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Previous studies have reported that dissociative symptoms (DIS) are associated with self-harm (SH) in adolescents. However, most of these studies were cross-sectional, which limits the understanding of their theoretical relationship. We aimed to investigate the longitudinal relationship between DIS and SH in the general adolescent population. We used data from the Tokyo Teen Cohort study (N = 3007). DIS and SH were assessed at times 1 and 2 (T1 and T2) (12 years of age and 14 years of age, respectively). DIS were assessed using the parent-report Child Behavior Checklist (CBCL), and severe dissociative symptoms (SDIS) were defined as a score above the top 10th percentile. The experience of SH within 1 year was assessed by a self-report questionnaire. The longitudinal relationship between DIS and SH was examined using regression analyses. Using logistic regression analyses, we further investigated the risk for SH at T2 due to persistent SDIS and vice versa. DIS at T1 tended to predict SH at T2 (odds ratio (OR) 1.11, 95% CI 0.99 to 1.25, p = 0.08), while SH at T1 did not predict DIS at T2 (B = − 0.03, 95% CI − 0.26 to 0.20, p = 0.81). Compared with adolescents without SDIS, those with persistent SDIS had an increased risk of SH at T2 (OR 2.61, 95% CI 1.28 to 5.33, p = 0.01). DIS tended to predict future SH, but SH did not predict future DIS. DIS may be a target to prevent SH in adolescents. Intensive attention should be given to adolescents with SDIS due to their increased risk of SH. [ABSTRACT FROM AUTHOR]

Although cortical feedback signals are essential for modulating feedforward processing, no feedback error signal across hierarchical cortical areas has been reported. Here, we observed such a signal in the auditory cortex of awake common marmoset during an oddball paradigm to induce auditory duration mismatch negativity. Prediction errors to a deviant tone presentation were generated as offset calcium responses of layer 2/3 neurons in the rostral parabelt (RPB) of higher-order auditory cortex, while responses to non-deviant tones were strongly suppressed. Within several hundred milliseconds, the error signals propagated broadly into layer 1 of the primary auditory cortex (A1) and accumulated locally on top of incoming auditory signals. Blockade of RPB activity prevented deviance detection in A1. Optogenetic activation of RPB following tone presentation nonlinearly enhanced A1 tone response. Thus, the feedback error signal is critical for automatic detection of unpredicted stimuli in physiological auditory processing and may serve as backpropagation-like learning.The brain can quickly detect sounds that are not predicted. Here, the authors show that propagation of prediction error signals from higher-order auditory cortex to primary auditory cortex is critical for the change detection in the non-human primates. [ABSTRACT FROM AUTHOR]

Adolescents with high autistic traits are at increased risk of depression. Despite the importance of seeking help for early intervention, evidence on help-seeking intentions amongst this population is scarce. Using a population-based cohort in Japan, we examined adolescents' help-seeking intentions and preferences by the level of autistic traits and tested its mediating role on the association between high autistic traits and depressive symptoms. At age 12, we measured parent-rated autistic traits using the short version of the Autism Spectrum Quotient and classified the adolescents into two groups (≥ 6 as AQhigh, < 6 as AQlow); help-seeking intentions and preferences were assessed through a depression vignette. At age 14, depressive symptoms were self-rated using the Short Mood and Feelings Questionnaire. Hypothesised associations between autistic traits and help-seeking intentions or depressive symptoms were tested applying multivariable regression modelling, while mediation was tested with structural equation modelling. Of the 2505 adolescent participants, 200 (8%) were classified as AQhigh. In both groups, the main source of help-seeking was their family; however, 40% of the AQhigh group reported having no help-seeking intentions compared to 27% in the AQlow. The AQhigh group was at increased risk of not having help-seeking intentions (OR 1.84, 95% CI 1.35–2.50) and higher depressive symptoms (b coefficient 1.06, 0.33–1.79). Help-seeking intentions mediated 18% of the association mentioned above. Interventions to promote help-seeking intentions among adolescents with high autistic traits could reduce their subsequent depressive symptoms. Ideally, such interventions should be provided prior to adolescence and with the involvement of their parents. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the association between parenting stress, maternal depressive symptoms, and use of physical punishment when the child is 10 years old. Methods: Data from the Tokyo Early Adolescence Survey on early adolescents and primary caregivers (N = 4478) were used. Frequency of using physical punishment, level of depressive symptoms (Kessler Psychological Distress Scale 6), and maternal parenting stress experienced at 1, 3, 9, 18, and 36 months after birth were evaluated. Multiple linear and multinomial logistic regression analyses were conducted. Results: Mothers (1633) who provided information on parenting stress at all the five points were included for the analysis. After controlling for the child's age, sex, birth weight, maternal age, and annual household income, presence of maternal parenting stress at every time point, except at three months after birth, was significantly associated with an increased risk of using physical punishment with the 10-year-old. After adjusting for levels of depressive symptoms, significant associations were found between use of physical punishment and maternal parenting stress at 1 month (adjusted odds ratio [OR] 1.71, 95% confidence interval [Cl] 1.12–2.61) and 36 months (adjusted OR 1.70, 95% CI 1.10–2.61) after birth. Conclusion: Maternal parenting stress experienced at 1 and 36 months after birth predicted use of physical punishment, even after adjusting for maternal depressive symptoms. Maternal support should, therefore, be provided to mothers to cope with parenting stress even three years after birth to prevent the use of physical punishment in early adolescence. [ABSTRACT FROM AUTHOR]

