The neural underpinnings of cognitive flexibility and their disruption in psychotic illness

Poly (I:C)-induced maternal immune activation generates impairment of reversal learning performance in offspring

Maternal immune activation (MIA) induces a variety of behavioral and brain abnormalities in offspring of rodent models, compatible with neurodevelopmental disorders, such as schizophrenia or autism. However, it remains controversial whether MIA impairs reversal learning, a basic expression of cognitive flexibility that seems to be altered in schizophrenia. In the present study, MIA was induced by administration of a single dose of polyriboinosinic-polyribocytidylic acid (Poly (I:C) (5 mg/kg i.p.)) or saline to mouse pregnant dams in gestational day (GD) 9.5. Immune activation was monitored through changes in weight and temperature. The offspring were evaluated when they reached adulthood (8 weeks) using a touchscreen-based system to investigate the effects of Poly (I:C) on discrimination and reversal learning performance. After an initial pre-training, mice were trained to discriminate between two different stimuli, of which only one was rewarded (acquisition phase). When the correct response reached above 80% values for two consecutive days, the images were reversed (reversal phase) to assess the adaptation capacity to a changing environment. Maternal Poly (I:C) treatment did not interfere with the learning process but induced deficits in reversal learning compared to control saline animals. Thus, the accuracy in the reversal phase was lower, and Poly (I:C) animals required more sessions to complete it, suggesting impairments in cognitive flexibility. This study advances the knowledge of how MIA affects behavior, especially cognitive domains that are impaired in schizophrenia. The findings support the validity of the Poly (I:C)-based MIA model as a tool to develop pharmacological treatments targeting cognitive deficits associated with neurodevelopmental disorders.

Structural and functional connectivity in relation to executive functions in antipsychotic-naïve patients with first episode schizophrenia and levels of glutamatergic metabolites

Patients with schizophrenia exhibit structural and functional dysconnectivity but the relationship to the well-documented cognitive impairments is less clear. This study investigates associations between structural and functional connectivity and executive functions in antipsychotic-naïve patients experiencing schizophrenia. Sixty-four patients with schizophrenia and 95 matched controls underwent cognitive testing, diffusion weighted imaging and resting state functional magnetic resonance imaging. In the primary analyses, groupwise interactions between structural connectivity as measured by fixel-based analyses and executive functions were investigated using multivariate linear regression analyses. For significant structural connections, secondary analyses examined whether functional connectivity and associations with executive functions also differed for the two groups. In group comparisons, patients exhibited cognitive impairments across all executive functions compared to controls (p < 0.001), but no group difference were observed in the fixel-based measures. Primary analyses revealed a groupwise interaction between planning abilities and fixel-based measures in the left anterior thalamic radiation (p = 0.004), as well as interactions between cognitive flexibility and fixel-based measures in the isthmus of corpus callosum and cingulum (p = 0.049). Secondary analyses revealed increased functional connectivity between grey matter regions connected by the left anterior thalamic radiation (left thalamus with pars opercularis p = 0.018, and pars orbitalis p = 0.003) in patients compared to controls. Moreover, a groupwise interaction was observed between cognitive flexibility and functional connectivity between contralateral regions connected by the isthmus (precuneus p = 0.028, postcentral p = 0.012), all p-values corrected for multiple comparisons. We conclude that structural and functional connectivity appear to associate with executive functions differently in antipsychotic-naïve patients with schizophrenia compared to controls.

Linking haploinsufficiency of the autism- and schizophrenia-associated gene Cyfip1 with striatal-limbic-cortical network dysfunction and cognitive inflexibility

Impaired behavioural flexibility is a core feature of neuropsychiatric disorders and is associated with underlying dysfunction of fronto-striatal circuitry. Reduced dosage of Cyfip1 is a risk factor for neuropsychiatric disorder, as evidenced by its involvement in the 15q11.2 (BP1-BP2) copy number variant: deletion carriers are haploinsufficient for CYFIP1 and exhibit a two- to four-fold increased risk of schizophrenia, autism and/or intellectual disability. Here, we model the contributions of Cyfip1 to behavioural flexibility and related fronto-striatal neural network function using a recently developed haploinsufficient, heterozygous knockout rat line. Using multi-site local field potential (LFP) recordings during resting state, we show that Cyfip1 heterozygous rats (Cyfip1+/-) harbor disrupted network activity spanning medial prefrontal cortex, hippocampal CA1 and ventral striatum. In particular, Cyfip1+/- rats showed reduced influence of nucleus accumbens and increased dominance of prefrontal and hippocampal inputs, compared to wildtype controls. Adult Cyfip1+/- rats were able to learn a single cue-response association, yet unable to learn a conditional discrimination task that engages fronto-striatal interactions during flexible pairing of different levers and cue combinations. Together, these results implicate Cyfip1 in development or maintenance of cortico-limbic-striatal network integrity, further supporting the hypothesis that alterations in this circuitry contribute to behavioural inflexibility observed in neuropsychiatric diseases including schizophrenia and autism.

Large-scale coupling of prefrontal activity patterns as a mechanism for cognitive control in health and disease: evidence from rodent models

Cognitive control of behavior is crucial for well-being, as allows subject to adapt to changing environments in a goal-directed way. Changes in cognitive control of behavior is observed during cognitive decline in elderly and in pathological mental conditions. Therefore, the recovery of cognitive control may provide a reliable preventive and therapeutic strategy. However, its neural basis is not completely understood. Cognitive control is supported by the prefrontal cortex, structure that integrates relevant information for the appropriate organization of behavior. At neurophysiological level, it is suggested that cognitive control is supported by local and large-scale synchronization of oscillatory activity patterns and neural spiking activity between the prefrontal cortex and distributed neural networks. In this review, we focus mainly on rodent models approaching the neuronal origin of these prefrontal patterns, and the cognitive and behavioral relevance of its coordination with distributed brain systems. We also examine the relationship between cognitive control and neural activity patterns in the prefrontal cortex, and its role in normal cognitive decline and pathological mental conditions. Finally, based on these body of evidence, we propose a common mechanism that may underlie the impaired cognitive control of behavior.

Parkinson's disease and schizophrenia interactomes contain temporally distinct gene clusters underlying comorbid mechanisms and unique disease processes

Genome-wide association studies suggest significant overlaps in Parkinson's disease (PD) and schizophrenia (SZ) risks, but the underlying mechanisms remain elusive. The protein-protein interaction network ('interactome') plays a crucial role in PD and SZ and can incorporate their spatiotemporal specificities. Therefore, to study the linked biology of PD and SZ, we compiled PD- and SZ-associated genes from the DisGeNET database, and constructed their interactomes using BioGRID and HPRD. We examined the interactomes using clustering and enrichment analyses, in conjunction with the transcriptomic data of 26 brain regions spanning foetal stages to adulthood available in the BrainSpan Atlas. PD and SZ interactomes formed four gene clusters with distinct temporal identities (Disease Gene Networks or 'DGNs'1-4). DGN1 had unique SZ interactome genes highly expressed across developmental stages, corresponding to a neurodevelopmental SZ subtype. DGN2, containing unique SZ interactome genes expressed from early infancy to adulthood, correlated with an inflammation-driven SZ subtype and adult SZ risk. DGN3 contained unique PD interactome genes expressed in late infancy, early and late childhood, and adulthood, and involved in mitochondrial pathways. DGN4, containing prenatally-expressed genes common to both the interactomes, involved in stem cell pluripotency and overlapping with the interactome of 22q11 deletion syndrome (comorbid psychosis and Parkinsonism), potentially regulates neurodevelopmental mechanisms in PD-SZ comorbidity. Our findings suggest that disrupted neurodevelopment (regulated by DGN4) could expose risk windows in PD and SZ, later elevating disease risk through inflammation (DGN2). Alternatively, variant clustering in DGNs may produce disease subtypes, e.g., PD-SZ comorbidity with DGN4, and early/late-onset SZ with DGN1/DGN2.

Cognitive Inflexibility Predicts Negative Symptoms Severity in Patients with First-Episode Psychosis: A 1-Year Follow-Up Study

Negative symptoms and cognitive deficits play a major role in psychosis and significantly influence the functional outcomes of patients, particularly those with a first episode of psychosis (FEP). However, limited research has explored the predictive capacity of cognitive deficits during FEP for subsequent negative symptomatology. Drawing from the Athens FEP research study, we conducted a retrospective longitudinal study in 80 individuals with FEP. All patients were drug naive at admission. Cognitive tests were administered at 1-month and 1-year post-admission, while negative symptomatology was assessed at the same time points using PANSS by trained raters. We considered confounding factors such as age, gender, duration of untreated psychosis (DUP), treatment received, premorbid social adjustment, and premorbid IQ. Univariate regression analysis identified cognitive domains that correlated with negative symptomatology. These, along with the confounders, were incorporated into a multiple regression, with the 1-year PANSS negative scale serving as the dependent variable. Employing the backward elimination technique, we found a statistically significant inverse relationship between the categories completed in the Wisconsin card sorting test (WCST) and the 1-year PANNS negative scale (p = 0.01), beyond the associations with DUP and the 1-month PANSS negative scale. Our results suggest that cognitive flexibility, a key component of executive functions, predicts negative symptom severity one year after FEP.

