise the importance of broader themes associated with the measurement and quantification of emotion in preclinical animal studies. First, a multi-faceted approach is utilised enabling quantification of both the autonomic and behavioural aspects of emotion. In so doing, the experiments maintain relevance to studies which assess these correlates in isolation, both in humans (which typically measure subjective responses and physiology) and in rodents (which frequently assess behaviour in isolation). The assessment of more than one dimension of emotion confers these studies with improved power to detect maladaptive changes. Second, the experiments described were conducted in the marmoset, a new-world primate. The extensive anatomical homology between marmoset and human prefrontal cortex facilitates the forward-translation of functional results. In combination with the appropriate assays, this renders marmosets as an invaluable species to study the causal contributions of vmPFC subregions to symptoms of psychiatric disorders. I believe that the results of these experiments provide important insights into the causal role primate vmPFC has in relation to the behavioural and physiological aspects of psychiatric symptomatology. Most importantly, I hope that they serve as the foundation for future work to further elucidate the neuropathological processes underlying mental disorders.MRC DTP Studentshi

Building functional neuromarkers from resting state fMRI to describe physiopathological traits

2016 - 2017The overarching goal of this work has been that of devising novel methods for building functional neuromarkers from resting-state fMRI data to describe healthy and pathological human behaviour. Observing spontaneous uctuations of the BOLD signal, resting-state fMRI allows to have an insight into the functional organisation of the brain and to detect functional networks that are consistent across subjects. Studying how patterns of functional connectivity vary both in healthy subjects and in subjects a ected by a neurodegenerative disease is a way to shed light on the physiological and pathological mechanisms governing our nervous system. The rst part of this thesis is devoted to the description of fully data-driven feature extraction techniques based on clustering aimed at supporting the diagnosis of neurodegenerative diseases (e.g., amyotrophic lateral sclerosis and Parkinson's disease). The high-dimensional nature of resting state fMRI data implies the need of suitable feature selection techniques. Traditional univariate techniques are fast and straightforward to interpret, but are unable to unveil relationships among multiple features. For this reason, this work presents a methodology based on consensus clustering, a particular approach to the clustering problem that consists in combining di erent partitions of the same data set to produce more stable solutions. One of the objectives of fMRI data analysis is to determine regions that show an abnormal activity with respect to a healthy brain and this is often attained with comparative statistical models applied to single voxels or brain parcels within one or several functional networks. Here, stochastic rank aggregation is applied to identify brain regions that exhibit a coherent behaviour in groups of subjects a ected by the same disorder. The proposed methodology was validated on real data and the results are consistent with previous literature, thus indicating that this approach might be suitable to support early diagnosis of neurodegenerative diseases... [edited by Author]XXX cicl

Indiviididevahelised erinevused depressioonisoodumuses: aju regionaalne energiametabolism, serotoniinisüsteemi talitlus ja käitumine loomkatsemudelites

