Selection for spontaneous or priming-induced audiogenic seizure susceptibility in mice

Four lines of mice were selectively bred from a heterogeneous foundation stock for audiogenic seizure prone (SP), priming prone (PP), moderately priming prone (MPP), and seizure resistant (SR). Significant changes in proportions of animals showing the desired phenotypes were found after two generations of selection, indicating involvement of genetic components in these behavioral characteristics. Although response to selection for spontaneous seizure proneness was rapid, the results do not support a view that initial seizure risk is controlled by a single recessive gene. The effects of tympanic membrane perforation on development of seizure susceptibility in these four selected lines were investigated in Experiment 2. Results indicate that the method is highly effective in inducing seizure susceptibility in the PP mice and the SR mice, but not so effective for the SP and the MPP lines. These results suggest that spontaneous and priming-induced seizure susceptibility could be due to development of hyperreactivity in centripetal auditory structures brought about by reduction of auditory input. They also suggest that the phenotypic difference between the PP and the SR lines could be due to differences in their cochlear susceptibility to stimulation damage but that a qualitatively different mechanism is involved in the MPP line.

Short-term and serial memory in autistic, retarded, and normal children

Experimental data on memory ability of autistic children is scarce and contradictory. It is suggested that this may in part be the result of failure to control for acquisition of the correct response before memory is tested. In the first experiment reported, acquisition was controlled in a delayed-response visual discrimination task. The performance of autistic children was compared with MA matched normal and retarded controls. Recall deteriorated with increasing delay interval in each group. There were no significant group differences. The second experiment was designed to measure the effects of interference on memory using a serial memory task. No differences were found among groups in rate of learning, although the autistic children improved significantly on the second and longer series. There was no relationship between performance on the STM and the serial memory tasks over the same time intervals for any group. The results are interpreted as supporting the view that when MA and response acquisition level are equated with normal and retarded children in a memory task, autistic children do not show any specific memory deficits.

[Analysis of the mode of action of ifenprodil on cerebral and peripheral circulation in dogs]

Pharmacological properties of ifenprodil, a vasodilating agent similar in chemical structure to isoxsuprine were investigated. In anesthetized dogs and cats, ifenprodil (0.3 approximately 1 mg/kg, i.v.) caused a temporary prominent depressor response with an increment in heart rate and an occasional enlargement of pulse pressure followed by a mildly durable hypotension. These two phases of hypotension of ifenprodil could not be demonstrated in spinal rats and cats. Ifenprodil also decreased the pressor response of norepinephrine and reversed the pressor effect of epinephrine to a depressor one. The lowering effect of ifenprodil on the constant-rate perfused pressure of vertebral artery in dogs was half as potent as isoxsuprine. Ifenprodil significantly reduced the contraction to norepinephrine in the isolated guinea-pig vas deferens. This was greater than the constrictor response produced by preganglionic sympathetic nerve stimulation. The inhibitory effect of ifenprodil was less potent than that of phentolamine on the responses to norepinephrine in isolated rabbit ascending aorta strips. In the isolated guinea-pig right atrium, ifenprodil (10(-5) g/ml) showed slightly negative inotropic and chronotropic effects, and reduced the responses to isoproterenol. It is suggested that the two phases of lowering effects of ifenprodil on the constant-rate perfusion pressure of either vertebral or femoral artery in dogs are due to a possible neurogenic and an alpha-adrenolytic action, but the precise mechanism is not clear. Ifenprodil like isoxsuprine has a weak beta-sympathetic effect.

Effects of food deprivation on the performance of a two-turn task in a temporal circular maze

Ten hooded rats were trained to perform a two-turn task in a temporal circular maze. The effects of levels of food deprivation (2, 26, 50, 74, 98, 122 hr.) on performance were evaluated. It was found that the correct responses were not affected, but both running time and competing behaviour decreased significantly with increase in hours of food deprivation. In a second experiment 8 rats were trained in a similar way and after attaining a stable performance, were run for a further 4 sessions at 24 hr. deprivation, and then at 72 hr. deprivation. The results precluded the possibility that the results obtained in Experiment I were due to practice effects, and support the findings on the effects of deprivation.