Preserved Suppression of Salient Irrelevant Stimuli During Visual Search in Age-Associated Memory Impairment.

Laura Lorenzo-López,Elena Amenedo,Carmen De Labra,Ana Maseda,José C Millán-Calenti,Ana Buján

doi:10.3389/fpsyg.2015.02033

Abstract

Previous studies have suggested that older adults with age-associated memory impairment (AAMI) may show a significant decline in attentional resource capacity and inhibitory processes in addition to memory impairment. In the present paper, the potential attentional capture by task-irrelevant stimuli was examined in older adults with AAMI compared to healthy older adults using scalp-recorded event-related brain potentials (ERPs). ERPs were recorded during the execution of a visual search task, in which the participants had to detect the presence of a target stimulus that differed from distractors by orientation. To explore the automatic attentional capture phenomenon, an irrelevant distractor stimulus defined by a different feature (color) was also presented without previous knowledge of the participants. A consistent N2pc, an electrophysiological indicator of attentional deployment, was present for target stimuli but not for task-irrelevant color stimuli, suggesting that these irrelevant distractors did not attract attention in AAMI older adults. Furthermore, the N2pc for targets was significantly delayed in AAMI patients compared to healthy older controls. Together, these findings suggest a specific impairment of the attentional selection process of relevant target stimuli in these individuals and indicate that the mechanism of top-down suppression of entirely task-irrelevant stimuli is preserved, at least when the target and the irrelevant stimuli are perceptually very different.

Highlights

Memory impairment is common in people over the age of 65
Previous neurophysiological and neuropsychological studies have concluded that, in addition to memory impairment and in comparison with age-matched controls, associated memory impairment (AAMI) older adults may show a significant decline in attentional resource capacity and executive functions associated with frontal lobe function (Hänninen et al, 1997; Anderer et al, 2003)
Mean Reaction times (RTs) in healthy older adults and AAMI patients are summarized in Table 1 as a function of array type

Summary

Introduction

Memory impairment is common in people over the age of 65. When this memory decline has no underlying medical cause, it is known as age-associated memory impairment (AAMI), which has been considered as a non-progressive normal decline due to aging (Crook et al, 1986; Youngjohn and Crook, 1993; Hänninen et al, 1995). Previous neurophysiological and neuropsychological studies have concluded that, in addition to memory impairment and in comparison with age-matched controls, AAMI older adults may show a significant decline in attentional resource capacity and executive functions associated with frontal lobe function (Hänninen et al, 1997; Anderer et al, 2003). Electrophysiological studies trying to elucidate the mechanisms that underlie visual selective attention processes in AAMI are inexistent. This is an interesting point taking into account that the ability to suppress distracting information or resist interference, a critical aspect of selective attention mechanisms, plays an important role in a broad range of cognitive functions including working memory (Gazzaley et al, 2005; Hasher, 2007; Solesio-Jofre et al, 2011, 2012)

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Results

Conclusion