Structural and functional differences in medial prefrontal cortex underlie distractibility and suppression deficits in ageing.

Older adults experience deficits in working memory (WM) that are acutely exacerbated by the presence of distracting information. Human neurophysiological studies have revealed that these changes are accompanied by a diminished ability to suppress visual cortical activity associated with task-irrelevant information. Although this is often attributed to deficits in top-down control from a prefrontal cortical source, this has not yet been directly demonstrated. Here we evaluate the neural basis of distraction's negative impact on WM and the impairment in neural suppression in older adults by performing structural and functional MRIs while older participants engage in tasks that require remembering relevant visual stimuli in the context of overlapping irrelevant stimuli. Analysis supports both an age-related distraction effect and neural suppression deficit, and extends our understanding by revealing an alteration in functional connectivity between visual cortices and a region in the default network, the medial prefrontal cortex (mPFC). Moreover, within the older population, the magnitude of WM distractibility and neural suppression are both associated with individual differences in cortical volume and activity of the mPFC, as well as its associated white-matter tracts

Adolescents’ neural reactivity to acute psychosocial stress: dysfunctional regulation habits are linked to temporal gyrus response

Mid-adolescence is a critical time for the development of stress-related disorders and it is associated with significant social vulnerability. However, little is known about normative neural processes accompanying psychosocial stress at this time. Previous research found that emotion regulation strategies critically influence the relationship between stress and the development of psychiatric symptoms during adolescence. Using functional magnetic resonance imaging (fMRI), we examined neural responses to acute stress and analyzed whether the tendency to use adaptive or maladaptive emotion regulation strategies is related to neural and autonomic stress responses. Results show large linear activation increases from low to medium to high stress levels mainly in medial prefrontal, insulae and temporal areas. Caudate and subgenual anterior cingulate cortex, neural areas related to reward and affective valuations, showed linearly decreasing activation. In line with our hypothesis, the current adolescent neural stress profile resembled social rejection and was characterized by pronounced activation in insula, angular and temporal cortices. Moreover, results point to an intriguing role of the anterior temporal gyrus. Stress-related activity in the anterior temporal gyrus was positively related to maladaptive regulation strategies and stress-induced autonomic activity. Maladaptive coping might increase the social threat and reappraisal load of a stressor, relating to higher stress sensitivity of anterior temporal cortices

Extrinsic and default mode networks in psychiatric conditions: Relationship to excitatory-inhibitory transmitter balance and early trauma.

Over the last three decades there has been an accumulation of Magnetic Resonance Imaging (MRI) studies reporting that aberrant functional networks may underlie cognitive deficits and other symptoms across a range of psychiatric diagnoses. The use of pharmacological MRI and H-1-Magnetic Resonance Spectroscopy (H-1-MRS) has allowed researchers to investigate how changes in network dynamics are related to perturbed excitatory and inhibitory neurotransmission in individuals with psychiatric conditions. More recently, changes in functional network dynamics and excitatory/inhibitory (E/I) neurotransmission have been linked to early childhood trauma, a major antecedents for psychiatric illness in adulthood. Here we review studies investigating whether perturbed network dynamics seen across psychiatric conditions are related to changes in E/I neurotransmission, and whether such changes could be linked to childhood trauma. Whilst there is currently a paucity of studies relating early traumatic experiences to altered E/I balance and network function, the research discussed here lead towards a plausible mechanistic hypothesis, linking early traumatic experiences to cognitive dysfunction and symptoms mediated by E/I neurotransmitter imbalances

The Neuroscience of Mathematical Cognition and Learning

The synergistic potential of cognitive neuroscience and education for efficient learning has attracted considerable interest from the general public, teachers, parents, academics and policymakers alike. This review is aimed at providing 1) an accessible and general overview of the research progress made in cognitive neuroscience research in understanding mathematical learning and cognition, and 2) understanding whether there is sufficient evidence to suggest that neuroscience can inform mathematics education at this point. We also highlight outstanding questions with implications for education that remain to be explored in cognitive neuroscience. The field of cognitive neuroscience is growing rapidly. The findings that we are describing in this review should be evaluated critically to guide research communities, governments and funding bodies to optimise resources and address questions that will provide practical directions for short- and long-term impact on the education of future generations

