Eye-position signals in successive saccades

Accuracy of the eye-position signal (EPS) in successive-saccade conditions was examined by analyzing the subject’s performance in tracking his gaze by pointing with his unobservable hand in the dark. The size of constant error in manual pointing was found to increase with the number of the component saccades and to be inversely proportional to the size of the largest component saccade. The results are interpreted as showing that, in successive-saccade conditions, subjects are not able to use the sum of EPSs from each component saccade, but rather use only the EPS from the largest component saccade.     

Toward neuroanatomical models of analogy: a positron emission tomography study of analogical mapping

Several brain regions associated with analogical mapping were identified using (15)O-positron emission tomography with 12 normal, high intelligence adults. Each trial presented during scanning consisted of a source picture of colored geometric shapes, a brief delay, and a target picture of colored geometric shapes. Analogous pictures did not share similar geometric shapes but did share the same system of abstract visuospatial relations. Participants judged whether each source-target pairing was analogous (analogy condition) or identical (literal condition). The results of the analogy-literal comparison showed activation in the dorsomedial frontal cortex and in the left hemisphere; the inferior, middle, and medial frontal cortices; the parietal cortex; and the superior occipital cortex. Based on these results as well as evidence from relevant cognitive neuroscience studies of reasoning and of executive working memory, we hypothesize that analogical mapping is mediated by the left prefrontal and inferior parietal cortices.     

Presentation of a visual nearby moving object alters stream/bounce event perception

Two identical visual objects moving across each other in a two-dimensional display can be perceived as either streaming through or bouncing off each other. The bouncing event percept is promoted by the presentation of a brief sound at the point of coincidence of the two objects. In this study, we examined the effect of the presence of a moving object near the two objects as well as the brief sound on the stream/bounce event perception. When both the nearby moving object and brief sound were presented, a streaming event, not a bouncing event, was robustly perceived (experiment 1). The percentage of the streaming percept was also systematically affected by the proximity of the nearby object (experiment 2). These results suggest that the processing of intramodal grouping between a nearby moving object and either of the two objects in the stream/bounce display interferes with crossmodal (audiovisual) processing. Moreover, we demonstrated that, depending on the trajectory of the nearby moving object, the processing of intramodal grouping can promote the bouncing percept, just as crossmodal processing does (experiment 3).     

Confluence Proofs of Lambda-Mu-Calculi by Z Theorem

Studia Logica - This paper applies Dehornoy et al.’s Z theorem and its variant, called the compositional Z theorem, to prove confluence of Parigot’s $$\lambda \mu $$ -calculi extended...     

The stream/bounce effect occurs for luminance- and disparity-defined motion targets

We generalised the stream/bounce effect to dynamic random element displays containing luminance- or disparity-defined targets. Previous studies investigating audio-visual interactions in this context have exclusively employed motion sequences with luminance-defined disks or squares and have focused on properties of the accompanying brief stimuli rather than the visual properties of the motion targets. We found that the presence of a brief sound temporally close to coincidence, or a visual flash at coincidence significantly promote bounce perception for motion targets defined by either luminance contrast or disparity contrast. A brief tone significantly promoted bouncing of luminance-defined targets above a no-sound baseline when it was presented at least 250 ms before coincidence and 100 ms after coincidence. A similar pattern was observed for disparity-defined targets, though the tone promoted bouncing above the no-sound baseline when presented at least 350 ms before and 300 ms after coincidence. We further explored the temporal properties of audio-visual interactions for these two display types and found that bounce perception saturated at similar durations after coincidence. The stream/bounce illusion manifests itself in dynamic random-element displays and is similar for luminance- and disparity-defined motion targets.     

Leptin inhibits and ghrelin augments hypothalamic noradrenaline release after stress

Metabolic conditions affect hypothalamo-pituitary-adrenal responses to stressful stimuli. Here we examined effects of food deprivation, leptin and ghrelin upon noradrenaline release in the hypothalamic paraventricular nucleus (PVN) and plasma adrenocorticotropic hormone (ACTH) concentrations after stressful stimuli. Food deprivation augmented both noradrenaline release in the PVN and the increase in plasma ACTH concentration following electrical footshocks (FSs). An intracerebroventricular injection of leptin attenuated the increases in hypothalamic noradrenaline release and plasma ACTH concentrations after FSs, while ghrelin augmented these responses. These data suggest that leptin inhibits and ghrelin facilitates neuroendocrine stress responses via noradrenaline release and indicate that a decrease in leptin and an increase in ghrelin release after food deprivation might contribute to augmentation of stress-induced ACTH release in a fasting state.     

Discrete cortical regions associated with the musical beauty of major and minor chords

Previous research has demonstrated that the degree of aesthetic pleasure a person experiences correlates with the activation of reward functions in the brain. However, it is unclear whether different affective qualities and the perceptions of beauty that they evoke correspond to specific areas of brain activation. Major and minor musical keys induce two types of affective qualities--bright/happy and dark/sad--that both evoke aesthetic pleasure. In the present study, we used positron emission tomography to demonstrate that the two musical keys (major and minor) activate distinct brain areas. Minor consonant chords perceived as beautiful strongly activated the right striatum, which has been assumed to play an important role in reward and emotion processing, whereas major consonant chords perceived as beautiful induced significant activity in the left middle temporal gyrus, which is believed to be related to coherent and orderly information processing. These results suggest that major and minor keys, both of which are perceived as beautiful, are processed differently in the brain.     

A new response-time measure of object persistence in the tunnel effect

The recognition of information about an object is facilitated by a preview of the information concerning that object. This facilitation is regarded as evidence for the representational persistence of the object. It is not known, however, if such facilitation is obtained even under the tunnel effect, in which a moving object is temporarily occluded. This facilitation may be a new way to measure the representational persistence of a moving object in the tunnel effect. We addressed this question by a "same-different" judgment task of a target symbol (" composite function" or "+"), drawn within the moving object, before and after encountering the occluder. Response times (RTs) were shorter when the object reappeared with spatial continuity at the proper place than it reappeared at the improper place, as in Experiments 1 and 3. Thus, facilitation was obtained even in the tunnel effect. When the occluder was invisible and deletion/accretion cues along the contour of the occluder were either removed (Experiment 2) or given improperly (Experiment 4), no facilitation was found. These results clearly indicate that the facilitated recognition was caused by amodal integration of the persisting representation from the unoccluded and modal phases. The present study demonstrates that the facilitated recognition (RT measurement) can be used to investigate the representational persistence in the tunnel effect.     

The extraretinal signal from the pursuit-eye-movement system: its role in the perceptual and the egocentric localization systems

The accuracy of perceptual judgment of the distance of a moving target tracked at various velocities by pursuit eye movements was examined in relation to the amount of two types of eye movement (smooth pursuit eye movement and compensatory saccade) involved in eye tracking. The perceptually judged distance became shorter as the amount of pursuit-eye-movement component in eye tracking increased. A detailed analysis of the eye-movement data and the size of perceptual underestimation indicated that the underestimation was mainly caused by inaccurate extraretinal information derived from the pursuit-eye-movement system, which underestimated the distance at a constant ratio, irrespective of the velocity of tracking. Egocentric localization was not affected by the mode of eye movements, indicating that the egocentric localization system functions without interference from the inaccurate information from the pursuit-eye-movement system.