Development of attentional networks during childhood and adolescence: A functional MRI study.

Attention ability is one of the most important cognitive functions. It develops mainly during school age. However, the neural basis for the typical development of attentional functions has not been fully investigated. To clarify the development of the aforementioned function and its neural basis, this study examined brain function in children and adolescents during the performance of an attention network test (ANT) using functional magnetic resonance imaging. One hundred and sixty-three volunteers (8-23 years, 80 female) participated in this study. Using a modified version of ANT, we assessed the efficiency of two attentional functions-orienting and executive attention-by measuring how reaction time is affected by spatial cue location and flanker congruency and examined the functional brain areas-attentional networks-associated with two attentional functions. Consistent with the findings of previous studies, the superior parietal lobule, visual association cortex, left precentral gyrus, and supplementary motor area were activated during the orienting attention, while the anterior cingulate cortex, visual association cortex, lateral prefrontal cortex, thalamus, and caudate were activated during the executive attention. Moreover, negative correlations with age were found for activations in the inferior frontal gyrus, dorsomedial prefrontal cortex, and caudate nucleus in the orienting attention, while no correlations with age related to executive attention were found. In conclusion, this study revealed common and distinct features in the neural basis of the attentional functions in children and adolescents compared with that of adults and their developmental changes with age.

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.

Autistic empathy toward autistic others.

Individuals with autism spectrum disorder (ASD) are thought to lack self-awareness and to experience difficulty empathizing with others. Although these deficits have been demonstrated in previous studies, most of the target stimuli were constructed for typically developing (TD) individuals. We employed judgment tasks capable of indexing self-relevant processing in individuals with and without ASD. Fourteen Japanese men and 1 Japanese women with high-functioning ASD (17-41 years of age) and 13 Japanese men and 2 TD Japanese women (22-40 years of age), all of whom were matched for age and full and verbal intelligence quotient scores with the ASD participants, were enrolled in this study. The results demonstrated that the ventromedial prefrontal cortex was significantly activated in individuals with ASD in response to autistic characters and in TD individuals in response to non-autistic characters. Although the frontal-posterior network between the ventromedial prefrontal cortex and superior temporal gyrus participated in the processing of non-autistic characters in TD individuals, an alternative network was involved when individuals with ASD processed autistic characters. This suggests an atypical form of empathy in individuals with ASD toward others with ASD.

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

Detection of the contingency between one's 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 another's actions and their actions being imitated by the other. As the extrastriate body area (EBA) receives efference copies of one's 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.

Depressive mood modulates the anterior lateral CA1 and DG/CA3 during a pattern separation task in cognitively intact individuals: a functional MRI study.

Although patients with major depressive disorder typically have a reduced hippocampal volume, particularly in the cornu ammonis 1 (CA1), animal studies suggest that depressive mood is related to the dentate gyrus (DG). In this study, our objective was to clarify which hippocampal subregions are functionally associated with depressive mood in humans. We conducted a functional MRI (fMRI) study on 27 cognitively intact volunteers. Subjects performed a modified version of a delayed matching-to-sample task in an MRI scanner to investigate pattern separation-related activity during each phase of encoding, delay, and retrieval. In each trial, subjects learned a pair of sample cues. Functional MR images were acquired at a high spatial resolution, focusing on the hippocampus. Subjects also completed the Beck Depression Inventory (BDI), a questionnaire about depressive mood. Depending on the similarity between sample cues, activity in the DG/CA3 and medial CA1 in the anterior hippocampus changed only during encoding. Furthermore, the DG/CA3 region was more active during successful encoding trials compared to false trials. Activity in the DG/CA3 and lateral CA1 was negatively correlated with BDI scores. These results suggest that the DG/CA3 is the core region for pattern separation during the encoding phase and interacts with the medial CA1, depending on the similarity of the stimuli, to achieve effective encoding. Impaired activity in the DG/CA3, as well as in the lateral CA1, was found to be associated with depressive symptoms, even at a subclinical level.

Neural substrates of phasic alertness: a functional magnetic resonance imaging study.

The "warning effect" refers to the decrease in motor response reaction times to a target when its presentation is preceded by a stimulus indicating that the target will appear shortly. We hypothesized that cue presentation phasically enhances alertness, which in turn facilitates the preparation of a motor response. To test this hypothesis, we conducted functional magnetic resonance imaging during a Go/NoGo task with a warning stimulus. Fifteen subjects completed a visual Go/NoGo task, and 12 completed an analogous task in the auditory modality. After a warning stimulus was presented, a Go or NoGo stimulus was presented with equal probability. Both auditory and visual warning stimuli activated the midbrain, thalamus, and the anterior cingulate cortex (ACC) extending to the pre-supplementary motor area (pre-SMA). The warning-related activation in the pre-SMA and thalamus was greater when warnings were followed by Go events with faster reaction times than when followed by events with slower reaction times. The midbrain, thalamus, and ACC are known to be associated with vigilance or intrinsic alertness, and the pre-SMA is involved in movement selection and preparation. Thus, the warning effect may be partly mediated by the potentiation of the pre-SMA through the midbrain-thalamus-ACC alerting network.