Increased novelty-induced grooming in aged rats: a preliminary observation

Age-related changes in grooming activity in female Fischer-344 rats were observed in a home cage and in a novel testing chamber for 50 min. Compared to the home cage condition with brief handling treatment, excessive grooming was found in the novel situation. The amount of novelty-induced grooming of aged rats (26-28 months) was about two times that of young animals (6-8 months). This increase in novelty-induced grooming of aged animals was attributable to an increase in the number of grooming bouts, prolongation of each grooming bout, and a slight increase in the duration of licking elements. However, there were no age differences in the percentage of face washing and the duration of face-washing elements. These results are discussed in terms of behavioral aging and age-related changes in peptidergic pathways in the brain.     

Information processing of pictograms and the visual field difference

The main purpose was to investigate how we process pictograms and to examine the effects of learning on visual field differences when participants overlearn the meaning of each pictogram. 15 students were required to judge whether the referent of each symbol was either larger or smaller than the referent of the standard stimulus (Test 1). Several days later the same task was conducted (Test 2). Although a right visual field advantage was observed in Test 1, it was not apparent at Test 2 after participants had studied the pictogram list repeatedly. These results suggest that pictograms might be processed in much the same way as other ordinary verbal stimuli at a very early stage of learning. Participants could, however, comprehend the pictograms by employing a kind of imagery processing after they were familiar with the symbols.     

Effects of single trial of heart-rate biofeedback during ramp bicycling exercise

We examined whether a single trial of heart-rate biofeedback was effective to attenuate heart-rate responses during ramp exercise despite a lack of biofeedback conditioning. 35 healthy women exercised in two trials while they tried to attenuate their heart rate by watching biofeedback signals or they only exercised without biofeedback signals (Control trial). 17 subjects were able to attenuate the heart rate during Biofeedback trial (Can group) whereas the remaining subjects were not (Cannot group). In the Can group, the magnitude of heart-rate attenuation in all exercise time was equivalent to 11+/-3% of the preexercise heart rate. Since the heart-rate reduction was similar to that achieved after the heart-rate biofeedback conditioning in previous studies, it is likely that the single trial of heart-rate biofeedback was effective for almost half the subjects to attenuate the heart-rate responses during ramp exercise.     

Novel visual stimuli activate a population of neurons in the primate orbitofrontal cortex

Neurons were found in the rhesus macaque anterior orbitofrontal cortex that respond to novel but not to familiar visual stimuli. Some of these neurons responded to all novel stimuli, and others to only a subset (e.g., to novel faces). The neurons have no responses to familiar reward- or punishment-associated visual stimuli, nor to taste, olfactory or somatosensory inputs. The responses of the neurons typically habituated with repeated presentations of a novel stimulus, and five presentations each 1s was the median number for the response to reach half-maximal. The neurons did not respond to stimuli which had been novel and shown a few times on the previous day, indicating that the neurons were involved in long-term memory. The median latency of the neuronal responses was 120 ms. The median spontaneous firing rate was 1.3 spikes/s, and the median response to novel visual stimuli was 6.0 spikes/s. These findings indicate that the long-term memory for visual stimuli is information that is represented in a region of the primate anterior orbitofrontal cortex.     

Investigating the acute effect of an aerobic dance exercise program on neuro-cognitive function in the elderly

ObjectiveThe present study investigated the types of aerobic dance programs that positively impact cognition, such as executive function, in elderly people.DesignRandomized controlled trial.MethodThe study compared the effects of acute aerobic dance exercise on cognitive performance using two 40-min aerobic dance programs. Thirty-four elderly participants, aged 65–75 years, were randomly assigned into either free (N = 17) or combination (N = 17) style workout groups. The free style (FR) workout consisted of several patterns of movement, while the combination style (CB) workout consisted of similar patterns of movement to FR, but the patterns were joined to form a long choreographic routine. Both dance programs were controlled to be the same in exercise intensity, approximately 40% heart rate reserve. Reaction time and correct rates were measured using a task-switching reaction time test to evaluate executive cognitive performance immediately before and after the 40-min dance exercise.ResultsA two-way (dance program × pre-post dance exercise) repeated-measures analysis of variance for switch reaction time increase (switch cost) demonstrated a significant interaction (p = .006), showing that the switch cost in the CB group became smaller after the dance exercise than before (p = .009).ConclusionThe results suggest that the executive cognitive network was facilitated in a CB dance workout that has a dual-task nature and induces movement (task) interference with unexpected movement changes.     

