Trying to Put the Puzzle Together: Age and Performance Level Modulate the Neural Response to Increasing Task Load within Left Rostral Prefrontal Cortex.

Eva Bauer,Max Toepper,Gebhard Sammer

doi:10.1155/2015/415458

Abstract

Age-related working memory decline is associated with functional cerebral changes within prefrontal cortex (PFC). Kind and meaning of these changes are heavily discussed since they depend on performance level and task load. Hence, we investigated the effects of age, performance level, and load on spatial working memory retrieval-related brain activation in different subregions of the PFC. 19 younger (Y) and 21 older (O) adults who were further subdivided into high performers (HP) and low performers (LP) performed a modified version of the Corsi Block-Tapping test during fMRI. Brain data was analyzed by a 4 (groups: YHP, OHP, YLP, and OLP) × 3 (load levels: loads 4, 5, and 6) ANOVA. Results revealed significant group × load interaction effects within rostral dorsolateral and ventrolateral PFC. YHP showed a flexible neural upregulation with increasing load, whereas YLP reached a resource ceiling at a moderate load level. OHP showed a similar (though less intense) pattern as YHP and may have compensated age-effects at high task load. OLP showed neural inefficiency at low and no upregulation at higher load. Our findings highlight the relevance of age and performance level for load-dependent activation within rostral PFC. Results are discussed in the context of the compensation-related utilization of neural circuits hypothesis (CRUNCH) and functional PFC organization.

Highlights

Orientation and navigation in everyday life require a permanent adaptation of the spatial memory system
We investigated the effects of age, performance level, and load on spatial working memory retrieval-related brain activation in different subregions of the prefrontal cortex (PFC). 19 younger (Y) and 21 older (O) adults who were further subdivided into high performers (HP) and low performers (LP) performed a modified version of the Corsi Block-Tapping test during Functional magnetic resonance imaging (fMRI)
We used fMRI to investigate the effects of age, performance level, and load on prefrontal brain activation associated with spatial working memory retrieval

Summary

Introduction

Orientation and navigation in everyday life require a permanent adaptation of the spatial memory system. The efficient control and coordination of these processes depend on effective spatial working memory operations which find their neural substrate in an anterior-posterior network of prefrontal and parietal brain regions [1,2,3]. Damage to this network caused by stroke or neurodegeneration, for example, causes working memory deficits. Age-related alterations are evident for most regions of the spatial working memory network.

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