Distinguishing the Visual Working Memory Training and Practice Effects by the Effective Connectivity During n-back Tasks: A DCM of ERP Study

Visual working memory (WM) training and practice can result in improved task performance and increased P300 amplitude; however, only training can yield N160 enhancements. N160 amplitudes are related to the spatial attention, the detection of novelty and the inhibitory control, while P300 amplitudes are related to the selective attention. Therefore, it could be speculated that the mechanisms underlying N160 and P300 production may differ to accommodate to their functions. Based on the different N160 engagements and different functional roles of N160 and P300, we hypothesized that the effects of visual WM training and practice can be dissociated by their brain effective connectivity patterns. We compared different neural connectivity configurations for the main task-related brain activities including N160 and P300 during the visual three-back task in subjects after visual WM training (the WM group) and after repetitive task practice (the control group). The behavioral result shows significantly greater improvement in accuracy after training and suggests that visual WM training can boost the learning process of this simple task. The N160 peak amplitude increased significantly after training over the anterior and posterior brain areas but decreased after practice over the posterior areas, indicating different mechanisms for mediating the training and practice effects. In support of our hypothesis, we observed that visual WM training alters the frontal-parietal connections, which comprise the executive control network (ECN) and the dorsal attention network (DAN), whereas practice modulates the parietal-frontal connections underpinning P300 production for selective attention. It should be noted that the analytic results in this study are conditional on the plausible models being tested and the experimental settings. Studies that employ different tasks, devices and plausible models may lead to different results. Nevertheless, our findings provide a reference for distinguishing the visual WM training and practice effects by the underlying neuroplasticity

Effect and clinical medicine observation after phacoemulsification for herpes simplex keratitis with cataract

AIM: To research the vision changes after phacoemulsification for herpes simplex keratitis(HSK)with cataract, and the clinical effect of antiviral drugs in preventing HSK relapse as well.<p>METHODS:Twenty-two cases(22 eyes)with HSK combined cataract were treated by phacoemulsification and intraocular lens implantation, and then randomly divided into two groups. The patients in treatment group received aciclovir tablets and ganciclovir ophthalmic gel, those in control group received ganciclovir ophthalmic gel only. The vision changes after phacoemulsification were observed and the HSK relapse was analyzed.<p>RESULTS: After follow-up of 6 months, the visions of patients in both groups were improved. No relapse of HSK was found in the treatment group, and only one relapse of HSK was found in the control group after 6 months. There were no significant differences in therapy effects. <p>CONCLUSION: Under the protection of antiviral drug, cataract surgery can be applied to patients with HSK recurrence-free more than 6 months, and improve the visions effectively. Ganciclovir ophthalmic gel can effectively prevent the relapse of HSK after cataract surgery