Problematic Internet use (PIU), hyperactivity/inattention, and depressive symptoms are comorbid problems in adolescence, but the causal relationships among these issues are unclear. To assess the relationships among PIU, hyperactivity/inattention, and depressive symptoms in adolescents in the general population. This longitudinal cohort study used data from the Tokyo Teen Cohort study in Tokyo, Japan, for two years between October 2012 and January 2015. Of the 3171 pairs of children and parents, 3007 pairs continued to participate in the second wave of the Tokyo Teen Cohort study. A total of 3007 children were included in the analysis (mean [standard deviation] age, 9.7 [0.4] years; 1418 women [47.2%]. Cross-lagged panel analysis revealed that PIU at timepoint 1 was significantly associated with hyperactivity/inattention at timepoint 2 (β = 0.03; 95% confidence interval (CI) 0.01–0.06), and hyperactivity/inattention at timepoint 1 was also significantly associated with PIU at timepoint 2 (β = 0.07; 95% CI 0.04–0.10), even after adjustments were made for depressive symptoms. Furthermore, PIU at timepoint 1 was significantly associated with depressive symptoms at timepoint 2 (β = 0.05; 95% CI 0.01–0.12), and depressive symptoms at timepoint 1 were also significantly associated with PIU at timepoint 2 (β = 0.05; 95% CI 0.02–0.07), even after adjustments were made for hyperactivity/inattention. These results support the bidirectional relationships among PIU, hyperactivity/inattention, and depressive symptoms. PIU may be a target to improve hyperactivity/inattention and depressive symptoms in adolescents. [ABSTRACT FROM AUTHOR]

Purpose: Studies of mental illness stigma reduction interventions have been criticised for failing to evaluate behavioural outcomes and mechanisms of action. This project evaluates training for medical students entitled 'Responding to Experienced and Anticipated Discrimination' (READ), developed to focus on skills in addition to attitudes and knowledge. We aimed to (i) evaluate the effectiveness of READ with respect to knowledge, attitudes, and clinical communication skills in responding to mental illness-related discrimination, and (ii) investigate whether its potential effectiveness was mediated via empathy or/and intergroup anxiety. Methods: This is an international multisite non-randomised pre- vs post-controlled study. Eligible medical students were currently undertaking their rotational training in psychiatry. Thirteen sites across ten countries (n = 570) were included in the final analysis. Results: READ was associated with positive changes in knowledge (mean difference 1.35; 95% CI 0.87 to 1.82), attitudes (mean difference − 2.50; 95% CI − 3.54 to − 1.46), skills (odds ratio 2.98; 95% CI 1.90 to 4.67), and simulated patient perceived empathy (mean difference 3.05; 95% CI 1.90 to 4.21). The associations of READ with knowledge, attitudes, and communication skills but not with simulated patient perceived empathy were partly mediated through student reported empathy and intergroup anxiety. Conclusion: This is the first study to identify mediating effects of reduced intergroup anxiety and increased empathy in an evaluation of anti-stigma training that includes behavioural measures in the form of communication skills and perceived empathy. It shows the importance of both mediators for all of knowledge, skills, and attitudes, and hence of targeting both in future interventions. [ABSTRACT FROM AUTHOR]

