Neural mechanisms of spatial working memory: Contributions of the dorsolateral prefrontal cortex and the thalamic mediodorsal nucleus

The dorsolateral prefrontal cortex (DLPFC) has been known to play an important role in working memory. Neurophysiological studies have revealed that delay period activity observed in the DLPFC is a neural correlate of the temporary storage mechanism for information and that this activity represents either retrospective or prospective information, although the majority represents retrospective information. However, the DLPFC is not the only brain area related to working memory. The analysis of neural activity in the thalamic mediodorsal (MD) nucleus reveals that the MD also participates in working memory. Although similar task-related activities were observed in the MD, the directional bias of these activities and the proportion of presaccadic activity are different between the MD and the DLPFC. These results indicate that, although the MD participates in working memory, the way it participates in this process is different between these two areas, in that the MD participates more in motor control aspects than the DLPFC does.     

Discriminative and reinforcing properties of paintings in Java sparrows (<Emphasis Type="Italic">Padda oryzivora</Emphasis>)

Previous studies suggest that non-human animals can discriminate two different artworks (such as music or paintings) that were created by humans. However, such studies rarely examined whether those animals were reinforced by one artwork more than another. It has been shown that music composed by humans has both discriminative and reinforcing properties when played for Java sparrows. Here, we investigated the effects of another artistic medium in Java sparrows, namely paintings. The first experiment tested the reinforcing properties. Staying time at three painting categories—Japanese, cubist, and impressionist—was measured as an index of their reinforcing properties. The second experiment used operant conditioning to reveal the discriminative properties of the different artistic styles of such paintings. Results suggest that the paintings have both discriminative and reinforcing properties for Java sparrows. However, the reinforcing properties vary from individual to individual. This is the first report demonstrating reinforcing properties of visual artworks in non-human animals.     

Short-term memory for event duration: Modality specificity and goal dependency

Time perception is involved in various cognitive functions. This study investigated the characteristics of short-term memory for event duration by examining how the length of the retention period affects inter- and intramodal duration judgment. On each trial, a sample stimulus was followed by a comparison stimulus, after a variable delay period (0.5?C5?s). The sample and comparison stimuli were presented in the visual or auditory modality. The participants determined whether the comparison stimulus was longer or shorter than the sample stimulus. The distortion pattern of subjective duration during the delay period depended on the sensory modality of the comparison stimulus but was not affected by that of the sample stimulus. When the comparison stimulus was visually presented, the retained duration of the sample stimulus was shortened as the delay period increased. Contrarily, when the comparison stimulus was presented in the auditory modality, the delay period had little to no effect on the retained duration. Furthermore, whenever the participants did not know the sensory modality of the comparison stimulus beforehand, the effect of the delay period disappeared. These results suggest that the memory process for event duration is specific to sensory modality and that its performance is determined depending on the sensory modality in which the retained duration will be used subsequently.     

Psychometric Properties of the Revised Chen Internet Addiction Scale (CIAS-R) in Chinese Adolescents

The Revised Chen Internet Addiction Scale (CIAS-R) was developed to assess Internet addiction in Chinese populations, but its psychometric properties in adolescents have not been examined. This study aimed to evaluate the factor structure and psychometric properties of CIAS-R in Hong Kong Chinese adolescents. 860 Grade 7 to 13 students (38 % boys) completed the CIAS-R, the Young’s Internet Addiction Test (IAT), and the Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA) in a survey. The prevalence of Internet addiction as assessed by CIAS-R was 18 %. High internal consistency and inter-item correlations were reported for the CIAS-R. Results from the confirmatory factor analysis suggested a four-factor structure of Compulsive Use and Withdrawal, Tolerance, Interpersonal and Health-related Problems, and Time Management Problems. Moreover, results of hierarchical multiple regression supported the incremental validity of the CIAS-R to predict mental health outcomes beyond the effects of demographic differences and self-reported time spent online. The CIAS is a reliable and valid measure of internet addiction problems in Hong Kong adolescents. Future study is warranted to validate the cutoffs of the CIAS-R for identification of adolescents with Internet use problems who may have mental health needs.     

Influence of gender membership on sequential decisions of face attractiveness

Responses in a current trial are biased by the stimulus and response in the preceding trial. In a mixed-category sequence, the sequential dependency is weaker when the stimuli of the current and preceding trials fall under different categories. In the present study, we investigated the influence of the gender membership of faces on the sequential dependency. Forty-eight pictures of male and female faces were presented successively. Participants rated the attractiveness, roundness, or intelligence of each face on a 7-point scale. The sequential effect was robustly observed, irrespective of the property to be judged. However, between-gender sequential dependency was weaker than within-gender dependency only in the attractiveness judgment. These findings suggest that the gender of faces serves as a cue for forming category representations when face attractiveness is of interest, and hence that the formation of categories in sequential decisions is an adaptive process that depends on the property to be judged.     

