Verification of the validity of the visual N-back task as a cognitive stress test for clinical diagnosis using fMRI M Kunimi, S Kiyama, T Nakai |
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National Center for Geriatrics and Gerontology, Japan
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| It has been pointed out that the BOLD signal is augmented depending on aging (Aizenstein et al., 2004). However, the pattern and extent of age-related change depends on the task and its difficulty. In this study, we attempted to evaluate the validity of visual N-back task (vNb) as a cognitive stress test for clinical diagnosis using fMRI. Twenty healthy normal young and 20 healthy normal elderly volunteers participated in this study. Experiment conditions were task difficulty (N = 1, 2, 3). Functional data were obtained using a T2* weighted gradient recalled echo EPI sequence (TR = 3000 ms, TE = 30 ms, 39 axial slices, 3 mm thick, FOV = 19.2 cm) on a 3T MRI scanner. The functional images were realigned, normalized and analyzed by SPM8. In the visual cortex ([BA] 17, 18, 19) and dorsolateral prefrontal cortex ([BA] 45, 46), significant activations were observed in all conditions (p < 0.001, uncorrected, RFX). These brain activations depending on the difficulty of vNb were different between the two age groups. These results showed that vNb may be applied for clinical diagnosis to detect the influence of aging on both cognitive domain of visuo-spacial recognition and learning objectively. |
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