Cerebellar dopamine D2 receptors regulate social behaviors

Repeated treatment with JWH-018 progressively increases motor activity and aggressiveness in male mice: involvement of CB1 cannabinoid and D1/D2 dopaminergic receptors

RATIONALE

To date, the exposure to Synthetic Cannabinoids (SCs) has been linked to unanticipated psychiatric symptoms such as agitation, psychosis, and aggressive behavior. In line with this, preclinical studies have shown that acute and long-term exposure to these compounds can result in psychostimulant effects that may be related to CB1-mediated and dopamine-dependent mechanisms.

OBJECTIVES

This study focuses on the progressive effects induced by repeated injection of 1-pentyl-3-(1-naphthoyl)indole JWH-018 (6 mg/kg, i.p.) on the locomotor activity and aggressive behavior in adult male ICR-CD1® mice. Thus, the interaction with the cannabinoid CB1 receptor-preferring antagonist/inverse agonist AM-251 (6 mg/kg, i.p.), the dopamine D1/5 receptor antagonist SCH23390 (0.1 mg/kg, i.p.), and the dopamine D2/3 receptor antagonist haloperidol (0.05 mg/kg, i.p.) have been evaluated. Expression and distribution of D1 and D2 receptors and tyrosine hydroxylase (TH) have been also investigated by immunohistochemistry on brain and cerebellar samples to explore potential neuroplastic events.

RESULTS

The repeated treatment with JWH-018 lead to the exacerbation of unanticipated psychomotor agitation, progressively increasing spontaneous locomotion and aggressiveness. Pre-treatment with AM-251 prevents the effects induced by the SC first, third and seventh injection. SCH23390 and haloperidol significantly attenuate and fully prevent the effects induced by JWH-018 seventh injection when pre-administered, respectively, alone and in combination. Behavioral changes observed in JWH-018-treated mice are accompanied by alterations in cortical, hippocampal, striatal and cerebellar D1, D2 and TH gene expression levels.

CONCLUSION

The present results demonstrated that repeated treatment with high dosage of JWH-018 induces psycho-stimulants effects via both CB1 receptor-mediated and dopamine-dependent mechanisms.

The role of dopamine in foraging decisions in social insects

Animals often need to make decisions about whether to confront risks, and climate change is making these decisions even more critical by increasing environmental stress. Biogenic amines are crucial for modulating behavior in all animals and may contribute to behavioral adaptations to changing environments through supporting decision-making involving risk. Our review focuses on the neuromodulator dopamine in insects because of its role in risk-related behavioral choices, particularly in the context of ant foraging activity. In ants, individual decisions contribute to the collective regulation of foraging activity. We consider the role of dopamine in the regulation of collective foraging activity to manage water loss in the desert red harvester ant, Pogonomyrmex barbatus, in the southwest US that is undergoing severe drought. We discuss dopaminergic circuitry and its involvement in decisions about foraging risk, drawing from both the vertebrate and invertebrate literature, to outline areas of future research in the role of dopamine in collective decision-making in response to changing environmental conditions.

Cerebellar Crus II Regulates Recognition and Spatial Memory in Mice

The cerebellar Crus II is implicated in the late stages of Alzheimer's disease (AD), yet its specific roles in memory regulation and therapeutic potential remain unclear. Using in vivo fiber photometry, we observed robust activation of Crus II neurons in healthy mice during recognition memory tasks. Acute chemogenetic inhibition of Crus II neurons impaired recognition and spatial memory in mice. Polysynaptic circuit tracing revealed that Crus II neurons modulate neural activity in the contralateral prelimbic cortex (PrL) via the Crus II-cerebellar lateral nucleus (LN)-ventromedial thalamus/zona incerta (VM/ZI)-PrL pathway. In 5 × FAD mice, β-amyloid (Aβ) plaque deposition in Crus II exhibited age-dependent progression, occurring later and less severely compared to the prefrontal cortex. Chronic activation of Crus II neurons ameliorated recognition and spatial memory deficits in 5 × FAD mice. These findings highlight the cerebellar Crus II as a modulator of cognitive function and a potential therapeutic target for AD.

Serotonergic Input into the Cerebellar Cortex Modulates Anxiety-Like Behavior

Because of the important roles of both serotonin (5-HT) and the cerebellum in regulating anxiety, we asked whether 5-HT signaling within the cerebellum is involved in anxiety behavior. Physiological 5-HT levels were measured in vivo by expressing a fluorescent sensor for 5-HT in lobule VII of the cerebellum, while using fiber photometry to measure sensor fluorescence during anxiety behavior on the elevated zero maze. Serotonin increased in lobule VII when male mice were less anxious and decreased when mice were more anxious. To establish a causal role for this serotonergic input in anxiety behavior, we photostimulated or photoinhibited serotonergic terminals in lobule VII while mice were in an elevated zero maze. Photostimulating these terminals reduced anxiety behavior in mice, while photoinhibiting them enhanced anxiety behavior. Our findings add to evidence that cerebellar lobule VII is a topographical locus for anxiety behavior and establish that 5-HT input into this lobule is necessary and sufficient to bidirectionally influence anxiety behavior. These results represent progress toward understanding how the cerebellum regulates anxiety behavior and provide new evidence for a functional connection between the cerebellum and the serotonin system within the anxiety circuit.

The abnormal accumulation of pathological proteins and compensatory functional connectivity enhancement of insula subdivisions in mild cognitive impairment

Background

The insula is a critical node of the salience network responsible for initiating network switching, and its dysfunctional connections are linked to the mechanisms of mild cognitive impairment (MCI). This study aimed to explore the changes in functional connectivity (FC) of insular subregions in MCI patients with varying levels of cerebrospinal fluid (CSF) pathological proteins, and to investigate the impact of these proteins on the brain network alterations in MCI.

Methods

Based on CSF Amyloid-beta (Aβ, A) and phosphorylated tau protein (p-tau, T), MCI patients were classified into 54 A-T-, 28 A+T-, and 52 A+T+ groups. Seed-based FC analysis was employed to compare the FC differences of insular subregions across the three groups. Correlation analysis was further conducted to explore the relationship between altered FC and cognitive function. Finally, ROC curve analysis was used to assess the diagnostic value of altered FC of insular subregion in distinguishing between the groups.

Results

In the left ventral anterior insula, left dorsal anterior insula, and bilateral posterior insular subnetworks, both the A+T- and A+T+ groups showed increased FC compared to the A-T- group, with the A+T+ group showing further increased FC compared to the A+T- group. Additionally, FC of the left cerebellar posterior lobe was negatively correlated with RAVLT-learning, and FC of the left middle frontal gyrus was negatively correlated with p-tau levels. Finally, logistic regression analysis demonstrated that multivariable analysis had high sensitivity and specificity in distinguishing between the groups.

Conclusion

This study showed that MCI patients with abnormal CSF pathological protein levels exhibit compensatory increases in FC of insular subregions, which in turn affect cognitive function. Our findings contributed to a better understanding of the pathophysiology and underlying neural mechanisms of MCI.

