Publications by authors named "Ryosaku Kawada"

Aim: Recently, a machine-learning (ML) technique has been used to create generalizable classifiers for psychiatric disorders based on information of functional connections (FCs) between brain regions at resting state. These classifiers predict diagnostic labels by a weighted linear sum (WLS) of the correlation values of a small number of selected FCs. We aimed to develop a generalizable classifier for gambling disorder (GD) from the information of FCs using the ML technique and examine relationships between WLS and clinical data.

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Gambling disorder (GD) patients show excessively risky decision-making in the financial domain. We aimed to clarify whether GD patients show risky decision-making in domain-general or in domain-specific. Furthermore, we also investigated the effect of the well-known cognitive bias, the framing effect on GD's decision-making under risk.

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The insula is considered an important structure involved in addiction and in the context of dynamic activity switching between large-scale brain networks, such as the default mode network (DMN) and the central executive network. Although insular-DMN resting-state functional connectivity (rsFC), which could affect such switching, has been examined in substance addiction populations, the results have been inconsistent, partly because of the confounding neural effects of the abused substances. To investigate this subject, using MRI, we examined insular-DMN rsFC in gambling disorder (GD) patients without a history of substance use.

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Background: Anorexia nervosa (AN) patients are assumed to express high levels of guilt and envy. Ultimatum game (UG) is a standard behavioral task that focuses on interpersonal behavior when splitting a sum of money between two players. UG studies consistently demonstrate that people tend to decrease their inequity in outcomes, one explanation being that economically irrational decision-making may partly arise from the emotions guilt and envy.

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The sunk cost effect is the tendency to continue an investment, or take an action, even though it has higher future costs than benefits, if costs of time, money, or effort were previously incurred. This type of decision bias is pervasive in real life and has been studied in various disciplines. Previous studies and clinical observations suggest that decision-making under sunk costs is altered in gambling disorder (GD).

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Although behavioral flexibility and conflict regulation may rely on executive function, the mechanism underlying these relationships remains obscure. We studied whether subjects' conflict ratings were associated with right dorsolateral prefrontal cortex (rDLPFC) and temporoparietal junction (rTPJ) activity during flexible decision-making in a moral dilemma task using inter-subject correlation (ISC)-based approach (i.e.

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We are constantly exposed to socially conflicting situations in everyday life, and cognitive flexibility is essential for adaptively coping with such difficulties. Flexible goal choice and pursuit are not exclusively conscious, and therefore cognitive flexibility involves both explicit and implicit forms of processing. However, it is unclear how individual differences in explicit and implicit aspects of flexibility are associated with neural activity in a resting state.

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It is widely known that there is a high prevalence of cigarette smoking in schizophrenia. One of the explanations is the self-medication hypothesis. Based on this hypothesis, it has been suggested that nicotine has procognitive effect or even neuroprotective effect in schizophrenia.

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The regulation of cue-induced craving for cigarettes is a key factor in smoking cessation. Outcomes of smoking cessation have been linked to self-efficacy, faith in one's own ability, in smokers. However, no study has examined the neural basis of self-efficacy during the control of craving.

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Behavioural flexibility is essential for everyday life. This involves shifting attention between different perspectives. Previous studies suggest that flexibility is mainly subserved by the dorsolateral prefrontal cortex (DLPFC).

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Article Synopsis
  • Studying brain abnormalities in gambling disorder (GD) helps to rule out the influence of neurotoxic substance exposure, enhancing our understanding of addiction overall.
  • Previous brain imaging studies on GD have yielded inconsistent results, but the disorder may vary in risk attitudes among individuals.
  • Our research examined GD's heterogeneity through a behavioral economics task and MRI scans, revealing specific brain structure changes linked to different levels of loss aversion in GD patients, which could inform more effective treatment strategies.
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When making decisions in everyday life, we often have to choose between uncertain outcomes. Economic studies have demonstrated that healthy people tend to prefer options with known probabilities (risk) than those with unknown probabilities (ambiguity), which is referred to as "ambiguity aversion." However, it remains unclear how patients with schizophrenia behave under ambiguity, despite growing evidence of their altered decision-making under uncertainty.

