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Neuropsychopharmacology of Psychosis: Relation of Brain Signals, Cognition and Chemistry

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889193356 Year: Pages: 276 DOI: 10.3389/978-2-88919-335-6 Language: English
Publisher: Frontiers Media SA
Subject: Psychiatry --- Medicine (General)
Added to DOAB on : 2016-03-10 08:14:32
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Abstract

Previous research over the past decades has identified diverse neurobiological underpinnings of psychosis. In particular, by combining a variety of different neuroimaging modalities, it has been shown that psychotic states and the actual transition phase from a clinical high-risk state to established psychosis is characterized by structural, functional and neurochemical changes across different brain regions.Further evidence revealed that maybe not only focal brain abnormalities are characteristic for psychosis but specifically also an abnormal functional integration among various brain areas. Some evidence also suggests that dysfunctional brain connectivity proceeds during the development of psychosis when subjects perform a cognitive task. Notably, altered brain connectivity during cognitive challenges was often found to be associated with psychopathological measures, suggesting a mechanistic relation between functional network integrity and the clinical expression of psychosis.Several works proposed that disordered brain connectivity in psychosis results from abnormal N-methyl- D -aspartate receptor (NMDAR)-dependent synaptic plasticity, which can be mediated by other neurotransmitter systems such as dopamine or serotonin. Specific chemically mediated changes in synaptic plasticity may contribute to abnormal functional integration among brain regions and in consequence to impaired learning performances and inferences. Model-based connectivity investigations on synaptic signalling demonstrated for example that manipulation of the NMDA or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor system altered synaptic plasticity in healthy volunteers, which was predictive for subjects’ cognitive performance and psychopathology. In patients with psychosis, the activity in the prefrontal cortex during the processing of prediction errors, a specific form of learning, which is conveyed via synaptic connections, was linked with individuals’ formation of delusions. These results fit well with many works suggesting that psychotic symptoms or also drug-induced psychosis-like experiences can be explained by disturbances within a hierarchically organized neuronal network, leading to maladaptive integrations of new incoming evidence and thereby to false formations of prediction errors and false beliefs.In this research topic, we like to cover the most recent neurobiological correlates for early stage psychosis and in particular for the prediction of psychosis by using different neurophysiological measures (e.g. structural and functional MRI, EEG, DTI or PET). Studies exploring effective connectivity or complex brain networks such as small-world properties with techniques like dynamic causal modelling, structural equation modelling, or graph theory analysis are highly appreciated. Very welcome are studies proving a link between clinical features such as psychopathology and cognition, brain signals, and chemistry (also in regard of antipsychotic treatments or substance-induced psychotic states). Moreover, environmental factors that may influence psychosis onset or its’ developmental processes will be brought together with a diversity of different research modalities. We also collect critical reviews, mini-reviews or theoretical reflections from leading international researcher and clinicians in this field. The purpose of our research topic is intended to provide a state-of-the-art cognitive perspective to consider developing psychosis, which might shed more lights into the pathophysiological and neurobiological mechanisms of psychosis.

Reward Processing in Motivational and Affective Disorders

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199860 Year: Pages: 117 DOI: 10.3389/978-2-88919-986-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Psychology
Added to DOAB on : 2016-01-19 14:05:46
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Preferential reward processing is the hallmark of addiction, where salient cues become overvalued and trigger compulsion. In depression, rewards appear to lose their incentive properties or become devalued. In the context of schizophrenia, aberrations in neural reward signalling are thought to contribute to the overvaluation of irrelevant stimuli on the one hand and the onset of negative symptoms on the other. Accordingly, reward processing has emerged as a key variable in contemporary, evidence based, diagnostic frameworks, such as the Research Domain Criteria launched by the United States National Institute of Mental Health. Delineation of the underlying mechanisms of aberrant or blunted reward processing can be of trans-diagnostic importance across several neuropsychiatric disorders. Reward processing can become automatic thus raising the question of cognitive control, a core theme of this Topic, which aims at justifying the necessity of reward processing as a potential therapeutic target in clinical settings. Empirical and theoretical contributions on the following themes were expected to: *Explore new avenues of research by investigating the processing of rewards at the cognitive, behavioral, motivational, neural systems and individual difference levels. A developmental focus is promising in this regard, probing the core processes that shape reward processing and thus subsequent liability to motivational and affective disorders. *Develop and refine conceptual models of reward processing from computational neuroscience. *Promote greater understanding and development of emergent therapeutic approaches such as cognitive bias modification and behavioural approach or avoidance training. A key question is the feasibility of reversing or modifying maladaptive patterns of reward processing to therapeutic ends. *Refine and augment the evidential database for tried and tested therapies such as Contingency Management and Behavioral Activation by focusing on core cognitive processes mediating rewards. *Provide a potential dimensional approach for reward processing deficits that can be of trans-diagnostic importance in clinically relevant disorders, including depression and addiction * Investigate the subjective experience of pleasure- the hedonic aspect of reward seeking and consumption – and how this can be distinguished from the motivational, sometimes compulsive, component of reward pursuit. This promises more nuanced and effective interventions. Depression, for instance, could be seen as the restricted pursuit of pleasure rather than blunted pleasure experience; addiction can be viewed as accentuated drug seeking despite diminished consummatory pleasure. This aims to place motivation centre stage in both scenarios, emphasising the transdiagnostic theme of the Topic. *Temporal discounting of future rewards, whereby smaller, more immediate rewards are chosen even when significantly more valuable deferred rewards are available, is another trans-diagnostic phenomenon of interest in the in the present context. Factors that influence this, such as discounting of future reward are thought to reflect compulsion in the addictive context and hopelessness on the part of people experiencing depression. The executive cognitive processes that regulate this decision making are of both scientific and clinical significance. Empirical findings, theoretical contributions or commentaries bearing on cognitive or executive control were therefore welcome.

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