What Is Line Bisection in Unilateral Spatial Neglect?: Analysis of Perceptual and Motor Aspects in Line Bisection Tasks

Three patients with unilateral spatial neglect could detect the difference of length between the right and left segments when a line had a transection mark. To examine the effect of response mode, the manual line bisection task and a new “line bisection task by fixation” were given to the patients. In tasks that used lines with no landmark, they showed apparent rightward errors. The results suggest that line bisection is not a task that examines the ability of patients with neglect to compare the right and left extents of a line. Where to fixate as the subjective midpoint may determine the rightward errors of bisection, whether manual response is used or not.     

Disruption of kinematic coordination in throwing under stress

The present study tested the conscious-control theory of the relationship between stress and performance. Performers under stress conditions consciously attempted to control their movements, disrupting the automaticity of control. Twenty-two male subjects (11 in Experiment 1 and 11 in Experiment 2) performed an underhand ball-throwing task using the non-dominant hand. The inter-trial variability of two kinematic measures was analyzed, namely arm-joint coordination during the throw and hand position at release (release point). Experiment 1 confirmed the validity of regarding these variability measures as indices of automaticity, as they did not vary in spite of resource shortage induced by a dual-task paradigm. In Experiment 2, in which stress led to a detriment in performance, the variability of joint coordination increased, whereas the release point became more fixed. These findings imply that throwing performance is impaired when the coordination is disrupted as a result of inflexible movement executed by conscious control.     

Conscientiousness mediates the relation between perceived parental socialisation and self‐rated health

The pathways between parenting behaviours, personality and physical health have all been separately studied. Prior research has paid little attention to the indirect effects of personality in the path between parenting behaviours and better health. The purpose of this study was to explore the mediational effects of conscientiousness on the relationships between parental socialisation of responsibility and self‐rated health, and to examine potential age differences in this mediational pathway. In total, 736 female and 749 male members across Japan participated in this study. They were divided into three groups by age category: younger‐, middle‐aged and older‐aged. Conscientiousness and health were concurrently rated, while parental socialisation of responsibility was retrospectively assessed. Our analyses revealed that parental socialisation of responsibility is positively associated with conscientiousness and self‐rated health, that conscientiousness is positively associated with self‐rated health, and that conscientiousness fully mediated the effect of parental socialisation of responsibility on self‐rated health. The mediational links were consistent across younger, middle‐aged and older‐aged cohorts. Our findings suggest that greater parental socialisation of responsibility relates to higher conscientiousness, and consequently healthier adults. These findings imply that parental behaviours could be a plausible target for intervention to foster the development of conscientiousness and better health.     

Dynamic modulation of an orientation preference map by GABA responsible for age-related cognitive performance

Accumulating evidence suggests that cognitive declines in old (healthy) animals could arise from depression of intracortical inhibition, for which a decreased ability to produce GABA during senescence might be responsible. By simulating a neural network model of a primary visual cortical (V1) area, we investigated whether and how a lack of GABA affects cognitive performance of the network: detection of the orientation of a visual bar-stimulus. The network was composed of pyramidal (P) cells and GABAergic interneurons such as small (S) and large (L) basket cells. Intrasynaptic GABA-release from presynaptic S or L cells contributed to reducing ongoing-spontaneous (background) neuronal activity in a different manner. Namely, the former exerted feedback (S-to-P) inhibition and reduced the frequency (firing rate) of action potentials evoked in P cells. The latter reduced the number of saliently firing P cells through lateral (L-to-P) inhibition. Non-vesicular GABA-release, presumably from glia and/or neurons, into the extracellular space reduced the both, activating extrasynaptic GABAa receptors and providing P cells with tonic inhibitory currents. By this combinatorial, spatiotemporal inhibitory mechanism, the background activity as noise was significantly reduced, compared to the stimulus-evoked activity as signal, thereby improving signal-to-noise (S/N) ratio. Interestingly, GABA-spillover from the intrasynaptic cleft into the extracellular space was effective for improving orientation selectivity (orientation bias), especially when distractors interfered with detecting the bar-stimulus. These simulation results may provide some insight into how the depression of intracortical inhibition due to a reduction in GABA content in the brain leads to age-related cognitive decline.     

Emotion colors time perception unconsciously

Emotion modulates our time perception. So far, the relationship between emotion and time perception has been examined with visible emotional stimuli. The present study investigated whether invisible emotional stimuli affected time perception. Using continuous flash suppression, which is a kind of dynamic interocular masking, supra-threshold emotional pictures were masked or unmasked depending on whether the retinal position of continuous flashes on one eye was consistent with that of the pictures on the other eye. Observers were asked to reproduce the perceived duration of a frame stimulus that was concurrently presented with a masked or unmasked emotional picture. As a result, negative emotional stimuli elongated the perceived duration of the frame stimulus in comparison with positive and neutral emotional stimuli, regardless of the visibility of emotional pictures. These results suggest that negative emotion unconsciously accelerates an internal clock, altering time perception.     

Nonretinotopic processing is related to postdictive size modulation in apparent motion

The present study briefly examined how the perceived size of a leading flash would be modulated by trailing motion signals. Observers were presented with two vertical green bars that were followed by white bars with different lengths, which were presented at different locations from the green bars. The task of observers was to discriminate which of the green bars was shorter than the other (Experiment 1) or whether the lengths of the green bars were equal or not (Experiments 2 and 3). One green bar producing apparent motion with the following shorter white bar was reported to be shorter than the other green bar producing apparent motion with the following longer white bar, not only when motion correspondence was determined on the basis of retinal proximity (Experiments 1 and 2),but also when motion correspondence was determined on the basis of nonretinotopic information-that is, a relative location within each perceptual group of bars (Experiment 3). These results indicate that motion processing involving object updating or motion deblurring in the nonretinotopic frame of reference is related to postdictive size modulation.     

Necessary condition for forward progression in ballistic walking

Ballistic walking requires an appropriate configuration of posture and velocity at toe-off to avoid backward falling. In this study, we investigated a determinant of the state of the body center of mass (COM) at the toe-off with regard to ballistic walking. We used an inverted pendulum model to represent ballistic trajectories and the necessary condition for forward progression by a simple relationship between the COM states (position and velocity) at toe-off. This condition was validated through a computer simulation of a 7-link musculoskeletal model and measurement experiments of human movements involving stepping and walking. The results of the model simulation were in good agreement with some of the results predicted by the inverted pendulum model. The measurement experiments of walking and stepping movements showed that most COM states at toe-off satisfied the condition for forward progression and the measured trajectories during single support phase were similar to the ballistic trajectories although humans are capable of walking in non-ballistic ways. These results suggested that the necessary condition for forward progression can predict the COM states at toe-off for efficient movement and for avoiding backward falling during single support phase.