Spatial distortion induced by imperceptible visual stimuli

Previous studies have explored the effects of attention on spatial representation. Specifically, in the attentional repulsion effect, a transient visual cue that captures attention has been shown to alter the perceived position of a target stimulus to the direction away from the cue. The effect is also susceptible to retrospective influence, that attention appears to attract the target when the cue appears afterwards. This study examined the necessity of visual awareness of the cue in these phenomena. We found that when the cues were rendered invisible by backward visual masks, both repulsion and attraction effects were weakened but still observed. The results suggest that the effects possibly depend on processes that are not necessarily associated with conscious visual awareness of the cues. We conjecture that attentional shift produced by the weak, invisible cues may play a role in spatial distortion; but other possible accounts including non-attentional ones are also discussed.     

Texture and grain boundary character distribution (GBCD) in rapidly solidified and annealed Fe–6·5 mass% Si ribbons

Abstract

The type and frequency of grain boundaries, the so-called grain boundary character distribution (GBCD), has been determined in rapidly solidified and subsequently annealed Fe-6·5 mass% Si alloy ribbon by the scanning electron microscopy-electron channelling pattern (SEM-ECP) technique. High frequencies of low-angle boundaries and coincidence boundaries with Σ3, Σ9, Σ11, Σ17 and Σ19 were observed in a fully annealed ribbon with well defined {110} texture. The total frequency of low-angle boundaries and coincidence boundaries is almost one-half of all grain boundaries. The coincidence boundaries which occurred more frequently are exactly those predicted theoretically from the coincidence orientations for 〈110〉 rotation in cubic crystals, similar to those observed previously in {100} textured ribbons of the same alloy produced by the same processing method. The presence of a close relationship between the type of texture and GBCD has been confirmed by experiment on differently textured ribbons of the same material.     

Visualization of stress distribution using mechanoluminescence from Sr3Al2O6: Eu and the nature of the luminescence mechanism

We have investigated the dependence of the mechanoluminescence intensity from Sr3Al2O6: Eu on compressive stress. The distribution of the mechanoluminescence intensity, which is clearly visible to the naked eye, is consistent with the calculated stress distribution. The luminescence centre has been identified as the Eu2+ ion from spectra of the mechanoluminescence and also from photoluminescence studies of Sr3Al2O6: Eu. The mechanoluminescence intensity decreases on repetitive application of stress but recovers completely on irradiation with ultraviolet light. The Sr3Al2O6: Eu is a p-type semiconductor and has hole traps of depth 0.11 eV. It is suggested that the mechanoluminescence mechanism arises from the movement of dislocations and recombination between electrons and holes released from these traps which are associated with Eu2+ centres.     

Evolution of a sharp {110} texture in microcrystalline Fe78Si9B13 during magnetic crystallization from the amorphous phase

The effect of magnetic crystallization on texture evolution and control in nanocrystalline materials has been studied using a melt-spun amorphous Fe₇₈Si₉B₁₃ alloy. The magnetic crystallization was conducted at temperatures ranging from 653 to 853?K in a magnetic field up to 6?T. The temperatures used for magnetic crystallization were chosen on the basis of the Curie and crystallization temperatures of the amorphous phase, and the Curie temperature of the crystallized phase. The resultant microstructure was characterized by X-ray diffraction and FE-SEM/EBSP/OIM techniques. It was found that a sharp {110} texture developed when the amorphous precursor was crystallized at 853?K in a magnetic field of 6?T applied in a direction parallel to the ribbon surface.     

The fractal property of internal structure of facial affect recognition: A complex system approach

Based on a circumplex model of facial affect, four inner affective circumplexes, assumed to have 100%, 75%, 50%, and 25% emotional intensities, were investigated in terms of fractal, which is a concept of complex systems. Results revealed that the perimeters of the circumplex excluding the 25% condition possessed fractal property characterised by features specific to fractals. Results also showed that fractal dimension in the 50% condition (1.58 dimension) was significantly higher than that in the 100% (1.45 dimension) and 75% (1.45 dimension) conditions, indicating that the cognitive structure of facial affect in the 50% condition was more complex than that in the 100% and 75% conditions.