(1) Grad. School of Human & Environmental Studies 201, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyou-ku, Kyoto City, 606-8501, Japan Fax: +81-(0)75-753-6574 Email: gvtonder@yahoo.co.uk (2) ATR Media Information Science Labs 2-2-2 Hikaridai, Seika-cho Soraku-gun, Kyoto 619-0288, Japan Email: mlyons@atr.co.jp
Working memory is an important component of higher-order cognitive processes which are negatively impacted by aging effects. Recent researches have shown that plentiful behavioral training had positive impact on working memory. However, it remains difficult to achieve significant training results and thus improve the ability of working memory and general cognitive function for older adults who was suffered with cognitive decline. Based on this premise, our study aims to compare the working memory training effects in younger and older participants, and hopes to found reliable ways to improve training effects for older and cognitive ability-damaged subjects. To achieve this purpose, we recruited 42 younger (12 men, 4 women; mean age: 25.4 years) and older adults (12 men, 12 women; mean age: 69.9 years) who were divided into two subgroups randomly to participate the current experiment. We executed a visual orientation discrimination task and a modified visual orientation sequence tasks to train the visual working memory for all participants, and evaluated the training effects by comparing results of the same pre and posttests. Our results showed that both younger and older participants could benefit from the designed training tasks. These findings indicated the robust plasticity of working memory even in aging brain, and our results further suggest that more effective training gains could be achieved by adjusting the difficulty of training task for participants with different cognitive ability.
In humans, visual information in the peripheral visual field is processed differently from such information in the central visual field. For example, peripheral vision prefers coarser information, while central vision prefers finer details. Recent advances in neuroimaging allowed us to non-invasively explore the neural substrates underlying the distinctiveness of peripheral and central vision. In the human visual cortex, there is a mosaic of orderly representations of the visual field, and this organization is called a visual field map. In this review, we summarize the various strands of research on visual field maps, which are crucial to understand human peripheral vision. We first describe the techniques that are used to measure visual field maps by means of functional magnetic resonance imaging (fMRI). We then review several studies that have tried to locate human visual areas using these techniques. We focused particularly on the findings of retinotopic organization for “far” peripheral visual field and tried to find the cortical regions that are crucial for peripheral vision. Keywords: fMRI, peripheral vision, retinotopic mapping, visual cortex, visual field map.
The basal ganglia, which have been shown to be a significant multisensory hub, are disordered in Parkinson’s disease (PD). This study was to investigate the audiovisual integration of peripheral stimuli in PD patients with/without sleep disturbances. Thirty-six age-matched normal controls (NC) and 30 PD patients were recruited for an auditory/visual discrimination experiment. The mean response times for each participant were analyzed using repeated measures ANOVA and race model. The results showed that the response to all stimuli was significantly delayed for PD compared to NC (allp<0.01). The response to audiovisual stimuli was significantly faster than that to unimodal stimuli in both NC and PD (p<0.001). Additionally, audiovisual integration was absent in PD; however, it did occur in NC. Further analysis showed that there was no significant audiovisual integration in PD with/without cognitive impairment or in PD with/without sleep disturbances. Furthermore, audiovisual facilitation was not associated with Hoehn and Yahr stage, disease duration, or the presence of sleep disturbances (allp>0.05). The current results showed that audiovisual multisensory integration for peripheral stimuli is absent in PD regardless of sleep disturbances and further suggested the abnormal audiovisual integration might be a potential early manifestation of PD.
Touch shape discrimination is not only closely related to tactile mechanoreceptors but also higher cognitive function. However, previous shape discrimination methods are difficult to complete in a short time, and the devices are complicated to operate and not user-friendly for nonprofessionals. Here, we propose a new method, the evaluation quantity of which is the angle discrimination threshold. In addition, to make this method easy to use for nonprofessionals, we designed a haptic angle sorting system, including the device and software. To evaluate this method, the angle sorting and two-angle discrimination experiments were compared, and it was found that participants spent significantly less time in the former experiment than in the latter. At the same time, there is a strong correlation between the performance of angle sorting and two-angle discrimination, which shows that the angle threshold obtained by the new method can also be used to evaluate the ability of touch discrimination. Moreover, the angle sorting results of different age groups also further demonstrate the feasibility of the method. The efficiency of this new method and the effectiveness of the system also provide a convenient means for evaluating haptic shape discrimination, which may have potential clinical application value in the early diagnosis of peripheral neuropathy and even in the evaluation of cognitive function.
Previous studies have paid special attention to the relationship between local features (e.g., raised dots) and human roughness perception. However, the relationship between global features (e.g., curved surface) and haptic roughness perception is still unclear. In the present study, a series of roughness estimation experiments was performed to investigate how global features affect human roughness perception. In each experiment, participants were asked to estimate the roughness of a series of haptic stimuli that combined local features (raised dots) and global features (sinusoidal-like curves). Experiments were designed to reveal whether global features changed their haptic roughness estimation. Furthermore, the present study tested whether the exploration method (direct, indirect, and static) changed haptic roughness estimations and examined the contribution of global features to roughness estimations. The results showed that sinusoidal-like curved surfaces with small periods were perceived to be rougher than those with large periods, while the direction of finger movement and indirect exploration did not change this phenomenon. Furthermore, the influence of global features on roughness was modulated by local features, regardless of whether raised-dot surfaces or smooth surfaces were used. Taken together, these findings suggested that an object's global features contribute to haptic roughness perceptions, while local features change the weight of the contribution that global features make to haptic roughness perceptions.
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