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Near‐infrared spectroscopy (NIRS) is a noninvasive optical technique that uses the near‐infrared spectrum for functional neuroimaging by measuring oxygenation and hemodynamic changes in the cerebral cortex. The advantages of NIRS include its portability and ease of application, which allows for testing with the subject in natural positions, such as sitting or standing. Since 1994, NIRS has been increasingly used to conduct functional activation studies on different psychiatric disorders, most prominently schizophrenia, depression, bipolar disorder, and neurodevelopmental disorders. However, limited information on its use among child and adolescent patients is available. We herein review recent findings obtained using NIRS measurements of the brain during cognitive tasks in neurodevelopmental disorders, such as autism spectrum disorder, attention‐deficit/hyperactivity disorder, obsessive–compulsive disorder, and Tourette's disorder. This will facilitate evaluations of the causation and treatment of prefrontal cortex dysfunctions.

Social isolation during the juvenile critical window is detrimental to proper functioning of the prefrontal cortex (PFC) and establishment of appropriate adult social behaviors. However, the specific circuits that undergo social experience-dependent maturation to regulate social behavior are poorly understood. We identify a specific activation pattern of parvalbumin-positive interneurons (PVIs) in dorsal-medial PFC (dmPFC) prior to an active bout, or a bout initiated by the focal mouse, but not during a passive bout when mice are explored by a stimulus mouse. Optogenetic and chemogenetic manipulation reveals that brief dmPFC-PVI activation triggers an active social approach to promote sociability. Juvenile social isolation decouples dmPFC-PVI activation from subsequent active social approach by freezing the functional maturation process of dmPFC-PVIs during the juvenile-to-adult transition. Chemogenetic activation of dmPFC-PVI activity in the adult animal mitigates juvenile isolation-induced social deficits. Therefore, social experience-dependent maturation of dmPFC-PVI is linked to long-term impacts on social behavior. Isolation during critical periods of development prevents development of normal social behaviours in mice, and this is thought to involve the prefrontal cortex. Here, the authors identify an activation pattern in parvalbumin-positive interneurons in the dorsal medial prefrontal cortex that when activated promotes sociability behaviours in mice.

Juvenile social isolation reduces sociability in adulthood, but the underlying neural circuit mechanisms are poorly understood. We found that, in male mice, 2 weeks of social isolation immediately following weaning leads to a failure to activate medial prefrontal cortex neurons projecting to the posterior paraventricular thalamus (mPFC→pPVT) during social exposure in adulthood. Chemogenetic or optogenetic suppression of mPFC→pPVT activity in adulthood was sufficient to induce sociability deficits without affecting anxiety-related behaviors or preference toward rewarding food. Juvenile isolation led to both reduced excitability of mPFC→pPVT neurons and increased inhibitory input drive from low-threshold-spiking somatostatin interneurons in adulthood, suggesting a circuit mechanism underlying sociability deficits. Chemogenetic or optogenetic stimulation of mPFC→pPVT neurons in adulthood could rescue the sociability deficits caused by juvenile isolation. Our study identifies a pair of specific medial prefrontal cortex excitatory and inhibitory neuron populations required for sociability that are profoundly affected by juvenile social experience.Yamamuro et al. show that juvenile social isolation disrupts prefrontal neurons projecting to the paraventricular thalamus and associated prefrontal somatostatin interneurons, and thereby impairs sociability in adulthood.

The mechanisms by which common risk variants of small effect interact to contribute to complex genetic disorders are unclear. Here, we apply a genetic approach, using isogenic human induced pluripotent stem cells, to evaluate the effects of schizophrenia (SZ)-associated common variants predicted to function as SZ expression quantitative trait loci (eQTLs). By integrating CRISPR-mediated gene editing, activation and repression technologies to study one putative SZ eQTL ( FURIN rs4702) and four top-ranked SZ eQTL genes ( FURIN , SNAP91 , TSNARE1 and CLCN3 ), our platform resolves pre- and postsynaptic neuronal deficits, recapitulates genotype-dependent gene expression differences and identifies convergence downstream of SZ eQTL gene perturbations. Our observations highlight the cell-type-specific effects of common variants and demonstrate a synergistic effect between SZ eQTL genes that converges on synaptic function. We propose that the links between rare and common variants implicated in psychiatric disease risk constitute a potentially generalizable phenomenon occurring more widely in complex genetic disorders. Combinatorial perturbation of schizophrenia risk loci in human induced pluripotent stem cell–derived neuronal cells demonstrates a synergistic effect converging on synaptic function.

