Effects of hand clasping and arm folding on academic performance

BACKGROUND：Similar to handedness, hand clasping and arm folding are also lateral preferences. Previous studies showed a variation frequency for hand clasping and arm folding among different populations. OBJECTIVE： To investigate the relationship between patterns of lateral preferences （hand clasping or arm folding） and academic performance of middle school students. DESIGN, TIME AND SETTINGS： Cross-sectional investigation. The data were collected in the Beijing Zhongguancun High School in Beijing in May 2007. Data analysis was performed in the State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University during June to July 2007. PARTICIPANTS： A total of 102 senior-grade students from Beijing Zhongguancun High School, including 58 males and 44 females, were selected for this study. METHODS： Different forms of hand clasping and arm folding were recorded. More specifically, hand clasping was either right-thumb-top or left-thumb-top, and arm folding was either right-arm-top or left-arm-top. Students with congruent preference used right-thumb-top-right-arm-top or left-thumb-top-left-arm-top, and incongruent preference was displayed by right-thumb-top-left-arm-top or left-thumb-top-right-arm-top. Academic performances were collected from midterm exams in six subjects （Chinese, Mathematics, English, Physics, Chemistry, and Biology）, with a total points = 100 for each. A three-way （hand clasping, arm folding, and sex） ANOVA was performed to determine the effect on academic performances. MAIN OUTCOME MEASURES： The relationship between hand clasping, arm folding, sex, and academic performance of students. RESULTS： （1） There was no significant difference in distribution frequency between right-thumb-top and left-thumb-top （P 〉 0.05）, or between right-arm-top and left-arm-top （P 〉 0.05）. The distribution frequency difference between boys and girls was not significant for any subtype （P 〉 0.05）. （2） hand clasping had no significant main effect on any of the six subjects （P 〉 0.05）. The right-arm-top students received significantly higher points in Chinese, Physics, Chemistry, and Biology, compared with the left-arm-top students （P 〈 0.05）. A significant sexual difference was detected in academic performance in Chinese and English; girls had higher scores than the boys （P 〈 0.05）. The students with congruent preference scored higher in English, compared with those with incongruent preference （P 〈 0.05）. CONCLUSION： The arm folding form of lateral preference had a significant effect on academic performance of middle school students, implying that this human laterality index is of great functional importance.

Caliper-based precise positioning of the target(CALIPPOT)for transcranial magnetic stimulation without neuronavigation system

To the editor:Transcranial magnetic stimulation(TMS)is a non-invasive brain modulation technique.One important usage of TMS is the transient interruption of cognitive brain function(also named virtual lesion)for investigating precisely where and when a specific cortical region contributes to a specific cognitive function.1 A more important usage of TMS is the treatment of brain disorders by repetitive TMS(rTMS).

Frequency-specific abnormalities in regional homogeneity among children with attention deficit hyperactivity disorder: a resting-state f MRI study

Although many functional magnetic resonance imaging(f MRI) studies have investigated the neurophysiology of attention deficit hyperactivity disorder(ADHD),the existing studies have not yielded consistent findings.This may be related to the different properties of different frequency bands. To investigate the frequency-specific regional homogeneity(Re Ho) of spontaneous neural activities in ADHD, the current study used resting-state f MRI to explore the Re Ho properties of five frequency bands, slow-5(0.01–0.027 Hz), slow-4(0.027–0.073 Hz),slow-3(0.073–0.198 Hz), slow-2(0.198–0.25 Hz) and the extra-low frequency(0–0.01 Hz), in 30 drug-naive boys with ADHD and 30 healthy controls. Compared with controls, the ADHD group showed decreased Re Ho in the default mode network(DMN) including the medial prefrontal cortex and precuneus, middle frontal gyrus and angular gyrus. ADHD patients also showed increased Re Ho in the posterior cerebellum. Significant interactions between frequency band and group were observed predominantly in the dorsolateral prefrontal and parietal cortices, orbital frontal cortex, supplementary motor area,inferior occipital gyrus, thalamus and anterior cerebellum.In particular, we found that the between-group difference in the extra-low frequency band(0–0.01 Hz) seemed to be greater than that in the other frequency bands for most brain regions. The findings suggest that ADHD children display widespread abnormalities in regional brain activity,particularly in the DMN and attention network, and these abnormalities show frequency specificity.

Effects of methylphenidate on resting-state brain activity in normal adults: an fMRI study

Methylphenidate （MPH） is one of the most commonly used stimulants for the treatment of attention deficit hyperactivity disorder （ADHD）. Although several studies have evaluated the effects of MPH on human brain activation during specific cognitive tasks using functional magnetic resonance imaging （fMRI）, few studies have focused on spontaneous brain activity. In the current study, we investigated the effect of MPH on the intra-regional synchronization of spontaneous brain activity during the resting state in 18 normal adult males. A handedness questionnaire and the Wechsler Adult Intelligence Scale were applied before medication, and a resting-state fMRI scan was obtained 1 h after medication （20 mg MPH or placebo, order counterbalanced between participants）. We demonstrated that： （1） there were no significant differences in the performance of behavioral tasks between the MPH and placebo groups; （2） the left middle and superior temporal gyri had stronger MPH-related regional homogeneity （ReHo）; and （3） the left lingual gyrus had weaker MPH-related ReHo. Our findings showed that the ReHo in some brain areas changes with MPH compared to placebo in normal adults, even though there are no behavioral differences. This method can be applied to patients with mental illness who may be treated with MPH, and be used to compare the difference between patients taking MPH and normal participants, to help reveal the mechanism of how MPH works.