Substantial Heritability Underlies Fairness Norm Adaptation Capability and its Neural Basis

The present research uncovers the shared genetic underpinnings of fairness norm adaptation capability, its neural correlates, and long-term mental health outcomes. One hundred and eighty-six twins are recruited and played as responders in the Ultimatum Game (UG) while undergoing fMRI scanning in their early adulthood (Study-1) and are measured on depressive symptoms eight years later (Study-2). With computational modeling, the process of norm adaptation is differentiated from that of fairness valuation in UG. The two processes both have moderate levels of heritability. The anterior insula has a significant phenotypic correlation, whereas the Supplementary Motor Area/Medial Frontal Gyrus (SMA/mSFG) shows both a significant phenotypic correlation and a shared genetic influence with the learning rate, an index for norm adaptation. The dopaminergic DRD2 polymorphisms correlate with both the learning rate and the SMA/mSFG encoding of prediction error, constituting of their common genetic basis. Regional gene expression analysis reveals the high expression of dopamine-related genes in the SMA/mSFG. Moreover, the learning rate can predict depressive symptom severity eight years later, with the DRD2 polymorphisms constituting their shared genetic basis. This suggests that heritability is a non-negligible driving force behind norm adaptation, which facilitates the learning of social norms in changing environments and preserves long-term mental health.

Temporal and spatial variability of large-scale dynamic brain networks in ASD

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by significant impairments in social-cognitive functioning. Prior studies have identified abnormal brain functional connectivity (FC) patterns in individuals with ASD, which are associated with core symptoms and serve as potential biomarkers for diagnosis. However, the patterns of temporal and spatial variability in dynamic functional connectivity networks (dFCNs) in ASD and their relationship with ASD behaviors remain underexplored. This study uses fuzzy entropy to analyze the temporal variability and spatial variability of dFCNs, aiming to reveal distinctive FC patterns in ASD and identify new biomarkers. We conducted a comparative analysis between ASD and healthy controls (HCs), examining the association with clinical symptoms. Our findings indicate increased FC temporal variability in sensorimotor, subcortical, and cerebellar networks in ASD compared to HCs. Additionally, increased spatial variability was observed primarily in visual, limbic, subcortical, and cerebellar networks. Notably, these variability patterns correlated with symptom severity in ASD. Utilizing these spatiotemporal variability features, we developed multi-site classification models that achieved high accuracy (81.25%) in identifying ASD. These results provide novel insights into the neural mechanisms and clinical characteristics of ASD, suggesting that integrated spatiotemporal dFCN features may enhance diagnostic accuracy.

The effect of 3-di-o-tolylguanidine on the level of neurotransmitters in the cerebellum and related disorders of social behavior

It is common knowledge that the cerebellum is a structure of the central nervous system that influences the processes of balance and motor coordination. Recently its influence on social interactions has also been emphasized. The sigma receptor agonist: 3-di-o-tolylguanidine (DTG) is characterized by high affinity for sigma 1 and sigma 2 receptors, widely distributed in the cerebellum. In the experiment we assessed the effect of long term administration of DTG to adult male Sprague Dawley rats on social behavior and the concentration of neurotransmitters in the cerebellum. DTG was administered orally at a dose of 3 mg/kg body weight (bw) (DTG3), 10 mg/kg bw (DTG10) and 30 mg/kg bw (DTG30) for 9 weeks before the behavioral test. After the experiment, the concentration of catecholamines and amino acids in the cerebellum was assessed using high performance liquid chromatography (HPLC). Treatment groups showed reductions in social interactions such as grooming, sniffing and total time spent interacting. At the same time, it was shown that in the group receiving the lowest dose of the drug, a decrease in the concentration of dopamine and serotonin in the cerebellum was observed. Furthermore, changes in the concentration of taurine, alanine, glutamic acid and gamma-aminobutyric acid were observed in the treated groups. We found that long term administration of DTG disturbs animals' social interactions and the concentration of neurotransmitters in the cerebellum.

Neonatal infection with Bordetella pertussis promotes autism-like phenotypes in mice

Autism spectrum disorder (ASD) has been linked with infections early in life. Here we demonstrate that the infection of neonatal mice with the respiratory pathogen Bordetella pertussis leads to neuroinflammation, neurodevelopmental defects, and ASD-like behaviors. Following the respiratory challenge of neonatal mice with B. pertussis, multiple atypical CNS findings were observed, including blood-brain barrier disruption, dissemination of live B. pertussis bacteria to the brain with the concomitant infiltration of inflammatory monocytes, neutrophils, and activated IL-17A- and IFN-γ-producing CD4 T cells. Microglia from infected mice were activated, with impaired phagocytic function, resulting in defective synaptic pruning and disrupted neuronal circuit formation. Impaired neurodevelopment in B. pertussis-infected post-natal mice was associated with ASD-like behavioral abnormalities in young adulthood. Our data indicate that infection with virulent B. pertussis during infancy increases the risk of autism-like behavior in young adult mice. A study into the potential role of B. pertussis in human ASD is warranted.

Altered brain regional homogeneity, depressive symptoms, and cognitive impairments in medication-free female patients with current depressive episodes in bipolar disorder and major depressive disorder

BACKGROUND

Although symptoms of depressive episodes in patients with bipolar depressive episodes (BDE) and major depressive disorder (MDD) are similar, the treatment strategies for these disorders are completely different, suggesting that BDE and MDD have different neurobiological backgrounds. In this study, we examined the relationship between brain function and clinical symptoms, particularly cognitive function, in female individuals with bipolar disorder and MDD experiencing depressive episodes.

METHODS

Regional homogeneity (ReHo) was analyzed in 51 medication-free female patients with BDE, 63 medication-free female patients with MDD, and 45 female healthy controls (HCs). Depressive symptom severity was assessed using the 24-item Hamilton Depression Rating Scale (HAMD-24), and multidimensional cognitive function was evaluated using the MATRICS Consensus Cognition Battery. Partial correlation analysis was used to explore the links between the brain regions and clinical characteristics. A support vector machine (SVM) was used to assess the classification accuracy.

RESULTS

Compared with HCs, patients with BDE and MDD had decreased ReHo in the left lobule VI of the cerebellum and increased ReHo in the left precuneus. Patients with BDE also had reduced ReHo in the left lobules IV-V of the cerebellum and increased ReHo in the right putamen, unlike patients with MDD who had no significant differences in these regions. Patients with BDE exhibited more severe cognitive deficits in processing speed, attention, word learning, and overall cognitive function than those with MDD. In patients with BDE, a significant negative correlation was found between the right putamen and HAMD-24 scores. However, no significant association was observed between abnormal ReHo levels and cognitive function. The SVM effectively differentiated between patients with BDE, MDD, and HCs.

CONCLUSION

Cognitive impairment was more severe in female patients with BDE than in those with MDD. Changes in the ReHo values of the right putamen and left lobules IV-V may serve as unique neuroimaging markers for BDE. Alterations in the ReHo values of the left precuneus and left lobule VI could serve as common pathophysiological mechanisms for BDE and MDD in women and indicate depressive states.

Monoaminergic network abnormalities are associated with fatigue in pediatric multiple sclerosis

BACKGROUND

Fatigue is commonly observed in pediatric multiple sclerosis (pedMS) patients, but its underlying mechanisms remain largely unexplored. We evaluated whether resting-state (RS) functional connectivity (FC) abnormalities in monoaminergic networks contributed to explain fatigue in pedMS.

METHODS

Fifty-five pedMS and twenty-three matched healthy controls (HC) underwent clinical and RS functional MRI assessment. Patients with Fatigue Severity Scale (FSS) score ≥ 4 were classified as fatigued (F). Patterns of dopamine-, noradrenaline- and serotonin-related RS FC were derived by constrained independent component analysis, using PET atlases for dopamine, noradrenaline, and serotonin transporters obtained in HCs' brain.

