An exploratory study of the effects of spatial working-memory load on prefrontal activation in low- and high-performing elderly

摘要: Older adults show more bilateral prefrontal activation during cognitive performance than younger adults, who typically unilateral activation. This over-recruitment has been interpreted as compensation for declining structure and function of the brain. Here we examined how relationship between behavioral is modulated by different levels working-memory load. Eighteen healthy older (70.8 ± 5.0 years; MMSE 29.3 0.9) performed a spatial task (n-back). Oxygenated ([O2Hb]) deoxygenated ([HHb]) hemoglobin concentration changes were registered two functional Near-Infrared Spectroscopy (fNIRS) channels located over left right cortex. Increased load resulted in worse compared to control condition. [O2Hb] increased with rising both fNIRS channels. Based on high condition, group was divided into low performers. A significant interaction effect level hemisphere increase found, indicating that performers better able keep cortex engaged under demand. Furthermore, group, individuals larger decline from condition had [O2Hb]. The did not correlation related changes. Thus, additional necessarily result performance. Our study showed may always be successfully compensatory. Individual should taken account distinguish successful unsuccessful or declined neural efficiency.