Psychophysical scaling of circular vection (CV) produced by optokinetic (OKN) motion: individual differences and effects of practice.

Vection (V) refers to the compelling visual illusion of self-motion experienced by stationary individuals when viewing moving visual surrounds. The phenomenon is of theoretical interest because of its relevance for understanding the neural basis of ordinary self-motion perception, and of practical importance because it is the experience that makes simulation, virtual reality displays, and entertainment devices more vicarious. This experiment was performed to address whether an optokinetically induced vection illusion exhibits monotonic and stable psychometric properties and whether individuals differ reliably in these (V) perceptions.

Selective vulnerability and early progression of hippocampal CA1 pyramidal cell degeneration and GFAP-positive astrocyte reactivity in the rat four-vessel occlusion model of transient global ischemia.

Selective, delayed-onset vulnerability of hippocampal CA1 pyramidal cells has been reported as a unique phenomenon in man and the rat four-vessel occlusion (4-VO) model of global ischemia. This has become of great interest for clarification of CA1 pathophysiology and pharmacological intervention after global ischemia. Studies of pathophysiology and pharmacotherapy appear to be impeded by variability in specific criteria and duration of 4-VO ischemia for producing selective CA1 and differential CA1-CA3 damage.

Distinct immunoreactivity to 110 kDa laminin-binding protein in adult and lesioned rat forebrain.

A phosphorylated, approximately 110 kDa laminin-binding protein (110 kDa LBP) from mouse brain has been previously identified. This protein recognizes a neurite-outgrowth promoting 19-amino acid synthetic peptide (PA 22-2) derived from the laminin A chain. In the present study, an antibody against the 110 kDa LBP was used to localize immunoreactivity in the normal adult rat brain and also following a stab wound and ischemic lesion.

Preclinical profile of stereoisomers of the anticonvulsant remacemide in mice.

Stereoisomers of remacemide (racemate form) were compared for anticonvulsant efficacy and safety in mice. In the maximal electroshock seizure (MES) test for oral efficacy, the (-) stereoisomer, FPL 14145, was more potent than the racemate or the (+) stereoisomer, FPL 14144. Respective ED50 values (expressed as mg/kg) were: remacemide, 58; FPL 14145, 45; FPL 14144, 79.

Preclinical profile of remacemide: a novel anticonvulsant effective against maximal electroshock seizures in mice.

Anticonvulsant tests in mice revealed specific, potent actions of remacemide for protection of mice against maximal electroshock seizures (MES). Comparisons of oral efficacy to reference compounds yielded the following ED50 values (expressed as mg/kg): remacemide = 33, phenytoin = 11, phenobarbital = 20, carbamazepine = 13 and valproate = 631. The duration for protection by remacemide was longer than carbamazepine or valproate, but shorter than phenytoin or phenobarbital.

Motor and cognitive testing of bone marrow transplant patients after chemoradiotherapy.

Assessment of cognitive and motor performance of bone marrow transplant patients prior to, during, and following intensive toxic chemoradiotherapy may provide an important adjunct to measures of physiological and medical status. The present study is an attempt to assess whether, as side-effects, these aggressive treatments result in cognitive performance deficits, and if so, whether such changes recover posttreatment. Measurement of cognitive ability in this situation presents special problems not encountered with one-time tests intended for healthy adults.

An animal model of human-type memory loss based on aging, lesion, forebrain ischemia, and drug studies with the rat.

The goals of this research were to develop a within-subject test of spatial working memory and performance for the rat in a T-maze, based on a delayed alternation, or "win-shift" foraging strategy. Using this model, specific aims were to compare the effects of: (1) age, (2) basal forebrain, medial septal, and amygdala lesions, (3) four vessel occlusion (4-VO), forebrain ischemia, and (4) physostigmine, scopolamine, arecoline, piracetam, and clonidine on memory and performance of young middle-aged, and old rats. Aging significantly impaired working memory and performance of Long-Evans rats.

Effect of exercise on longevity, body weight, locomotor performance, and passive-avoidance memory of C57BL/6J mice.

Studies of human and animal subjects have suggested that exercise may retard aging, help prevent age-related diseases, and prolong life span. Earlier studies focused on the effects of exercise on the heart, skeletal muscles, lungs, metabolism, and longevity. Researchers recently have begun to direct their attention to possible benefits of exercise on the brain.

