Hemispheric asymmetry reduction in older adults: The HAROLD model.

A model of the effects of aging on brain activity during cognitive performance is introduced. The model is called HAROLD (hemispheric asymmetry reduction in older adults), and it states that, under similar circumstances, prefrontal activity during cognitive performances tends to be less lateralized in older adults than in younger adults. The model is supported by functional neuroimaging and other evidence in the domains of episodic memory, semantic memory, working memory, perception, and inhibitory control. Age-related hemispheric asymmetry reductions may have a compensatory function or they may reflect a dedifferentiation process. They may have a cognitive or neural origin, and they may reflect regional or network mechanisms. The HAROLD model is a cognitive neuroscience model that integrates ideas and findings from psychology and neuroscience of aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related differences in irrelevant-speech effects.

Three experiments examined age-related differences in irrelevant-speech effects. Younger and older adults were required to recall short prose texts or lists of semantically related words presented visually together with distractor speech. In all experiments, older adults made more semantically related intrusion errors from the irrelevant speech than younger adults. Results of a source memory test suggested that these age-related differences in interference are most likely due to both inhibitory deficits and source-monitoring problems. The results lend partial support to the inhibition deficit theory of cognitive aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effects of Age and Dementia of the Alzheimer's Type on Phonological False Memories.

The authors conducted 3 experiments that examined the effects of age and dementia of the Alzheimer's type (DAT) on phonological false memories. In addition, the study was designed to investigate the role of inhibitory control in mediating phonological false memories. In Experiment 1, both young-old and old-old participants exhibited increased susceptibility to false remembering, compared with young adults. In Experiment 2, auditory Stroop interference was used as an index of inhibitory abilities and was found to account for a significant percentage of the variance in false recollection. Experiment 3 provided converging evidence for the importance of inhibitory control in phonological false memories by demonstrating that DAT patients are more susceptible to false recall and recognition than healthy older adults. The results are discussed within the inhibitory deficit framework of cognitive aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of aging on the neural correlates of successful item and source memory encoding.

To investigate the neural basis of age-related source memory (SM) deficits, young and older adults were scanned with fMRI while encoding faces, scenes, and face-scene pairs. Successful encoding activity was identified by comparing encoding activity for subsequently remembered versus forgotten items or pairs. Age deficits in successful encoding activity in hippocampal and prefrontal regions were more pronounced for SM (pairs) as compared with item memory (faces and scenes). Age-related reductions were also found in regions specialized in processing faces (fusiform face area) and scenes (parahippocampal place area), but these reductions were similar for item and SM. Functional connectivity between the hippocampus and the rest of the brain was also affected by aging; whereas connections with posterior cortices were weaker in older adults, connections with anterior cortices, including prefrontal regions, were stronger in older adults. Taken together, the results provide a link between SM deficits in older adults and reduced recruitment of hippocampal and prefrontal regions during encoding. The functional connectivity findings are consistent with a posterior-anterior shift with aging previously reported in several cognitive domains and linked to functional compensation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging increases inattentional blindness to the gorilla in our midst.

When engaged in an attention-demanding task, people are surprisingly vulnerable to inattentional blindness—the failure to notice an unexpected event. Two theories of cognitive aging, attentional capacity models and inhibitory deficit models, make opposite predictions about age differences in susceptibility to inattentional blindness. We tested these predictions using an inattentional blindness paradigm developed by Simons and Chabris (1999) and found that older adults were more likely to experience inattentional blindness than young adults. These results are compatible with attentional capacity models of cognitive aging but not with current inhibitory deficit models. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Stroop performance in healthy younger and older adults and in individuals with dementia of the Alzheimer's type

Components of the Stroop task were examined to investigate the role that inhibitory processes play in cognitive changes in healthy older adults and in individuals with dementia of the Alzheimer's type (DAT). Inhibitory breakdowns should result in an increase in Stroop interference. The results indicate that older adults show a disproportionate increase in interference compared with younger adults. DAT individuals show interference proportionate to older adults but a disproportionate increase in facilitation for congruent color-word trials, and an increased intrusion of word naming on incongruent color naming trials. An ex-Gaussian analysis of response time distributions indicated that the increased interference observed in older adults was due to an increase in the tail of the distribution. Application of the process dissociation analysis of the Stroop task (D.S. Lindsay & L.L. Jacoby, 1994) indicated that older adults showed increased word process estimates, whereas DAT individuals showed differences in both color and word process estimates. Taken together, the results are consistent with an inhibitory breakdown in normal aging and an accelerated breakdown in inhibition in DAT individuals.     

Context processing in older adults: Evidence for a theory relating cognitive control to neurobiology in healthy aging.