Attention-deficit/hyperactivity disorder (ADHD) is characterized by age-inappropriate and impairing levels of inattention, hyperactivity, or impulsivity, or a combination of these characteristics. It is estimated to affect around 4% of adults worldwide. In the past few decades, prescriptions for ADHD drugs (psychostimulants and non-psychostimulants) have increased significantly. However, the efficacy and safety of adult ADHD medications remains controversial. Guanfacine extended-release (GXR) is a non-psychostimulant ADHD drug that is a selective α2A-adrenergic receptor agonist, first approved for treatment of adult ADHD in Japan in June 2019. Our aim was to provide an overview of GXR pharmacology and review the studies on efficacy and safety that have been conducted in adults with ADHD. The beneficial actions of guanfacine are thought to be attributed to the strengthening of prefrontal cortical network connections, which regulate attention, emotion, and behavior via the activity at post-synaptic α2A receptors. Current evidence of GXR efficacy and safety suggests that GXR is an effective monotherapy treatment option for adults with ADHD.

Aim Autism spectrum disorder (ASD) is a neurodevelopmental condition that markedly impairs the physical, emotional, and social domains of health‐related quality of life (HRQOL). Children with ASD typically report lower HRQOL than their neurotypical peers. This study investigated the impact of self‐esteem and depressive symptoms on HRQOL in children with ASD and explored the discrepancies between parent‐reported and self‐reported HRQOL. Methods This study involved 94 participants, comprising 50 children with ASD and 44 typically developed. HRQOL was measured using the J‐KIDSCREEN‐52 (self‐reported and parent‐reported). Self‐esteem, depressive symptoms, and social support were assessed using the Rosenberg Self‐Esteem Scale, the Depression Self‐Rating Scale for Children, and the Multidimensional Scale of Perceived Social Support, respectively. Discrepancies between parent‐reported and self‐reported HRQOL were examined. Multiple regression analyses were performed to determine the influence of depressive symptoms and self‐esteem on HRQOL. Results Children with ASD showed markedly lower HRQOL than their neurotypical peers. Discrepancies between parent‐reported and self‐reported HRQOL revealed differing perspectives. Higher depressive symptoms were strongly correlated with poorer HRQOL. Conversely, higher self‐esteem was linked to better HRQOL, notably in terms of self‐perception. Social support also markedly influenced HRQOL. Conclusion This study underscores the necessity of addressing depressive symptoms, self‐esteem, and social support as interventions to enhance HRQOL in children with ASD. The differences between parent‐reported and self‐reported HRQOL highlight the need to incorporate both views into clinical assessments for comprehensive and effective interventions. Future research should explore these dynamics longitudinally and across diverse populations to refine the intervention strategies. This study examined the impact of self‐esteem and depressive symptoms on health‐related quality of life (HRQOL) in children with autism spectrum disorder, highlighting significant discrepancies between parent‐reported and self‐reported HRQOL. Higher depressive symptoms were strongly correlated with poorer HRQOL. Conversely, higher self‐esteem was linked to better HRQOL. Social support also markedly influenced HRQOL.

