Self-reference and emotional memory effects in older adults at increased genetic risk of Alzheimer’s disease

The present study investigated whether cognitively healthy older adults who are carriers of the ε4 allele of apolipoprotein E, the most prevalent genetic risk factor for late-onset Alzheimer’s disease, benefit from self-referential processing and emotional processing to the same degree as noncarriers of this gene. Participants encoded emotional and nonemotional narratives using a baseline-orienting task, semantic elaboration, or imagination-based self-referential processing and then completed a recognition memory test. Both groups of older adults showed enhanced recognition memory for narrative information following self-referential processing relative to semantic elaboration, and the magnitude of this memory effect was not affected by ε4 status. However, older adult ε4 carriers did not show an emotional enhancement effect, whereas older adult ε4 noncarriers did. These results indicate that whereas the self-reference effect is not attenuated in cognitively healthy older adults ε4 carriers, deficits in emotional memory may be an early cognitive marker of abnormal decline.     

Algorithmic modeling of the irrelevant sound effect (ISE) by the hearing sensation fluctuation strength

Background sounds, such as narration, music with prominent staccato passages, and office noise impair verbal short-term memory even when these sounds are irrelevant. This irrelevant sound effect (ISE) is evoked by so-called changing-state sounds that are characterized by a distinct temporal structure with varying successive auditory-perceptive tokens. However, because of the absence of an appropriate psychoacoustically based instrumental measure, the disturbing impact of a given speech or nonspeech sound could not be predicted until now, but necessitated behavioral testing. Our database for parametric modeling of the ISE included approximately 40 background sounds (e.g., speech, music, tone sequences, office noise, traffic noise) and corresponding performance data that was collected from 70 behavioral measurements of verbal short-term memory. The hearing sensation fluctuation strength was chosen to model the ISE and describes the percept of fluctuations when listening to slowly modulated sounds (f(mod) < 20?Hz). On the basis of the fluctuation strength of background sounds, the algorithm estimated behavioral performance data in 63 of 70 cases within the interquartile ranges. In particular, all real-world sounds were modeled adequately, whereas the algorithm overestimated the (non-)disturbance impact of synthetic steady-state sounds that were constituted by a repeated vowel or tone. Implications of the algorithm's strengths and prediction errors are discussed.     

Working and reference memory of pigs (Sus scrofa domesticus) in a holeboard spatial discrimination task: the influence of environmental enrichment

Interest in cognitive research in pigs is increasing, but little is known about the impact of environmental conditions on pigs’ cognitive capabilities. The present study investigated the effect of environmental enrichment on cognitive performance of pigs in a holeboard spatial task, in which they had to discriminate four baited buckets out of 16. Pigs (n = 32) were either housed in stimulus-poor, barren pens, or in larger pens enriched with rooting substrates. Pigs were subjected to 30 holeboard trials. Both working memory (WM), that is, the ratio (baited visits/total number of (re)visits to baited buckets), and reference memory (RM), that is, the ratio ((re)visits to baited buckets/total number of visits to all buckets), improved over trials. WM scores were higher in pigs from enriched pens than in pigs from barren pens. Housing did not affect RM scores. Personality type of the pigs, as assessed early in life using a backtest, did not affect WM or RM. In conclusion, housing conditions of pigs did not affect reference memory, but environmental enrichment improved working memory of pigs in a spatial discrimination task. Based on the findings of this study, we suggest that cognitive functioning of pigs may be impaired under commonly used housing conditions.