Impaired cognitive flexibility across psychiatric disorders

OBJECTIVE

Problems with cognitive flexibility have been associated with multiple psychiatric disorders, but there has been little understanding of how cognitive flexibility compares across these disorders. This study examined problems of cognitive flexibility in young adults across a range of psychiatric disorders using a validated computerized trans-diagnostic flexibility paradigm. We hypothesized that obsessive-compulsive spectrum disorders (eg, obsessive-compulsive disorder, trichotillomania, and skin-picking disorder) would be associated with pronounced flexibility problems as they are most often associated with irrational or purposeless repetitive behaviors.

METHODS

A total of 576 nontreatment seeking participants (aged 18-29 years) were enrolled from general community settings, provided demographic information, and underwent structured clinical assessments. Each participant undertook the intra-extra-dimensional task, a validated computerized test measuring set-shifting ability. The specific measures of interest were total errors on the task and performance on the extra-dimensional (ED) shift, which reflects the ability to inhibit and shift attention away from one stimulus dimension to another.

RESULTS

Participants with depression and PTSD had elevated total errors on the task with moderate effect sizes; and those with the following had deficits of small effect size: generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), antisocial personality disorder, and binge-eating disorder. For ED errors, participants with PTSD, GAD, and binge-eating disorder exhibited deficits with medium effect sizes; those with the following had small effect size deficits: depression, social anxiety disorder, OCD, substance dependence, antisocial personality disorder, and gambling disorder.

CONCLUSIONS

These data indicate cognitive flexibility deficits occur across a range of mental disorders. Future work should explore whether these deficits can be ameliorated with novel treatment interventions.

The Atypical Dopamine Transporter Inhibitor CE-158 Enhances Dopamine Neurotransmission in the Prefrontal Cortex of Male Rats: A Behavioral, Electrophysiological, and Microdialysis Study

BACKGROUND

Dopamine plays a key role in several physiological functions such as motor control, learning and memory, and motivation and reward. The atypical dopamine transporter inhibitor S,S stereoisomer of 5-(((S)-((S)-(3-bromophenyl)(phenyl)methyl)sulfinyl)methyl)thiazole (CE-158) has been recently reported to promote behavioral flexibility and restore learning and memory in aged rats.

METHODS

Adult male rats were i.p. administered for 1 or 10 days with CE-158 at the dose of 1 or 10 mg/kg and tested for extracellular dopamine in the medial prefrontal cortex by means of intracerebral microdialysis and single unit cell recording in the same brain area. Moreover, the effects of acute and chronic CE-158 on exploratory behavior, locomotor activity, prepulse inhibition, working memory, and behavioral flexibility were also investigated.

RESULTS

CE-158 dose-dependently potentiated dopamine neurotransmission in the medial prefrontal cortex as assessed by intracerebral microdialysis. Moreover, repeated exposure to CE-158 at 1 mg/kg was sufficient to increase the number of active pyramidal neurons and their firing frequency in the same brain area. In addition, CE-158 at the dose of 10 mg/kg stimulates exploratory behavior to the same extent after acute or chronic treatment. Noteworthy, the chronic treatment at both doses did not induce any behavioral alterations suggestive of abuse potential (e.g., motor behavioral sensitization) or pro-psychotic-like effects such as disruption of sensorimotor gating or impairments in working memory and behavioral flexibility as measured by prepulse inhibition and Y maze.

CONCLUSIONS

Altogether, these findings confirm CE-158 as a promising pro-cognitive agent and contribute to assessing its preclinical safety profile in a chronic administration regimen for further translational testing.

Stress, associative learning, and decision-making

Exposure to acute and chronic stress has significant effects on the basic mechanisms of associative learning and memory. Stress can both impair and enhance associative learning depending on type, intensity, and persistence of the stressor, the subject's sex, the context that the stress and behavior is experienced in, and the type of associative learning taking place. In some cases, stress can cause or exacerbate the maladaptive behavior that underlies numerous psychiatric conditions including anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorder, substance use disorder, and others. Therefore, it is critical to understand how the varied effects of stress, which may normally facilitate adaptive behavior, can also become maladaptive and even harmful. In this review, we highlight several findings of associative learning and decision-making processes that are affected by stress in both human and non-human subjects and how they are related to one another. An emerging theme from this work is that stress biases behavior towards less flexible strategies that may reflect a cautious insensitivity to changing contingencies. We consider how this inflexibility has been observed in different associative learning procedures and suggest that a goal for the field should be to clarify how factors such as sex and previous experience influence this inflexibility.

Rumination as a Transdiagnostic Phenomenon in the 21st Century: The Flow Model of Rumination

Rumination and its related mental phenomena share associated impairments in cognition, such as executive functions and attentional processes across different clinical conditions (e.g., in psychotic disorders). In recent decades, however, the notion of rumination has been increasingly narrowed to the "self-focused" type in depressive disorders. A closer review of the literature shows that rumination may be construed as a broader process characterized by repetitive thoughts about certain mental contents that interfere with one's daily activities, not only limited to those related to "self". A further examination of the construct of rumination beyond the narrowly focused depressive rumination would help expand intervention opportunities for mental disorders in today's context. We first review the development of the clinical construct of rumination with regard to its historical roots and its roles in psychopathology. This builds the foundation for the introduction of the "Flow Model of Rumination (FMR)", which conceptualizes rumination as a disruption of a smooth flow of mental contents in conscious experience that depends on the coordinated interactions between intention, memory, affect, and external events. The conceptual review concludes with a discussion of the impact of rapid technological advances (such as smartphones) on rumination. Particularly in contemporary societies today, a broader consideration of rumination not only from a cognition viewpoint, but also incorporating a human-device interaction perspective, is necessitated. The implications of the FMR in contemporary mental health practice are discussed.

Cognitive flexibility in schizophrenia: A confirmatory factor analysis of neuropsychological measures

Cognitive flexibility (CF) is the ability to adapt cognitive strategies according to the changing environment. The deficit in CF has often been linked to various neurological and psychiatric disorders including schizophrenia. However, the operationalization and assessment of CF have not been unified and the current research suggests that the available instruments measure different aspects of CF. The main objective of the present study was to compare three frequently used neuropsychological measures of CF-Wisconsin Card Sorting Test (WCST), Trail Making Test (TMT) and Stroop Color and Word Test (SCWT) in a population of patients (N = 220) with first-episode schizophrenia spectrum disorders in order to evaluate their convergent validity. The hypothesis of an underlying latent construct was tested via a confirmatory factor analysis. We used a one-factor CF model with scores from WCST, SCWT and TMT as observed variables. The established model showed a good fit to the data (χ² = 1.67, p = 0.43, SRMR = 0.02, RMSEA = 0.0, CFI = 1.00). The highest factor loading was found in WCST as CF explained most of the variance in this neuropsychological measure compared to the other instruments. On the other hand, a TMT ratio index and a SCWT interference demonstrated lowest loadings in the model. The findings suggest that not all the frequently used measures share an underlying factor of CF or may capture different aspects of this construct.

Reinstatement of nicotine conditioned place preference in a transgenerational model of drug abuse vulnerability in psychosis: Impact of BDNF on the saliency of drug associations

RATIONALE

Psychotic disorders such as schizophrenia are often accompanied by high rates of cigarette smoking, reduced quit success, and high relapse rates, negatively affecting patient outcomes. However, the mechanisms underlying altered relapse-like behaviors in psychosis are poorly understood.

OBJECTIVES

The present study analyzed changes in extinction and reinstatement of nicotine conditioned place preference (CPP) and resulting changes in brain-derived neurotrophic factor (BDNF) in a novel heritable rodent model of psychosis, demonstrating increased dopamine D2 receptor sensitivity, to explore mechanisms contributing to changes in relapse-like behaviors.

METHODS

Male and female offspring of two neonatal quinpirole-treated (1 mg/kg quinpirole from postnatal day (P)1-21; QQ) and two neonatal saline-treated (SS) Sprague-Dawley rats (F1 generation) were tested on an extended CPP paradigm to analyze extinction and nicotine-primed reinstatement. Brain tissue was analyzed 60 min after the last nicotine injection for BDNF response in the ventral tegmental area (VTA), the infralimbic (IfL) and prelimbic (PrL) cortices.

RESULTS

F1 generation QQ offspring demonstrated delayed extinction and more robust reinstatement compared to SS control animals. In addition, QQ animals demonstrated an enhanced BDNF response to nicotine in the VTA, IfL and Prl cortices compared to SS offspring.