Effect of prenatal ionizing radiation on the visual cortex and hippocampus of newborn squirrel monkeys.

Five squirrel monkeys were exposed to 200 rads whole-body ionizing irradiation (60Co) at 0.4 rads per second on approximately the seventy-fifth day of gestation, and six squirrel monkeys were sham-irradiated. The mean cortical depth and the mean number of neurons per mm3 in the visual cortex was less in irradiated animals than in controls, but the differences were not statistically significant.

Motion sickness in the squirrel monkey.

Because it is of the same taxonomic order as man, the squirrel monkey has been introduced as a nonhuman primate model for the study of such aspects of motion and space sickness as susceptibility, prevention, treatment, and neural mechanisms. In this study on susceptibility, the specific aims were to examine the effects of combined vertical rotation and horizontal acceleration, phenotype, sex, visual cues, morning and afternoon testing, and repeated test exposures on incidence, frequency, and latency of emetic responses. The highest emetic incidence of 89%, with an emetic frequency of 2.

Visual acuity and foveal cone density in the retina of the aged rhesus monkey.

The specific aims of this study were to examine age differences in visual acuity among young adult (5 years), middle aged (12 years) and aged (22 years) rhesus monkeys in relation to foveal cone density in the diurnal duplex retina. Classically, acuity has been defined as the reciprocal of the least resolvable detail measured in minutes of visual angle. The minimum separable binocular acuity mean of the young adult group was 0.

Localization of cellular changes within multimodal sensory regions in aged monkey brain: possible implications for age-related cognitive loss.

Young (4 to 7 years) and aged (18 to 28 years) rhesus monkeys were sacrificed and various neuromorphometric analyses performed to determine age differences in gross topography, cell population and patterns of cellular degeneration. Two brain regions implicated for their role in age-related cognitive disturbances, the hippocampus and the gyri bordering the principal sulcus in the frontal cortex were selected for these comparisons. Reliable morphometric differences between age groups were observed in both neural areas.

Age pigments, cell loss and hippocampal function.

The specific aims of this study were to perform direct correlational analyses of age differences in learning, short-term memory and arousal in relation to cell loss and lipofuscin increase in the hippocampus CA1 zone and in visual area 17 of the Fisher 344 rat. The following tentative conclusions can be made from the results presented in this study: (1) significant age differences in 2 and 6 hour passive-avoidance retention or memory between mature and old rats were related to non-significant age differences in days to criterion learning, starting latencies, running distance and time in original approach learning, and (2) significant age differences in 2 and 6 hours retention of old, compared to mature rats were correlated significantly with loss of neurons, and very significantly with increases in intraneuronal lipofuscin in the hippocampus CA1 zone and in visual area 17.

Age differences in short-term memory and cell loss in the cortex of the rat.

Studies with human and animal subjects have indicated age declines in short-term memory and cell loss in the cortex. Cell loss has been estamated by descriptive nonautomated methods. Declines in short-term memory may be related to reduced learning, movtivation, motor capacity, or some combination of these factors.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: appendix I. Condition of flight animals on recovery; food intake; observations on hypothalamus, pituitary, and adrenal glands.

The rationale for studying certain hypothalamic nuclei and the pituitary and adrenal glands of the pocket mice that flew on Apollo XVII was the need to evaluate the effects of the potentially severe stress on these animals in the foreign environment of flight canister, weightlessness, increased G forces, and other unnatural conditions. Decrease in body weight and variability of food intake were significant among the four flight animals that were recovered alive. The mean nuclear diameter of neurons in the arcuate and ventromedial hypothalamic nuclei did not differ significantly from the values obtained in the control animals.

The effects of cosmic radiation on pocket mice aboard Apollo XVII: V. preflight studies on tolerance of pocket mice to oxygen and heat. Part IV. observations on the brain.

Experiments designed to ascertain the effects of oxgen at 8, 10, and 12 psi partial pressure on the brains of pocket mice (Perognathus longimembris) were carried out at room temperature (24 degrees C, 75 degrees F) and at 32 degrees C (93 degrees F). The animals exposed to 8-12 psi at 32 degrees C had been in earlier KO2 oxygen tests. Five animals exposed either to 10 or 12 psi (517 mm or 620 mm HG) PO2 at 32 degrees C died during the course of the tests, possibly as a consequence of injury sustained by the earlier PO2 testing.