Yuko Okamoto

Role of the precuneus in the detection of incongruency between tactile and visual texture information: A functional MRI study

Visual clues as to the physical substance of manufactured objects can be misleading. For example, a plastic ring can appear to be made of gold. However, we can avoid misidentifying an object׳s substance by comparing visual and tactile information. As compared to the spatial properties of an object (e.g., orientation), however, little information regarding physical object properties (material properties) is shared between vision and touch. How can such different kinds of information be compared in the brain? One possibility is that the visuo-tactile comparison of material information is mediated by associations that are previously learned between the two modalities. Previous studies suggest that a cortical network involving the medial temporal lobe and precuneus plays a critical role in the retrieval of information from long-term memory. Here, we used functional magnetic resonance imaging (fMRI) to test whether these brain regions are involved in the visuo-tactile comparison of material properties. The stimuli consisted of surfaces in which an oriented plastic bar was placed on a background texture. Twenty-two healthy participants determined whether the orientations of visually- and tactually-presented bar stimuli were congruent in the orientation conditions, and whether visually- and tactually-presented background textures were congruent in the texture conditions. The texture conditions revealed greater activation of the fusiform gyrus, medial temporal lobe and lateral prefrontal cortex compared with the orientation conditions. In the texture conditions, the precuneus showed greater response to incongruent stimuli than to congruent stimuli. This incongruency effect was greater for the texture conditions than for the orientation conditions. These results suggest that the precuneus is involved in detecting incongruency between tactile and visual texture information in concert with the medial temporal lobe, which is tightly linked with long-term memory.

Ventral striatum dysfunction in children and adolescents with reactive attachment disorder: functional MRI study

Background Child maltreatment is a major risk factor for psychopathology, including reactive attachment disorder (RAD). Aims To examine whether neural activity during reward processing was altered in children and adolescents with RAD. Method Sixteen children and adolescents with RAD and 20 typically developing (TD) individuals performed tasks with high and low monetary rewards while undergoing functional magnetic resonance imaging. Results Significantly reduced activity in the caudate and nucleus accumbens was observed during the high monetary reward condition in the RAD group compared with the TD group (P=0.015, family-wise error-corrected cluster level). Significant negative correlations between bilateral striatal activity and avoidant attachment were observed in the RAD and TD groups. Conclusions Striatal neural reward activity in the RAD group was markedly decreased. The present results suggest that dopaminergic dysfunction occurs in the striatum of children and adolescents with RAD, leading towards potential future risks for psychopathology. Declaration of interest None. Copyright and usage

Altered frontal pole development affects self-generated spatial working memory in ADHD.

BACKGROUND Spatial working memory (SWM) dysfunction is a feature of attention deficit hyperactivity disorder (ADHD). Previous studies suggested that behavioral performance in self-generated SWM improves through development in children with and without ADHD. Nevertheless, developmental changes in the neural underpinnings of self-generated SWM are unknown. METHOD Using near-infrared spectroscopy, hemodynamic activity in the prefrontal cortex (PFC) was measured in 30 children with ADHD (9.5 ± 1.6 years-old) and 35 TD children (9.0 ± 1.6 years-old) while they performed a self-generated SWM task. We then investigated correlations between age and behavioral performance, and between age and hemodynamic activity in the PFC for each group. RESULTS Both groups showed a negative correlation with age and number of errors [ADHD: r(28)=-0.37, p=0.040; TD: r(33)=-0.59, p<0.001], indicating that self-generated SWM improves through development. The TD group showed a positive correlation between age and oxygenated hemoglobin in the frontal pole [10ch: r(33)=0.41, p=0.013; 11ch; r(33)=0.44, p=0.008] and bilateral lateral PFC [4ch: r(33)=0.34, p=0.049; 13ch; r(33)=0.54, p=0.001], while no significant correlation was found in the ADHD group. Furthermore, regression slopes for the frontal pole significantly differed between the TD and ADHD groups [10ch: t(61)=2.35, p=0.021; 11ch: t(61)=2.05, p=0.044]. CONCLUSION Children with ADHD showed abnormalities in functional maturation of the frontal pole, which plays a role in manipulating and maintaining information associated with self-generated behavior.

Attenuation of the contingency detection effect in the extrastriate body area in autism spectrum disorder

Detection of the contingency between ones own behavior and consequent social events is important for normal social development, and impaired contingency detection may be a cause of autism spectrum disorder (ASD). To depict the neural underpinnings of this contingency effect, 19 adults with ASD and 22 control participants underwent functional MRI while imitating anothers actions and their actions being imitated by the other. As the extrastriate body area (EBA) receives efference copies of ones own movements, we predicted that the EBA would show an atypical response during contingency detection in ASD. We manipulated two factors: the congruency of the executed and observed actions, and the order of action execution and observation. Both groups showed the congruency effect in the bilateral EBA during imitation. When action preceded observation, the left EBA of the control group showed the congruency effect, representing the response to being imitated, indicating contingency detection. The ASD group showed a reduced contingency effect in the left EBA. These results indicate that the function of the EBA in the contingency detection is altered in ASD.