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Käesolev doktoriväitekiri keskendub depressiooni funktsionaalse neuroanatoomia ja depressiivse käitumise uurimisele, kasutades meeleoluhäirete loomkatsemudeleid. Depressiooni põhjustavad nii korduvad stressirikkad elusündmused kui ka individuaalne soodumus ja eelkõige nende kahe teguri koosmõju. Depressioonisoodumust saab mudeldada selekteerides rotte afektiivse käitumise testide alusel või mõjustades pikaajaliselt nende ajus depressiooni tõenäolisi neuraalseid alusmehhanisme. Käesolevas väitekirjas käsitletakse nelja depressioonisoodumuse mudelit - osaline serotonergiline närvikahjustus, puudulik emahool vastsündinueas, vähene püsi-sotsiaalsus ja püsiv magusaeelistus. Keskkonnast tuleneva stressi mudeldamiseks kasutati kroonilist muutlikku stressi, mille depressiooni-põhjustav mõju rajaneb mitmete mõõdukalt ebameeldivate stiimulite korduval esitamisel, ja kroonilist sotsiaalset stressi, mis rajaneb looma korduval alistamisel agressiivse liigikaaslase poolt. Ajupiirkondade pikaajalise närviaktiivsuse määramiseks hinnati mitokondriaalse elektronide transpordi-ahela talitlust tsütokroom c oksüdaasi aktiivsuse histokeemilise mõõtmise kaudu. Kõik depressioonisoodumuse ja kroonilise stressi mudelid eraldiseisvaina põhjustasid mõnedes ajupiirkondades muutuse närviaktiivsuses, kuid eri mudelite piirkondlikud aktivatsioonimustrid ei kattunud. Kui kroonilist stressi rakendati depressioonisoodumusega loomadele, ilmnesid mudelitevahelised kokkulangevused närviaktiivsuses eesmises taalamuses, hippokampuse CA3 alas ja mediaalses mandelkehas, s.o. piirkondades, mis on kesksel kohal organismi stressivastuse, õppimise ja hirmuga seotud käitumiste kontrollis. Kui tsütokroom c oksüdaasi aktiivsuse andmeid erinevatest katsetest koos analüüsiti, ilmnes, et depresioonisoodumusega rottidel oli närvitegevus aktiivsem retro-spleniaalses ajukoores ja retikulaarses taalamuses, krooniline stress aga taandas selle aktiivsuse kontroll-loomadega samale tasemele. Funktsionaalse ühenduvuse analüüs näitas, et depressioonisoodumus ja krooniline stress nõrgendasid ajupiirkondadevahelist seotust haistesibulate, tsentraalse mandelkeha, terminaaljuti sängituumade, prefrontaalkoore ja vöökääruga seotud ajuringetes. Käesolev töö tõi välja mitmeid ajupiirkondi, mida tasuks üksikasjalikumalt edasi uurida, nagu näiteks võrgustik, mis hõlmab eesmist taalamust, retrospleniaalset ajukoort, eesmist vöökääru, hippokampust ja retikulaarset taalamust.This doctoral dissertation focuses on the functional neuroanatomy and behaviour in animal models of affective disorders. Depression is caused by stressful life events, by inherent individual vulnerability, and most potently by a combination of these two factors. Vulnerability to depression can be modelled in rats by selection in behavioural tests for a trait related to low affect or by experimentally producing a neurobiological state that possibly serves as the substrate of depression. In this dissertation four vulnerability phenotypes were studied - partial serotonergic denervation, neonatal maternal separation, low expression of the sociability trait and sucrose preference trait. Environmental stress was induced by chronic variable stress that led to a depressive state by repeated administration of several mildly noxious stimuli to the animal, and chronic social stress, that is based on the repeated social defeat of the target animal by an aggressive congener. To detect cerebral regional long-term neural activation the function of mitochondrial electron transport chain was assessed via cytochrome c oxidase histochemistry. All the vulnerability phenotypes and chronic stress regimens caused a change in long-term neuronal activity on their own in specific brain regions, but there was no overlap between the regional activity patterns in different models. When chronic stressors were applied in combination with vulnerability factors, communalities between different models in energy metabolism were detected in anterior thalamus, hippocampal CA3 area and medial amygdala, areas crucially involved in stress response, fear and learning. When cytochrome oxidase activity data from all models were collapsed and analysed jointly, it was revealed that rats with the vulnerable phenotype had more active energy metabolism in retrosplenial cortex and reticular thalamus, and stress reversed this activation to control-like levels. Functional connectivity analysis revealed that vulnerability phenotypes and chronic stress decreased inter-regional connectivity in the brain circuits including olfactory bulbi, central amygdala, bed nucleus of stria terminalis, prefrontal and cingulate cortices. Thus this work has indicated several new anatomical targets for more detailed study, for example the highly interconnected nuclei of anterior thalamus, retrosplenial cortex, anterior cingulate, hippocampus and reticular thalamus

Vascular Risk, Functional Connectivity, and Episodic Memory in Older Adults

Resting-state functional magnetic resonance imaging and functional connectivity (FC) analyses are used to explore functional brain networks underlying a diverse array of abilities. Functional networks are composed of regions throughout the brain whose activity is closely linked to form a coherent network. One functional network, the default mode network (DMN), is thought to subserve self-referential thought and autobiographical memory. DMN regions include the ventromedial prefrontal cortex, inferior parietal lobe, hippocampus, and the primary hub of this network, the posterior cingulate cortex (PCC). For reasons yet unknown, DMN FC declines in aging, which is associated with memory impairment. Vascular risk may be an important contributor to age-related DMN disruption through its effects on gray and white matter integrity. The present study examined relationships among vascular risk, DMN FC, and episodic memory in older adults using FC analyses and structural equation modeling. Several regions found to be functionally related to the PCC were those identified in prior research on the DMN, but also included areas not typically implicated in the DMN, such as the cerebellum and basal ganglia. Stronger FC between the PCC and parahippocampal gyrus predicted better memory performance, confirming the importance of medial temporal lobe structures for memory. FC between the PCC and several other areas, such as the cerebellum, basal ganglia, and limbic regions, also predicted memory performance, suggesting the importance of executive functioning and emotion for memory in aging. Correlations between FC and vascular risk were found in the basal ganglia, cerebellum, and inferior temporal gyrus, suggesting vascular risk may modify associations between the DMN and cortical and subcortical regions. Finally, a mediational model was tested in which DMN FC mediated the relationship between vascular risk and memory. This was compared to an alternative model with depressive symptoms as a mediator. Vascular risk was unrelated to memory and DMN FC in all models, while stronger DMN FC predicted poorer memory performance. Neither DMN FC nor depressive symptoms acted as mediators. The impact of vascular risk on the DMN in aging should be further explored using a comprehensive multimethod approach, along with other potential causes of age-related DMN disruption