CONCLUSIONS

This study is the first to demonstrate altered relapse-like behavior in a heritable rodent model with relevance to comorbid drug abuse and psychosis. This altered pattern of behavior is hypothesized to be related to elevated activity-dependent BDNF in brain areas associated with drug reinforcement during conditioning that persists through the extinction phase, rendering aberrantly salient drug associations resistant to extinction and enhancing relapse vulnerability.

M1-selective muscarinic allosteric modulation enhances cognitive flexibility and effective salience in nonhuman primates

Acetylcholine (ACh) in cortical neural circuits mediates how selective attention is sustained in the presence of distractors and how flexible cognition adjusts to changing task demands. The cognitive domains of attention and cognitive flexibility might be differentially supported by the M1 muscarinic acetylcholine receptor (mAChR) subtype. Understanding how M1 mAChR mechanisms support these cognitive subdomains is of highest importance for advancing novel drug treatments for conditions with altered attention and reduced cognitive control including Alzheimer's disease or schizophrenia. Here, we tested this question by assessing how the subtype-selective M1 mAChR positive allosteric modulator (PAM) VU0453595 affects visual search and flexible reward learning in nonhuman primates. We found that allosteric potentiation of M1 mAChRs enhanced flexible learning performance by improving extradimensional set shifting, reducing latent inhibition from previously experienced distractors and reducing response perseveration in the absence of adverse side effects. These procognitive effects occurred in the absence of apparent changes of attentional performance during visual search. In contrast, nonselective ACh modulation using the acetylcholinesterase inhibitor (AChEI) donepezil improved attention during visual search at doses that did not alter cognitive flexibility and that already triggered gastrointestinal cholinergic side effects. These findings illustrate that M1 mAChR positive allosteric modulation enhances cognitive flexibility without affecting attentional filtering of distraction, consistent with M1 activity boosting the effective salience of relevant over irrelevant objects specifically during learning. These results suggest that M1 PAMs are versatile compounds for enhancing cognitive flexibility in disorders spanning schizophrenia and Alzheimer's diseases.

Components of emotion regulation flexibility and psychosis: The association between psychosis-proneness and context sensitivity

OBJECTIVES

Emotion regulation flexibility has been conceptualized as a multi-componential construct involving context sensitivity, repertoire and feedback responsiveness. Psychosis research has yet to incorporate these new developments in the study of emotion regulation. Thus, we sought to advance even further the knowledge on emotion regulation in psychosis by adopting the emotion regulation flexibility approach as proposed by Bonanno and Burton (Perspectives on Psychological Science, 2013, 8, 591).

METHOD

In total, 401 participants completed 4 scales assessing the multi-components of emotion regulation flexibility and psychosis-proneness.

RESULTS

Our results indicated that Context Sensitivity (i.e., Cue Absence) and Feedback Responsiveness (i.e., Evaluation) were associated with psychosis-proneness. Cue absence was specifically associated with the positive dimension, while both Cue Absence and Enhancement ability were associated with the negative dimension.

CONCLUSIONS

Overall, our results suggest that emotional context insensitivity is the most relevant component of regulatory flexibility in the case of psychosis-proneness. Thus, the disruption in this first step of flexible emotion regulation might be already present in those prone to psychosis. Difficulties in decoding appropriately the contextual cues might further disrupt the other steps of emotion regulation contributing to the psychotic (-like) experiences. This study needs replication in clinical and non-clinical samples.

Longitudinal assessment of the temporal stability and predictive validity of the Revised Paranormal Belief Scale

The Revised Paranormal Belief Scale (RPBS) is the prevailing measure of supernatural credence. However, there exists only limited evidence to support the temporal stability and predictive validity of the instrument over time. Acknowledging this, the present study assessed the test-retest reliability of the RPBS using a large, heterogeneous sample across multiple trials. In addition, predictive validity was tested using a longitudinal statistical model, which focused on allied health outcomes (Perceived Stress and Somatic Complaints). A sample of 1,665 (M _age = 54.40, 853 females, 804 males, five non-binary and three not disclosing of gender) completed study measures at three time points separated by 2 month intervals. Prior to assessing temporal stability, assessment of structural validity and longitudinal invariance occurred. Test-retest reliability of the RPBS was in the moderate to high range across time intervals, and good internal consistency was observed. Furthermore, satisfactory stability coefficients existed for RPBS subfactors. Data-model fit for the predictive model was acceptable. Belief in the paranormal explained low variance over time in Perceived Stress and Somatic Complaints (between 2.4 and 4.2%). Findings supported the stability and reliability of the RPBS. In addition, they aligned with the notion that paranormal belief in the absence of high scores on cognitive-perceptual factors (e.g. transliminality and schizotypy), has a benign influence on perceived health.

Novelty selectively permits learning-associated plasticity in ventral tegmental-hippocampal-prefrontal circuitry

Modifying established behavior in novel situations is essential, and patients with neuropsychiatric disorders often lack this flexibility. Understanding how novelty affects behavioral flexibility therefore has therapeutic potential. Here, novelty differentially impacts connectivity within the ventral tegmental-hippocampal-medial prefrontal (VTA-HPC-mPFC) circuit, thereby enhancing the ability of mice to overcome established behavioral bias and adapt to new rules. Circuit connectivity was measured by local field potential (LFP) coherence. As mice exposed to novelty learned to overcome previously established spatial bias, the ventral HPC (vHPC) strengthens its coherence with the VTA and mPFC in theta frequency (4-8 Hz). Novelty or learning did not affect circuits involving the dorsal HPC (dHPC). Without novelty, however, mice continued following established spatial bias and connectivity strength remained stable in the VTA-HPC-mPFC circuit. Pharmacologically blocking dopamine D1-receptors (D1Rs) in the vHPC abolished the behavioral and physiological impacts of novelty. Thus, novelty promotes behavioral adaptation by permitting learning-associated plasticity in the vHPC-mPFC and VTA-vHPC circuit, a process mediated by D1Rs in the vHPC.

Towards an understanding of psychedelic-induced neuroplasticity

Classic psychedelics, such as LSD, psilocybin, and the DMT-containing beverage ayahuasca, show some potential to treat depression, anxiety, and addiction. Importantly, clinical improvements can last for months or years after treatment. It has been theorized that these long-term improvements arise because psychedelics rapidly and lastingly stimulate neuroplasticity. The focus of this review is on answering specific questions about the effects of psychedelics on neuroplasticity. Firstly, we review the evidence that psychedelics promote neuroplasticity and examine the cellular and molecular mechanisms behind the effects of different psychedelics on different aspects of neuroplasticity, including dendritogenesis, synaptogenesis, neurogenesis, and expression of plasticity-related genes (e.g., brain-derived neurotrophic factor and immediate early genes). We then examine where in the brain psychedelics promote neuroplasticity, particularly discussing the prefrontal cortex and hippocampus. We also examine what doses are required to produce this effect (e.g., hallucinogenic doses vs. "microdoses"), and how long purported changes in neuroplasticity last. Finally, we discuss the likely consequences of psychedelics' effects on neuroplasticity for both patients and healthy people, and we identify important research questions that would further scientific understanding of psychedelics' effects on neuroplasticity and its potential clinical applications.

Investigating cognitive flexibility deficit in schizophrenia using task-based whole-brain functional connectivity

Background

Cognitive flexibility is a core cognitive control function supported by the brain networks of the whole-brain. Schizophrenic patients show deficits in cognitive flexibility in conditions such as task-switching. A large number of neuroimaging studies have revealed abnormalities in local brain activations associated with deficits in cognitive flexibility in schizophrenia, but the relationship between impaired cognitive flexibility and the whole-brain functional connectivity (FC) pattern is unclear.

Method

We investigated the task-based functional connectivity of the whole-brain in patients with schizophrenia and healthy controls during task-switching. Multivariate pattern analysis (MVPA) was utilized to investigate whether the FC pattern can be used as a feature to discriminate schizophrenia patients from healthy controls. Graph theory analysis was further used to quantify the degrees of integration and segregation in the whole-brain networks to interpret the different reconfiguration patterns of brain networks in schizophrenia patients and healthy controls.

Results

The results showed that the FC pattern classified schizophrenia patients and healthy controls with significant accuracy. Moreover, the altered whole-brain functional connectivity pattern was driven by a lower degree of network integration and segregation in schizophrenia, indicating that both global and local information transfers at the entire-network level were less efficient in schizophrenia patients than in healthy controls during task-switching processing.

Conclusion

These results investigated the group differences in FC profiles during task-switching and not only elucidated that FC patterns are changed in schizophrenic patients, suggesting that task-based FC could be used as a potential neuromarker to discriminate schizophrenia patients from healthy controls in cognitive flexibility but also provide increased insight into the brain network organization that may contribute to impaired cognitive flexibility.

Belief Updating and Paranoia in Individuals With Schizophrenia

BACKGROUND

Persecutory delusions are among the most common delusions in schizophrenia and represent the extreme end of the paranoia continuum. Paranoia is accompanied by significant worry and distress. Identifying cognitive mechanisms underlying paranoia is critical for advancing treatment. We hypothesized that aberrant belief updating, which is related to paranoia in human and animal models, would also contribute to persecutory beliefs in individuals with schizophrenia.

