Hippocampal tauopathy in tau transgenic mice coincides with impaired hippocampus-dependent learning and memory, and attenuated late-phase long-term depression of synaptic transmission

We evaluated various forms of hippocampus-dependent learning and memory, and hippocampal synaptic plasticity in THY-Tau22 transgenic mice, a murine tauopathy model that expresses double-mutated 4-repeat human tau, and shows neuropathological tau hyperphosphorylation and aggregation throughout the brain. Focussing on hippocampus, immunohistochemical studies in aged THY-Tau22 mice revealed prominent hyper- and abnormal phosphorylation of tau in CA1 region, and an increase in glial fibrillary acidic protein (GFAP) in hippocampus, but without signs of neuronal loss. These mice displayed spatial, social, and contextual learning and memory defects that could not be reduced to subtle neuromotor disability. The behavioral defects coincided with changes in hippocampal synaptic functioning and plasticity as measured in paired-pulse and novel long-term depression protocols. These results indicate that hippocampal tauopathy without neuronal cell loss can impair neural and behavioral plasticity, and further show that transgenic mice, such as the THY-Tau22 strain, might be useful for preclinical research on tauopathy pathogenesis and possible treatment.     

Do working-memory executive components mediate the effects of age on strategy selection or on strategy execution? Insights from arithmetic problem solving

Younger and older adults performed an inequality verification task (7+6 < 15, Yes/No?) in a control condition and in a dual-task condition where they simultaneously performed an executive-component task. Arithmetic-problem characteristics were manipulated in order to test strategy selection (i.e., choice of appropriate strategies in order to improve performance) and strategy execution (i.e., performance of the cognitive processes involved in each strategy). Results revealed that strategy selection changes with age: Older adults mainly selected one type of strategies in contrast to younger adults who used several types of strategies. These age-related changes were similar in the control and dual-task conditions. Strategy execution also changed with age, as shown by larger age-related differences on hardest problems. These age-related changes were larger in the dual-task condition, compared to the control condition. This impact of executive components as mediator of age-related changes depended on general age-related slowing. We discuss these findings in order to further understand the effects of age on arithmetic performance.     

Aging and strategic retrieval in a cued-recall test: the role of executive functions and fluid intelligence

Cued-recall in episodic memory was investigated in relation to low and high cognitive support at retrieval, executive function level and fluid intelligence level in 81 healthy adults divided first into two age groups (young and elderly adults). The first analyses showed that age-related differences were greater when a low cognitive support was provided to recall the words. An individual index of loss of performance when the number of cues was decreased was then calculated. Hierarchical regression analysis revealed that the executive functions measure (perseverative errors on the Wisconsin Card Sorting Test) was a better candidate than the fluid intelligence measure (Cattell's culture fair test) to account for the age-related variance of the size of performance loss. These findings suggest that age differences in implementing strategic retrieval may be mainly due to a decline in executive functions.     

Children's perception and understanding of (dis)similarities among dynamic bodily/facial expressions of happiness, pleasure, anger, and irritation

The current study examined the abilities of children (6 and 8 years of age) and adults to freely categorize and label dynamic bodily/facial expressions designed to portray happiness, pleasure, anger, irritation, and neutrality and controlled for their level of valence, arousal, intensity, and authenticity. Multidimensional scaling and cluster analyses showed that children (n = 52) and adults (n = 33) structured expressions in systematic and broadly similar ways. Between 6 and 8 years of age, there was a quantitative, but not a qualitative, improvement in labeling. When exposed to rich and dynamic emotional cues, children as young as 6 years can successfully perceive differences between close expressions (e.g., happiness, pleasure), and can categorize them with clear boundaries between them, with the exception of irritation, which had fuzzier borders. Children’s classifications were not reliant on lexical semantic abilities and were consistent with a model of emotion categories based on their degree of valence and arousal.     

