Effects of arachidonic acid on the spatial cognition of aged rats

Abstract:  To examine the effects of arachidonic acid (AA) on age-related cognitive deficits, Fischer 344 rats were given an AA-supplemented powder diet for 12 weeks from 18.6 months old as part of the old AA (OA) group. Other age-matched rats were fed a non-AA-supplemented powder diet as part of the old control (OC) group, and young rats were fed lab pellets as part of the young control (YC) group. When the aged rats reached 20.0 months old, all animals were tested for spontaneous activity in an open field, followed by the Morris water maze place and cue tasks. Escape latencies for the place task showed that the YC rats were fastest, and there was no difference between the OA and OC groups. However, the probe test and the first block of the cue task indicated that the OA rats remembered the location of an invisible platform better than the OC rats. Although the amount of hippocampal AA was larger in the OA rats than in the OC rats, the difference was not significant. The results showed that AA administration to aged animals may alleviate age-related deficits in spatial cognition.     

Using secondary students’ views about influences on their spiritual well‐being to inform pastoral care

Spiritual well‐being is reflected in the quality of relationships that each person has in up to four different domains, namely with self, with others, with the environment and/or with God. This study investigated how secondary students perceived relationships with family, friends, school and church community (including God) impacted on their spiritual well‐being. This paper reports the views of 1002 secondary school students aged from 12‐ to 18‐years‐old in Catholic, Christian community and other independent schools in Victoria, Australia. ANOVA and multiple regression analyses of students’ responses on the Quality Of Life Influences Survey developed in this study, and the Spiritual Health And Life‐Orientation Measure, a spiritual well‐being questionnaire for secondary students, revealed significant differences in perceptions students held about influences on their spiritual well‐being. A case study illustrates how these instruments can be used to inform pastoral care of young people.     

儿童能力自我知觉的影响因素概述

该文在综合大量实证研究成果的基础上,全面概括并细致分析了影响儿童能力自我知觉发展与表现的三方面主要因素,即1)主体因素,包括能力概念、认知发展水平、需要动机及相关经验等;2)教育环境;3)任务性质。     

How does glance behavior influence crash and injury risk? A ‘what-if’ counterfactual simulation using crashes and near-crashes from SHRP2

As naturalistic driving data become increasingly available, new analyses are revealing the significance of drivers’ glance behavior in traffic crashes. Due to the rarity of crashes, even in the largest naturalistic datasets, near-crashes are often included in the analyses and used as surrogates for crashes. However, to date we lack a method to assess the extent to which driver glance behavior influences crash and injury risk across both crashes and near-crashes. This paper presents a novel method for estimating crash and injury risk from off-road glance behavior for crashes and near-crashes alike; this method can also be used to evaluate the safety impact of secondary tasks (such as tuning the radio). We apply a ‘what-if’ (counterfactual) simulation to 37 lead-vehicle crashes and 186 lead-vehicle near-crashes from lead-vehicle scenarios identified in the SHRP2 naturalistic driving data. The simulation combines the kinematics of the two conflicting vehicles with a model of driver glance behavior to estimate two probabilities: (1) that each event becomes a crash, and (2) that each event causes a specific level of injury. The usefulness of the method is demonstrated by comparing the crash and injury risk of normal driving with the risks of driving while performing one of three secondary tasks: the Rockwell radio-tuning task and two hypothetical tasks. Alternative applications of the method and its metrics are also discussed. The method presented in this paper can guide the design of safer driver–vehicle interfaces by showing the best tradeoff between the percent of glances that are on-road, the distribution of off-road glances, and the total task time for different tasks.     

The Relationship between Performance in Near Match-to-Sample Tasks and Fluid Intelligence

Match-to-sample is a timed task in which a subject is presented with a visual stimulus (the probe) and must select a match to that stimulus (the target) from among an array of distractors. These tasks are frequently employed as tests of basic cognitive abilities and demonstrate consistent correlations with measures of intelligence. In the current study, a match-to-sample task was modified to produce near-match conditions (trials for which no exact match existed). Two factors were manipulated: type of discrepancy between the target and probe (additive or subtractive) and degree of discrepancy between target and probe (1 element or 2 elements). It was hypothesized that introducing near-match conditions would change the processing demands of the task, resulting in increased correlations between decision time and fluid intelligence. Degree and type of discrepancy affected decision times: participants required more time for 2 element discrepancies and additive type discrepancies. Contrary to expectations, increased decision time on a task did not correspond to higher correlations with fluid intelligence. For type, correlations were larger when participants needed to mentally subtract elements from the target in order to make it match the probe (mean r_additive = .399; mean r_subtractive = .451). For degree, correlations were larger for trials where the probe and target differed by one element (mean r = .470) than for trials where the probe and target differed by two elements (mean r = .380). These results seem to indicate that the relationship between the complexity of a task and general intelligence is not as straightforward as has been commonly believed.     

