Age-related differences in the neural bases of phonological and semantic processes in the context of task-irrelevant information.

As we age we have increasing difficulty with phonological aspects of language production. Yet semantic processes are largely stable across the life span. This suggests a fundamental difference in the cognitive and potentially neural architecture supporting these systems. Moreover, language processes such as these interact with other cognitive processes that also show age-related decline, such as executive function and inhibition. The present study examined phonological and semantic processes in the presence of task-irrelevant information to examine the influence of such material on language production. Older and younger adults made phonological and semantic decisions about pictures in the presence of either phonologically or semantically related words, which were unrelated to the task. FMRI activation during the semantic condition showed that all adults engaged typical left-hemisphere language regions, and that this activation was positively correlated with efficiency across all adults. In contrast, the phonological condition elicited activation in bilateral precuneus and cingulate, with no clear brain-behavior relationship. Similarly, older adults exhibited greater activation than younger adults in several regions that were unrelated to behavioral performance. Our results suggest that as we age, brain-behavior relations decline, and there is an increased reliance on both language-specific and domain-general brain regions that are seen most prominently during phonological processing. In contrast, the core semantic system continues to be engaged throughout the life span, even in the presence of task-irrelevant information.

Age-related differences in resolving semantic and phonological competition during receptive language tasks.

Receptive language (e.g., reading) is largely preserved in the aging brain, and semantic processes in particular may continue to develop throughout the lifespan. We investigated the neural underpinnings of phonological and semantic retrieval in older and younger adults during receptive language tasks (rhyme and semantic similarity judgments). In particular, we were interested in the role of competition on language retrieval and varied the similarities between a cue, target, and distractor that were hypothesized to affect the mental process of competition. Behaviorally, all participants responded faster and more accurately during the rhyme task compared to the semantic task. Moreover, older adults demonstrated higher response accuracy than younger adults during the semantic task. Although there were no overall age-related differences in the neuroimaging results, an Age×Task interaction was found in left inferior frontal gyrus (IFG), with older adults producing greater activation than younger adults during the semantic condition. These results suggest that at lower levels of task difficulty, older and younger adults engaged similar neural networks that benefited behavioral performance. As task difficulty increased during the semantic task, older adults relied more heavily on largely left hemisphere language regions, as well as regions involved in perception and internal monitoring. Our results are consistent with the stability of language comprehension across the adult lifespan and illustrate how the preservation of semantic representations with aging may influence performance under conditions of increased task difficulty.

Aging in two languages: Implications for public health.

With the population aging and a dramatic increase in the number of senior citizens, public health systems will be increasingly burdened with the need to deal with the care and treatment of individuals with dementia. We review evidence demonstrating how a particular experience, bilingualism, has been shown to protect cognitive function in older age and delay onset of symptoms of dementia. This paper describes behavioral and brain studies that have compared monolingual and bilingual older adults on measures of cognitive function or brain structure and reviews evidence demonstrating a protective effect of bilingualism against symptoms of dementia. We conclude by presenting some data showing the potential savings in both human costs in terms of demented patients and economic considerations in terms of public money if symptoms of dementia could be postponed.

Mood congruity and episodic memory in young children.

Although mood congruity effects on episodic memory have been reported extensively in adults, they have not been reported for children younger than 10 years. The current research investigated mood congruity effects in story recall using an embodied approach to mood induction involving a facial manipulation task with 3- and 4-year-old children. Participants held a chopstick or a popsicle stick in their mouths in a way to either produce or inhibit a smile while they listened to a story featuring happy events for a happy character and sad events for a sad character. Children's mood ratings before and after mood induction indicated that mood became more positive in the smile condition, with no change in the no smile condition. Children in the smile condition, but not in the no smile condition, remembered more about the happy character than the sad character in the story. These results extend mood congruity effects to 3- and 4-year olds, suggesting that at this age representations of emotion interact with basic memory processes. Moreover, the efficacy of reenactment of sensorimotor components of emotion in modifying mood is consistent with embodied representation of emotion during early childhood.

Aging, Emotion, Attention, and Binding in the Taboo Stroop Task: Data and Theories.