RESULTS

Compared to non-fatigued (NF)-pedMS patients and HC, F-pedMS patients (15/55, 27.3%) showed decreased dopamine-related RS FC in the right postcentral gyrus. They also showed decreased dopamine-related RS FC in the left insula vs. HC and increased dopamine-related RS FC in the left middle temporal gyrus and cerebellum (lobule VI) vs. NF patients. In the noradrenaline-related network, F-pedMS patients showed decreased RS FC in the left superior parietal lobule and increased RS FC in the right thalamus vs. HC and NF-pedMS. Compared to HC, F-pedMS patients also showed decreased RS FC in the right calcarine cortex and increased RS FC in the right middle frontal gyrus. In the serotonin-related network, F-pedMS patients showed decreased RS FC in the right angular gyrus and increased RS FC in the right postcentral gyrus vs. NF-pedMS patients.

DISCUSSION

In pedMS, fatigue is associated with specific monoaminergic network abnormalities, providing pathological markers for this bothersome symptom and putative targets for its treatment.

Correlations between alterations in global brain functional connectivity in patients with major depressive disorder and their genetic characteristics

This study aims to elucidate the neuroimaging changes associated with major depressive disorder (MDD) and their relationship with genetic characteristics. We conducted a global-brain functional connectivity (GFC) and genetic-neuroimaging correlation analysis on 42 MDD patients and 42 healthy controls (HCs), exploring the correlation between GFC abnormalities and clinical variables. Results showed that compared to HCs, MDD patients had significantly decreased GFC values in the bilateral posterior cingulate cortex/precuneus and increased GFC values in the left and right cerebellum Crus I/II. Additionally, a negative correlation was observed between the GFC values of the left cerebellum Crus I/II and subjective support scores, as well as social support revalued scale total scores. We identified genes associated with GFC changes in MDD, which are enriched in biological processes such as synaptic transmission and ion transport. Our findings indicate the presence of abnormal GFC values in severe depression, complementing the pathological research on the condition. Furthermore, this study provides preliminary evidence for the correlation between social support levels and brain functional connectivity, offering insights into the potential association between GFC changes and gene expression in MDD patients.

Increased understanding of complex neuronal circuits in the cerebellar cortex

The prevailing belief has been that the fundamental structures of cerebellar neuronal circuits, consisting of a few major neuron types, are simple and well understood. Given that the cerebellum has long been known to be crucial for motor behaviors, these simple yet organized circuit structures seemed beneficial for theoretical studies proposing neural mechanisms underlying cerebellar motor functions and learning. On the other hand, experimental studies using advanced techniques have revealed numerous structural properties that were not traditionally defined. These include subdivided neuronal types and their circuit structures, feedback pathways from output Purkinje cells, and the multidimensional organization of neuronal interactions. With the recent recognition of the cerebellar involvement in non-motor functions, it is possible that these newly identified structural properties, which are potentially capable of generating greater complexity than previously recognized, are associated with increased information capacity. This, in turn, could contribute to the wide range of cerebellar functions. However, it remains largely unknown how such structural properties contribute to cerebellar neural computations through the regulation of neuronal activity or synaptic transmissions. To promote further research into cerebellar circuit structures and their functional significance, we aim to summarize the newly identified structural properties of the cerebellar cortex and discuss future research directions concerning cerebellar circuit structures and their potential functions.

Converging and Diverging Cerebellar Pathways for Motor and Social Behaviors in Mice

Evidence from clinical and preclinical studies has shown that the cerebellum contributes to cognitive functions, including social behaviors. Now that the cerebellum's role in a wider range of behaviors has been confirmed, the question arises whether the cerebellum contributes to social behaviors via the same mechanisms with which it modulates movements. This review seeks to answer whether the cerebellum guides motor and social behaviors through identical pathways. It focuses on studies in which cerebellar cells, synapses, or genes are manipulated in a cell-type specific manner followed by testing of the effects on social and motor behaviors. These studies show that both anatomically restricted and cerebellar cortex-wide manipulations can lead to social impairments without abnormal motor control, and vice versa. These studies suggest that the cerebellum employs different cellular, synaptic, and molecular pathways for social and motor behaviors. Future studies warrant a focus on the diverging mechanisms by which the cerebellum contributes to a wide range of neural functions.

Consensus Paper: Cerebellum and Reward

Cerebellum is a key-structure for the modulation of motor, cognitive, social and affective functions, contributing to automatic behaviours through interactions with the cerebral cortex, basal ganglia and spinal cord. The predictive mechanisms used by the cerebellum cover not only sensorimotor functions but also reward-related tasks. Cerebellar circuits appear to encode temporal difference error and reward prediction error. From a chemical standpoint, cerebellar catecholamines modulate the rate of cerebellar-based cognitive learning, and mediate cerebellar contributions during complex behaviours. Reward processing and its associated emotions are tuned by the cerebellum which operates as a controller of adaptive homeostatic processes based on interoceptive and exteroceptive inputs. Lobules VI-VII/areas of the vermis are candidate regions for the cortico-subcortical signaling pathways associated with loss aversion and reward sensitivity, together with other nodes of the limbic circuitry. There is growing evidence that the cerebellum works as a hub of regional dysconnectivity across all mood states and that mental disorders involve the cerebellar circuitry, including mood and addiction disorders, and impaired eating behaviors where the cerebellum might be involved in longer time scales of prediction as compared to motor operations. Cerebellar patients exhibit aberrant social behaviour, showing aberrant impulsivity/compulsivity. The cerebellum is a master-piece of reward mechanisms, together with the striatum, ventral tegmental area (VTA) and prefrontal cortex (PFC). Critically, studies on reward processing reinforce our view that a fundamental role of the cerebellum is to construct internal models, perform predictions on the impact of future behaviour and compare what is predicted and what actually occurs.

Gene discovery and biological insights into anxiety disorders from a large-scale multi-ancestry genome-wide association study

We leveraged information from more than 1.2 million participants, including 97,383 cases, to investigate the genetics of anxiety disorders across five continental groups. Through ancestry-specific and cross-ancestry genome-wide association studies, we identified 51 anxiety-associated loci, 39 of which were novel. In addition, polygenic risk scores derived from individuals of European descent were associated with anxiety in African, admixed American and East Asian groups. The heritability of anxiety was enriched for genes expressed in the limbic system, cerebral cortex, cerebellum, metencephalon, entorhinal cortex and brain stem. Transcriptome-wide and proteome-wide analyses highlighted 115 genes associated with anxiety through brain-specific and cross-tissue regulation. Anxiety also showed global and local genetic correlations with depression, schizophrenia and bipolar disorder and widespread pleiotropy with several physical health domains. Overall, this study expands our knowledge regarding the genetic risk and pathogenesis of anxiety disorders, highlighting the importance of investigating diverse populations and integrating multi-omics information.

The communication mechanism of the gut-brain axis and its effect on central nervous system diseases: A systematic review

Gut microbiota is involved in intricate and active metabolic processes the host's brain function, especially its role in immune responses, secondary metabolism, and symbiotic connections with the host. Gut microbiota can promote the production of essential metabolites, neurotransmitters, and other neuroactive chemicals that affect the development and treatment of central nervous system diseases. This article introduces the relevant pathways and manners of the communication between the brain and gut, summarizes a comprehensive overview of the current research status of key gut microbiota metabolites that affect the functions of the nervous system, revealing those adverse factors that affect typical communication between the brain-gut axis, and outlining the efforts made by researchers to alleviate these neurological diseases through targeted microbial interventions. The relevant pathways and manners of communication between the brain and gut contribute to the experimental design of new treatment plans and drug development. The factors that may cause changes in gut microbiota and affect metabolites, as well as current intervention methods are summarized, which helps improve gut microbiota brain dialogue, prevent adverse triggering factors from interfering with the gut microbiota system, and minimize neuropathological changes.