The Effect of Acute Stress on Time-Based Prospective Memory

Time-based prospective memory (TBPM) is the ability to remember to perform an action at a specific point in time. During a stressful day, one usually encounters many instances where TBPM is required. The objective of this project was to see if acute stress (situational) has an effect upon TBPM. Trinity College undergraduates ages 18-22 were used in this study. The Socially Evaluated Cold Pressor Test (SECPT) was performed to induce acute stress and raise cortisol levels in participants. Each participant had an electroencephalogram recording collected during a computer-generated TBPM Paradigm. The resulting data were analyzed within group as well as compared to nonstressed students. Comparing the groups, there was a significant increase in response time on TBPM tasks. Additionally, comparisons of simple event related potentials recorded from 0-900 milliseconds post ongoing task response between control and stress groups indicated significant differences in frontal electrodes (FP1, F1). To our knowledge, this is the first study to investigate the electrophysiological correlates of TBPM in response to acute stress

Neurocognitive Mechanisms Associated with Real-world Financial Savings among Individuals from Lower Income Households

Lower financial savings among individuals experiencing adverse social determinants of health (SDoH) such as low socioeconomic status (low-SES) increases health inequities during times of crisis. Despite evidence suggesting that economic stability established by better money-saving behavior may minimize socioeconomic disparities, neurocognitive mechanisms that regulate money-saving behavior remains to be understood. In the current studies, we utilized neuroimaging, behavioral, self-report, and real-world behavior data to examine neurocognitive mechanisms associated with money-saving behavior among low-SES population. In study 1, we utilized Balloon Analogue Risk task (BART) to probe decision-making (DM) related brain activity and further examined the relationship between brain activity, BART-performance, and real-world money-saving behavior. In study 2, we utilized n-back task to probe working memory (WM) mechanism and characterized the relationship between WM-related brain activity, WM-performance, and money-saving behavior. In study 3, we utilized resting-state fMRI data to characterize the resting-state functional connectivity (rsFC) of the brain regions associated with WM and their relationship with money-saving behavior. Regarding DM related brain-behavior relationship, elevated risk-related amygdala activity was associated with improved strategic-DM (i.e., BART task-performance measure) and improved strategic-DM, in turn, predicted better savings. Additionally, in an exploratory analysis, personality trait (i.e., alexithymia) moderated this mediation such that for individuals with low alexithymia (versus higher alexithymia), elevated risk-related amygdala activity was associated with better savings. Regarding WM related brain activity and associated behavior, laboratory WM performance (dprime) mediated the association between WM related DMN deactivation and real-world savings behavior such that increased DMN deactivation improves dprime which, in turn, results in better savings. Further, considering the rsFC of brain regions related to WM and associated behavior, dprime mediated the effect of fronto-limbic and fronto-frontal connectivity on real-world saving behavior such that higher frontal-limbic connectivity predicted worsened WM performance, which in turn, predicted reduced savings. Similarly, higher fronto-frontal connectivity predicted better WM performance, and, in turn, better WM performance predicted improved savings. This present study provides evidence that interventions targeting brain activity related to higher order executive function (DM and WM) and associated cognitive performance can augment success in terms of real-world money-saving behavior