How does aging impact relations between emotion, memory, and attention? To address this question, young and older adults named the font colors of taboo and neutral words, some of which recurred in the same font color or screen location throughout two color-naming experiments. The results indicated longer color-naming response times (RTs) for taboo than neutral base-words (taboo Stroop interference); better incidental recognition of colors and locations consistently associated with taboo versus neutral words (taboo context-memory enhancement); and greater speed-up in color-naming RTs with repetition of color-consistent than color-inconsistent taboo words, but no analogous speed-up with repetition of location-consistent or location-inconsistent taboo words (the consistency type by repetition interaction for taboo words). All three phenomena remained constant with aging, consistent with the transmission deficit hypothesis and binding theory, where familiar emotional words trigger age-invariant reactions for prioritizing the binding of contextual features to the source of emotion. Binding theory also accurately predicted the interaction between consistency type and repetition for taboo words. However, one or more aspects of these phenomena failed to support the inhibition deficit hypothesis, resource capacity theory, or socio-emotional selectivity theory. We conclude that binding theory warrants further test in a range of paradigms, and that relations between aging and emotion, memory, and attention may depend on whether the task and stimuli trigger fast-reaction, involuntary binding processes, as in the taboo Stroop paradigm.

Age-related differences in the neural bases of phonological and semantic processes.

Changes in language functions during normal aging are greater for phonological compared with semantic processes. To investigate the behavioral and neural basis for these age-related differences, we used fMRI to examine younger and older adults who made semantic and phonological decisions about pictures. The behavioral performance of older adults was less accurate and less efficient than younger adults' in the phonological task but did not differ in the semantic task. In the fMRI analyses, the semantic task activated left-hemisphere language regions, and the phonological task activated bilateral cingulate and ventral precuneus. Age-related effects were widespread throughout the brain and most often expressed as greater activation for older adults. Activation was greater for younger compared with older adults in ventral brain regions involved in visual and object processing. Although there was not a significant Age × Condition interaction in the whole-brain fMRI results, correlations examining the relationship between behavior and fMRI activation were stronger for younger compared with older adults. Our results suggest that the relationship between behavior and neural activation declines with age, and this may underlie some of the observed declines in performance.

Stroke experiences in weblogs: a feasibility study of sex differences.

BACKGROUND: Research on cerebral stroke symptoms using hospital records has reported that women experience more nontraditional symptoms of stroke (eg, mental status change, pain) than men do. This is an important issue because nontraditional symptoms may delay the decision to get medical assistance and increase the difficulty of correct diagnosis. In the present study, we investigate sex differences in the stroke experience as described in stories on weblogs. OBJECTIVE: The goal of this study was to investigate the feasibility of using the Internet as a source of data for basic research on stroke experiences. METHODS: Stroke experiences described in blogs were identified by using StoryUpgrade, a program that searches blog posts using a fictional prototype story. In this study, the prototype story was a description of a stroke experience. Retrieved stories coded by the researchers as relevant were used to update the search query and retrieve more stories using relevance feedback. Stories were coded for first- or third-person narrator, traditional and nontraditional patient symptoms, type of stroke, patient sex and age, delay before seeking medical assistance, and delay at hospital and in treatment. RESULTS: There were 191 relevant stroke stories of which 174 stories reported symptoms (52.3% female and 47.7% male patients). There were no sex differences for each traditional or nontraditional stroke symptom by chi-square analysis (all Ps>.05). Type of narrator, however, affected report of traditional and nontraditional symptoms. Female first-person narrators (ie, the patient) were more likely to report mental status change (56.3%, 27/48) than male first-person narrators (36.4%, 16/44), a marginally significant effect by logistic regression (P=.056), whereas reports of third-person narrators did not differ for women (27.9%, 12/43) and men (28.2%, 11/39) patients. There were more reports of at least 1 nontraditional symptom in the 92 first-person reports (44.6%, 41/92) than in the 82 third-person reports (25.6%, 21/82, P=.006). Ischemic or hemorrhagic stroke was reported in 67 and 29 stories, respectively. Nontraditional symptoms varied with stroke type with 1 or more nontraditional symptoms reported for 79.3% (23/29) of hemorrhagic stroke patients and 53.7% (36/67) of ischemic stroke patients (P=.001). CONCLUSIONS: The results replicate previous findings based on hospital interview data supporting the reliability of findings from weblogs. New findings include the effect of first- versus third-person narrator on sex differences in the report of nontraditional symptoms. This result suggests that narrator is an important variable to be examined in future studies. A fragmentary data problem limits some conclusions because important information, such as age, was not consistently reported. Age trends strengthen the feasibility of using the Internet for stroke research because older adults have significantly increased their Internet use in recent years.