METHODS

Belief updating was assessed in 42 participants with schizophrenia and 44 healthy control participants using a 3-option probabilistic reversal learning task. Hierarchical Gaussian Filter was used to estimate computational parameters of belief updating. Paranoia was measured using the Positive and Negative Syndrome Scale and the revised Green et al. Paranoid Thoughts Scale. Unusual thought content was measured with the Psychosis Symptom Rating Scale and the Peters et al. Delusions Inventory. Worry was measured using the Dunn Worry Questionnaire.

RESULTS

Paranoia was significantly associated with elevated win-switch rate and prior beliefs about volatility both in schizophrenia and across the whole sample. These relationships were specific to paranoia and did not extend to unusual thought content or measures of anxiety. We observed a significant indirect effect of paranoia on the relationship between prior beliefs about volatility and worry.

CONCLUSIONS

This work provides evidence that relationships between belief updating parameters and paranoia extend to schizophrenia, may be specific to persecutory beliefs, and contribute to theoretical models implicating worry in the maintenance of persecutory delusions.

Paranormal belief, cognitive-perceptual factors, and well-being: A network analysis

By assessing interrelationships among variables within a specified theoretical framework, network analysis (NA) provides nuanced insights into how associations between psychological constructs are related to outcome measures. Noting this, the authors used NA to examine connections between Paranormal Belief, cognitive-perceptual factors (Schizotypy, Transliminality, and Manic-Depressive Experience), and well-being (Life Satisfaction, Meaning in Life, Somatic Complaints, Perceived Stress, Depressive Symptoms). Data derived from a sample of 3,090 participants (mean age = 50.30, standard deviation = 15.20; 46.5% male, 53.1% female) who completed standardised self-report measures capturing the study constructs online. Transliminality, Unusual Experiences (positive schizotypy), and Depressive Experience demonstrated high expected influence centrality. This indicated that these factors were the most strongly connected and influential in the network. Moreover, Transliminality was a connecting variable between Paranormal Belief, positive schizotypy, and psychopathology. Depressive Experience bridged the relationship between Transliminality and well-being. The conceptual implications of these outcomes are discussed with regards to better understanding relationships between Paranormal Belief, cognitive-perceptual factors, and well-being.

A generative framework for the study of delusions

Despite the ubiquity of delusional information processing in psychopathology and everyday life, formal characterizations of such inferences are lacking. In this article, we propose a generative framework that entails a computational mechanism which, when implemented in a virtual agent and given new information, generates belief updates (i.e., inferences about the hidden causes of the information) that resemble those seen in individuals with delusions. We introduce a particular form of Dirichlet process mixture model with a sampling-based Bayesian inference algorithm. This procedure, depending on the setting of a single parameter, preferentially generates highly precise (i.e. over-fitting) explanations, which are compartmentalized and thus can co-exist despite being inconsistent with each other. Especially in ambiguous situations, this can provide the seed for delusional ideation. Further, we show by simulation how the excessive generation of such over-precise explanations leads to new information being integrated in a way that does not lead to a revision of established beliefs. In all configurations, whether delusional or not, the inference generated by our algorithm corresponds to Bayesian inference. Furthermore, the algorithm is fully compatible with hierarchical predictive coding. By virtue of these properties, the proposed model provides a basis for the empirical study and a step toward the characterization of the aberrant inferential processes underlying delusions.

Everything is connected: Inference and attractors in delusions

Delusions are, by popular definition, false beliefs that are held with certainty and resistant to contradictory evidence. They seem at odds with the notion that the brain at least approximates Bayesian inference. This is especially the case in schizophrenia, a disorder thought to relate to decreased - rather than increased - certainty in the brain's model of the world. We use an active inference Markov decision process model (a Bayes-optimal decision-making agent) to perform a simple task involving social and non-social inferences. We show that even moderate changes in some model parameters - decreasing confidence in sensory input and increasing confidence in states implied by its own (especially habitual) actions - can lead to delusions as defined above. Incorporating affect in the model increases delusions, specifically in the social domain. The model also reproduces some classic psychological effects, including choice-induced preference change, and an optimism bias in inferences about oneself. A key observation is that no change in a single parameter is both necessary and sufficient for delusions; rather, delusions arise due to conditional dependencies that create 'basins of attraction' which trap Bayesian beliefs. Simulating the effects of antidopaminergic antipsychotics - by reducing the model's confidence in its actions - demonstrates that the model can escape from these attractors, through this synthetic pharmacotherapy.

LSD, afterglow and hangover: Increased episodic memory and verbal fluency, decreased cognitive flexibility

Psychedelics acutely impair cognitive functions, but these impairments decline with growing experiences with psychedelics and microdoses may even exert opposing effects. Given the recent evidence that psychedelics induce neuroplasticity, this explorative study aimed at investigating the potential of psychedelics to sub-acutely change cognition. For this, we applied a randomized, double-blind, placebo-controlled, crossover study with 24 healthy volunteers receiving 50 μg lysergic acid diethylamide (LSD) or an inactive placebo. Sub-acute changes in cognition were measured 24 h after dosing, including memory (Rey-Osterrieth Complex Figure, ROCF; 2D Object-Location Memory Task, OLMT; Rey Auditory-Verbal Learning Test, RAVLT), verbal fluency (phonological; semantic; switch), design fluency (basic; filter; switch), cognitive flexibility (Wisconsin Card Sorting Test, WCST), sustained and switching attention (Trail Making Test, TMT), inhibitory control (Stroop Task) and perceptual reasoning (Block Design Test, BDT). The results show that when compared to placebo and corrected for Body Mass Index (BMI) and abstinence period from psychedelics, LSD sub-acutely improved visuospatial memory (ROCF immediate recall points and percentage, OLMT consolidation percentage) and phonological verbal fluency and impaired cognitive flexibility (WCST: fewer categories achieved; more perseveration, errors and conceptual level responses). In conclusion, the low dose of LSD moderately induced both "afterglow" and "hangover". The improvements in visuospatial memory and phonological fluency suggest that LSD-assisted therapy should be explored as a novel treatment perspective in conditions involving memory and language declines such as brain injury, stroke or dementia.

Disrupted-in-schizophrenia 1 Protein Misassembly Impairs Cognitive Flexibility and Social Behaviors in a Transgenic Rat Model

Alterations in cognitive functions, social behaviors and stress reactions are commonly diagnosed in chronic mental illnesses (CMI). Animal models expressing mutant genes associated to CMI represent either rare mutations or those contributing only minimally to genetic risk. Non-genetic causes of CMI can be modeled by disturbing downstream signaling pathways, for example through inducing protein misassembly or aggregation. The Disrupted-in-Schizophrenia 1 (DISC1) gene was identified to be disrupted and thereby haploinsufficient in a large pedigree where it associated to CMI. The DISC1 protein misassembles to an insoluble protein in a subset of CMI patients and this has been modeled in a rat (tgDISC1 rat) where the full-length, non mutant human transgene was overexpressed and cognitive impairments were observed. Here, we investigated the scope of effects of DISC1 protein misassembly by investigating spatial memory, social behavior and stress resilience. In water maze tasks, the tgDISC1 rats showed intact spatial learning and memory, but were deficient in flexible adaptation to spatial reversal learning compared to littermate controls. They also displayed less social interaction. Additionally, there was a trend towards increased corticosterone levels after restraint stress in the tgDISC1 rats. Our findings suggest that DISC1 protein misassembly leads to disturbances of cognitive flexibility and social behaviors, and might also be involved in stress sensitization. Since the observed behavioral features resemble symptoms of CMI, the tgDISC1 rat may be a valuable model for the investigation of cognitive, social and - possibly - also stress-related symptoms of major mental illnesses.

Simulated visual hallucinations in virtual reality enhance cognitive flexibility

Historically, psychedelic drugs are known to modulate cognitive flexibility, a central aspect of cognition permitting adaptation to changing environmental demands. Despite proof suggesting phenomenological similarities between artificially-induced and actual psychedelic altered perception, experimental evidence is still lacking about whether the former is also able to modulate cognitive flexibility. To address this, we measure participants' cognitive flexibility through behavioral tasks after the exposure to virtual reality panoramic videos and their hallucinatory-like counterparts generated by the DeepDream algorithm. Results show that the estimated semantic network has a flexible structure when preceded by altered videos. Crucially, following the simulated psychedelic exposure, individuals also show an attenuated contribution of the automatic process and chaotic dynamics underlying the decision process. This suggests that simulated altered perceptual phenomenology enhances cognitive flexibility, presumably due to a reorganization in the cognitive dynamics that facilitates the exploration of uncommon decision strategies and inhibits automated choices.

Olfactory capacity in anorexia nervosa: correlations with set-shifting ability

PURPOSE

The purpose of this study is to examine olfactory capacity in adults with anorexia nervosa (AN), in terms of odor identification and odor threshold and search for possible correlations between odor identification and cognitive flexibility in this population.