La théorie de la privation relative et les réactions au handicap: Le rôle des comparaisons intrapersonnelles dans la gestion de l'estime de soi

Relative deprivation (RD) theory usually distinguishes between interpersonal and intergroup comparisons, but neglects intrapersonal comparisons. This research reveals that the comparisons between the actual and the future selves lead to relative gratification (RG) feelings which in turn are related to self‐esteem. A first study (N = 581) confirms that intrapersonal RG positively contributes to self‐esteem. A second study, involving students with a disability (n = 31) and without (n = 50), reveals that if disabled students exhibit a higher level of self‐esteem than nondisabled ones, this preservation is only explained by intrapersonal RG. Finally, intergroup RD and intrapersonal RG are two distinct predictors of militancy in favour of disabled people These results testify to the importance of differentiating comparison levels.     

Effect of face familiarity on age decision

The present experiment was planned to check whether the extraction of apparent age is affected by face identity (familiarity) or not. According to the traditional view, age estimation should be carried out independently of face identity, because it is one of the visually derived semantic codes (like gender and ethnicity). However, little is known about its underlying mechanisms. Moreover, some recent studies have cast doubt on the parallel thesis regarding facial expression, facial speech, ethnicity, and gender. Given the promising results of a pilot experiment (n=24), 16 Caucasian participants were enrolled in an "age decision" task on morphed faces derived from one old and one young source-face, in the proportion 70:30. The respondents had previously been familiarised with half the source faces by a learning procedure (associating the face, surname, occupation and city of residence of the person displayed), while the remaining half were unfamiliar. The results showed that age decision was affected by face familiarity, at least when the task was perceptually difficult enough. This adds support to the thesis that the identification of identity and the extraction of visually derived semantic codes are not made independently from each other. The status of age, within the visually derived semantic codes, is also discussed.     

Reorganization of learning-associated prefrontal synaptic plasticity between the recall of recent and remote fear extinction memory

We have previously shown that fear extinction is accompanied by an increase of synaptic efficacy in inputs from the ventral hippocampus (vHPC) and mediodorsal thalamus (MD) to the medial prefrontal cortex (mPFC) and that disrupting these changes to mPFC synaptic transmission compromises extinction processes. The aim of this study was to examine whether these extinction-related changes undergo further plasticity as the memory of extinction becomes more remote. Changes in synaptic efficacy in both vHPC-mPFC and MD-mPFC inputs were consequently analyzed when the memory was either 1 d or 7 d old. Increases of synaptic efficacy in the vHPC-mPFC pathway were observed when the memory was 1 d old, but not 7 d after initial extinction. In contrast, potentiation of synaptic efficacy in the MD-mPFC pathway increased over time. In rats that received low-frequency vHPC stimulation immediately after extinction, both vHPC-mPFC and MD-mPFC inputs failed to develop potentiation, and the recall of extinction (both recent and remote memories) was impaired. These findings suggest that post-extinction potentiation in vHPC-mPFC inputs may be necessary for both the recall of recent memory and post-extinction potentiation in the MD-mPFC inputs. This late potentiation process may be required for the recall of remote extinction memory.     

Does a yellow filter improve visual object categorization in normal aging?

Previous studies have shown that a yellow filter (CPF450) can increase contrast, motion sensitivity, vergence, and accommodation. We investigated whether a yellow filter can reduce age-related visual deficits. We tested two groups of 60 observers (mean age 24 vs. 72) in an object categorization task. Grayscale photographs of natural objects and artifacts were displayed either centrally or peripherally (21°) at low (8%) or medium (30%) contrast. There were three filter conditions (no filter, placebo filter, and yellow filter). Both groups of observers performed similarly on central and medium-contrast pictures. The deleterious effects of reduced contrast and eccentricity were stronger in elderly individuals. Moreover, the yellow filter globally improved the speed of categorization for the elderly participants. The decrease in response time in the yellow filter condition was larger when the stimuli were displayed peripherally in both groups. A yellow filter should be considered as a potential means for visual improvement in normal aging.