Purpose: Lifestyle factors of children and adolescents' mental health problems are an emerging health issue in low- and middle-income countries (LMICs). However, there is a lack of studies on lifestyle factors in LMICs. This study examined the socioeconomic and lifestyle factors associated with mental health problems among school-age children in Mongolia. Methods: A population-based cross-sectional survey was conducted among 4th-year students at public elementary schools in one district in Ulaanbaatar. The Strengths and Difficulties Questionnaire (SDQ) and a self-administrated socioeconomic and lifestyle questionnaire were completed by participants' guardians. A multivariate logistic regression analysis was performed. Results: Of the 2301 children surveyed, 1694 without missing responses were included in the analysis. The multivariate logistic regression analysis showed that male gender [adjusted odds ratio (AOR) 1.64 (1.29–2.10)], low maternal education [AOR 1.89 (1.16–3.05)], short sleep [AOR 1.41 (1.10–1.80)], no physical activity [AOR 1.31 (1.03–1.67)], and long screen time (AOR 1.53 (1.20–1.94)) were associated with high risk of mental health problems. Low maternal education, low household income, no physical activity habit, and long screen time were associated with internalising problems. Meanwhile, male gender, low maternal education, and long screen time were associated with externalising problems. Conclusion: The results are consistent with previous studies in high-income countries, indicating that there are globally common socioeconomic and lifestyle risk factors. The findings of this study may help develop a targeted preventive intervention for high-risk groups, such as socioeconomically disadvantaged groups, as well as a universal preventive intervention to foster a healthy lifestyle in Mongolia. [ABSTRACT FROM AUTHOR]

Changes in the surface morphology of the orbitofrontal cortex (OFC), such as a fewer orbital sulci and altered sulcogyral pattern of the 'H-shaped' orbital sulcus, have been reported in schizophrenia, possibly reflecting abnormal neurodevelopment during gestation. However, whether high-risk subjects for developing psychosis also exhibit these gross morphologic anomalies is not well documented. This multicenter MRI study from four scanning sites in Japan investigated the distribution of the number of intermediate and posterior orbital sulci, as well as the OFC sulcogyral pattern, in 125 individuals with an at-risk mental state (ARMS) [of whom 22 later developed psychosis (ARMS-P) and 89 did not (ARMS-NP)] and 110 healthy controls. The ARMS group as a whole had a significantly lower number of intermediate and posterior orbital sulci compared with the controls, which was associated with prodromal symptomatology. However, there was no group difference in OFC pattern distribution. The ARMS-P and -NP groups did not differ in OFC surface morphology. These results suggest that gross morphology of the OFC in high-risk subjects may at least partly reflect neurodevelopmental pathology related to vulnerability to psychosis. [ABSTRACT FROM AUTHOR]

Although methylphenidate hydrochloride (MPH) is a first-line treatment for children with attention-deficit hyperactivity disorder (ADHD), the non-response rate is 30%. Our aim was to develop a supplementary neuroimaging biomarker for predicting the clinical effect of continuous MPH administration by using near-infrared spectroscopy (NIRS). After baseline assessment, we performed a double-blind, placebo-controlled, crossover trial with a single dose of MPH, followed by a prospective 4-to-8-week open trial with continuous MPH administration, and an ancillary 1-year follow-up. Twenty-two drug-naïve and eight previously treated children with ADHD (NAÏVE and NON-NAÏVE) were compared with 20 healthy controls (HCs) who underwent multiple NIRS measurements without intervention. We tested whether NIRS signals at the baseline assessment or ΔNIRS (single dose of MPH minus baseline assessment) predict the Clinical Global Impressions-Severity (CGI-S) score after 4-to-8-week or 1-year MPH administration. The secondary outcomes were the effect of MPH on NIRS signals after single-dose, 4-to-8-week, and 1-year administration. ΔNIRS significantly predicted CGI-S after 4-to-8-week MPH administration. The leave-one-out classification algorithm had 81% accuracy using the NIRS signal. ΔNIRS also significantly predicted CGI-S scores after 1 year of MPH administration. For secondary analyses, NAÏVE exhibited significantly lower prefrontal activation than HCs at the baseline assessment, whereas NON-NAÏVE and HCs showed similar activation. A single dose of MPH significantly increased activation compared with the placebo in NAÏVE. After 4-to-8-week administration, and even after MPH washout following 1-year administration, NAÏVE demonstrated normalized prefrontal activation. Supplementary NIRS measurements may serve as an objective biomarker for clinical decisions and monitoring concerning continuous MPH treatment in children with ADHD. [ABSTRACT FROM AUTHOR]