METHODS

Thirty-nine patients diagnosed with AN and 60 healthy participants, participated. Odor identification was assessed using the University Pennsylvania Smell Identification Test and a two alternative forced choice, ascending method with n-butanol was used to assess odor threshold. Cognitive flexibility was determined using the Intra/Extra-Dimensional Set-Shift test (IED), a subtest of the Cambridge Neuropsychological Test Automated Battery (CANTAB).

RESULTS

Patients with AN presented a poorer performance in odor identification compared with controls (p = 0.001). No differences were found in odor threshold, between the two groups. Patients with AN exhibited poor cognitive flexibility compared with controls (p = 0.003). A significant correlation between odor identification and cognitive flexibility was documented in AN (p = 0.01), but not in controls.

CONCLUSION

Our findings suggest that olfactory capacity is altered in AN: Qualitative characteristics of olfaction were affected in patients with AN (lower odor identification), while there was no difference in quantitative characteristics (odor threshold) compared with controls. Furthermore, odor identification in AN was correlated to cognitive flexibility.

LEVEL OF EVIDENCE

Level III: case-control analytic study.

Twelve-month outcomes in overweight/obese users with mental disorders following a multi-element treatment including diet, physical activity, and positive thinking: The real-world "An Apple a Day" controlled trial

The present study aimed to evaluate the 12-month effectiveness of a real-world weight loss transdiagnostic intervention in overweight/obese participants affected by mental disorders under psychopharmacological treatment. We conducted a real-world, controlled, pragmatic outpatient trial. We allocated 58 overweight/obese adults under psychopharmacological treatment from a mental health outpatient unit and 48 overweight/obese adults from a cardiovascular prevention outpatient unit, and assigned them to an intervention or treatment usual as condition (TAU) enriched by life-style advice. Participants in both intervention groups took part in a diet programme (the modified OMNIHeart dietary protocol) and monitoring of regular aerobic activity. A brief group programme ("An Apple a Day" Metacognitive Training, Apple-MCT) was added in the intervention group of participants affected by mental disorders. The primary outcome was weight loss. Secondary outcomes included anthropometric, clinical, and metabolic variables. Psychopathology and health-related quality of life were also evaluated in the psychiatric sample. At 12 months, both intervention groups showed a more marked mean decrease in weight (6.7 kg, SD: 3.57) than the TAU group (0.32 kg, SD: 1.96), and a statistically significant improvement in metabolic variables compared with the control groups. Furthermore, the participants affected by mental disorders included in the intervention group reported improved health-related quality of life. Our findings suggest the need to implement integrated interventions based on a dietary protocol, physical activity, and modification of cognitive style in overweight/obese users with mental disorders.

L-DOPA administration shifts the stability-flexibility balance towards attentional capture by distractors during a visual search task

RATIONALE

The cognitive control dilemma describes the necessity to balance two antagonistic modes of attention: stability and flexibility. Stability refers to goal-directed thought, feeling, or action and flexibility refers to the complementary ability to adapt to an ever-changing environment. Their balance is thought to be maintained by neurotransmitters such as dopamine, most likely in a U-shaped rather than linear manner. However, in humans, studies on the stability-flexibility balance using a dopaminergic agent and/or measurement of brain dopamine are scarce.

OBJECTIVE

The study aimed to investigate the causal involvement of dopamine in the stability-flexibility balance and the nature of this relationship in humans.

METHODS

Distractibility was assessed as the difference in reaction time (RT) between distractor and non-distractor trials in a visual search task. In a randomized, placebo-controlled, double-blind, crossover study, 65 healthy participants performed the task under placebo and a dopamine precursor (L-DOPA). Using ¹⁸F-DOPA-PET, dopamine availability in the striatum was examined at baseline to investigate its relationship to the RT distractor effect and to the L-DOPA-induced change of the RT distractor effect.

RESULTS

There was a pronounced RT distractor effect in the placebo session that increased under L-DOPA. Neither the RT distractor effect in the placebo session nor the magnitude of its L-DOPA-induced increase were related to baseline striatal dopamine.

CONCLUSIONS

L-DOPA administration shifted the stability-flexibility balance towards attentional capture by distractors, suggesting causal involvement of dopamine. This finding is consistent with current theories of prefrontal cortex dopamine function. Current data can neither confirm nor falsify the inverted U-shaped function hypothesis with regard to cognitive control.

Alterations in Emotional Diversity Correspond With Increased Severity of Attenuated Positive and Negative Symptoms in the Clinical High-Risk Syndrome

Background: Alterations in emotional functioning are a key feature of psychosis and are present in individuals with a clinical high-risk (CHR) syndrome. However, little is known about alterations in emotional diversity (i.e., the variety and relative abundance of emotions that humans experience) and clinical correlates in this population. Methods: Individuals meeting criteria for a CHR syndrome (N = 47) and matched healthy controls (HC) (N = 58) completed the modified Differential Emotions Scale (used to derive scores of total, positive, and negative emotional diversity) and clinical interviews (i.e., Structured Interview for Psychosis-Risk Syndromes). Results: Findings showed that the CHR group experienced lower levels of positive emotional diversity compared to HCs. Among the CHR individuals, lower levels of positive and higher levels of negative emotional diversity were associated with more severe attenuated positive and negative symptoms. Analyses controlled for mean levels of emotion and current antipsychotic medication use. Discussion: Results demonstrate that altered emotional diversity (in particular lower levels of positive and higher levels of negative emotional diversity) is a clinically relevant marker in CHR individuals, above and beyond alterations in mean levels of emotional experiences. Future studies may probe sources, downstream consequences, and potential modifiability of decreased emotional diversity in individuals at CHR.

Psychedelic Therapy's Transdiagnostic Effects: A Research Domain Criteria (RDoC) Perspective

Accumulating clinical evidence shows that psychedelic therapy, by synergistically combining psychopharmacology and psychological support, offers a promising transdiagnostic treatment strategy for a range of disorders with restricted and/or maladaptive habitual patterns of emotion, cognition and behavior, notably, depression (MDD), treatment resistant depression (TRD) and addiction disorders, but perhaps also anxiety disorders, obsessive-compulsive disorder (OCD), Post-Traumatic Stress Disorder (PTSD) and eating disorders. Despite the emergent transdiagnostic evidence, the specific clinical dimensions that psychedelics are efficacious for, and associated underlying neurobiological pathways, remain to be well-characterized. To this end, this review focuses on pre-clinical and clinical evidence of the acute and sustained therapeutic potential of psychedelic therapy in the context of a transdiagnostic dimensional systems framework. Focusing on the Research Domain Criteria (RDoC) as a template, we will describe the multimodal mechanisms underlying the transdiagnostic therapeutic effects of psychedelic therapy, traversing molecular, cellular and network levels. These levels will be mapped to the RDoC constructs of negative and positive valence systems, arousal regulation, social processing, cognitive and sensorimotor systems. In summarizing this literature and framing it transdiagnostically, we hope we can assist the field in moving toward a mechanistic understanding of how psychedelics work for patients and eventually toward a precise-personalized psychedelic therapy paradigm.

A network analysis and empirical validation of executive deficits in patients with psychosis and their healthy siblings

BACKGROUND

Psychopathological symptoms and cognitive impairment are core features of patients with psychotic disorders. Executive dysfunctions are commonly observed and typically assessed using tests like the Wisconsin Card Sorting Test (WCST). However, the structure of executive deficits remains unclear, and the underlying processes may be different. This study aimed to explore and compare the network structure of WCST measures in patients with psychosis and their unaffected siblings and to empirically validate the resulting network structure of the patients.

METHODS

The subjects were 298 patients with a DSM 5 diagnosis of a psychotic disorder and 89 of their healthy siblings. The dimensionality and network structure of the WCST were examined by means of exploratory graph analysis (EGA) and network centrality parameters.

RESULTS

The WCST network structure comprised 4 dimensions: perseveration (PER), inefficient sorting (IS), failure to maintain set (FMS) and learning (LNG). The patient and sibling groups showed a similar network structure, which was reliably estimated. PER and IS showed common and strong associations with antecedent, concurrent and outcome validators. The LNG dimension was also moderately associated with these validators, but FMS did not show significant associations.

CONCLUSIONS

Four cognitive processes underlying WCST performance were identified by the network analysis. PER, IS and LNG were associated with and shared common antecedent, concurrent and outcome validators, while FMS was not associated with external validators. These four underlying dysfunctions might help disentangle the neurofunctional basis of executive deficits in psychosis.

Preliminary evidence for the phosphodiesterase type-4 inhibitor, roflumilast, in ameliorating cognitive flexibility deficits in patients with schizophrenia

BACKGROUND

Cognitive flexibility deficits are present in patients with schizophrenia and are strong predictors of functional outcome but, as yet, have no pharmacological treatments.

AIMS

The purpose of this study was to investigate whether the phosphodiesterase type-4 inhibitor, roflumilast, can improve cognitive flexibility performance and functional brain activity in patients with schizophrenia.