Alteration in temporal-cerebellar effective connectivity can effectively distinguish stable and progressive mild cognitive impairment

Background

Stable mild cognitive impairment (sMCI) and progressive mild cognitive impairment (pMCI) represent two distinct subtypes of mild cognitive impairment (MCI). Early and effective diagnosis and accurate differentiation between sMCI and pMCI are crucial for administering targeted early intervention and preventing cognitive decline. This study investigated the intrinsic dysconnectivity patterns in sMCI and pMCI based on degree centrality (DC) and effective connectivity (EC) analyses, with the goal of uncovering shared and distinct neuroimaging mechanisms between subtypes.

Methods

Resting-state functional magnetic resonance imaging combined with DC analysis was used to explore the functional connectivity density in 42 patients with sMCI, 31 patients with pMCI, and 82 healthy control (HC) participants. Granger causality analysis was used to assess changes in EC based on the significant clusters found in DC. Furthermore, correlation analysis was conducted to examine the associations between altered DC/EC values and cognitive function. Receiver operating characteristic curve analysis was performed to determine the accuracy of abnormal DC and EC values in distinguishing sMCI from pMCI.

Results

Compared with the HC group, both pMCI and sMCI groups exhibited increased DC in the left inferior temporal gyrus (ITG), left posterior cerebellum lobe (CPL), and right cerebellum anterior lobe (CAL), along with decreased DC in the left medial frontal gyrus. Moreover, the sMCI group displayed reduced EC from the right CAL to bilateral CPL, left superior temporal gyrus, and bilateral caudate compared with HC. pMCI demonstrated elevated EC from the right CAL to left ITG, which was linked to episodic memory and executive function. Notably, the EC from the right CAL to the right ITG effectively distinguished sMCI from pMCI, with sensitivity, specificity, and accuracy of 0.5806, 0.9512, and 0.828, respectively.

Conclusion

This study uncovered shared and distinct alterations in DC and EC between sMCI and pMCI, highlighting their involvement in cognitive function. Of particular significance are the unidirectional EC disruptions from the cerebellum to the temporal lobe, which serve as a discriminating factor between sMCI and pMCI and provide a new perspective for understanding the temporal-cerebellum. These findings offer novel insights into the neural circuit mechanisms involving the temporal-cerebellum connection in MCI.

Extraction, Phytochemical profile, and neuroprotective activity of Phyllanthus emblica fruit extract against sodium valproate-induced postnatal autism in BALB/c mice

The aim of the present study was to evaluate the effect of the ethyl acetate fraction of amla (EAFA) extract on valproic acid (VPA)-induced postnatal autism in BALB/c mice. Our study revealed that mice treated with VPA on postnatal day 14 (PND14) showed significant abnormal behaviours such as social interaction, social affiliation, anxiety, and motor coordination compared to the control group, while EAFA extract treatment (100 mg/kg) ameliorated these symptoms. Our study highlights the protective effect of EAFA extract on improving behavioural alterations, significantly restoring anti-oxidative enzymes such as GST and GR, and reducing MDA and NO levels. Furthermore, the EAFA-treated group significantly lowered the proinflammatory markers (IL-1β and TNF-α) and the expression of up-regulated 5-HT1D, 5-HT2A, and D2 receptor proteins. Based on histopathological studies, the percentage of neuronal injury in the EAFA-treated group as well as cellular structural changes were reduced using SEM analysis. In conclusion, the present study suggests that treatment with EAFA extract ameliorates VPA-induced autism due to its anti-oxidant and neuroprotective activity.

New clues for the role of cerebellum in schizophrenia and the associated cognitive impairment

Schizophrenia (SZ) is a complex neuropsychiatric disorder associated with severe cognitive dysfunction. Although research has mainly focused on forebrain abnormalities, emerging results support the involvement of the cerebellum in SZ physiopathology, particularly in Cognitive Impairment Associated with SZ (CIAS). Besides its role in motor learning and control, the cerebellum is implicated in cognition and emotion. Recent research suggests that structural and functional changes in the cerebellum are linked to deficits in various cognitive domains including attention, working memory, and decision-making. Moreover, cerebellar dysfunction is related to altered cerebellar circuit activities and connectivity with brain regions associated with cognitive processing. This review delves into the role of the cerebellum in CIAS. We initially consider the major forebrain alterations in CIAS, addressing impairments in neurotransmitter systems, synaptic plasticity, and connectivity. We then focus on recent findings showing that several mechanisms are also altered in the cerebellum and that cerebellar communication with the forebrain is impaired. This evidence implicates the cerebellum as a key component of circuits underpinning CIAS physiopathology. Further studies addressing cerebellar involvement in SZ and CIAS are warranted and might open new perspectives toward understanding the physiopathology and effective treatment of these disorders.

The influence of acute dopamine transporter inhibition on manic-, depressive-like phenotypes, and brain oxidative status in adult zebrafish

Functional changes in dopamine transporter (DAT) are related to various psychiatric conditions, including bipolar disorder (BD) symptoms. In experimental research, the inhibition of DAT induces behavioral alterations that recapitulate symptoms found in BD patients, including mania and depressive mood. Thus, developing novel animal models that mimic BD-related conditions by pharmacologically modulating the dopaminergic signaling is relevant. The zebrafish (Danio rerio) has been considered a suitable vertebrate system for modeling BD-like responses, due to the well-characterized behavioral responses and evolutionarily conservation of the dopaminergic system of this species. Here, we investigate whether GBR 12909, a selective inhibitor of DAT, causes neurobehavioral alterations in zebrafish similar to those observed in BD patients. Behaviors were recorded after a single intraperitoneal (i.p.) administration of GBR 12909 at different doses (3.75, 7.5, 15 and 30 mg/kg). To observe temporal effects on behavior, swim path parameters were measured immediately after the administration period during 30 min. Locomotion, anxiety-like behavior, social preference, aggression, despair-like behavior, and oxidative stress-related biomarkers in the brain were measured 30 min post administration. GBR 12909 induced prominent effects on locomotor activity and vertical exploration during the 30-min period. Hyperactivity was observed in GBR 30 group after 25 min, while all doses markedly reduced vertical drifts. GBR 12909 elicited hyperlocomotion, anxiety-like behavior, decreased social preference, aggression, and induced depressive-like behavior in a behavioral despair task. Depending on the dose, GBR 12909 also decreased SOD activity and TBARS levels, as well as increased GR activity and NPSH content. Collectively, our novel findings show that a single GBR 12909 administration evokes neurobehavioral changes that recapitulate manic- and depressive-like states observed in rodents, fostering the use of zebrafish models to explore BD-like responses in translational neuroscience research.

Dopamine receptors of the rodent fastigial nucleus support skilled reaching for goal-directed action

The dopaminergic (DA) system regulates both motor function, and learning and memory. The cerebellum supports motor control and the acquisition of procedural memories, including goal-directed behavior, and is subjected to DA control. Its fastigial nucleus (FN) controls and interprets body motion through space. The expression of dopamine receptors has been reported in the deep cerebellar nuclei of mice. However, the presence of dopamine D1-like (D1R) and D2-like (D2R) receptors in the rat FN has not yet been verified. In this study, we first confirmed that DA receptors are expressed in the FN of adult rats and then targeted these receptors to explore to what extent the FN modulates goal-directed behavior. Immunohistochemical assessment revealed expression of both D1R and D2R receptors in the FN, whereby the medial lateral FN exhibited higher receptor expression compared to the other FN subfields. Bilateral treatment of the FN with a D1R antagonist, prior to a goal-directed pellet-reaching task, significantly impaired task acquisition and decreased task engagement. D2R antagonism only reduced late performance post-acquisition. Once task acquisition had occurred, D1R antagonism had no effect on successful reaching, although it significantly decreased reaching speed, task engagement, and promoted errors. Motor coordination and ambulation were, however, unaffected as neither D1R nor D2R antagonism altered rotarod latencies or distance and velocity in an open field. Taken together, these results not only reveal a novel role for the FN in goal-directed skilled reaching, but also show that D1R expressed in FN regulate this process by modulating motivation for action.