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor, which is important for neuronal survival, development and synaptic plasticity. Accumulating evidence suggests that epigenetic modifications of BDNF are associated with the pathophysiology of psychiatric disorders, such as schizophrenia and mood disorders. Patients with psychiatric disorders generally show decreased neural BDNF levels, which are often associated with increased DNA methylation at the specific BDNF promoters. Importantly, observed DNA methylation changes are consistent across tissues including brain and peripheral blood, which suggests potential usefulness of these findings as a biomarker of psychiatric disorders. Here we review DNA methylation characteristics of BDNF promoters of cellular, animal and clinical samples and discuss future perspectives. [ABSTRACT FROM AUTHOR]

Epidemiological studies have revealed that schizophrenia is highly heritable. However, genetic studies have not fully elucidated its etiology. Accumulating evidence suggests that epigenetic alterations may provide an additional explanation of its pathophysiology. We investigated the methylation profiles of DNA in peripheral blood cells from 18 patients with first-episode schizophrenia (FESZ) and from 15 normal controls. Schizophrenia patients were confined to those at the stage of first-episode psychosis. We analyzed the DNA methylation status of 27 578 CpG sites by means of the Illumina Infinium HumanMethylation27 BeadChip array. Differentially methylated CpG sites, which were particularly abundant within CpG islands, were enriched in genes related to the nuclear lumen, to transcription factor binding, and to nucleotide binding. We also observed differential methylation of the promoters of HTR1E and COMTD1, which are functionally related to genes found to be differentially methylated in schizophrenia patients in previous studies. Our results indicate the site-specific epigenetic alterations in patients with FESZ. [ABSTRACT FROM AUTHOR]

Introduction: The study was conducted to evaluate simultaneously gray matter changes and white matter changes in patients with schizophrenia. Methods: Cortical thickness, gray matter volume, and white matter anisotropy and diffusivity changes in schizophrenic patients ( n = 21) were assessed relative to age-, gender-, and parental socioeconomic status-matched healthy controls ( n = 21). We used a newly described semi-automated method (FreeSurfer version 4.5) to determine cortical thickness and gray matter volume and used the tract-based spatial statistics method to evaluate white matter anisotropy and diffusivity. Results: Schizophrenic patients showed a significant decrease in hippocampal volume compared with healthy controls. No significant thickness deficits or anisotropy and diffusivity changes were found in schizophrenic patients compared with healthy controls. Stepwise multivariate analysis revealed that hippocampal volume was positively related to duration of illness in schizophrenic patients. Conclusion: Our results suggest that hippocampal volume is smaller in schizophrenic patients compared with healthy controls and that progressive hippocampal volume loss occurs in the early course of illness in schizophrenic patients but not in the more chronic stages. [ABSTRACT FROM AUTHOR]

Introduction: The effects of aging on brain volume are generally investigated using voxel-based morphometry (VBM) or the manually traced region-of-interest (ROI) method. We introduce an atlas-based method as a methodological alternative that calculates absolute volume as a non-biased and semi-automatic whole-brain technique. Methods: We enrolled 115 healthy females (mean age, 36.7 years) and 130 healthy males (mean age, 37.1 years). Volume data were acquired using a 1.5 tesla magnetic resonance scanner. After spatial normalization, a lobar-based atlas template was applied, and the absolute volumes of the frontal, temporal, parietal, and occipital lobes and the sublobar and limbic areas were calculated bilaterally. The effects of age on regional brain volume were evaluated statistically. Results: The volume of all ROIs declined linearly with increasing age. The bilateral frontal lobes showed the steepest involution. Analysis of variance revealed significant laterality and interaction of gender and age. Conclusion: The atlas-based method introduced in the present study has advantages over the manually traced ROI method in its objectivity, coverage, and time requirement and has an advantage over the VBM method in its computability of absolute volume. The results are largely in agreement with those reported previously, thereby reconfirming the importance of matching gender and age in analyzing brain disorders. [ABSTRACT FROM AUTHOR]

