Recognition Memory In Older Adults Research Articles

Effects of transcranial direct current stimulation combined with listening to preferred music on memory in older adults

Listening to autobiographically-salient music (i.e., music evoking personal memories from the past), and transcranial direct current stimulation (tDCS) have each been suggested to temporarily improve older adults’ subsequent performance on memory tasks. Limited research has investigated the effects of combining both tDCS and music listening together on cognition. The present study examined whether anodal tDCS stimulation over the left dorsolateral prefrontal cortex (2 mA, 20 min) with concurrent listening to autobiographically-salient music amplified subsequent changes in working memory and recognition memory in older adults than either tDCS or music listening alone. In a randomized sham-controlled crossover study, 14 healthy older adults (64–81 years) participated in three neurostimulation conditions: tDCS with music listening (tDCS + Music), tDCS in silence (tDCS-only), or sham-tDCS with music listening (Sham + Music), each separated by at least a week. Working memory was assessed pre- and post-stimulation using a digit span task, and recognition memory was assessed post-stimulation using an auditory word recognition task (WRT) during which electroencephalography (EEG) was recorded. Performance on the backwards digit span showed improvement in tDCS + Music, but not in tDCS-only or Sham + Music conditions. Although no differences in behavioural performance were observed in the auditory WRT, changes in neural correlates underlying recognition memory were observed following tDCS + Music compared to Sham + Music. Findings suggest listening to autobiographically-salient music may amplify the effects of tDCS for working memory, and highlight the potential utility of neurostimulation combined with personalized music to improve cognitive performance in the aging population.

List-strength effects in older adults in recognition and free recall.

The present investigation provides a novel extension of the retrieving effectively from memory (REM) model to examine free-recall and recognition memory in older adults to inform our understanding of age-related cognitive decline. When some items on a list are strengthened through distributed repetitions, memory for the nonstrengthened items on that list may become impaired depending on how memory is tested-a phenomenon known as the list-strength effect (LSE; e.g., Tulving & Hastie, Journal of Experimental Psychology, 92, 297-304, 1972). When the strengthening operation involves distributed repetitions, LSE is robust in free recall, but it is reliably absent in recognition (Malmberg & Shiffrin, Journal of Experimental Psychology, 31, 322-336, 2005; Ratcliff, Clark, & Shiffrin, Journal of Experimental Psychology, 16, 163-178, 1990). Two experiments investigated LSE in recall and recognition in older adults and young adults who encoded items with full or divided attention. Despite showing impaired recall and recognition, older adults showed patterns of LSEs across both experiments that were similar to young adults with full attention rather than young adults with divided attention. In recognition, there was a null LSE in older and young adults, but a positive LSE was observed under divided attention. In contrast, in free recall, there was a positive LSE in older and young adults, but a null LSE under divided attention. Collectively, the results suggest that older adults do not have impaired encoding of context information (evidenced by intact LSE in recall), and they do not have impaired differentiation of item representations (evidenced by the null LSE in recognition). Age-related impairment in both memory tasks can be accounted for by sparse encoding of item-based information.

Semantically Congruent Visual Information Can Improve Auditory Recognition Memory in Older Adults.

In the course of normal aging, memory functions show signs of impairment. Studies of memory in the elderly have previously focused on a single sensory modality, although multisensory encoding has been shown to improve memory performance in children and young adults. In this study, we investigated how audiovisual encoding affects auditory recognition memory in older (mean age 71 years) and younger (mean age 23 years) adults. Participants memorized auditory stimuli (sounds, spoken words) presented either alone or with semantically congruent visual stimuli (pictures, text) during encoding. Subsequent recognition memory performance of auditory stimuli was better for stimuli initially presented together with visual stimuli than for auditory stimuli presented alone during encoding. This facilitation was observed both in older and younger participants, while the overall memory performance was poorer in older participants. However, the pattern of facilitation was influenced by age. When encoding spoken words, the gain was greater for older adults. When encoding sounds, the gain was greater for younger adults. These findings show that semantically congruent audiovisual encoding improves memory performance in late adulthood, particularly for auditory verbal material.