Self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal superior longitudinal fasciculus III network

Proprioception is somatic sensation that allows us to sense and recognize position, posture, and their changes in our body parts. It pertains directly to oneself and may contribute to bodily awareness. Likewise, ones face is a symbol of oneself, so that visual self-face recognition directly contributes to the awareness of self as distinct from others. Recently, we showed that right-hemispheric dominant activity in the inferior fronto-parietal cortices, which are connected by the inferior branch of the superior longitudinal fasciculus (SLF III), is associated with proprioceptive illusion (awareness), in concert with sensorimotor activity. Herein, we tested the hypothesis that visual self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal SLF III network. We scanned brain activity using functional magnetic resonance imaging while twenty-two right-handed healthy adults performed two tasks. One was a proprioceptive illusion task, where blindfolded participants experienced a proprioceptive illusion of right hand movement. The other was a visual self-face recognition task, where the participants judged whether an observed face was their own. We examined whether the self-face recognition and the proprioceptive illusion commonly activated the inferior fronto-parietal cortices connected by the SLF III in a right-hemispheric dominant manner. Despite the difference in sensory modality and in the body parts involved in the two tasks, both tasks activated the right inferior fronto-parietal cortices, which are likely connected by the SLF III, in a right-side dominant manner. Here we discuss possible roles for right inferior fronto-parietal activity in bodily awareness and self-awareness.

Sex-different abnormalities in the right second to fourth digit ratio in Japanese individuals with autism spectrum disorders

BackgroundThe prevalence of autism spectrum disorders (ASDs) is higher in men than in women. The extreme male brain theory proposes that excessive prenatal testosterone activity could be a risk factor for ASDs. However, it is unclear whether prenatal sex hormone activity is a risk factor for women. The ratio of the length of the second to fourth digits (2D:4D) is considered to be a biomarker of the prenatal ratio of testosterone to estrogen. Therefore, this study compared the 2D:4D ratios of women with and without ASDs to determine if prenatal sex hormone activity could be a risk factor for ASDs in women.MethodsThe study included 35 Japanese men with ASDs, 17 Japanese women with ASDs, 59 typically developed (TD) Japanese men, and 57 TD Japanese women. We measured digit lengths and compared the 2D:4D ratios among the four groups. We also examined the relationship between the 2D:4D ratio and the autism-spectrum quotient score of each group.ResultsIn our cohort, men with ASDs tended to have lower right-hand 2D:4D ratios relative to TD men. In contrast, the right 2D:4D ratios in women with ASDs were higher compared to those of TD women. No significant correlations were found between the 2D:4D ratios and the autism-spectrum quotient scores in any group. The higher right 2D:4D ratios in women could not be explained by age or full-scale intelligent quotients. This group difference was not found for the left 2D:4D or right–left 2D:4D ratios.ConclusionsWe found a reverse direction of abnormality in the right 2D:4D ratio for men and women with ASDs. It has been posited that high prenatal testosterone levels lead to a lower 2D:4D ratio. However, a recent animal study showed that testosterone injection to dam leads to a higher right 2D:4D ratio especially for female offspring, which might be mediated by abnormal adipose accumulation in the fingertip. Therefore, the present findings suggest that high prenatal testosterone could be a risk factor both for Japanese men and women with ASDs, elucidating one potential etiology of ASDs in women.

Effect of intranasal oxytocin on the core social symptoms of autism spectrum disorder: a randomized clinical trial

