%0 Journal Article
%T Early and Late Shift of Brain Laterality in STG, HG, and Cerebellum with Normal Aging during a Short-Term Memory Task
%A Hanani Abdul Manan
%A Ahmad Nazlim Yusoff
%A Elizabeth A. Franz
%A Siti Zamratol-Mai Sarah Mukari
%J ISRN Neurology
%D 2013
%R 10.1155/2013/892072
%X Evidence suggests that cognitive performance deteriorates in noisy backgrounds and the problems are more pronounced in older people due to brain deficits and changes. The present study used functional MRI (fMRI) to investigate the neural correlates of this phenomenon during short-term memory using a forward repeat task performed in quiet (STMQ) and in noise: 5-dB SNR (STMN) on four groups of participants of different ages. The performance of short-term memory tasks was measured behaviourally. No significant difference was found across age groups in STMQ. However, older adults (50¨C65 year olds) performed relatively poorly on the STMN. fMRI results on the laterality index indicate changes in hemispheric laterality in the superior temporal gyrus (STG), HeschlĄŻs gyrus (HG), and cerebellum, and a leftward asymmetry in younger participants which changes to a more rightward asymmetry in older participants. The results also indicate that the onset of the laterality shift varies from one brain region to another. STG and HG show a late shift while the cerebellum shows an earlier shift. The results also reveal that noise influences this shifting. Finally, the results support the hypothesis that functional networks that underlie STG, HG, and cerebellum undergo reorganization to compensate for the neural deficit/cognitive decline. 1. Introduction Studies of memory and aging suggest that some functions are impaired in the elderly, whereas other functions are altered only slightly or not at all [1]. Normal age-associated memory decline is not uniform and some cognitive changes are likely to begin in early adulthood. The previous literature on cross-sectional and longitudinal studies suggests that subtle memory changes can begin as early as the early or middle twenties and continue to decline linearly with age [2, 3]. Short-term memory (STM), for example, appears to remain relatively stable until about the age of 70, at which point it begins to drop [3, 4]. Furthermore, normal aging is associated with decline of cognitive performance [1, 5], and these age-related alterations are linked to changes in brain structure and function. One example of the alteration in brain structure and function is a compensatory right side activation in older adults for tasks that are normally left-side lateralized in young adults. This is thought to be related with age-related cognitive decline which affects the right hemisphere more than the left hemisphere. The effect is proposed to be due to grey/white matter ratio which is greater in the left compared to the right hemisphere [6, 7].
%U http://www.hindawi.com/journals/isrn.neurology/2013/892072/