Associative memory and underlying brain correlates in older adults with mild cognitive impairment

This study investigated associative recognition memory by using unique features of the Chinese language and the underlying neuroanatomical correlates. The study participants were 22 Chinese speakers with mild cognitive impairment (MCI) and 25 cognitively normal (CN) Chinese speakers. The results revealed that the MCI group demonstrated impaired associative memory performance, despite exhibiting item memory performance comparable with that of the CN group, and that associative memory performance in older adults was associated with gray matter integrity in the medial temporal regions as well as executive function. An abnormal elevation was also observed in false-positive errors related to features unique to Chinese characters, namely orthographical errors, in addition to rearranged and semantic errors in the MCI group relative to the CN group, and the three error subtypes were differentially associated with gray matter integrity in the hippocampus or lateral prefrontal regions. Overall, these results demonstrate the value of evaluating associative memory in people with prodromal Alzheimer's disease (AD), and further elucidate the underlying neural substrates related to associative recognition memory in older adults.

Electrophysiological evidence for the effects of unitization on associative recognition memory in older adults

Normal aging is associated with greater decline in associative memory relative to item memory due to impaired recollection. Familiarity may also contribute to associative recognition when stimuli are perceived as a ‘unitized’ representation. Given that familiarity is relatively preserved in older adults, we explored whether age-related associative memory deficits could be attenuated when associations were unitized (i.e., compounds) compared with those non-unitized (i.e., unrelated word pairs). Young and older adults performed an associative recognition task while electroencephalogram (EEG) was recorded. Behavioral results showed that age differences were smaller for recognition of compounds than for unrelated word pairs. ERP results indicated that only compounds evoked an early frontal old/new effect in older adults. Moreover, the early frontal old/new effect was positively correlated with associative discrimination accuracy. These findings suggest that reduced age-related associative deficits under unitized condition may be associated with the presence of familiarity-based retrieval of compounds in older adults.

Is faster better? Effects of response deadline on ERP correlates of recognition memory in younger and older adults

Aging studies generally suggest that recollection is impaired whereas familiarity-based recognition remains relatively preserved in healthy older adults. The present event-related potential (ERP) study explores whether age-related impairments in recognition memory can be reduced under conditions in which recognition decisions are primarily driven by familiarity. Old and young adults performed an item recognition task with perceptually rich visual stimuli. A response deadline procedure was employed following previous studies which have shown that limiting response times attenuates recollection but leaves familiarity relatively unaffected. Age effects on memory performance were large in the non-speeded response condition in which recollection contributes to performance. When response time was limited, performance differences between groups were negligible. In the non-speeded condition the ERP correlate of recollection was not detectable in old adults. Conversely, in the speeded condition ERP correlates of familiarity were obtained in both age groups, though attenuated for old adults. For old adults in the speeded condition a temporally extended posterior negativity was obtained which was more pronounced for low performing participants. The results suggest that even though the neural generators of the familiarity signal degrade with age, familiarity is an important contributor to recognition memory in older adults and can lead to a disproportional benefit in memory in conditions designed to specifically enhance familiarity-based responding.

RECOGNITION MEMORY IN OLDER ADULTS: ADJUSTMENT TO CHANGING CONTINGENCIES

Four older and 4 younger men were given extended exposure to a continuous-recognition memory procedure. Experimental variables included the type of stimulus (alphanumeric strings, words, or sentences), the intervals separating repeated items, gains and losses for correct and incorrect recognitions, and the extent of practice with the memory task. Signal detection analyses indicated that the older men generally were less accurate (sensitivity), particularly when the stimuli were strings, but that age differences decreased with practice. Under conditions in which the payoff matrix was neutral, the older and younger men showed equivalent rates of hits and false alarms (bias). Alteration of the matrix to require more liberal or more conservative patterns of recognition responding led to corresponding changes for men of both ages. Adjustments by the older men, however, were not as close to the bias values called for by the new matrices.