Developmental differences in working memory: Where do they come from?

Several models assume that working memory development depends on age-related increases in efficiency and speed of processing. However, age-related increases in the efficiency of the mechanisms that counteract forgetting and restore memory traces may also be important. This hypothesis was tested in three experiments by manipulating both the processing duration within a working memory task and the time available to restore memory traces. Third- and sixth-grade children performed a complex span task in which they maintained series of letters while adding numbers to series of digits. When we equated processing and restoration times between ages, the developmental difference in working memory span was reduced but remained significant. However, this residual difference was eliminated when the time available to reactivate memory traces was tailored to the processing speed of each age group. This indicates that children employ active mechanisms for maintenance and restoration of memory traces that develop with age.     

The effects of interference on recognition of haptic pictures in blindfolded sighted participants: the modality of representation of haptic information

Haptic picture recognition was tested in 36 undergraduate students to determine whether haptic representations are visual or multi-modal. Participants explored target haptic pictures and were asked to recognize the target from three alternatives. Each participant completed eight control and eight interference trials in visual, lexical and tactile recognition modalities. For interference, participants were assigned to either an articulatory suppression (repeat "the" at a constant rate) or a visual interference (watch a visual display) condition, to prevent recoding into a verbal or visual code. The results showed that accuracy was higher at control compared to interference trials and for tactile compared to lexical recognition. Additionally, lexical and tactile recognition decreased with articulatory suppression whereas only tactile recognition decreased with visual interference. These findings suggest that haptic pictures may be represented by coordinating visual and verbal codes.     

Ageing and secondary-distinctiveness-based effects: The orthographic distinctiveness effect is more robust than the bizarreness effect

Differences related to ageing were investigated in two cases of secondary-distinctiveness-based effects: the bizarreness effect and the orthographic distinctiveness effect. A secondary distinctiveness effect means that items that are unusual compared to one's general knowledge stored in permanent memory are better remembered than common items. Experiment 1 confirmed that ageing diminishes the facilitative effects of bizarreness in a mixed list design with equal numbers of bizarre and common images. We suggest that the impaired bizarreness effect in older adults (above age 70) may be due to reduced attentional resources, since no bizarreness effect was observed for younger adults in the divided attention condition. Experiment 2 studied the orthographic distinctiveness effect in ageing for the first time. Contrary to our expectations, an orthographic distinctiveness effect was observed for all participants including older adults and younger adults in a divided attention condition. Because reduced attentional resources due to normal ageing or to experimental manipulation did not impact the facilitative effects of orthographic distinctiveness, our findings suggest that the orthographic distinctiveness effect may be mediated by more automatic processing.     

Stimulus–response compatibility for mixed mappings and tasks with unique responses

For two stimulus locations mapped to two keypresses, reaction time is shorter when the mapping is compatible than when it is not (the stimulus–response compatibility, SRC, effect). A similar result, called the Simon effect, occurs when stimulus location is irrelevant, and colour is relevant. When compatibly mapped trials are intermixed with incompatibly mapped trials or Simon task trials, the compatibility effect is eliminated, and the Simon effect is influenced by the location mapping. In five experiments, we examined whether similar mixing effects occur when the two spatial mappings or location-relevant and location-irrelevant tasks use distinct keypresses on the left and right hands. Mixing had considerably less influence on the SRC and Simon effects than it does when the intermixed trial types or tasks share the same responses, even though response time was lengthened to a similar extent. Mixing two tasks for which stimulus location was irrelevant yielded no within-task Simon effect, but the effect was also absent when four stimuli were assigned to two responses on a single hand. The relative lack of influence of mixing on the SRC and Simon effects when the tasks have unique responses implies that suppression of direct activation of the corresponding response occurs primarily when the tasks share responses.