Social experience during development is crucial for the functional maturation of the prefrontal cortex (PFC). Juvenile social isolation (JSI) causes severe PFC dysfunction. JSI reduces intrinsic excitability and excitatory synaptic inputs for a subtype of layer-5 (L5) pyramidal cells showing prominent h-current (PH cells) in the medial PFC. PH cells do not have commissural or associational cortical output; instead, they project into subcortical areas. However, which subcortical area is the projection target of L5 pyramidal cells affected by JSI remains unascertained. Using retrograde neuronal tracing, we identified L5 pyramidal cells having three different projection targets: the mediodorsal thalamus, striatum, or pontine nuclei. We elucidated differences in functional properties among the three subclasses of L5 pyramidal cells and examined how JSI affects the intrinsic membrane properties and excitatory inputs for each class of L5 pyramidal cells. Pyramidal cells projecting to the pontine nuclei had more excitatory synaptic inputs and more distinguishing intrinsic properties than pyramidal cells projecting to the mediodorsal thalamus and striatum. JSI increased the firing responsiveness of pyramidal cell projecting to mediodorsal thalamus and reduced excitatory synaptic inputs only onto pyramidal cells projecting to the pontine nuclei. JSI affects the development of L5 pyramidal cells based on their projection target.

Social isolation is an important factor in the development of psychiatric disorders. It is necessary to develop an effective psychological treatment, such as cognitive rehabilitation, for children who have already suffered from social isolation, such as neglect and social rejection. We used socially isolated mice to validate whether elaborate re-socialization after juvenile social isolation can restore hypomyelination in the medial prefrontal cortex (mPFC) and the attendant functions manifested in socially isolated mice. While mice who underwent re-socialization with socially isolated mice after juvenile social isolation (Re-IS mice) demonstrated less mPFC activity during exposure to a strange mouse, as well as thinner myelin in the mPFC than controls, mice who underwent re-socialization with socially housed mice after juvenile social isolation (Re-SH mice) caught up with the controls in terms of most mPFC functions, as well as myelination. Moreover, social interaction of Re-IS mice was reduced as compared to controls, but Re-SH mice showed an amount of social interaction comparable to that of controls. These results suggest that the mode of re-socialization after juvenile social isolation has significant effects on myelination in the mPFC and the attendant functions in mice, indicating the importance of appropriate psychosocial intervention after social isolation.

During brain development, the design of primary neural networks is primarily determined by environmental stimuli after their formation. In particular, the juvenile period is critical, during which neuronal circuits that consist of both excitatory and inhibitory neurons are remodeled by experience. Social isolation during the juvenile period profoundly affects brain development and contributes to the development of psychiatric disorders. We previously reported that 2 weeks of social isolation after weaning reduced excitatory synaptic inputs and intrinsic excitability in a subtype of layer 5 pyramidal cells, which we defined as prominent h-current (PH) cells, in the medial prefrontal cortex (mPFC) in mice. However, it remains unclear how juvenile social isolation affects inhibitory neuronal circuits that consist of pyramidal cells and interneurons. We found that 2 weeks of social isolation after weaning increased inhibitory synaptic inputs exclusively onto PH cells with a concomitant deterioration of action potential properties. Although social isolation did not alter the inhibitory synaptic release mechanisms or the number of inhibitory functional synapses on PH cells, we found that it increased the intrinsic excitability of fast-spiking interneurons with less excitatory synaptic inputs and more h-current. Our findings indicate that juvenile social isolation enhances the activity of inhibitory neuronal circuits in the mPFC.

Childhood maltreatment is defined as experiencing of physical, emotional and sexual abuse and neglect in childhood. Maltreatment in childhood leads to substantial psychosocial problems later in life in the general population. Individuals with autism spectrum disorder (ASD) have a higher risk of experiencing stressful and traumatic events, such as maltreatment, during childhood. Although childhood maltreatment reportedly leads to psychosocial problems in adults with ASD, the biological associations between childhood experiences and brain function in this population remain understudied. Here, we evaluated the relationships between childhood experiences and event-related potential (ERP) components during the auditory odd-ball task in adults with ASD (N = 21) and typically developed (TD) individuals (N = 22). We found that the higher the severity of sexual abuse, the larger the amplitude of P300 at Fz, Cz, C3, and C4 in individuals with ASD. Conversely, the severity of child maltreatment was associated with P300 latency at Cz and C3 in TD individuals. Moreover, full IQ was significantly associated with the MMN amplitude at Fz, Cz, C3, and C4 in TD individuals. These findings provide the first evidence that ERPs could be used to study the impacts childhood experiences on the brain of individuals with ASD and that childhood sexual abuse has salient impacts on brain function in this population.