METHODS

This was a within-subject, randomised, double-blind, placebo-controlled, three-period crossover study using a version of the Intradimensional/Extradimensional (ID/ED) task, optimised for functional magnetic resonance imaging (fMRI), in 10 patients with schizophrenia who were scanned after receiving placebo, 100 µg or 250 µg roflumilast for 8 consecutive days. Data from an additional fMRI ID/ED study of 18 healthy participants on placebo was included to contextualise the schizophrenia-related performance and activations. The fMRI analyses included a priori driven region of interest (ROI) analysis of the dorsal frontoparietal attention network.

RESULTS

Patients on placebo demonstrated broad deficits in task performance compared to the healthy comparison group, accompanied by preserved network activity for solution search, but reduced activity in left ventrolateral prefrontal cortex (VLPFC) and posterior parietal cortex for attentional set-shifting and reduced activity in left dorsolateral prefrontal cortex (DLPFC) for reversal learning. These ROI deficits were ameliorated by 250 µg roflumilast, whereas during solution search 100 µg roflumilast reduced activity in the left orbitofrontal cortex, right DLPFC and bilateral PPC, which was associated with an improvement in formation of attentional sets.

CONCLUSIONS

The results suggest roflumilast has dose-dependent cognitive enhancing effects on the ID/ED task in patients with schizophrenia, and provides sufficient support for larger studies to test roflumilast's role in improving cognitive flexibility deficits in this clinical population.

Syn3 Gene Knockout Negatively Impacts Aspects of Reversal Learning Performance

Behavioral flexibility enables the ability to adaptively respond to changes in contingency requirements to maintain access to desired outcomes, and deficits in behavioral flexibility have been documented in many psychiatric disorders. Previous research has shown a correlation between behavioral flexibility measured in a reversal learning test and Syn3, the gene encoding synapsin III, which negatively regulates phasic dopamine release. Syn3 expression in the hippocampus, striatum, and neocortex is reported to be negatively correlated with reversal learning performance, so here, we used a global knock-out line to investigate reversal learning in mice homozygous wild type, heterozygous null, and homozygous null for the Syn3 gene. Compared with wild-type animals, we found a reversal-specific effect of genetic Syn3 deficiency that resulted in a greater proportional increase in trials required to reach a preset performance criterion during contingency reversal, despite no observed genotype effects on the ability to acquire the initial discrimination. Behavioral flexibility scores, which quantified the likelihood of switching subsequent choice behavior following positive or negative feedback, became significantly more negative in reversal only for Syn3 homozygous-null mice, suggesting a substantial increase in perseverative behavior in the reversal phase. Syn3 ablation reduced the number of anticipatory responses made per trial, often interpreted as a measure of waiting impulsivity. Overall, Syn3 expression negatively affected behavioral flexibility in a reversal-specific manner but may have reduced waiting impulsivity.

Foreign Language Learning as Cognitive Training to Prevent Old Age Disorders? Protocol of a Randomized Controlled Trial of Language Training vs. Musical Training and Social Interaction in Elderly With Subjective Cognitive Decline

Introduction: With aging comes a reduction of cognitive flexibility, which has been related to the development of late-life depression and progression of general cognitive decline. Several factors have been linked to attenuating such decline in cognitive flexibility, such as education, physical exercise and stimulating leisure activities. Speaking two or more languages has recently received abundant attention as another factor that may build up cognitive reserve, thereby limiting the functional implications of compromised cognition that accompany old age. With the number of older adults reaching record levels, it is important to attenuate the development of old-age disorders. Learning to speak a foreign language might offer a powerful tool in promoting healthy aging, but up to date effect studies are sparse. Here, the protocol that forms the foundation of the current study is presented. The present study aims to: (1) examine the effects of a foreign language training on cognitive flexibility and its neural underpinnings, and on mental health; and (2) assess the unique role of foreign language training vs. other cognitive or social programs. Method: One-hundred and ninety-eight Dutch elderly participants reporting subjective cognitive decline are included and randomized to either a language intervention, a music intervention, or a social control intervention. During 3 to 6 months, the language group learns English, the music group learns to play the guitar and the social group participates in social meetings where art workshops are offered. At baseline, at a 3-month follow-up, and at 6 months after termination of the training program, clinical, cognitive and brain activity measurements (combined EEG and fNIRS methods) are taken to assess cognitive flexibility and mental health. Discussion: This is the first trial addressing combined effects of language learning in elderly on cognition, language proficiency, socio-affective measures, and brain activity in the context of a randomized controlled trial. If successful, this study can provide insights into how foreign language training can contribute to more cognitively and mentally healthy years in older adulthood. Clinical Trial Registration: The trial is registered at the Netherlands Trial Register, July 2, 2018, trial number NL7137. https://www.trialregister.nl/trial/7137.

GABA Supplementation Negatively Affects Cognitive Flexibility Independent of Tyrosine

Increasing evidence, particularly from animal studies, suggests that dopamine and GABA are important modulators of cognitive flexibility. In humans, increasing dopamine synthesis through its precursor tyrosine has been shown to result in performance improvements, but few studies have reported the effects of GABA supplementation in healthy participants. We conducted a double-blind, placebo-controlled, randomized experiment to test the interactive effects of tyrosine and GABA administration on two measures of cognitive flexibility, response inhibition and task switching. A total of 48 healthy volunteers were split into four groups (placebo, tyrosine alone, GABA alone, and tyrosine and GABA combined). They completed cognitive flexibility tasks at baseline and after drug administration. We found that tyrosine alone had no impact on the measures of cognitive flexibility, whereas GABA alone and in combination with tyrosine worsened task switching. Our results provide preliminary evidence that putative increases in GABA and dopamine synthesis do not interact to affect cognitive flexibility performance.

The protective effect of olanzapine on ketamine induced cognitive deficit and increased NR1 expression in rat model of schizophrenia

BACKGROUND

Impaired cognitive flexibility is the core manifestation of schizophrenia (SZ). Previous literature raised a claim against the effect of atypical antipsychotic drugs (AAD) on cognitive and executive functions whose cause needs further investigation. Attention set-shifting task (ASST) tests the prefrontal cortex's (PFC) executive and flexibility functions.

GOALS

To examine Olanzapine (OLZ) effect on ASST, expression of N-methyl-D-aspartate receptor 1 (NMDR-NR1) in prefrontal cortex (PFC), and metabolic comorbidity in ketamine (KET) model of SZ.

METHODS

Sixty-two male rats were divided into three groups: 8 for ASST and 30 for open field, ELISA and immunohistochemistry sub-chronic study, and 24 for regular serological and histopathological examination. Rats treated with V: vehicle; K: KET and KO: OLZ plus KET.

RESULTS

KET caused significant increase in time, trials, and errors to reach criterion. OLZ co-administration reversed effects of KET in ASST with no reduction of locomotor activity. OLZ normalized KET-induced rise of NR1 expression and protected against KET-induced degenerative changes in hippocampus and PFC. Significant increase in serum liver enzymes, total bilirubin, and lipids with chronic compared to sub-chronic OLZ administration. In contrast, insignificant difference between sub-chronic OLZ and vehicle was found.

CONCLUSIONS

Current study demonstrated the efficacy of OLZ to reverse KET-induced cognitive deficits in ASST with neither reduction in NR1 expression in PFC nor metabolic malfunction in the sub-chronic study. It also showed the protective effect of OLZ on KET induced neuronal degeneration and necrosis. We suggest that chronic OLZ treatment-induced-metabolic malfunction might be the cause of time-dependent cognitive deterioration.

The Role of Parvalbumin Interneuron GIRK Signaling in the Regulation of Affect and Cognition in Male and Female Mice

Pathological impairments in the regulation of affect (i.e., emotion) and flexible decision-making are commonly observed across numerous neuropsychiatric disorders and are thought to reflect dysfunction of cortical and subcortical circuits that arise in part from imbalances in excitation and inhibition within these structures. Disruptions in GABA transmission, in particular, that from parvalbumin-expressing interneurons (PVI), has been highlighted as a likely mechanism by which this imbalance arises, as they regulate excitation and synchronization of principle output neurons. G protein-gated inwardly rectifying potassium ion (GIRK/Kir3) channels are known to modulate excitability and output of pyramidal neurons in areas like the medial prefrontal cortex and hippocampus; however, the role GIRK plays in PVI excitability and behavior is unknown. Male and female mice lacking GIRK1 in PVI (Girk1flox/flox:PVcre) and expressing td-tomato in PVI (Girk1flox/flox:PVCre:PVtdtom) exhibited increased open arm time in the elevated plus-maze, while males showed an increase in immobile episodes during the forced swim test (FST). Loss of GIRK1 did not alter motivated behavior for an appetitive reward or impair overall performance in an operant-based attention set-shifting model of cognitive flexibility; however it did alter types of errors committed during the visual cue test. Unexpectedly, baseline sex differences were also identified in these tasks, with females exhibiting overall poorer performance compared to males and distinct types of errors, highlighting potential differences in task-related problem-solving. Interestingly, reductions in PVI GIRK signaling did not correspond to changes in membrane excitability but did increase action potential (AP) firing at higher current injections in PVI of males, but not females. This is the first investigation on the role that PVI GIRK-signaling has on membrane excitability, AP firing, and their role on affect and cognition together increasing the understanding of PVI cellular mechanisms and function.