Cognitive, Emotional, and Other Non-motor Symptoms of Spinocerebellar Ataxias

PURPOSE OF REVIEW

Spinocerebellar ataxias (SCAs) are autosomal dominant degenerative syndromes that present with ataxia and brain stem abnormalities. This review describes the cognitive and behavioral symptoms of SCAs in the context of recent knowledge of the role of the cerebellum in higher intellectual function.

RECENT FINDINGS

Recent studies suggest that patients with spinocerebellar ataxia can display cognitive deficits even early in the disease. These have been given the term cerebellar cognitive affective syndrome (CCAS). CCAS can be tracked using newly developed rating scales. In addition, patients with spinocerebellar ataxia also display impulsive and compulsive behavior, depression, anxiety, fatigue, and sleep disturbances. This review stresses the importance of recognizing non-motor symptoms in SCAs. There is a pressing need for novel therapeutic interventions to address these symptoms given their deleterious impact on patients' quality of life.

Clinically approved immunomodulators ameliorate behavioral changes in a mouse model of hereditary spastic paraplegia type 11

We have previously demonstrated that neuroinflammation by the adaptive immune system acts as a robust and targetable disease amplifier in a mouse model of Spastic Paraplegia, type 11 (SPG11), a complicated form of Hereditary Spastic Paraplegia (HSP). While we identified an impact of neuroinflammation on distinct neuropathological changes and gait performance, neuropsychological features, typical and clinically highly relevant symptoms of complicated HSPs, were not addressed. Here we show that the corresponding SPG11 mouse model shows distinct behavioral abnormalities, particularly related to social behavior thus partially reflecting the neuropsychological changes in patients. We provide evidence that some behavioral abnormalities can be mitigated by genetic inactivation of the adaptive immune system. Translating this into a clinically applicable approach, we show that treatment with the established immunomodulators fingolimod or teriflunomide significantly attenuates distinct behavioral abnormalities, with the most striking effect on social behavior. This study links neuroinflammation to behavioral abnormalities in a mouse model of SPG11 and may thus pave the way for using immunomodulators as a treatment approach for SPG11 and possibly other complicated forms of HSP with neuropsychological involvement.

Gene Discovery and Biological Insights into Anxiety Disorders from a Multi-Ancestry Genome-wide Association Study of >1.2 Million Participants

We leveraged information from more than 1.2 million participants to investigate the genetics of anxiety disorders across five continental ancestral groups. Ancestry-specific and cross-ancestry genome-wide association studies identified 51 anxiety-associated loci, 39 of which are novel. Additionally, polygenic risk scores derived from individuals of European descent were associated with anxiety in African, Admixed-American, and East Asian groups. The heritability of anxiety was enriched for genes expressed in the limbic system, the cerebral cortex, the cerebellum, the metencephalon, the entorhinal cortex, and the brain stem. Transcriptome- and proteome-wide analyses highlighted 115 genes associated with anxiety through brain-specific and cross-tissue regulation. We also observed global and local genetic correlations with depression, schizophrenia, and bipolar disorder and putative causal relationships with several physical health conditions. Overall, this study expands the knowledge regarding the genetic risk and pathogenesis of anxiety disorders, highlighting the importance of investigating diverse populations and integrating multi-omics information.

A review of the neurotransmitter system associated with cognitive function of the cerebellum in Parkinson's disease

The dichotomized brain system is a concept that was generalized from the 'dual syndrome hypothesis' to explain the heterogeneity of cognitive impairment, in which anterior and posterior brain systems are independent but partially overlap. The dopaminergic system acts on the anterior brain and is responsible for executive function, working memory, and planning. In contrast, the cholinergic system acts on the posterior brain and is responsible for semantic fluency and visuospatial function. Evidence from dopaminergic/cholinergic imaging or functional neuroimaging has shed significant insight relating to the involvement of the cerebellum in the cognitive process of patients with Parkinson's disease. Previous research has reported evidence that the cerebellum receives both dopaminergic and cholinergic projections. However, whether these two neurotransmitter systems are associated with cognitive function has yet to be fully elucidated. Furthermore, the precise role of the cerebellum in patients with Parkinson's disease and cognitive impairment remains unclear. Therefore, in this review, we summarize the cerebellar dopaminergic and cholinergic projections and their relationships with cognition, as reported by previous studies, and investigated the role of the cerebellum in patients with Parkinson's disease and cognitive impairment, as determined by functional neuroimaging. Our findings will help us to understand the role of the cerebellum in the mechanisms underlying cognitive impairment in Parkinson's disease.

Human cerebellar organoids with functional Purkinje cells

Research on human cerebellar development and disease has been hampered by the need for a human cell-based system that recapitulates the human cerebellum's cellular diversity and functional features. Here, we report a human organoid model (human cerebellar organoids [hCerOs]) capable of developing the complex cellular diversity of the fetal cerebellum, including a human-specific rhombic lip progenitor population that have never been generated in vitro prior to this study. 2-month-old hCerOs form distinct cytoarchitectural features, including laminar organized layering, and create functional connections between inhibitory and excitatory neurons that display coordinated network activity. Long-term culture of hCerOs allows healthy survival and maturation of Purkinje cells that display molecular and electrophysiological hallmarks of their in vivo counterparts, addressing a long-standing challenge in the field. This study therefore provides a physiologically relevant, all-human model system to elucidate the cell-type-specific mechanisms governing cerebellar development and disease.

Dopamine D2 receptors in pyramidal neurons in the medial prefrontal cortex regulate social behavior

Drugs acting on dopamine D2 receptors are widely used for the treatment of several neuropsychiatric disorders, including schizophrenia and depression. Social deficits are a core symptom of these disorders. Pharmacological manipulation of dopamine D2 receptors (Drd2), a Gi-coupled subtype of dopamine receptors, in the medial prefrontal cortex (mPFC) has shown that Drd2 is implicated in social behaviors. However, the type of neurons expressing Drd2 in the mPFC and the underlying circuit mechanism regulating social behaviors remain largely unknown. Here, we show that Drd2 were mainly expressed in pyramidal neurons in the mPFC and that the activation of the Gi-pathway in Drd2+ pyramidal neurons impaired social behavior in male mice. In contrast, the knockdown of D2R in pyramidal neurons in the mPFC enhanced social approach behaviors in male mice and selectively facilitated the activation of mPFC neurons projecting to the nucleus accumbens (NAc) during social interaction. Remarkably, optogenetic activation of mPFC-to-NAc-projecting neurons mimicked the effects of conditional D2R knockdown on social behaviors. Altogether, these results demonstrate a cell type-specific role for Drd2 in the mPFC in regulating social behavior, which may be mediated by the mPFC-to-NAc pathway.

Spatiomolecular Characterization of Dopamine D2 Receptors Cells in the Mouse External Globus Pallidus

The external globus pallidus (GPe) is part of the basal ganglia circuit and plays a key role in controlling the actions. Although, many evidence indicate that dopamine through its activation of dopamine D2 receptors (D2Rs) modulates the GPe neuronal activity, the precise spatiomolecular characterization of cell populations expressing D2Rs in the mouse GPe is still lacking. By combining single molecule in situ hybridization, cell type-specific imaging analyses, and electrophysiology slice recordings, we found that GPe D2R cells are neurons preferentially localized in the caudal portion of GPe. These neurons comprising pallido-striatal, pallido-nigral, and pallido-cortical neurons segregate into two distinct populations displaying molecular and electrophysiological features of GPe GABAergic PV/NKX2.1 and cholinergic neurons respectively. By clarifying the spatial molecular identity of GPe D2R neurons in the mouse, this work provides the basis for future studies aiming at disentangling the action of dopamine within the GPe.