Consciousness, Anesthesia and Brain Resting State Networks

Consciousness is a great mystery to science. Despite several attempts, none of the current theories have managed to explain how and why it exists. Theories struggle with fundamental philosophical questions, such as the hard problem, that contests how something mental, like consciousness, can be explained by physical phenomena such as neural activity. Modern neuroscientific study of consciousness puts aside this and a few other yet unreachable questions. It focuses on finding the neural correlates of consciousness (NCC) comprising the physical phenomena, which correlate with certain aspects of consciousness. In the NCC studies, consciousness is usually taken to have two aspects: the states of consciousness, encompassing awake, dreaming, and unconscious states, and contents of consciousness, such as an experienced perceptual stimulus. Experimental anesthesia and functional brain imaging are essential tools for the search of the NCC. Anesthesia offers a reliable and reversible method to alter the subject's state of consciousness. The brain function during these altered states of consciousness can be measured with functional imaging methods, such as functional magnetic resonance imaging (fMRI). It measures neuronal activity via a blood oxygen level dependent (BOLD) signal. Functional connectivity analysis of the BOLD-signal can be used to explore the organization of spatially distinct brain areas into functional networks, which are associated with specific cognitive functions such as attention control and emotional regulation. Recently, several studies have shown that changes in functional connectivity between and within these networks are also associated with altered states of consciousness induced by anesthetic drugs. This review will cover the essential questions and methodology of current exploration of neural correlates of states of consciousness, focusing on the resting state networks and the use of fMRI and experimental anesthesia as research tools. Effects of different anesthetics on these networks are also compared. Different anesthetics used in experimental anesthesia have quite distinct pharmacological mechanisms of action, even though the induced brain functional connectivity patterns resemble each other. Propofol-induced unconsciousness is mediated either from corticocortical or thalamocortical disconnection. The nonspecific thalamic nodes, related to arousal and distribution of information, may have an important role in propofol-induced unconsciousness. Dexmedetomidine has similar patterns in connectivity changes as propofol, but the connectivity between deeper brain regions and thalamus remains less affected, possibly explaining the easier arousal from dexmedetomidine-induced unconsciousness. Ketamine increases the overall functional connectivity but disrupts the connectivity in the higher-order networks of the brain inducing “dissociative anesthesia”. The role of thalamic functional connectivity during ketamine anesthesia has not been studied and would be an interesting subject for future studies.Tietoisuuden syntymekanismi on yksi suurimmista ratkaisemattomista mysteereistä. Filosofiset kysymykset, kuten tietoisuuden niin kutsuttu vaikea ongelma ja selityksellinen kuilu, ovat edelleen ajankohtaisia ja ne kyseenalaistavat esimerkiksi pystytäänkö tietoisuuden syntymekanismeja koskaan selittämään tieteellisin keinoin. Nykyinen neurotieteellinen tutkimus pyrkii selvittämään tietoisuuden hermostollisia vastineita, eli kuvaamaan tiettyyn tietoisuuden tilaan tai sisältöön liittyviä aivotoiminnan mekanismeja. Näitä vastineita tutkittaessa käytetään jakoa tietoisuuden tiloihin, joita ovat hereillä olo, unennäkö ja tajuttomuus tai tietoisuuden komponentteihin joita ovat esimerkiksi koettu auditorinen tai visuaalinen ärsyke. Tässä katsausartikkelissa käydään läpi nykyisen tietoisuuden tutkimuksen ja sen tilojen neurologisten vastineiden etsimisen perusteet, keskittyen funktionaaliseen magneettikuvaukseen, lepotilaverkostoihin ja anestesiaan. Artikkelissa myös vertaillaan aikaisempien sellaisten tutkimusten tuloksia, jotka käsittelevät eri anesteettien vaikutuksista lepotilaverkostoihin. Kokeellista anestesiaa ja toiminnallista aivokuvantamista käytetään työkaluina tietoisuuden tiloihin liittyvien aivotoiminnan mekanismien tutkimisessa. Anestesian avulla voidaan luotettavasti ja palautuvasti aiheuttaa muutoksia koehenkilöiden tajunnan tilaan. Samalla tutkimuskysymyksiin etsitään vastauksia kuvantamalla tiettyihin tajunnan tiloihin tai niiden muutoksiin liittyviä aivotoiminnan mekanismeja. Kuvantamismenetelmistä toiminnallisella magneettikuvauksella pysytään mittaamaa hermokudoksen aktiivisuutta veren happipitoisuudesta riippuvalla signaalilla. Vertaamalla aktivoitumista tietyltä alueelta verraten sitä koko aivojen samanaikaiseen aktivoitumiseen, saadaan näkyviin toiminnallisia verkostoja, joilla on omia tehtäviä esimerkiksi kognitiivisessa prosessoinnissa ja tarkkaavaisuuden keskittämisessä. Myös tietoisuuden tasot korreloivat näiden verkostojen sisäisten ja keskinäisten yhteyksien sekä oikea-aikaisen aktivoitumisen kanssa. Kokeellista anestesiaa käytettäessä on huomioitava eri anesteettien erilaiset vaikutusmekanismit, vaikkakin aivokuvantamisella aktivoitumismuutokset muistuttavat toisiaan. Vertailtavissa anesteeteissa esiintyy yhtäläisyyksiä kortikaalisten verkostojen yhteyksien heikkenemiseen ja tietoisuuden häviämiseen liittyen. Propofolin keskeisenä mekanismina on joko yhteyksien katkaiseminen aivokuoren verkostoissa tai talamuksen ja aivokuoren välillä. Deksmedetomidiinin fMRI:llä mitatut vaikutukset muistuttavat paljon propofolia, mutta yhteys talamuksen ja syvempien aivoalueiden välillä säilyy, joka todennäköisesti mahdollistaa nopeamman heräämisen. Ketamiini lisää toiminnallista konnektiivisuutta verkostoissa, kuitenkin samalla hajottaen järjestäytymistä korkeamman asteen verkostoissa. Propofolista poiketen ketamiinin vaikutus toimintaverkostoon on vähäinen. Talamuksen merkitys yhteyksien muutoksissa yleisesti jää vielä epävarmaksi: ovatko muutokset syytä vai seurausta aivokuoren yhteyksien hajoamisesta

