Sleep is associated with offline improvement of motor sequence skill in children.

In adults, sleep is necessary for the offline improvement of certain skills, such as sequential finger tapping, but whether children show a similar effect is still debatable. Here, we tested whether sleep is associated with offline performance improvement in children. Nine- and 11-year-old children trained on an explicit sequential finger tapping task. On the night following training, their parents observed and recorded the duration of each child's sleep. The following day, all children performed a surprise retest session on the previously trained sequence. In both 9- and 11-year-old children, skill performance was significantly improved during the first retest session relative to the end of training on the previous day, confirming the offline improvement in performance. There was a significant correlation between the degree of improvement and sleep duration the night after training, suggesting that in children, as in adults, sleep is associated with offline skill enhancement.

A study of the standard brain in Japanese children: morphological comparison with the MNI template.

Functional magnetic resonance imaging (MRI) studies involve normalization so that the brains of different subjects can be described using the same coordinate system. However, standard brain templates, including the Montreal Neurological Institute (MNI) template that is most frequently used at present, were created based on the brains of Western adults. Because morphological characteristics of the brain differ by race and ethnicity and between adults and children, errors are likely to occur when data from the brains of non-Western individuals are processed using these templates. Therefore, this study was conducted to collect basic data for the creation of a Japanese pediatric standard brain. Participants in this study were 45 healthy children (contributing 65 brain images) between the ages of 6 and 9 years, who had nothing notable in their perinatal and other histories and neurological findings, had normal physical findings and cognitive function, exhibited no behavioral abnormalities, and provided analyzable MR images. 3D-T1-weighted images were obtained using a 1.5-T MRI device, and images from each child were adjusted to the reference image by affine transformation using SPM8. The lengths were measured and compared with those of the MNI template. The Western adult standard brain and the Japanese pediatric standard brain obtained in this study differed greatly in size, particularly along the anteroposterior diameter and in height, suggesting that the correction rates are high, and that errors are likely to occur in the normalization of pediatric brain images. We propose that the use of the Japanese pediatric standard brain created in this study will improve the accuracy of identification of brain regions in functional brain imaging studies involving children.

Distinction between the literal and intended meanings of sentences: a functional magnetic resonance imaging study of metaphor and sarcasm.

To comprehend figurative utterances such as metaphor or sarcasm, a listener must both judge the literal meaning of the statement and infer the speaker's intended meaning (mentalizing; Amodio and Frith, 2006). To delineate the neural substrates of pragmatic comprehension, we conducted functional magnetic resonance imaging (fMRI) with 20 normal adult volunteers. Participants read short stories followed by a target sentence. Depending on the context provided by the preceding stories, the target sentences were classified as follows: (1) metaphor versus literally coherent; (2) metaphor versus literally incoherent; (3) sarcasm versus literally coherent; and (4) sarcasm versus literally incoherent. For each task pair, we directly compared the activations evoked by the same target sentences in the different contexts. The contrast images were incorporated into a 2 (metaphor and sarcasm)×2 (literal coherency and incoherency) design. Metaphor-specific activation was found in the head of the caudate, which might be involved in associating statements with potential meanings, and restricting sentence meanings within a set of possible candidates for what the speaker intended. Sarcasm-specific activation was found in the left amygdala, which is an important component of the neural substrates of social behavior. Conjunction analysis revealed that both metaphor and sarcasm activated the anterior rostral medial frontal cortex (arMFC), which is a key node of mentalizing. A distinct literal coherency effect was found in the orbital MFC, which is thought to be involved in monitoring. These mesial frontal areas are jointly involved in monitoring literal coherency and mentalizing within social contexts in order to comprehend the pragmatic meanings of utterances.