Altered brain regional homogeneity is associated with cognitive dysfunction in first-episode drug-naive major depressive disorder: A resting-state fMRI study

BACKGROUND

Our study aimed to explore the abnormal spontaneous brain activity by regional homogeneity (ReHo) and its association with cognitive function to understand the neuropathology of major depressive disorder (MDD).

METHODS

ReHo was used to investigate brain activities of 60 patients with first-episode drug-naive MDD and 60 healthy controls (HCs). Partial correlation analysis was conducted on altered ReHo values and the severity of symptoms and cognitive deficits. Moreover, support vector machine analysis was used to evaluate the accuracy of abnormal ReHo values in distinguishing patients with MDD from HCs.

RESULTS

Compared with HCs, patients with MDD showed significantly increased ReHo values in the right cerebellum crus2 and right thalamus and decreased ReHo values in the right angular gyrus (AG) and right precuneus (PCUN). The ReHo values in right cerebellum crus2 and right AG were positively associated with working memory and visual learning, respectively. Furthermore, the combination of ReHo values in the right cerebellum crus2 and right PCUN discriminated the patients with MDD from HCs with specificity, sensitivity, and accuracy of 0.9688, 0.6250, and 0.90, respectively.

LIMITATIONS

The design of repeated cross-sectional surveys does not allow analyses of within individual changes.

CONCLUSIONS

Our study revealed that the pathophysiology mechanism of cognitive deficits in MDD may be related to abnormal spontaneous brain activity. Moreover, the combination of ReHo values in the right cerebellum crus2 and right PCUN can be used to discriminate patients with MDD from HCs effectively.

The cerebellum plays more than one role in the dysregulation of appetite: Review of structural evidence from typical and eating disorder populations

OBJECTIVE

Dysregulated appetite control is characteristic of anorexia nervosa (AN), bulimia nervosa (BN), and obesity (OB). Studies using a broad range of methods suggest the cerebellum plays an important role in aspects of weight and appetite control, and is implicated in both AN and OB by reports of aberrant gray matter volume (GMV) compared to nonclinical populations. As functions of the cerebellum are anatomically segregated, specific localization of aberrant anatomy may indicate the mechanisms of its relationship with weight and appetite in different states. We sought to determine if there were consistencies in regions of cerebellar GMV changes in AN/BN and OB, as well as across normative (NOR) variation.

METHOD

Systematic review and meta-analysis using GingerALE.

RESULTS

Twenty-six publications were identified as either case-control studies (nOB  = 277; nAN/BN  = 510) or regressed weight from NOR data against brain volume (total n = 3830). AN/BN and OB analyses both showed consistently decreased GMV within Crus I and Lobule VI, but volume reduction was bilateral for AN/BN and unilateral for OB. Analysis of the NOR data set identified a cluster in right posterior lobe that overlapped with AN/BN cerebellar reduction. Sensitivity analyses indicated robust repeatability for NOR and AN/BN cohorts, but found OB-specific heterogeneity.

DISCUSSION

Findings suggest that more than one area of the cerebellum is involved in control of eating behavior and may be differentially affected in normal variation and pathological conditions. Specifically, we hypothesize an association with sensorimotor and emotional learning via Lobule VI in AN/BN, and executive function via Crus I in OB.

Challenges and innovations in brain PET analysis of neurodegenerative disorders: a mini-review on partial volume effects, small brain region studies, and reference region selection

Positron Emission Tomography (PET) brain imaging is increasingly utilized in clinical and research settings due to its unique ability to study biological processes and subtle changes in living subjects. However, PET imaging is not without its limitations. Currently, bias introduced by partial volume effect (PVE) and poor signal-to-noise ratios of some radiotracers can hamper accurate quantification. Technological advancements like ultra-high-resolution scanners and improvements in radiochemistry are on the horizon to address these challenges. This will enable the study of smaller brain regions and may require more sophisticated methods (e.g., data-driven approaches like unsupervised clustering) for reference region selection and to improve quantification accuracy. This review delves into some of these critical aspects of PET molecular imaging and offers suggested strategies for improvement. This will be illustrated by showing examples for dopaminergic and cholinergic nerve terminal ligands.

CHL1 depletion affects dopamine receptor D2-dependent modulation of mouse behavior

Introduction

The dopaminergic system plays a key role in the appropriate functioning of the central nervous system, where it is essential for emotional balance, arousal, reward, and motor control. The cell adhesion molecule close homolog of L1 (CHL1) contributes to dopaminergic system development, and CHL1 and the dopamine receptor D2 (D2R) are associated with mental disorders like schizophrenia, addiction, autism spectrum disorder and depression.

Methods

Here, we investigated how the interplay between CHL1 and D2R affects the behavior of young adult male and female wild-type (CHL+/+) and CHL1-deficient (CHL1-/-) mice, when D2R agonist quinpirole and antagonist sulpiride are applied.

Results

Low doses of quinpirole (0.02 mg/kg body weight) induced hypolocomotion of CHL1+/+ and CHL1-/- males and females, but led to a delayed response in CHL1-/- mice. Sulpiride (1 mg/kg body weight) affected locomotion of CHL1-/- females and social interaction of CHL1+/+ females as well as social interactions of CHL1-/- and CHL1+/+ males. Quinpirole increased novelty-seeking behavior of CHL1-/- males compared to CHL1+/+ males. Vehicle-treated CHL1-/- males and females showed enhanced working memory and reduced stress-related behavior.

Discussion

We propose that CHL1 regulates D2R-dependent functions in vivo. Deficiency of CHL1 leads to abnormal locomotor activity and emotionality, and to sex-dependent behavioral differences.

A Functional Connectome-Based Neural Signature for Individualized Prediction of Antipsychotic Response in First-Episode Psychosis

OBJECTIVE

Identification of robust biomarkers that predict individualized response to antipsychotic treatment at the early stage of psychotic disorders remains a challenge in precision psychiatry. The aim of this study was to investigate whether any functional connectome-based neural traits could serve as such a biomarker.

METHODS

In a discovery sample, 49 patients with first-episode psychosis received multi-paradigm fMRI scans at baseline and were clinically followed up for 12 weeks under antipsychotic monotherapies. Treatment response was evaluated at the individual level based on the psychosis score of the Brief Psychiatric Rating Scale. Cross-paradigm connectivity and connectome-based predictive modeling were employed to train a predictive model that uses baseline connectomic measures to predict individualized change rates of psychosis scores, with model performance evaluated as the Pearson correlations between the predicted change rates and the observed change rates, based on cross-validation. The model generalizability was further examined in an independent validation sample of 24 patients in a similar design.

RESULTS

The results revealed a paradigm-independent connectomic trait that significantly predicted individualized treatment outcome in both the discovery sample (predicted-versus-observed r=0.41) and the validation sample (predicted-versus-observed r=0.47, mean squared error=0.019). Features that positively predicted psychosis change rates primarily involved connections related to the cerebellar-cortical circuitry, and features that negatively predicted psychosis change rates were chiefly connections within the cortical cognitive systems.

CONCLUSIONS

This study discovers and validates a connectome-based functional signature as a promising early predictor for individualized response to antipsychotic treatment in first-episode psychosis, thus highlighting the potential clinical value of this biomarker in precision psychiatry.