A theory of cognitive aging is presented in which healthy older adults are hypothesized to suffer from disturbances in the processing of context that impair cognitive control function across multiple domains, including attention, inhibition, and working memory. These cognitive disturbances are postulated to be directly related to age-related decline in the function of the dopamine (DA) system in the prefrontal cortex (PFC). A connectionist computational model is described that implements specific mechanisms for the role of DA and PFC in context processing. The behavioral predictions of the model were tested in a large sample of older (N = 81) and young (N = 175) adults performing variants of a simple cognitive control task that placed differential demands on context processing. Older adults exhibited both performance decrements and, counterintuitively, performance improvements that are in close agreement with model predictions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential Age Effects on Attention-Based Inhibition: Inhibitory Tagging and Inhibition of Return.

The purpose of this study was to determine whether 2 forms of attentional inhibition, inhibition of return (IOR) and inhibitory tagging, are differentially affected by the aging process. The authors tested 24 younger adults (mean age = 22 years) and 24 older adults (mean age = 69 years) on a combined IOR and Stroop task (Vivas & Fuentes, 2001). As predicted, younger adults' performance was consistent with inhibitory tagging of objects at inhibited locations. Although older adults demonstrated intact IOR, there was no evidence of inhibitory tagging. The results suggest that age deficits in inhibition are selective. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of age-related changes in inhibition and binding using eye movement monitoring.

Age-related memory deficits may result from attending to too much information (inhibition deficit) and/or storing too little information (binding deficit). The present study evaluated the inhibition and binding accounts by exploiting a situation in which deficits of inhibition should benefit relational memory binding. Older adults directed more viewing toward abrupt onsets in scenes compared with younger adults under instructions to ignore any such onsets, providing evidence for age-related inhibitory deficits, which were ameliorated with additional practice. Subsequently, objects that served as abrupt onsets underwent changes in their spatial relations. Despite successful inhibition of the onsets, eye movements of younger adults were attracted to manipulated objects. In contrast, the eye movements of older adults, who directed more viewing to the late onsets compared with younger adults, were not attracted toward manipulated regions. Similar differences between younger and older adults in viewing of manipulated regions were observed under free viewing conditions. These findings provide evidence for concurrent inhibition and binding deficits in older adults and demonstrate that age-related declines in inhibitory processing do not lead to enhanced relational memory for extraneous information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Breaking the waves: Age differences in electrical brain activity when reading text with distractors.

The authors tested whether older adults have greater difficulty than younger adults in ignoring task-irrelevant information during reading as a result of age-related decline in inhibitory processes. Participants were shown target sentences containing distractor words. They were instructed to read aloud each sentence and ignore distractors. The N400 event-related potential (ERP) was used to measure the extent of semantic processing of target and distracting information. It showed that younger adults semantically processed both target and distracting material, whereas online processing of target sentences in older adults was disrupted by the distractors. In older adults, memory for target information related to their susceptibility to distraction and inhibition efficiency. Implications for age-differences in inhibitory control, working memory, and resource capacity are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-dependent effects of muscle vibration and the Jendrassik maneuver on the patellar tendon reflex response

OBJECTIVE: To explore possible effects of aging on the excitability of spinal reflexes. DESIGN: Using a cross-sectional design, the influences of muscle vibration and the Jendrassik maneuver on patellar tendon reflex function were compared between 30 young adults and 15 older adults. SETTING: Motor control research laboratory. SUBJECTS: The young adults were volunteers of college age. The older adults (74.5 +/- 4.14 yr) were volunteers from the local community. All subjects were free of medications and neurological conditions that would affect normal neuromuscular responses. MAIN OUTCOME MEASURES: A force-time curve analysis of the patellar tendon reflex response was used to assess the inhibition and facilitation of spinal reflexes. In the experimental protocol to assess spinal reflex inhibition, 100 Hz vibration was applied to the right quadriceps muscle. In another experimental protocol, spinal reflex facilitation was assessed using the Jendrassik maneuver. To perform the Jendrassik maneuver, subjects were instructed to grasp their hands together and to pull as hard as possible while breathing normally. After a 2-second count, the tendon tap was delivered to the right leg and the subject was instructed to relax. In both experimental protocols, control patellar tendon reflexes were collected. RESULTS: Analysis of variance for reflex peak force revealed a significant 30% reduction in the amount of vibration-induced reflex inhibition with increasing age, and a similar 33% reduction in the amount of Jendrassik maneuver facilitation observed for the older adults as compared with the younger adults. CONCLUSION: These results support the hypothesis that inhibitory and excitatory influences acting on the alpha motoneuron pool are different in young and older adults.     

Aging, Subjective Experience, and Cognitive Control: Dramatic False Remembering by Older Adults.

Recent research suggests that older adults are more susceptible to interference effects than are young adults; however, that research has failed to equate differences in original learning. In 4 experiments, the authors show that older adults are more susceptible to interference effects produced by a misleading prime. Even when original learning was equated, older adults were 10 times as likely to falsely remember misleading information and were much less likely to increase their accuracy by opting not to answer under conditions of free responding. The results are well described by a multinomial model that postulates multiple modes of cognitive control. According to that model, older adults are likely to be captured by misleading information, a form of goal neglect or deficit in inhibitory functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and inhibition processes: The case of metaphor treatment.

