Partitioning age-related changes in brain activation using a virtual performance task to simulate complex movements

Abstract

Event Abstract Back to Event Partitioning age-related changes in brain activation using a virtual performance task to simulate complex movements Toshiharu Nakai1*, Ayuko Tanaka1, Mitsunobu Kunimi1, Sachiko Kiyama1 and Yoshiaki Shiraishi2 1 National Center for Geriatrics and Gerontology, Neuroimaging & Informatics, Japan 2 Nagoya Institute of Technology Graduate School of Engineering, Computer Science and Engineering, Japan Aging has become a serious social issue, especially in Asian countries. In order to maintain the activities of elderly people, social programs to promote physical and mental exercises are conducted. Although some investigations have reported that those activities potentially contribute to the prevention of cognitive decline [1], the neurological background has not been systematically verified. We investigated the availability of a virtual performance task designed from such exercises as a model to test age-related changes in brain function [2]. An event-related fMRI task representing the motor behavior in the bean transfer test (BTT), which is used as one component of the test battery to evaluate the physical ability of elderly in Japan, was designed. The task consisted of two operations using a 2 by 2 turnkey system. With the left-hand key, a small, round object (bean) is pinched with two lines representing chopsticks. Then, the object with chopsticks is moved to a round target (pot) with the right-hand key to put the bean in. The behavioral data were marked with 6 checkpoints (Fig.1). The onset of each trial was determined using the sum of two jittering factors, the execution time for each trial by the subject and periodically altering the interval time before the onset of each trial. fMRI data were obtained using the EPI sequence on a 3T MR scanner, and the data sets were analyzed using SPM8. fMRI data were obtained from 11 elderly (over 60, 6 females) and 7 non-elderly (under 54) volunteers. In the activation representing the total trial, the network for the upper visuo-spatial transformation tract and higher motor control was observed in the elderly (two-sample t-test, p<0.05). Differential peaks between the two age groups were detected as augmented activation in the left BA5 ([-23 -38 59]) and bilateral BA6 ([-60 -2 47], [60 2 38]) in the elderly group (Fig.2, CPall). In the partitioned maps, it was indicated that this difference was mostly contributed to by the first task switching point (CP2) and pinching the object (CP1). Activation of these areas was not significant in the CP3 and CP4 map in the elderly. On the other hand, activation was augmented in the dorsal visuo-motor pathway in the young subjects during these steps. It was suggested that these results represent: 1) a higher demand for visuo-spatial transformation by adjusting the asymmetric (two independent) rotation of the sticks, and 2) a lower frequency of object transference to the goal than pinching it in elderly subjects. By recording self-paced object manipulation in the interactive task, complex brain activation during a combined motor processing could be more precisely attributed to cognitive elements. This feature was useful to further partitioning age-related changes in brain activation. Figure 1 Figure 2 Acknowledgements This research was supported by a Grant-in-Aid for Scientific Research (KAKENHI) # 21300196 and 24300186 supported by MEXT.