Previous literature has suggested an important role of inferior frontal gyrus, which mainly consists of Brodmann's Area (BA) 44 and 45, in the pathophysiology of schizophrenia. While recent neuroimaging techniques have revealed differential functional correlates of BA 44 and 45 in healthy individuals, previous studies have not yet separately evaluated the gray matter volume reduction of BA 44 and 45 and their relationships to psychotic symptoms in patients with schizophrenia. In the present study, magnetic resonance images were obtained from 29 right-handed male patients with schizophrenia and from 29 age- and handedness-matched healthy male controls. The reliable manual tracing methodology was employed to measure the gray matter volume of BA 44 and BA 45. The severities of psychotic symptoms were evaluated using the five-factor model of positive and negative syndrome scale in the patient group. A significant gray matter volume reduction of both the BA 44 and BA 45 was found bilaterally in the patients with schizophrenia compared with the healthy controls. Among these inferior frontal sub-regions, reduced volume of right BA 45 revealed the largest effect size. In addition, the reduced volume of BA 45 in left hemisphere showed a significant association with the increased severity of delusional behavior, while the severity of disorganized and positive symptoms were correlated with the bilateral BA 45 volumes in the patient group. The findings support an important role of inferior frontal gyrus in the pathophysiology of schizophrenia. The present study further demonstrated that BA 45 might especially contribute to the production of psychotic symptoms in the patients with schizophrenia. [ABSTRACT FROM AUTHOR]

Diffusion tensor imaging (DTI) has provided important insights into the neurobiological basis for normal development and aging and various disease processes in the central nervous system. The aim of this article is to review the current protocols for DTI acquisition and preprocessing and statistical testing for a voxelwise analysis of DTI, focused on statistical parametric mapping (SPM) and tract-based spatial statistics (TBSS). We tested the effects of distortion correction induced by gradient nonlinearity on fractional anisotropy (FA) maps or FA skeletons processed via two SPM-based methods (coregistration and FA template methods), or TBSS-based method, respectively. With two SPM-based methods, we found similar results in some points (e.g., significant FA elevation for uncorrected images in anterior-dominant white matter and for corrected images in bilateral middle cerebellar peduncles) and different results in other points (e.g., significantly larger FA for corrected images with coregistration method, but significantly smaller with FA template method in bilateral internal capsules, extending to corona radiata, and semioval centers). In contrast, there was no area with significant difference between uncorrected and corrected FA skeletons with TBSS-based method. The discrepancy among these results was not explained in full, but possible explanations were misregistration and smoothing for the SPM-based methods and insensitivity to FA changes outside the local centers of white matter bundles for TBSS-based method. [ABSTRACT FROM AUTHOR]

Thought disorder is considered as one of the core features of schizophrenia and several research groups previously reported an association between P300 (P3b) amplitude and thought disorder in schizophrenia. However, previous studies have not evaluated two P300 subcomponents (P3a and P3b) to investigate whether the relationship with thought disorder was specific to P3b. In this study, we measured P3b and thought disorder of 60 patients with schizophrenia. We also measured P3a of 36 patients out of this sample. We replicated correlation between P3b amplitude and thought disorder and extended this finding by observing that this correlation was not present for the P3a subcomponent. These results suggest that specific electrophysiological abnormalities associated with context updating may underlie thought disorder in schizophrenia. [ABSTRACT FROM AUTHOR]

Neuregulin 1 ( NRG1) is one of the most promising candidate genes for schizophrenia. A number of replication studies have been conducted, although the results were inconsistent and no susceptible variant has yet been identified. The inconsistency might be attributed to the ethnic difference in allele and haplotype frequencies. However, it is equally possible that one or more genes interacting with NRG1 may also be implicated in schizophrenia and attribute to the inconsistency. To test the hypothesis, we conducted an interaction analysis between NRG1 and one of its receptor’s ( ERBB4) polymorphisms as well as the association analysis of the two genes associated with schizophrenia in Japanese. We observed no significant difference between patients and controls in allele frequencies or genotypic distributions of the 18 polymorphisms of the genes. The permutation test showed no significant differences in estimated haplotype frequencies between patients and controls, including the haplotype HAPICE. In the interaction analysis, significant interaction was observed between rs2919381 in NRG1 and rs7560730 in ERBB4 ( P = 0.047, corrected). Thus, our results suggest the possibility that interaction between variants in NRG1 and ERBB4 might contribute to susceptibility for schizophrenia in a Japanese population. Further investigation may be necessary to confirm our results. [ABSTRACT FROM AUTHOR]