The inhibitory deficit hypothesis has often been cited as a possible explanation for cognitive changes related to age. The aim of this study was to develop a new procedure for evaluating effortful inhibition on the basis of the comprehension of metaphors. Our experiment was carried out on younger and older adults, in whom we also measured inhibitory capacity, working memory, and processing speed. The results show that older participants required a longer time and made more frequent errors in rejecting metaphors versus literally false statements. The interference effect was predicted by the psychometric tests designed to evaluate inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schematic knowledge influences on memory for scene information in young and older adults.

Two experiments were conducted to examine the hypothesis that aging is associated with an increase in schema-related influences on memory performance. In both studies, groups of young and older adults studied organized and unorganized visual scenes containing objects that varied in their likelihood of occurrence. Measures of attention allocation and memory for both objects and their relative locations were obtained. Consistent with expectations, attention allocation during study was disrupted more by lack of scene organization in the older adults. In addition, relatively systematic age differences were also obtained for retention, with greater schematic effects observed in the memory performance of older adults than in that of young adults. The results are discussed relative to current views of aging and cognitive change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Goal-directed memory: The role of cognitive control in older adults' emotional memory.

The present study revealed that older adults recruit cognitive control processes to strengthen positive and diminish negative information in memory. In Experiment 1, older adults engaged in more elaborative processing when retrieving positive memories than they did when retrieving negative memories. In Experiment 2, older adults who did well on tasks involving cognitive control were more likely than those doing poorly to favor positive pictures in memory. In Experiment 3, older adults who were distracted during memory encoding no longer favored positive over negative pictures in their later recall, revealing that older adults use cognitive resources to implement emotional goals during encoding. In contrast, younger adults showed no signs of using cognitive control to make their memories more positive, indicating that, for them, emotion regulation goals are not chronically activated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bilingualism, Aging, and Cognitive Control: Evidence From the Simon Task.

Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age and rate of activation in semantic memory.

Two word-primed picture-naming experiments were carried out to test the hypothesis that rate of activation in semantic memory is slower for older adults than for young adults. The presence of priming effects, both positive and negative, was taken as evidence of activation. In Exp 1 there was no age difference in the time of onset of either facilitation or inhibition by primes. A computer simulation, based on a simple connectionist model, showed that slower processing would have only a minimal effect on the time of onset of priming effects under the assumptions of the model; however, offset of inhibition by primes would be delayed if processing rate were reduced. In Exp 2 older adults showed inhibition by primes over a longer interval than did young adults, which was taken as evidence that the general slowing associated with aging extends to the transmission of activation at the earliest levels of cognitive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and the Ranschburg effect: No evidence of reduced response suppression in old age.

Two experiments tested 1 aspect of L. Hasher and R. T. Zacks's (1988) reduced inhibition hypothesis, namely, that old age impairs the ability to suppress information in working memory that is no longer relevant. In Experiment 1, young and older adults were asked to recall lists of letters in the correct order. Half of the lists contained repeated items while half were control lists. Recall of nonadjacent repeated items was worse than that of control items. This Ranschburg effect was larger (i.e., greater response suppression) in older than in young adults. In Experiment 2, young and older adults were required either to recall the list or to report if there was a repeated item. Repetition detection was high and similar in the 2 age groups. When age differences in overall performance were taken into account, there was evidence of increased repetition inhibition with age in both experiments. Thus, contrary to the general reduced inhibition hypothesis, the specific process of response suppression during serial recall is not reduced by aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The association of anxiety and depressive symptoms with cognitive performance in community-dwelling older adults.

The authors examined the association of anxiety, depressive symptoms, and their co-occurrence on cognitive processes in 102 community-dwelling older adults. Participants completed anxiety and depression questionnaires as well as measures of episodic and semantic memory, word fluency, processing speed/shifting attention, and inhibition. Participants with only increased anxiety had poorer processing speed/shifting attention and inhibition, but depressive symptoms alone were not associated with any cognitive deficits. Although coexisting anxiety and depressive symptoms were associated with deficits in 3 cognitive domains, reductions in inhibition were solely attributed to anxiety. Findings suggest an excess cognitive load on inhibitory ability in normal older adults reporting mild anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visuospatial priming and latent inhibition in children and adults with Tourette's disorder.

Evidence suggests that there are deficits in cognitive inhibition in patients with Tourette's disorder (TD). The pathophysiology of TD includes abnormalities in basal ganglia structure and function. The authors assessed 2 measures of central inhibition—visuospatial priming (VSP) and latent inhibition—in TD patients and in age- and sex-matched controls that are believed to be regulated by brain regions that include the basal ganglia. Among children, TD patients exhibited reduced inhibitory priming and increased facilitatory priming in the VSP paradigm. In comparison with controls, both children and adult TD patients exhibited significantly reduced inhibition in relation to facilitation: this pattern paralleled the pattern of differences between control children and adults. Latent inhibition was intact in control and TD children and adults. Central inhibitory deficits in TD patients appear to be task specific and are not fixed across the life span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)