Oxytocin Receptor in Cerebellar Purkinje Cells Does Not Engage in Autism-Related Behaviors

The classical motor center cerebellum is one of the most consistent structures of abnormality in autism spectrum disorders (ASD), and neuropeptide oxytocin is increasingly explored as a potential pharmacotherapy for ASD. However, whether oxytocin targets the cerebellum for therapeutic effects remains unclear. Here, we report a localization of oxytocin receptor (OXTR) in Purkinje cells (PCs) of cerebellar lobule Crus I, which is functionally connected with ASD-implicated circuits. OXTR activation neither affects firing activities, intrinsic excitability, and synaptic transmission of normal PCs nor improves abnormal intrinsic excitability and synaptic transmission of PCs in maternal immune activation (MIA) mouse model of autism. Furthermore, blockage of OXTR in Crus I in wild-type mice does not induce autistic-like social, stereotypic, cognitive, and anxiety-like behaviors. These results suggest that oxytocin signaling in Crus I PCs seems to be uninvolved in ASD pathophysiology, and contribute to understanding of targets and mechanisms of oxytocin in ASD treatment.

Assessing the Location, Relative Expression and Subclass of Dopamine Receptors in the Cerebellum of Hemi-Parkinsonian Rats

Parkinson's Disease (PD) is a neurodegenerative disease with loss of dopaminergic neurons in the nigrostriatal pathway resulting in basal ganglia (BG) dysfunction. This is largely why much of the preclinical and clinical research has focused on pathophysiological changes in these brain areas in PD. The cerebellum is another motor area of the brain. Yet, if and how this brain area responds to PD therapy and contributes to maintaining motor function fidelity in the face of diminished BG function remains largely unanswered. Limited research suggests that dopaminergic signaling exists in the cerebellum with functional dopamine receptors, tyrosine hydroxylase (TH) and dopamine transporters (DATs); however, much of this information is largely derived from healthy animals and humans. Here, we identified the location and relative expression of dopamine 1 receptors (D1R) and dopamine 2 receptors (D2R) in the cerebellum of a hemi-parkinsonian male rat model of PD. D1R expression was higher in PD animals compared to sham animals in both hemispheres in the purkinje cell layer (PCL) and granule cell layer (GCL) of the cerebellar cortex. Interestingly, D2R expression was higher in PD animals than sham animals mostly in the posterior lobe of the PCL, but no discernible pattern of D2R expression was seen in the GCL between PD and sham animals. To our knowledge, we are the first to report these findings, which may lay the foundation for further interrogation of the role of the cerebellum in PD therapy and/or pathophysiology.

CSMD3 Deficiency Leads to Motor Impairments and Autism-Like Behaviors via Dysfunction of Cerebellar Purkinje Cells in Mice

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with highly heritable heterogeneity. Mutations of CUB and sushi multiple domains 3 (CSMD3) gene have been reported in individuals with ASD. However, the underlying mechanisms of CSMD3 for the onset of ASD remain unexplored. Here, using male CSMD3 knock-out (CSMD3 -/-) mice, we found that genetic deletion of CSMD3 produced core autistic-like symptoms (social interaction deficits, restricted interests, and repetitive and stereotyped behaviors) and motor dysfunction in mice, indicating that the CSMD3 gene can be considered as a candidate for ASD. Moreover, we discovered that the ablation of CSMD3 in mice led to abnormal cerebellar Purkinje cell (PC) morphology in Crus I/II lobules, including aberrant developmental dendritogenesis and spinogenesis of PCs. Furthermore, combining in vivo fiber photometry calcium imaging and ex vivo electrophysiological recordings, we showed that the CSMD3 -/- mice exhibited an increased neuronal activity (calcium fluorescence signals) in PCs of Crus I/II lobules in response to movement activity, as well as an enhanced intrinsic excitability of PCs and an increase of excitatory rather than inhibitory synaptic input to the PCs, and an impaired long-term depression at the parallel fiber-PC synapse. These results suggest that CSMD3 plays an important role in the development of cerebellar PCs. Loss of CSMD3 causes abnormal PC morphology and dysfunction in the cerebellum, which may underlie the pathogenesis of motor deficits and core autistic-like symptoms in CSMD3 -/- mice. Our findings provide novel insight into the pathophysiological mechanisms by which CSMD3 mutations cause impairments in cerebellar function that may contribute to ASD.SIGNIFICANCE STATEMENT Autism spectrum disorder (ASD) is a neurodevelopmental disorder with highly heritable heterogeneity. Advances in genomic analysis have contributed to numerous candidate genes for the risk of ASD. Recently, a novel giant gene CSMD3 encoding a protein with CUB and sushi multiple domains (CSMDs) has been identified as a candidate gene for ASD. However, the underlying mechanisms of CSMD3 for the onset of ASD remain largely unknown. Here, we unravel that loss of CSMD3 results in abnormal morphology, increased intrinsic excitabilities, and impaired synaptic plasticity in cerebellar PCs, subsequently leading to motor deficits and ASD-like behaviors in mice. These results provide novel insight into the pathophysiological mechanisms by which CSMD3 mutations cause impairments in cerebellar function that may contribute to ASD.

Glutamatergic cerebellar neurons differentially contribute to the acquisition of motor and social behaviors

Insults to the developing cerebellum can cause motor, language, and social deficits. Here, we investigate whether developmental insults to different cerebellar neurons constrain the ability to acquire cerebellar-dependent behaviors. We perturb cerebellar cortical or nuclei neuron function by eliminating glutamatergic neurotransmission during development, and then we measure motor and social behaviors in early postnatal and adult mice. Altering cortical and nuclei neurons impacts postnatal motor control and social vocalizations. Normalizing neurotransmission in cortical neurons but not nuclei neurons restores social behaviors while the motor deficits remain impaired in adults. In contrast, manipulating only a subset of nuclei neurons leaves social behaviors intact but leads to early motor deficits that are restored by adulthood. Our data uncover that glutamatergic neurotransmission from cerebellar cortical and nuclei neurons differentially control the acquisition of motor and social behaviors, and that the brain can compensate for some but not all perturbations to the developing cerebellum.

Little brain, little minds: The big role of the cerebellum in social development

Seminal work in the 1990's found alterations in the cerebellum of individuals with social disorders including autism spectrum disorder and schizophrenia. In neurotypical populations, distinct portions of the posterior cerebellum are consistently activated in fMRI studies of social cognition and it has been hypothesized that the cerebellum plays an essential role in social cognition, particularly in theory of mind. Here we review the lesion literature and find that the effect of cerebellar damage on social cognition is strongly linked to the age of insult, with dramatic impairments observed after prenatal insult, strong deficits observed after childhood damage, and mild and inconsistent deficits observed following damage to the adult cerebellum. To explain the developmental gradient, we propose that early in life, the forward model dominates cerebellar computations. The forward model learns and uses errors to help build schemas of our interpersonal worlds. Subsequently, we argue that once these schemas have been built up, the inverse model, which is the foundation of automatic processing, becomes dominant. We provide suggestions for how to test this, and also outline directions for future research.

Purkinje cell dopaminergic inputs to astrocytes regulate cerebellar-dependent behavior

Dopamine has a significant role in motor and cognitive function. The dopaminergic pathways originating from the midbrain have received the most attention; however, the relevance of the cerebellar dopaminergic system is largely undiscovered. Here, we show that the major cerebellar astrocyte type Bergmann glial cells express D1 receptors. Dopamine can be synthesized in Purkinje cells by cytochrome P450 and released in an activity-dependent fashion. We demonstrate that activation of D1 receptors induces membrane depolarization and Ca2+ release from the internal store. These astrocytic activities in turn modify Purkinje cell output by altering its excitatory and inhibitory synaptic input. Lastly, we show that conditional knockout of D1 receptors in Bergmann glial cells results in decreased locomotor activity and impaired social activity. These results contribute to the understanding of the molecular, cellular, and circuit mechanisms underlying dopamine function in the cerebellum, revealing a critical role for the cerebellar dopaminergic system in motor and social behavior.

