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.     

The influence of negative advertising frames on political cynicism and politician accountability

This research examined the influence of negative political advertising frames on the thoughts and feelings people generate in response to campaign advertising. Preparing and conducting this investigation involved the use of a multiple‐method strategy. Content analysis identified two advertising frames (i.e., candidate theme and ad hoc issue advertisements) and two experiments separately induced political cynicism and politician accountability. Three hundred and sixty people participated in the experimental studies, in which they read and responded, using a thought‐listing technique, to candidate theme or ad hoc issue negative advertisements. Results demonstrated that participants were more likely to generate cynical comments and hold politicians accountable for the country's ills when reading candidate theme advertisements than ad hoc issue advertisements. The results indicate that this contributes to a political climate of cynicism and may function to erode the electorate's overall trust in government.     

Automatic semantic priming with various category relations in Alzheimer's disease and normal aging.

The 6 experiments reported here tested the effects of various category relations on automatic semantic priming in 20 Alzheimer's disease (AD), 20 older control, and 22 younger control subjects. The tasks were either word pronunciation or lexical decision; the prime-target stimulus-onset asynchrony (SOA) was always 250 ms. A variety of category relationships between prime and target were examined: highly associated category comembers, subordinate-superordinate or superordinate-subordinate pairs, and pairs selected on the basis of category typically to form typical-typical, atypical-typical, typical-atypical, and atypical-atypical pairings. Both for AD versus older control subjects and for older versus younger control subjects, no significant group differences were found in the magnitude of overall semantic priming or in the effects on priming of factors pertaining to the prime-target relationship.     

Lifespan brain activity, β-amyloid, and Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of progressive cognitive decline and dementia in adults. While the amyloid cascade hypothesis of AD posits an initiating role for the β-amyloid (Aβ) protein, there is limited understanding of why Aβ is deposited. A growing body of evidence based on in vitro, animal studies and human imaging work suggests that synaptic activity increases Aβ, which is deposited preferentially in multimodal brain regions that show continuous levels of heightened activation and plasticity across the lifespan. Imaging studies of people with genetic predispositions to AD are consistent with these findings, suggesting a mechanism whereby neural efficiency or cognitive reserve may diminish Aβ deposition. The aggregated findings unify observations from cellular and molecular studies with human cognitive neuroscience to reveal potential mechanisms of AD development.