Although small-scale studies have described the effects of oxytocin on social deficits in autism spectrum disorder (ASD), no large-scale study has been conducted. In this randomized, parallel-group, multicenter, placebo-controlled, double-blind trial in Japan, 106 ASD individuals (18–48 y.o.) were enrolled between Jan 2015 and March 2016. Participants were randomly assigned to a 6-week intranasal oxytocin (48IU/day, n = 53) or placebo (n = 53) group. One-hundred-three participants were analyzed. Since oxytocin reduced the primary endpoint, Autism Diagnostic Observation Schedule (ADOS) reciprocity, (from 8.5 to 7.7; P < .001) but placebo also reduced the score (8.3 to 7.2; P < .001), no between-group difference was found (effect size −0.08; 95% CI, −0.46 to 0.31; P = .69); however, plasma oxytocin was only elevated from baseline to endpoint in the oxytocin-group compared with the placebo-group (effect size −1.12; −1.53 to −0.70; P < .0001). Among the secondary endpoints, oxytocin reduced ADOS repetitive behavior (2.0 to 1.5; P < .0001) compared with placebo (2.0 to 1.8; P = .43) (effect size 0.44; 0.05 to 0.83; P = .026). In addition, the duration of gaze fixation on socially relevant regions, another secondary endpoint, was increased by oxytocin (41.2 to 52.3; P = .03) compared with placebo (45.7 to 40.4; P = .25) (effect size 0.55; 0.10 to 1.0; P = .018). No significant effects were observed for the other secondary endpoints. No significant difference in the prevalence of adverse events was observed between groups, although one participant experienced temporary gynecomastia during oxytocin administration. Based on the present findings, we cannot recommend continuous intranasal oxytocin treatment alone at the current dose and duration for treatment of the core social symptoms of high-functioning ASD in adult men, although this large-scale trial suggests oxytocin’s possibility to treat ASD repetitive behavior.

Self-Face Recognition Begins to Share Active Region in Right Inferior Parietal Lobule with Proprioceptive Illusion During Adolescence

Abstract We recently reported that right-side dominance of the inferior parietal lobule (IPL) in self-body recognition (proprioceptive illusion) task emerges during adolescence in typical human development. Here, we extend this finding by demonstrating that functional lateralization to the right IPL also develops during adolescence in another self-body (specifically a self-face) recognition task. We collected functional magnetic resonance imaging (fMRI) data from 60 right-handed healthy children (8–11 years), adolescents (12–15 years), and adults (18–23 years; 20 per group) while they judged whether a presented face was their own (Self) or that of somebody else (Other). We also analyzed fMRI data collected while they performed proprioceptive illusion task. All participants performed self-face recognition with high accuracy. Among brain regions where self-face-related activity (Self vs. Other) developed, only right IPL activity developed predominantly for self-face processing, with no substantial involvement in other-face processing. Adult-like right-dominant use of IPL emerged during adolescence, but was not yet present in childhood. Adult-like common activation between the tasks also emerged during adolescence. Adolescents showing stronger right-lateralized IPL activity during illusion also showed this during self-face recognition. Our results suggest the importance of the right IPL in neuronal processing of information associated with one’s own body in typically developing humans.

Age-dependent atypicalities in body- and face-sensitive activation of the EBA and FFA in individuals with ASD

Individuals with autism spectrum disorder (ASD) have difficuly in recognizing bodies and faces, which are more pronounced in children than adults. If such difficulties originate from dysfunction of the extrastriate body area (EBA) and the fusiform face area (FFA), activation in these regions might be more atypical in children than in adults. We preformed functional magnetic resonance imaging while children and adults with ASD and age-matched typically developed (TD) individuals observed face, body, car, and scene. To examine various aspects, we performed individual region of interest (ROI) analysis, as well as conventional random effect group analysis. At individual ROI analysis, we examined the ratio of participants showing a category-sensitive response, the size of regions, location and activation patterns among the four object categories. Adults with ASD showed no atypicalities in activation of the EBA and FFA, whereas children with ASD showed atypical activation in these regions. Specifically, a smaller percentage of children with ASD showed face-sensitive activation of the FFA than TD children. Moreover, the size of the EBA was smaller in children with ASD than in TD children. Our results revealed atypicalities in both the FFA and EBA in children with ASD but not in adults with ASD.

Development of Right-hemispheric Dominance of Inferior Parietal Lobule in Proprioceptive Illusion Task

Abstract Functional lateralization can be an indicator of brain maturation. We have consistently shown that, in the adult brain, proprioceptive processing of muscle spindle afferents generating illusory movement of the right hand activates inferior frontoparietal cortical regions in a right‐side dominant manner in addition to the cerebrocerebellar motor network. Here we provide novel evidence regarding the development of the right‐dominant use of the inferior frontoparietal cortical regions in humans using this task. We studied brain activity using functional magnetic resonance imaging while 60 right‐handed blindfolded healthy children (8‐11 years), adolescents (12‐15 years), and young adults (18‐23 years) (20 per group) experienced the illusion. Adult‐like right‐dominant use of the inferior parietal lobule (IPL) was observed in adolescents, while children used the IPL bilaterally. In contrast, adult‐like lateralized cerebrocerebellar motor activation patterns were already observable in children. The right‐side dominance progresses during adolescence along with the suppression of the left‐sided IPL activity that emerges during childhood. Therefore, the neuronal processing implemented in the adults right IPL during the proprioceptive illusion task is likely mediated bilaterally during childhood, and then becomes right‐lateralized during adolescence at a substantially later time than the lateralized use of the cerebrocerebellar motor system for kinesthetic processing.