A computational and perceptual account of motion lines

To indicate motion in a static drawing, artists often include lines trailing a moving object. The use of these motion lines is notable because they do not seem to be related to anything in the optic array. The dynamic behavior of a neural-network model for contour detection is analyzed and it is shown that it generates trails of oriented responses behind moving stimuli. The properties of the oriented response trails are shown to correspond to motion lines. The model generates trails of different orientations depending on the speed and length of the movement, and thereby predicts different uses of two types of motion lines. The model further predicts that motion lines should bias real motion in some situations. An experiment relating motion lines to ambiguous motion percepts demonstrates that motion lines contribute to motion percepts.     

Role of monoamines in the control by hormones of sexual receptivity in the female rat.

The involvement of indole- and catecholamines in the hormonal regulation of sexual receptivity has been investigated in ovariectomized female rats. Drugs that reduce 5-hydroxytryptamine, dopamine, and adrenaline or increase noradrenaline neurotransmission tended to facilitate the occurrence of estrous behavior in estrogen-treated females, and drugs having opposite effects tended to inhibit receptivity induced by estrogen and progesterone. Estrogen decreased noradrenaline turnover in cortex and brain stem; progesterone enhanced this effect in brain stem but prevented it in cortex. Both hormones tended to block noradrenaline uptake in hypothalamus in vitro. In a schedule used to induce receptivity, estrogen accelerated serotonin turnover, an effect prevented by progesterone. Thus a number of monoamines may be involved in the control by hormones of estrous behavior. Furthermore, hormones affect both amine turnover and uptake mechanisms.     

Results of electroencephalographic and familial studies in Wilson's disease]

The results of electroencephalographic and familial studies of 31 Wilson's disease patients coming from 26 kindreds are presented. Prior to treatment, 8 patients showed pathological conditions, while 9 and 11 patients showed borderline and normal conditions, respectively, it having not been possible to determine electroencephalographic conditions characteristic of Wilson's disease and find any relationships between the intensity of E.E.G. changes and the clinical picture and stage of development of the disease, respectively. Under penicillamine treatment, there was observed a tendency toward normalization of pathological conditions rather than deterioration of normal E.E.G. findings. So far as familial studies are concerned, the authors report the results obtained for 9 fathers, 19 mothers, and 24 siblings from a total of 21 kindreds; what is remarkable in this connection is the comparatively small percentage of normal E.E.G. findings for healthy siblings. It was only in one single kindred that it was possible to observe similarities between E.E.G. variations of individual family members.     

Lithium tremor-combination treatment with beta receptor blockaders]

In addition to the various possibilities of influencing lithium tremor, experience gathered from the application of beta-receptor blockers is reported, and concepts investigated on the potential genesis and working mechanisms.