Cognitive and behavioural flexibility: neural mechanisms and clinical considerations

Cognitive and behavioural flexibility permit the appropriate adjustment of thoughts and behaviours in response to changing environmental demands. Brain mechanisms enabling flexibility have been examined using non-invasive neuroimaging and behavioural approaches in humans alongside pharmacological and lesion studies in animals. This work has identified large-scale functional brain networks encompassing lateral and orbital frontoparietal, midcingulo-insular and frontostriatal regions that support flexibility across the lifespan. Flexibility can be compromised in early-life neurodevelopmental disorders, clinical conditions that emerge during adolescence and late-life dementias. We critically evaluate evidence for the enhancement of flexibility through cognitive training, physical activity and bilingual experience.

Reset of hippocampal-prefrontal circuitry facilitates learning

The ability to rapidly adapt to novel situations is essential for survival, and this flexibility is impaired in many neuropsychiatric disorders¹. Thus, understanding whether and how novelty prepares, or primes, brain circuitry to facilitate cognitive flexibility has important translational relevance. Exposure to novelty recruits the hippocampus and medial prefrontal cortex (mPFC)² and may prime hippocampal-prefrontal circuitry for subsequent learning-associated plasticity. Here we show that novelty resets the neural circuits that link the ventral hippocampus (vHPC) and the mPFC, facilitating the ability to overcome an established strategy. Exposing mice to novelty disrupted a previously encoded strategy by reorganizing vHPC activity to local theta (4-12 Hz) oscillations and weakening existing vHPC-mPFC connectivity. As mice subsequently adapted to a new task, vHPC neurons developed new task-associated activity, vHPC-mPFC connectivity was strengthened, and mPFC neurons updated to encode the new rules. Without novelty, however, mice adhered to their established strategy. Blocking dopamine D1 receptors (D1Rs) or inhibiting novelty-tagged cells that express D1Rs in the vHPC prevented these behavioural and physiological effects of novelty. Furthermore, activation of D1Rs mimicked the effects of novelty. These results suggest that novelty promotes adaptive learning by D1R-mediated resetting of vHPC-mPFC circuitry, thereby enabling subsequent learning-associated circuit plasticity.

Cerebral and behavioral signs of impaired cognitive flexibility and stability in schizophrenia spectrum disorders

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Patients are impaired regarding both, cognitive flexibility and stability.

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Deficient prediction error discrimination is related to reduced striatal activation.

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Decreased ACC and hippocampus activation predicts impaired rule switch detection.

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Decreased frontal and insular activation predicts impaired distractor shielding.

Background

Manifold cognitive deficits have been reported in schizophrenia spectrum disorders, including disturbances in flexible updating to altered circumstances as well as stabilization deficits in the face of distractors. In this functional magnetic resonance imaging study, we examined the neural correlates of these deficits as two complementary components of predictive processing.

Methods

In 22 patients with schizophrenia spectrum disorders and 22 healthy matched control participants, we applied a serial predictive switch-drift task to assess flexibility as successful detection of prediction-rule switches, and stability as successfully ignoring distractors (“drifts”).

Results

Patients compared with controls less reliably detected rule switches and also less efficiently inhibited drifts. A reduced striatal response to switches or drifts correlated with weaker switch-drift-discrimination in patients, suggesting impaired gating of prediction errors. The increase in activity in anterior cingulate cortex and hippocampus for detected vs. undetected switches was reduced in patients compared to controls, which may reflect impaired behavioral adaptation following prediction errors. The comparison between shielding against distractions and undetected switches showed increased activity in the inferior frontal cortex and posterior insula in controls but not in patients.

Conclusion

Our results suggest new insights into the specific disruption of predictive flexibility and stability in schizophrenia spectrum disorders, which is characterized by impaired striatal gating and inadequate cortical encoding of predictive errors.

Phencyclidine-induced cognitive impairments in repeated touchscreen visual reversal learning tests in rats

Reversal learning, a component of executive functioning, is commonly impaired among schizophrenia patients and is lacking effective treatment. N-methyl-ᴅ-aspartate (NMDA) receptor antagonists, such as phencyclidine (PCP), impair reversal learning of rodents. Touchscreen-based pairwise visual discrimination and reversal test is a translational tool to assess reversal learning in rodents. However, to fully exploit this task in testing of novel compounds, it is necessary to perform several reversal learning experiments with trained animals. Firstly, we assessed whether PCP-induced deficits in visual reversal learning in rats would be detectable with a short (5 sessions) reversal learning phase, and whether the short reversal phases could be repeated with novel stimulus pairs. Secondly, we assessed whether the PCP-induced deficits in reversal learning could be seen upon repeated PCP challenges with the same animals. Finally, we tested the effect of a novel compound, a selective α_2C adrenoceptor antagonist, ORM-13070, to reverse PCP-induced cognitive deficits in this model. A 4-day PCP treatment at a dose of 1.5 mg/kg/day impaired early reversal learning in male Lister Hooded rats without inducing non-specific behavioral effects. We repeated the reversal learning experiment four times using different stimulus pairs with the same animals, and the PCP-induced impairment was evident in every single experiment. The α_2C adrenoceptor antagonist ameliorated the PCP-induced cognitive deficits. Our results suggest that repeated PCP challenges in the touchscreen set-up induce schizophrenia-like cognitive deficits in visual reversal learning, improve throughput of the test and provide a protocol for testing novel drugs.

Interplay of Prenatal and Postnatal Risk Factors in the Behavioral and Histological Features of a "Two-Hit" Non-Genetic Mouse Model of Schizophrenia

Schizophrenia is a multifactorial developmental neuropsychiatric disorder. This study examined the interplay of maternal infection and postweaning social isolation, which are prenatal and postnatal risk factors, respectively. Pregnant mice received poly I:C or saline injection on gestation day 9 and the pups were weaned at postnatal day 28. After weaning, male offspring were randomly assigned into group-rearing and isolation-rearing groups. In their adulthood, we performed behavioral tests and characterized the histochemical features of their mesocorticolimbic structures. The sociability and anxiety levels were not affected by either manipulation, but synergistic effects of the two hits on stress-coping behavior was observed. Either of the single manipulations caused defects in sensorimotor gating, novel object recognition and spatial memory tests, but the combination of the two hits did not further exacerbate the disabilities. Prenatal infection increased the number of dopaminergic neurons in midbrain, whereas postweaning isolation decreased the GABAergic neurons in cortex. Single manipulation reduced the dendritic complexity and spine densities of neurons in the medial prefrontal cortex (mPFC) and dentate gyrus. Our results support the current perspective that disturbances in brain development during the prenatal or postnatal period influence the structure and function of the brain and together augment the susceptibility to mental disorders, such as schizophrenia.

"Cool" and "Hot" Executive Functions in Patients With a Predominance of Negative Schizophrenic Symptoms

Background

Patients with psychosis often present significant neurocognitive deficits, with executive function deficits (EEFF) being one of the most relevant cognitive impairments with the greatest impact on the functioning of their daily lives. However, although various findings of executive involvement were reported, it is not entirely clear whether there is a differential pattern of involvement according to the clinical symptoms or the deficits occur in all or only in some subcomponents of EEFF.

Objective

The present study had a double objective: to study the specific deficits in the cool and hot EEFF in a group of psychotic patients with a predominance of negative symptoms; and determine the possible associations between the performance of the patients in the cool an hot EEFF tasks with the negative symptoms, and with the behavioral alterations associated with the dysexecutive syndrome.

Method

66 participants, 33 psychotic patients with a predominance of negative symptoms and 33 healthy control subjects matched in gender, age and educational level participated. Both groups were administered 4 cool EEFF tasks (coding/maintenance and updating of information in working memory, ability to change the mental set and planning), and 3 hot EEFF tasks (decision making in situations of uncertainty, recognition of emotions through facial expressions and theory of mind). In the group of patients, the Negative symptoms were evaluated through the Scale for the Evaluation of Negative Symptoms (SANS), and the behavioral alterations associated with dysexecutive syndrome through the subscale of "Executive Dysfunction" of the Frontal Systems Behavior Scale.

Results

Patients performed worse on three cool EEFF tasks and on two of the hot EEFF tasks. Additionally, we found a correlation between the SANS score and the "executive dysfunction" subscale, with the cold EEFF task that measures planning.

Conclusion

Our findings showed that in psychotic patients with a predominance of negative symptoms, both, the cognitive (cool) and emotional (hot) components of executive functions are affected. The results reinforce the need for a cognitive rehabilitation treatment of the executive components of the working memory and of those more socio-emotional aspects.