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.

On the tip-of-the-tongue: neural correlates of increased word-finding failures in normal aging.

Tip-of-the-tongue (TOT) experiences are frustrating word-finding failures where people are temporarily unable to produce a word they are certain they know. TOT frequency increases with normal aging during adulthood, and behavioral evidence suggests that the underlying deficit is in retrieving the complete phonology of the target word during production. The present study investigated the neural correlates of this phonological retrieval deficit. We obtained 3-D T1-weighted structural magnetic resonance images (MRI) for healthy participants between 19 and 88 years old and used voxel-based morphometry to measure gray matter density throughout the brain. In a separate session, participants named celebrities cued by pictures and descriptions, indicating when they had a TOT, and also completed Raven's Progressive Matrices (RPM), a task that does not involve phonological production. The number of TOTs increased with age and also with gray matter atrophy in the left insula, an area implicated in phonological production. The relation between TOTs and left insula atrophy cannot be attributed to the correlation of each variable with age because TOTs were related to insula atrophy even with age effects removed. Moreover, errors on the RPM increased with age, but performance did not correlate with gray matter density in the insula. These results provide, for the first time, an association between a region in the neural language system and the rise in age-related word-finding failures and suggest that age-related atrophy in neural regions important for phonological production may contribute to age-related word production failures.

Cherry pit primes Brad Pitt: Homophone priming effects on young and older adults' production of proper names.

This study investigated why proper names are difficult to retrieve, especially for older adults. On intermixed trials, young and older adults produced a word for a definition or a proper name for a picture of a famous person. Prior production of a homophone (e.g., pit) as the response on a definition trial increased correct naming and reduced tip-of-the-tongue experiences for a proper name (e.g., Pitt) on a picture-naming trial. Among participants with no awareness of the homophone manipulation, older but not young adults showed these homophone priming effects. With a procedure that reduced awareness effects (Experiment 2), prior production of a homophone improved correct naming only for older adults, but speeded naming latency for both age groups. We suggest that representations of proper names are susceptible to weak connections that cause deficits in the transmission of excitation, impairing retrieval especially in older adults. We conclude that homophone production strengthens phonological connections, increasing the transmission of excitation.

Do alternative names block young and older adults' retrieval of proper names?

This study evaluates whether tip of the tongue experiences (TOTs) are caused by a more accessible word which blocks retrieval of the target word, especially for older adults. In a "competitor priming" paradigm, young and older adults produced the name of a famous character (e.g., Eliza Doolittle) in response to a question and subsequently named a picture of a famous actor or actress depicting this character (e.g., Audrey Hepburn as Eliza Doolittle). Older adults produced more TOTs than young adults, but prior production of a related character name did not affect TOTs, although it did reduce incorrect responses. There were no age differences in knowledge of films and TV and thus the age-related increase in TOTs is not because older adults have more relevant knowledge. The findings are compatible with models in which alternate words are a consequence not a cause of TOT.

Aging and Language Production.

Experimental research and older adults' reports of their own experience suggest that the ability to produce the spoken forms of familiar words declines with aging. Older adults experience more word-finding failures, such as tip-of-the-tongue states, than young adults do, and this and other speech production failures appear to stem from difficulties in retrieving the sounds of words. Recent evidence has identified a parallel age-related decline in retrieving the spelling of familiar words. Models of cognitive aging must explain why these aspects of language production decline with aging whereas semantic processes are well maintained. We describe a model wherein aging weakens connections among linguistic representations, thereby reducing the transmission of excitation from one representation to another. The structure of the representational systems for word phonology and orthography makes them vulnerable to transmission deficits, impairing retrieval.

Asymmetric aging effects on semantic and phonological processes: naming in the picture-word interference task.

In 2 experiments, participants named pictures while ignoring auditory word distractors. For pictures with homophone names (e.g., ball), distractors semantically related to the nondepicted meaning (e.g., prom) facilitated naming by top-down phonological connections for young but not for older adults. Slowing from unrelated distractors and facilitation from phonologically related distractors were age invariant except in distractors that were both semantically and phonologically related. Only distractors semantically related to the picture interfered more for older than younger adults. These results ar einconsistent with age-linked deficits in inhibition of irrelevant information from either internal or external sources. Rather, aging affects priming transmission in a connectionist network with asymmetric effects on semantic and phonological connections involved in comprehension and production, respectively.