The structural abnormality of planum temporale (PT), a part of the superior temporal heteromodal association cortex involved in auditory and language processing, has been implicated in the pathophysiology of schizophrenia. However, its relationship to clinical manifestations remains unclear. Magnetic resonance images were obtained from 17 right-handed Japanese men with schizophrenia and from 22 age-, handedness-, and parental socioeconomic-status-matched healthy Japanese men in order to manually evaluate grey matter volumes of Heschl’s gyrus (HG) and PT. Psychiatric symptoms were assessed using positive and negative syndrome scale among the patients. Compared with healthy participants, patients with schizophrenia were associated with a statistically significant PT grey matter volume reduction without left or right lateralization, whereas HG volume was preserved. Smaller right PT volume was significantly correlated with more severe delusional behaviour in the patients. Previous investigations have focused on smaller-than-normal left PT in the pathophysiology of schizophrenia; however, the present results suggest a possible role of the right PT, which is involved in social cognition such as understanding the intentions of others, in the production of psychotic experiences in patients with schizophrenia. [ABSTRACT FROM AUTHOR]

In animals, exposure to severe stress can damage the hippocampus. Recent human studies show smaller hippocampal volume in individuals with the stress-related psychiatric condition posttraumatic stress disorder (PTSD). Does this represent the neurotoxic effect of trauma, or is smaller hippocampal volume a pre-existin9 condition that renders the brain more vulnerable to the development of pathological stress responses? In monozygotic twins discordant for trauma exposure, we found evidence that smaller hippocampi indeed constitute a risk factor for the development of stress-related psychopathology. Disorder severity in PTSD patients who were exposed to trauma was negatively correlated with the hippocampal volume of both the patients and the patients' trauma-unexposed identical co-twin. Furthermore, severe PTSD twin pairs--both the trauma-exposed and unexposed members--had significantly smaller hippocampi than non-PTSD pairs. [ABSTRACT FROM AUTHOR]

To examine the left temporal scalp area reductions of P300 amplitude, event-related potentials (ERPs) during a standard oddball task were recorded in 57 schizophrenic patients and 33 normal controls. The P300 amplitude at T3 was not significantly smaller than that at T4 in schizophrenic patients. In the ANOVA analysis of the P300 peak amplitude and PCA factor scores, significant lateral topographical differences in P300 were not present between patients and controls. However, in schizophrenia, patients in the low T3 P300 group were older and consuming higher doses of antipsychotic medicine than those in the high T3 P300 group, and they had relatively low P300 amplitudes and significantly delayed P300 latency, compared with those in the high T3 P300 group. These findings suggested that although the reduction in the left temporal P300 amplitude did not necessarily exist in schizophrenic patients, it may be associated with the severity of the disease process and/or impairment of cognitive function. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Panic disorder (PD) is a severe and chronic psychiatric disorder, with significant genetic components in the etiology. Brain-derived neurotrophic factor (BDNF) gene, which has regulatory effects on neurotransmitter systems such as serotonin and dopamine, is a candidate for susceptibility locus of PD. This study investigated three single-nucleotide polymorphisms (SNPs) of BDNF (rs6265 (Val66Met), rs11030104 and rs7103411) in Japanese patients with PD and controls. No significant association was observed between the three SNPs and PD. No association of the Val66Met was consistent with two small studies in Japanese and Chinese populations. We therefore conclude that the BDNF polymorphism may not play a major role in PD in the East Asian populations. [ABSTRACT FROM AUTHOR]

The auditory steady-state response (ASSR) has been used to detect auditory processing deficits in patients with psychiatric disorders. However, the methodology of ASSR recording from the brain surface has not been standardized in preclinical studies, limiting its use as a translational biomarker. The sites of maximal ASSR in humans are the vertex and/or middle frontal area, although it has been suggested that the auditory cortex is the source of the ASSR. We constructed and validated novel methods for ASSR recording using a switchable pedestal which allows ASSR recording alternatively from temporal or parietal cortex with a wide range of frequencies in freely moving rats. We further evaluated ASSR as a translational tool by assessing the effect of ketamine. The ASSR measured at parietal cortex did not show clear event-related spectral perturbation (ERSP) or inter-trial coherence (ITC) in any frequency bands or a change with ketamine. In contrast, the ASSR at temporal cortex showed clear ERSP and ITC where 40 Hz was maximal in both gamma-band frequencies. Ketamine exerted a biphasic effect in ERSP at gamma bands. These findings suggest that temporal cortex recording with a wide frequency range is a robust methodology to detect ASSR, potentially enabling application as a translational biomarker in psychiatric and developmental disorders. [ABSTRACT FROM AUTHOR]