Effects of speed of word processing on semantic access: the case of bilingualism

Bilingual speakers generally manifest slower word recognition than monolinguals. We investigated the consequences of the word processing speed on semantic access in bilinguals. The paradigm involved a stream of English words and pseudowords presented in succession at a constant rate. English-Welsh bilinguals and English monolinguals were asked to count the number of letters in pseudowords and actively disregard words. They were not explicitly told that pairs of words in immediate succession were embedded and could either be semantically related or not. We expected that slower word processing in bilinguals would result in semantic access indexed by semantic priming. As expected, bilinguals showed significant semantic priming, indexed by an N400 modulation, whilst monolinguals did not. Moreover, bilinguals were slower in performing the task. The results suggest that bilinguals cannot discriminate between pseudowords and words without accessing semantic information whereas monolinguals can dismiss English words on the basis of subsemantic information.     

The mere exposure effect for visual image

Mere exposure effect refers to a phenomenon in which repeated stimuli are evaluated more positively than novel stimuli. We investigated whether this effect occurs for internally generated visual representations (i.e., visual images). In an exposure phase, a 5 × 5 dot array was presented, and a pair of dots corresponding to the neighboring vertices of an invisible polygon was sequentially flashed (in red), creating an invisible polygon. In Experiments 1, 2, and 4, participants visualized and memorized the shapes of invisible polygons based on different sequences of flashed dots, whereas in Experiment 3, participants only memorized positions of these dots. In a subsequent rating phase, participants visualized the shape of the invisible polygon from allocations of numerical characters on its vertices, and then rated their preference for invisible polygons (Experiments 1, 2, and 3). In contrast, in Experiment 4, participants rated the preference for visible polygons. Results showed that the mere exposure effect appeared only when participants visualized the shape of invisible polygons in both the exposure and rating phases (Experiments 1 and 2), suggesting that the mere exposure effect occurred for internalized visual images. This implies that the sensory inputs from repeated stimuli play a minor role in the mere exposure effect. Absence of the mere exposure effect in Experiment 4 suggests that the consistency of processing between exposure and rating phases plays an important role in the mere exposure effect.     

Phase stability of Al3Nb as a function of nickel additions

Abstract

Phase stability of the intermetallic compound Al₃Nb is investigated as a function of nickel additions by band structure calculations based on an extended Hueckel tight-binding method. With this method, the electronic structure and total energies of the Al_6-n -Ni _n Nb₂ compounds (where n is an integer from 0 to 6) are calculated for both D0₂₂ and L1₂ structures under the assumption that nickel substitutes for aluminium. The electronic total energies obtained from integration of the energy states of all electrons considered have shown that the D0₂₂ structure is stable in the binary Al₃Nb compound as compared with the L1₂ structure; conversely, the L1₂ structure is stable for compounds with n values greater than 1. These calculations are in good agreement with X-ray diffraction results reported by Schubert and co-workers. Differences in the electronic total energy per atom between D0₂₂ and L1₂ are - 0·79 eV and 0·56 eV for n equal to 0 and 2, respectively.     

Secondary defects induced by ion and electron irradiation of GaSb

Secondary defects induced by ion and electron irradiation up to 6?dpa (displacements per atom) at liquid-nitrogen temperature in GaSb thin films are compared. For Sn ion (60?keV) irradiation, voids were observed. However, for high-energy electron (2?MeV) irradiation, interstitial-type dislocation loops were produced. The densities of voids and interstitial-type dislocation loops were almost equivalent (8?×?10¹⁴?voids/m² and 3?×?10¹⁴?loops/m²) after irradiations at the same damage level of 6?dpa. It is concluded that the formation of voids by ion irradiation follows the creation of localised vacancy defects in cascade damage.     

Structural and thermal investigations of a high-strength Cu-Zr-Ti-Co bulk metallic glass

Cu 55 Zr 30 Ti 10 Co 5 bulk metallic glass exhibits a high compressive fracture strength of 2.31 GPa and Young's modulus of 130 GPa, values that are higher than those of other Cu- and Zr-based metallic glasses. The addition of Co to the ternary Cu-Zr-Ti alloy stabilizes the supercooled liquid. On heating, the Cu 55 Zr 30 Ti 10 Co 5 metallic glass devitrified and formed an intermediate intermetallic compound prior to reaching equilibrium by diffusion-controlled growth at constant nucleation rate. In the fully annealed state the structure consists of the equilibrium Cu 10 Zr 7 phase with the slightly reduced lattice parameters a = 0.933 nm, b = 0.928 nm and c = 1.254 nm and a small fraction of an unidentified phase.