Examinations of pathomechanisms in schizophrenic and bipolar disorders – results from two functional magnetic resonance imaging studies

Psychiatric disorders, in particular schizophrenia and bipolar disorder, affect the patients’ lives deeply on many levels and place a heavy burden on the healthcare system. The treatment of these diseases is often complicated and marked by many setbacks. Symptoms that have the strongest consequences for coping with everyday life are the impairments of cognitive performance, for example memory or attention deficits. Therefore, it is of great interest to better understand the underlying pathomechanisms to eventually improve treatment options for those patients. In this thesis two different fMRI studies were used to investigate the functional correlates of patients suffering from schizophrenia or bipolar disorder while performing a combined oddball-incongruence task and a reward associated task. Study A conducted a categorical comparison between bipolar and schizophrenia patients of the brain activation during an oddball and incongruence task. The results showed pathophysiological differences in the activation intensities between bipolar and schizophrenia patients as well as between the patient groups and healthy individuals. Overall it seems as if the brain activation severely depended on the task difficulty leading to compensatory hyperactivations in frontal brain areas of bipolar patients during the oddball task. Schizophrenia patients demonstrated low threshold hyperactivations in the intraparietal cortex compared to healthy controls. In the cognitively more demanding incongruence condition these compensatory mechanisms seemed to fail leading to hypoactivations in various brain regions such as the middle frontal gyrus or ventral pathway. Pilot study B searched retrospectively for functional markers which enable support vector machine algorithms predicting specific treatment response to typical and atypical antipsychotics as well as aripiprazole in a transnosological sample consisting of bipolar and schizophrenia patients. Consequently, (de-)activation differences between responders and non-responders in their respective treatment arm resulting from the desire-reason-dilemma paradigm were applied to support vector machine algorithms. The implementation of parameter estimates from deactivations of aripiprazole non-responders in brain regions partially associated with the default mode network, led to a successful treatment response prediction of patients receiving aripiprazole. Even though in future studies the sample sizes should be increased and monotherapeutical treatment ensured, this thesis already provides important insights on the pathomechanisms of bipolar disorder and schizophrenia patients or more specifically within the spectrum of both diseases. Prospectively, further studies can help to specify potential functional biomarkers which also might be able to predict treatment response and consequently approach personalized precision treatment in psychiatric disorders