Activation of D1R signaling in the medial prefrontal cortex rescues maternal separation-induced behavioral deficits through restoration of excitatory neurotransmission

Lack of maternal care and attention during infancy and childhood increases the likelihood of developing a range of neuropsychiatric disorders, such as social deficits, working memory impairment, and anxiety-like behaviors, in adulthood. However, the neuroregulatory signaling through which early-life stress causes behavioral and cognitive abnormalities in the offspring is largely unexplored. Here, we show that in mice, unpredictable maternal separation (MS) during the early postnatal period impairs neuronal development in the medial prefrontal cortex (mPFC) and results in long-lasting behavioral changes. Additionally, MS disrupts excitatory neurotransmission and inhibits the neuronal activity of pyramidal neurons in the mPFC. Differentially expressed gene (DEG) analysis of RNA sequencing (RNA-seq) data of mPFC showed that dopamine D1 receptor (D1R) was significantly downregulated in MS animals. Finally, we show that pharmacological activation of D1R signaling specifically in the mPFC improves neuronal excitability and rescues behavioral and cognitive dysfunction of MS mice, whereas pharmacologically inhibiting of D1R in the mPFC mimics MS-induced behavioral abnormalities in control mice. Together, our results identify D1R signaling in the mPFC, at least in part, as a potential therapeutic target for the behavioral and cognitive abnormalities caused by deprivation of maternal care in early life.

The humanised CYP2C19 transgenic mouse exhibits cerebellar atrophy and movement impairment reminiscent of ataxia

AIMS

CYP2C19 transgenic mouse expresses the human CYP2C19 gene in the liver and developing brain, and it exhibits altered neurodevelopment associated with impairments in emotionality and locomotion. Because the validation of new animal models is essential for the understanding of the aetiology and pathophysiology of movement disorders, the objective was to characterise motoric phenotype in CYP2C19 transgenic mice and to investigate its validity as a new animal model of ataxia.

METHODS

The rotarod, paw-print and beam-walking tests were utilised to characterise the motoric phenotype. The volumes of 20 brain regions in CYP2C19 transgenic and wild-type mice were quantified by 9.4T gadolinium-enhanced post-mortem structural neuroimaging. Antioxidative enzymatic activity was quantified biochemically. Dopaminergic alterations were characterised by chromatographic quantification of concentrations of dopamine and its metabolites and by subsequent immunohistochemical analyses. The beam-walking test was repeated after the treatment with dopamine receptor antagonists ecopipam and raclopride.

RESULTS

CYP2C19 transgenic mice exhibit abnormal, unilateral ataxia-like gait, clasping reflex and 5.6-fold more paw-slips in the beam-walking test; the motoric phenotype was more pronounced in youth. Transgenic mice exhibited a profound reduction of 12% in cerebellar volume and a moderate reduction of 4% in hippocampal volume; both regions exhibited an increased antioxidative enzyme activity. CYP2C19 mice were hyperdopaminergic; however, the motoric impairment was not ameliorated by dopamine receptor antagonists, and there was no alteration in the number of midbrain dopaminergic neurons in CYP2C19 mice.

CONCLUSIONS

Humanised CYP2C19 transgenic mice exhibit altered gait and functional motoric impairments; this phenotype is likely caused by an aberrant cerebellar development.

The cerebellum and anxiety

Although the cerebellum is traditionally known for its role in motor functions, recent evidence points toward the additional involvement of the cerebellum in an array of non-motor functions. One such non-motor function is anxiety behavior: a series of recent studies now implicate the cerebellum in anxiety. Here, we review evidence regarding the possible role of the cerebellum in anxiety-ranging from clinical studies to experimental manipulation of neural activity-that collectively points toward a role for the cerebellum, and possibly a specific topographical locus within the cerebellum, as one of the orchestrators of anxiety responses.

Long-term postoperative quality of life in childhood survivors with cerebellar mutism syndrome

Background

To investigate the long-term quality of life (QoL) of children with cerebellar mutism syndrome (CMS) and explore the risk factors for a low QoL.

Procedure

This cross-sectional study investigated children who underwent posterior fossa surgery using an online Pediatric Quality of Life Inventory questionnaire. CMS and non-CMS patients were included to identify QoL predictors.

Results

Sixty-nine patients were included (male, 62.3%), 22 of whom had CMS. The mean follow-up time was 45.2 months. Children with CMS had a significantly lower mean QoL score (65.3 vs. 83.7, p < 0.001) and subdomain mean scores (physical; 57.8 vs. 85.3, p < 0.001; social: 69.5 vs. 85.1, p = 0.001; academic: p = 0.001) than those without CMS, except for the emotional domain (78.0 vs. 83.7, p = 0.062). Multivariable analysis revealed that CMS (coefficient = -14.748.61, p = 0.043), chemotherapy (coefficient = -7.629.82, p = 0.013), ventriculoperitoneal (VP) shunt placement (coefficient = -10.14, p = 0.024), and older age at surgery (coefficient = -1.1830, p = 0.007) were independent predictors of low total QoL scores. Physical scores were independently associated with CMS (coefficient = -27.4815.31, p = 0.005), VP shunt placement (coefficient = -12.86, p = 0.025), and radiotherapy (coefficient = -13.62, p = 0.007). Emotional score was negatively associated with age at surgery (coefficient = -1.92, p = 0.0337) and chemotherapy (coefficient = -9.11, p = 0.003). Social scores were negatively associated with male sex (coefficient = -13.68, p = 0.001) and VP shunt placement (coefficient = -1.36, p = 0.005), whereas academic scores were negatively correlated with chemotherapy (coefficient = -17.45, p < 0.001) and age at surgery (coefficient = -1.92, p = 0.002). Extent of resection (coefficient = 13.16, p = 0.021) was a good predictor of higher academic scores.

Conclusion

CMS results in long-term neurological and neuropsychological deficits, negatively affecting QoL, and warranting early rehabilitation.

Potential Interactions Between Cerebellar Dysfunction and Sleep Disturbances in Dystonia

Dystonia is the third most common movement disorder. It causes debilitating twisting postures that are accompanied by repetitive and sometimes intermittent co- or over-contractions of agonist and antagonist muscles. Historically diagnosed as a basal ganglia disorder, dystonia is increasingly considered a network disorder involving various brain regions including the cerebellum. In certain etiologies of dystonia, aberrant motor activity is generated in the cerebellum and the abnormal signals then propagate through a “dystonia circuit” that includes the thalamus, basal ganglia, and cerebral cortex. Importantly, it has been reported that non-motor defects can accompany the motor symptoms; while their severity is not always correlated, it is hypothesized that common pathways may nevertheless be disrupted. In particular, circadian dysfunction and disordered sleep are common non-motor patient complaints in dystonia. Given recent evidence suggesting that the cerebellum contains a circadian oscillator, displays sleep-stage-specific neuronal activity, and sends robust long-range projections to several subcortical regions involved in circadian rhythm regulation, disordered sleep in dystonia may result from cerebellum-mediated dysfunction of the dystonia circuit. Here, we review the evidence linking dystonia, cerebellar network dysfunction, and cerebellar involvement in sleep. Together, these ideas may form the basis for the development of improved pharmacological and surgical interventions that could take advantage of cerebellar circuitry to restore normal motor function as well as non-motor (sleep) behaviors in dystonia.