Masanori Isobe

Abnormal asymmetries in subcortical brain volume in schizophrenia

Subcortical structures, which include the basal ganglia and parts of the limbic system, have key roles in learning, motor control and emotion, but also contribute to higher-order executive functions. Prior studies have reported volumetric alterations in subcortical regions in schizophrenia. Reported results have sometimes been heterogeneous, and few large-scale investigations have been conducted. Moreover, few large-scale studies have assessed asymmetries of subcortical volumes in schizophrenia. Here, as a work completely independent of a study performed by the ENIGMA consortium, we conducted a large-scale multisite study of subcortical volumetric differences between patients with schizophrenia and controls. We also explored the laterality of subcortical regions to identify characteristic similarities and differences between them. T1-weighted images from 1680 healthy individuals and 884 patients with schizophrenia, obtained with 15 imaging protocols at 11 sites, were processed with FreeSurfer. Group differences were calculated for each protocol and meta-analyzed. Compared with controls, patients with schizophrenia demonstrated smaller bilateral hippocampus, amygdala, thalamus and accumbens volumes as well as intracranial volume, but larger bilateral caudate, putamen, pallidum and lateral ventricle volumes. We replicated the rank order of effect sizes for subcortical volumetric changes in schizophrenia reported by the ENIGMA consortium. Further, we revealed leftward asymmetry for thalamus, lateral ventricle, caudate and putamen volumes, and rightward asymmetry for amygdala and hippocampal volumes in both controls and patients with schizophrenia. Also, we demonstrated a schizophrenia-specific leftward asymmetry for pallidum volume. These findings suggest the possibility of aberrant laterality in neural pathways and connectivity patterns related to the pallidum in schizophrenia.

Factors associated with motivation and hesitation to work among health professionals during a public crisis: a cross sectional study of hospital workers in Japan during the pandemic (H1N1) 2009

BackgroundThe professionalism of hospital workers in Japan was challenged by the pandemic (H1N1) 2009. To maintain hospital function under critical situations such as a pandemic, it is important to understand the factors that increase and decrease the willingness to work. Previous hospital-based studies have examined this question using hypothetical events, but so far it has not been examined in an actual pandemic. Here, we surveyed the factors that influenced the motivation and hesitation of hospital workers to work in Japan soon after the pandemic (H1N1) 2009.MethodsSelf-administered anonymous questionnaires about demographic character and stress factors were distributed to all 3635 employees at three core hospitals in Kobe city, Japan and were collected from June to July, 2009, about one month after the pandemic (H1N1) in Japan.ResultsOf a total of 3635 questionnaires distributed, 1693 (46.7%) valid questionnaires were received. 28.4% (N = 481) of workers had strong motivation and 14.7% (N = 249) had strong hesitation to work. Demographic characters and stress-related questions were categorised into four types according to the odds ratios (OR) of motivation and hesitation to work: some factors increased motivation and lowered hesitation; others increased motivation only; others increased hesitation only and others increased both motivation and hesitation. The strong feeling of being supported by the national and local governments (Multivariate OR: motivation; 3.5; CI 2.2-5.4, hesitation; 0.2; CI 0.1-0.6) and being protected by hospital (Multivariate OR: motivation; 2.8; CI 2.2-3.7, hesitation; 0.5; CI 0.3-0.7) were related to higher motivation and lower hesitation. Here, protection included taking precautions to prevent illness among workers and their families, providing for the care of those who do become ill, reducing malpractice threats, and financial support for families of workers who die on duty. But 94.1% of the respondents answered protection by the national and local government was weak and 79.7% answered protection by the hospital was weak.ConclusionsSome factors have conflicting effects because they increase both motivation and hesitation. Giving workers the feeling that they are being protected by the national and local government and hospital is especially valuable because it increases their motivation and lowers their hesitation to work.

Estimated cognitive decline in patients with schizophrenia: A multicenter study

Studies have reported that cognitive decline occurs after the onset of schizophrenia despite heterogeneity in cognitive function among patients. The aim of this study was to investigate the degree of estimated cognitive decline in patients with schizophrenia by comparing estimated premorbid intellectual functioning and current intellectual functioning.

Neural mechanisms and personality correlates of the sunk cost effect

The sunk cost effect, an interesting and well-known maladaptive behavior, is pervasive in real life, and thus has been studied in various disciplines, including economics, psychology, organizational behavior, politics, and biology. However, the neural mechanisms underlying the sunk cost effect have not been clearly established, nor have their association with differences in individual susceptibility to the effect. Using functional magnetic resonance imaging, we investigated neural responses induced by sunk costs along with measures of core human personality. We found that individuals who tend to adhere to social rules and regulations (who are high in measured agreeableness and conscientiousness) are more susceptible to the sunk cost effect. Furthermore, this behavioral observation was strongly mediated by insula activity during sunk cost decision-making. Tight coupling between the insula and lateral prefrontal cortex was also observed during decision-making under sunk costs. Our findings reveal how individual differences can affect decision-making under sunk costs, thereby contributing to a better understanding of the psychological and neural mechanisms of the sunk cost effect.

