Effects of anodal transcranial direct current stimulation on implicit motor learning and language-related brain function: An fMRI study.

AIM: Anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) is known as a useful application for improving depressive symptoms or cognitive performance. Antidepressive effects by anodal tDCS over the left DLPFC are expected, but the neural mechanisms of these effects are still unclear. Further, in depression, reduced performance and left prefrontal hypofunction during the verbal fluency task (VFT) are generally known. However, few studies have examined the effect of tDCS on the language-related cerebral network. We aimed to investigate whether anodal tDCS at the left DLPFC affects cognitive performance and the neural basis of verbal fluency. METHODS: Nineteen healthy volunteers participated in this study. The effects of tDCS on cognitive behavior and cerebral function were evaluated by (i) performance and accuracy of implicit/explicit motor learning task (serial reaction time task/sequential finger-tapping task), and (ii) cerebral activation while the subjects were performing the VFT by using a functional MRI protocol of a randomized sham-controlled, within-subjects crossover design. RESULTS: Reaction times of the implicit motor learning task were significantly faster with tDCS in comparison with the sham. Further, language-related left prefrontal-parahippocampal-parietal activation was significantly less with tDCS compared with the sham. Significant correlation was observed between shortened response time in serial reaction time task and decreased cerebral activation during VFT with tDCS. CONCLUSION: Anodal tDCS over the left DLPFC could improve cognitive behavior of implicit motor learning by improving brain function of the frontoparietal-parahippocampal region related to motor learning, as well as language-related regions.

Modified activity-based anorexia paradigm dampens chronic food restriction-induced hyperadiponectinemia in adolescent female mice.

Anorexia nervosa (AN) is a chronic, life-threatening disease with mental and physical components that include excessive weight loss, persistent food restriction, and altered body image. It is sometimes accompanied by hyperactivity, day-night reversal, and amenorrhea. No medications have been approved specific to the treatment of AN, partially due to its unclear etiopathogenesis. Because adiponectin is an appetite-regulating cytokine released by adipose tissue, we hypothesized that it could be useful as a specific biomarker that reflects the disease state of AN, so we developed a modified AN mouse model to test this hypothesis. Twenty-eight 3-week-old female C57BL/6J mice were randomly assigned to the following groups: 1) no intervention; 2) running wheel access; 3) food restriction (FR); and 4) activity-based anorexia (ABA) that included running wheel access plus FR. After a 10-day cage adaptation period, the mice of the FR and ABA groups were given 40% of their baseline food intake until 30% weight reduction (acute FR), then the body weight was maintained for 2.5 weeks (chronic FR). Running wheel activity and the incidence of the estrous cycle were assessed. Spontaneous food restriction and the plasma adiponectin level were evaluated at the end of the acute and chronic FR phases. An increase in running wheel activity was found in the light phase, and amenorrhea was found solely in the ABA group, which indicates that this is a good model of AN. This group showed a slight decrease in spontaneous food intake accompanied with an attenuated level of normally induced plasma adiponectin at the end of the chronic FR phase. These results indicate that the plasma adiponectin level may be a useful candidate biomarker for the status or stage of AN.