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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.

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Pathological gambling (PG) is characterized by continual repeated gambling behavior despite negative consequences. PG is considered to be a disorder of altered decision-making under risk, and behavioral economics tools were utilized by studies on decision-making under risk. At the same time, PG was suggested to be a heterogeneous disorder in terms of personality traits as well as risk attitude.

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Improving quality of life has been recognized as an important outcome for schizophrenia treatment, although the fundamental determinants are not well understood. In this study, we investigated the association between brain structural abnormalities and objective quality of life in schizophrenia patients. Thirty-three schizophrenia patients and 42 age-, sex-, and education-matched healthy participants underwent magnetic resonance imaging.

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In recent years, there has been growing interest in understanding a person's reaction to ambiguous situations, and two similar constructs related to ambiguity, "ambiguity aversion" and "ambiguity intolerance," are defined in different disciplines. In the field of economic decision-making research, "ambiguity aversion" represents a preference for known risks relative to unknown risks. On the other hand, in clinical psychology, "ambiguity intolerance" describes the tendency to perceive ambiguous situations as undesirable.

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Non-competitive and non-threatening aspects of social hierarchy, such as politeness, are universal among human cultures, and might have evolved from ritualized submission in primates; however, these behaviors have rarely been studied. Honorific language is a type of polite linguistic communication that plays an important role in human social interactions ranging from everyday conversation to international diplomacy. Here, functional magnetic resonance imaging (fMRI) revealed selective precuneus activation during a verbal politeness judgment task, but not other linguistic-judgment or social-status recognition tasks.

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Pathological gambling (PG) is a chronic mental disorder characterized by a difficulty restraining gambling behavior despite negative consequences. Although brain abnormalities in patients with substance use disorders are caused by repetitive drug use and recover partly with drug abstinence, the relationship between brain activity and duration of illness or abstinence of gambling behavior in PG patients remains unclear. Here, using functional magnetic resonance imaging, we compared the brain activity of 23 PG patients recruited from a treatment facility with 27 demographically-matched healthy control subjects during reward anticipation, and examined the correlations between brain activity and duration of illness or abstinence in PG patients.

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Background: Empathy has a central role in successful interpersonal engagement. Several studies have reported altered empathy in major depressive disorder (MDD), which could lead to interpersonal difficulties. However, the neural basis of altered empathy in the disorder is still largely unknown.

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To identify the brain regions involved in the interpretation of intentional movement by patients with schizophrenia, we investigated the association between cerebral gray matter (GM) volumes and performance on a theory of mind (ToM) task using voxel-based morphometry. Eighteen patients with schizophrenia and thirty healthy controls participated in the study. Participants were given a moving shapes task that employs the interpretation of intentional movement.

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Previous neuroimaging studies have revealed that both gray matter (GM) and white matter (WM) are altered in several morphological aspects in schizophrenia patients. Although several studies reported associations between GM and WM alterations in restricted regions, the existence of a global association between GM and WM pathologies is unknown. Considering the wide distribution of GM morphological changes and the profound genetic background of WM abnormalities, it would be natural to postulate a global association between pathologies of GM and WM in schizophrenia.

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Subjective quality of life (QOL) has been recognized as an important consideration in schizophrenia. Several symptoms and neurocognitive functions were shown to be correlated with subjective QOL; however its determinants are not well understood. In this study, we investigated the association between brain structural abnormalities and subjective QOL in patients with schizophrenia.

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Alexithymia is characterized by deficits in emotional self-awareness. A number of previous studies have revealed impaired emotional self-awareness in schizophrenia. Although the pathology of schizophrenia is thought to involve disrupted white matter integrity, its relationship with alexithymia remains unclear.

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Context: Dysfunction of the thalamocortical pathway has been proposed as a putative underlying pathology of schizophrenia. Although the mechanisms involved remain unclear, postmortem studies suggest the involvement of altered neural projections from the thalamus to layers within the prefrontal cortex.

Objectives: To investigate thalamocortical connectivity in schizophrenia and to examine its possible association with cortical thinning in vivo.

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