Psychological impact of the pandemic (H1N1) 2009 on general hospital workers in Kobe.

Aims:u2002 In order for hospitals to work efficiently in a pandemic, it is important to know how a pandemic affects the hospital staff. The aim of the present study was to investigate the psychological impact of the pandemic (H1N1) 2009 on hospital workers and how it was affected by the characteristics of the hospital, gender, age, job and work environment.

Differences in neural responses to reward and punishment processing between anorexia nervosa subtypes: An fMRI study

Anorexia nervosa (AN) includes the restricting (AN‐r) and binge‐eating/purging (AN‐bp) subtypes, which have been reported to differ regarding their underlying pathophysiologies as well as their behavioral patterns. However, the differences in neural mechanisms of reward systems between AN subtypes remain unclear. The aim of the present study was to explore differences in the neural processing of reward and punishment between AN subtypes.

Multimodal neuroimaging as a window into the pathological physiology of schizophrenia: Current trends and issues

Visualizing the detailed brain anatomy of individuals with schizophrenia has been made possible by recent advances in magnetic resonance imaging (MRI). Although structural MRI cannot be currently used to diagnose schizophrenia, multimodal MRI can reveal insightful information on key clinical aspects of the pathological physiology of schizophrenia. However, in this regard, the number of multimodal MRI studies is still limited and definitely required. In this review, we discuss how classical and popular theories on the pathological physiology of schizophrenia can be re-examined using neuroimaging studies, and also discuss how multimodal MRI studies may provide additional findings. The pathological hypotheses examined include the progressive brain disease hypothesis and disconnection hypothesis. This article is discussed mainly based on recent findings published by our research group.

Lateralization of intrinsic frontoparietal network connectivity and symptoms in schizophrenia

It has been frequently reported that schizophrenia patients have reduced functional lateralization in the areas related to language processing. Furthermore, there is evidence supporting that schizophrenia patients have disrupted functional connectivity in the bilateral frontoparietal networks (FPNs), of which the left is strongly associated with a cognition-language paradigm, using resting-state functional magnetic resonance imaging (rsfMRI). To examine the laterality of resting-state functional connectivity in schizophrenia, we investigated the bilateral FPNs. We investigated 41 schizophrenia and 35 healthy participants using independent component analysis for rsfMRI. We extracted mean connectivity values of both left and right FPNs and calculated their laterality index by (left - right)/(left + right). Subsequently, we investigated group differences of these values and the correlation between these values and symptoms. In schizophrenia, mean connectivity values of both left and right FPNs were significantly lower than in healthy controls, whereas their laterality indices were not significantly different. However, correlation analyses revealed that the laterality index was negatively correlated with positive symptoms, and that mean connectivity of left FPN was negatively correlated with depressive symptoms in schizophrenia. Our results suggest that language-related networks and their laterality might be one of the neural correlates of schizophrenia symptoms.

Polymorphism within a Neuronal Activity-Dependent Enhancer of NgR1 Is Associated with Corpus Callosum Morphology in Humans.

The human Nogo-66 receptor 1 (NgR1) gene, also termed Nogo receptor 1 or reticulon 4 receptor (RTN4R) and located within 22q11.2, inhibits axonal growth and synaptic plasticity. Patients with the 22q11.2 deletion syndrome show multiple changes in brain morphology, with corpus callosum (CC) abnormalities being among the most prominent and frequently reported. Thus, we hypothesized that, in humans, NgR1 may be involved in CC formation. We focused on rs701428, a single nucleotide polymorphism of NgR1, which is associated with schizophrenia. We investigated the effects of the rs701428 genotype on CC structure in 50 healthy participants using magnetic resonance imaging. Polymorphism of rs701428 was associated with CC structural variation in healthy participants; specifically, minor A allele carriers had larger whole CC volumes and lower radial diffusivity in the central CC region compared with major G allele homozygous participants. Furthermore, we showed that the NgR1 3′ region, which contains rs701428, is a neuronal activity-dependent enhancer, and that the minor A allele of rs701428 is susceptible to regulation of enhancer activity by MYBL2. Our results suggest that NgR1 can influence the macro- and microstructure of the white matter of the human brain.

Effect of phase-encoding direction on group analysis of resting-state functional magnetic resonance imaging: Phase-encoding direction affects rsfMRI

Echo‐planar imaging is a common technique used in functional magnetic resonance imaging (fMRI); however, it suffers from image distortion and signal loss because of large susceptibility effects that are related to the phase‐encoding direction of the scan. Despite this relation, the majority of neuroimaging studies has not considered the influence of phase‐encoding direction. Here, we aimed to clarify how phase‐encoding direction can affect the outcome of an fMRI connectivity study of schizophrenia (SCZ).