Orexin deficiency modulates cognitive flexibility in a sex-dependent manner

Cognitive flexibility is an important executive function and refers to the ability to adapt behaviors in response to changes in the environment. Of note, many brain disorders are associated with impairments in cognitive flexibility. Several classical neurotransmitter systems including dopamine, acetylcholine and noradrenaline are shown to be important for cognitive flexibility, however, there is not much known about the role of neuropeptides. The neuropeptide orexin, which is brain-widely released by neurons in the lateral hypothalamus, is a major player in maintaining sleep/wake cycle, feeding behavior, arousal, and motivational behavior. Recent studies showed a role of orexin in attention, cognition and stress-induced attenuation of cognitive flexibility by disrupting orexin signaling locally or systemically. However, it is not known so far whether brain-wide reduction or loss of orexin affects cognitive flexibility. We investigated this question by testing male and female orexin-deficient mice in the attentional set shifting task (ASST), an established paradigm of cognitive flexibility. We found that orexin deficiency impaired the intra-dimensional shift phase of the ASST selectively in female homozygous orexin-deficient mice and improved the first reversal learning phase selectively in male homozygous orexin-deficient mice. We also found that these orexin-mediated sex-based modulations of cognitive flexibility were not correlated with trait anxiety, narcoleptic episodes, and reward consumption. Our findings highlight a sexually dimorphic role of orexin in regulating cognitive flexibility and the need for further investigations of sex-specific functions of the orexin circuitry.

Cognitive, Affective, and Feedback-Based Flexibility - Disentangling Shared and Different Aspects of Three Facets of Psychological Flexibility

Cognitive flexibility - the ability to adjust one ´s behavior to changing environmental demands - is crucial for controlled behavior. However, the term 'cognitive flexibility' is used heterogeneously, and associations between cognitive flexibility and other facets of flexible behavior have only rarely been studied systematically. To resolve some of these conceptual uncertainties, we directly compared cognitive flexibility (cue-instructed switching between two affectively neutral tasks), affective flexibility (switching between a neutral and an affective task using emotional stimuli), and feedback-based flexibility (non-cued, feedback-dependent switching between two neutral tasks). Three experimental paradigms were established that share as many procedural features (in terms of stimuli and/or task rules) as possible and administered in a pre-registered study plan (N = 100). Correlation analyses revealed significant associations between the efficiency of cognitive and affective task switching (response time switch costs). Feedback-based flexibility (measured as mean number of errors after rule reversals) did not correlate with task switching efficiency in the other paradigms, but selectively with the effectiveness of affective switching (error rate costs when switching from neutral to emotion task). While preregistered confirmatory factor analysis (CFA) provided no clear evidence for a shared factor underlying the efficiency of switching in all three domains of flexibility, an exploratory CFA suggested commonalities regarding switching effectiveness (accuracy-based switch costs). We propose shared mechanisms controlling the efficiency of cue-dependent task switching across domains, while the relationship to feedback-based flexibility may depend on mechanisms controlling switching effectiveness. Our results call for a more stringent conceptual differentiation between different variants of psychological flexibility.

Dysregulation of Midbrain Dopamine System and the Pathophysiology of Schizophrenia

Dysregulation of the dopamine system is central to many models of the pathophysiology of psychosis in schizophrenia. However, emerging evidence suggests that this dysregulation is driven by the disruption of upstream circuits that provide afferent control of midbrain dopamine neurons. Furthermore, stress can profoundly disrupt this regulatory circuit, particularly when it is presented at critical vulnerable prepubertal time points. This review will discuss the dopamine system and the circuits that regulate it, focusing on the hippocampus, medial prefrontal cortex, thalamic nuclei, and medial septum, and the impact of stress. A greater understanding of the regulation of the dopamine system and its disruption in schizophrenia may provide a more complete neurobiological framework to interpret clinical findings and develop novel treatments.

Paranoia as a deficit in non-social belief updating

Paranoia is the belief that harm is intended by others. It may arise from selective pressures to infer and avoid social threats, particularly in ambiguous or changing circumstances. We propose that uncertainty may be sufficient to elicit learning differences in paranoid individuals, without social threat. We used reversal learning behavior and computational modeling to estimate belief updating across individuals with and without mental illness, online participants, and rats chronically exposed to methamphetamine, an elicitor of paranoia in humans. Paranoia is associated with a stronger prior on volatility, accompanied by elevated sensitivity to perceived changes in the task environment. Methamphetamine exposure in rats recapitulates this impaired uncertainty-driven belief updating and rigid anticipation of a volatile environment. Our work provides evidence of fundamental, domain-general learning differences in paranoid individuals. This paradigm enables further assessment of the interplay between uncertainty and belief-updating across individuals and species.

Everyone has had fleeting concerns that others might be against them at some point in their lives. Sometimes these concerns can escalate into paranoia and become debilitating. Paranoia is a common symptom in serious mental illnesses like schizophrenia. It can cause extreme distress and is linked with an increased risk of violence towards oneself or others. Understanding what happens in the brains of people experiencing paranoia might lead to better ways to treat or manage it.

Some experts argue that paranoia is caused by errors in the way people assess social situations. An alternative idea is that paranoia stems from the way the brain forms and updates beliefs about the world. Now, Reed et al. show that both people with paranoia and rats exposed to a paranoia-inducing substance expect the world will change frequently, change their minds often, and have a harder time learning in response to changing circumstances.

In the experiments, human volunteers with and without psychiatric disorders played a game where the best choices change. Then, the participants completed a survey to assess their level of paranoia. People with higher levels of paranoia predicted more changes would occur and made less predictable choices. In a second set of experiments, rats were put in a cage with three holes where they sometimes received sugar rewards. Some of the rats received methamphetamine, a drug that causes paranoia in humans. Rats given the drug also expected the location of the sugar reward would change often. The drugged animals had harder time learning and adapting to changing circumstances.

The experiments suggest that brain processes found in both rats, which are less social than humans, and humans contribute to paranoia. This suggests paranoia may make it harder to update beliefs. This may help scientists understand what causes paranoia and develop therapies or drugs that can reduce paranoia. This information may also help scientists understand why during societal crises like wars or natural disasters humans are prone to believing conspiracies. This is particularly important now as the world grapples with climate change and a global pandemic. Reed et al. note paranoia may impede the coordination of collaborative solutions to these challenging situations.

Activity-dependent isomerization of Kv4.2 by Pin1 regulates cognitive flexibility

Voltage-gated K+ channels function in macromolecular complexes with accessory subunits to regulate brain function. Here, we describe a peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1)-dependent mechanism that regulates the association of the A-type K+ channel subunit Kv4.2 with its auxiliary subunit dipeptidyl peptidase 6 (DPP6), and thereby modulates neuronal excitability and cognitive flexibility. We show that activity-induced Kv4.2 phosphorylation triggers Pin1 binding to, and isomerization of, Kv4.2 at the pThr607-Pro motif, leading to the dissociation of the Kv4.2-DPP6 complex. We generated a novel mouse line harboring a knock-in Thr607 to Ala (Kv4.2TA) mutation that abolished dynamic Pin1 binding to Kv4.2. CA1 pyramidal neurons of the hippocampus from these mice exhibited altered Kv4.2-DPP6 interaction, increased A-type K+ current, and reduced neuronal excitability. Behaviorally, Kv4.2TA mice displayed normal initial learning but improved reversal learning in both Morris water maze and lever press paradigms. These findings reveal a Pin1-mediated mechanism regulating reversal learning and provide potential targets for the treatment of neuropsychiatric disorders characterized by cognitive inflexibility.

The abiding relevance of mouse models of rare mutations to psychiatric neuroscience and therapeutics

Studies using powerful family-based designs aided by large scale case-control studies, have been instrumental in cracking the genetic complexity of the disease, identifying rare and highly penetrant risk mutations and providing a handle on experimentally tractable model systems. Mouse models of rare mutations, paired with analysis of homologous cognitive and sensory processing deficits and state-of-the-art neuroscience methods to manipulate and record neuronal activity have started providing unprecedented insights into pathogenic mechanisms and building the foundation of a new biological framework for understanding mental illness. A number of important principles are emerging, namely that degradation of the computational mechanisms underlying the ordered activity and plasticity of both local and long-range neuronal assemblies, the building blocks necessary for stable cognition and perception, might be the inevitable consequence and the common point of convergence of the vastly heterogeneous genetic liability, manifesting as defective internally- or stimulus-driven neuronal activation patterns and triggering the constellation of schizophrenia symptoms. Animal models of rare mutations have the unique potential to help us move from "which" (gene) to "how", "where" and "when" computational regimes of neural ensembles are affected. Linking these variables should improve our understanding of how symptoms emerge and how diagnostic boundaries are established at a circuit level. Eventually, a better understanding of pathophysiological trajectories at the level of neural circuitry in mice, aided by basic human experimental biology, should guide the development of new therapeutics targeting either altered circuitry itself or the underlying biological pathways.