Lester M. Geller

Reliability of the Learning Style Inventory

The Learning Style Inventory, based upon Kolbs experiential theory of learning, is intended to measure an individuals emphasis on each of four learning modes: Concrete Experience (CE), Reflective Observation (RO), Abstract Conceptualization (AC), and Active Experimentation (AE). Two primary dimensions (combination scores), AC-CE and AE-RO, categorize learners into four types, namely, the converger, diverger, accommodator, and assimilator. Test-retest reliabilities (31-day interval) for the four learning modes and two combination scores, derived from 50 U. S. students enrolled in foreign medical schools who participated in a 6-wk. basic medical sciences review course, were: Concrete Experience, .56; Reflective Observation, .52; Abstract Conceptualization, .59; Active Experimentation, .61; Abstract Conceptualization-Concrete Experience, .70; and Active Experimentation-Reflective Observation, .55. Although these Pearson product-moment coefficients might be reasonably satisfactory for employing the inventory in distinguishing between the means of two relatively small groups with a narrow range of difference, they are unsatisfactory for its use in reliably differentiating among individuals or between the means of larger, more disparate groups. It is felt, however, that the inventory is a potentially valuable instrument and that there are possibilities for improvement which might enhance its reliability, at the same time contributing to its validity.

A simple technique for the permanent marking of newborn albino rats.

Routine methods of marking rats cannot be used for identifying litter members at, or shortly after, birth, nor can they be effectively applied until a few weeks later. Injection of India ink under or into the palm of the forefoot or the sole of the rear foot of the newborn rat, however, provides a clearly discernible, permanent mark which permits litter members to be differentiated with ease. This method, the details of which are described, has been used successfully on some 3,000 newborn albino rats, many of which have been studied for 20 to 30 mo. or longer.

Failure of Nicotine to Affect Development of Offspring When Administered to Pregnant Rats

Administration of nicotine to rats at any point in pregnancy has no apparent effect upon completion or duration of pregnancy, or upon body development, litter size, weight, or mortality of offspring. These results differ sharply from the effects in mice reported by others. The possible etiologic significance of anoxia in the malformations reported in mice is discussed.

Audiogenic seizure susceptibility of rats X-irradiated in utero late in pregnancy

Abstract Sherman strain rats exposed in utero to a maternal whole-body dose of 250 r of X-radiation, on Day 17, 18, or 19 of pregnancy, were tested for their susceptibility to sound-induced seizures at a median age of either 256, 266, or 322 days. There was no significant difference among the three prenatally X-irradiated groups or among the control groups, or between any X-irradiated group and its comparably aged control series, or between all X-irradiated animals grouped together and all control animals, in the number of rats displaying running attacks, or seizures, or both. Nor did the latency times (intervals between onset of bell and running attack) of prenatally X-irradiated reactors differ significantly from those of control reactors. No sex difference in susceptibility to sound-induced running attacks or seizures was found among the irradiated or control animals, or between them. The present findings are in line with and, indeed, complement those derived earlier from similarly treated animals tested for seizure susceptibility at a median age of 21 1 2 months. Apparently, the central neural changes produced in the rat by exposure in utero to maternal X-ray irradiation late in pregnancy (described by us and by others), do not collectively predispose or significantly affect the susceptibility of survivors to sound-induced seizures, at least at the ages when this was studied. Data supporting the reliability of some earlier reported age-seizure susceptibility relationships in the normal (Sherman) rat were also noted.

Pathologic changes in the inner ear of audiogenic seizure-susceptible mice treated with 6-aminonicotinamide

Abstract The inner ears were studied histologically to determine a possible morphological basis for our earlier finding of the abolition of sound-induced seizures in inbred audiogenic seizure-susceptible mice treated with 6-aminonicotinamide (6-AN). A single intraperitoneal injection of 20 mg/kg of 6-AN resulted in elimination of sound-induced seizures and produced severe degenerative lesions in the cochlear duct of the seizure-susceptible mice. Similar cochlear lesions were produced in a control mouse strain (CF#1). The earliest lesions, first sought and clearly evident at 24 hours after the injection, were localized in the spiral ligament, the epithelium of the external spiral sulcus, and the lateral portions of the papilla acoustica. The acute degeneration was at its highest 3–5 days after the injection, when the medial portions of the papilla were also involved. The damage to the spiral organ (Corti) seen at that time is incompatible with a normal sensory input. The degree of damage is sufficient to explain the loss of, or marked restriction in, response to auditory stimuli, and the abolition of audiogenic seizures. In all animals treated with 6-AN, the lower basal turn and the upper second turn were more extensively damaged than the rest of the cochlea. However, in the longest surviving 6-AN-treated mice not even a remnant of the spiral organ could be detected. The spiral ganglion nerve cells were not damaged in the acute stage of 6-AN intoxication. The atrophy of the spiral ganglion which appeared in the late stages was, like the degeneration of the spiral organ, most severe in the lower basal and upper second turns. The changes in the spiral ganglion were interpreted as being secondary to the acute destruction of the spiral organ.

Audiogenic seizure susceptibility of rats X-irradiated in utero during first one-third of pregnancy

Abstract Groups of Sherman rats exposed in utero to a maternal dose of 250 r of X-radiation, during the first one-third of pregnancy, were tested for susceptibility to sound-induced seizures at a median age or 175, 230, or 258 days. There was no significant difference between any irradiated group and control animals of comparable age in either number of running attacks or seizures. A need for caution in generalizing from these findings to other samples of rats, tested at equivalent ages, has been noted. The suggestion by others of decreased susceptibility in 4-month-old offspring of Sprague-Dawley rats exposed to lower doses of X-radiation, on gestational day 5 or 10, was found to be inadequately supported by their data. Well-known differences in audiogenic seizure susceptibility in relation to age in normal animals, evident in the present study, underscore the importance of the age-at-testing variable in evaluating susceptibility in the prenatally X-irradiated rat, as well as the need for longitudinal studies in making that determination. Beyond its special consideration in seizure studies, the variable of test age appears to be of fundamental importance in elaborating the functional consequences of prenatal X-irradiation. The present report reduces the already limited number of behavioral changes said to occur in rats surviving X-irradiation during the preorganogenetic period. In view of the absence of light microscopic evidence of damage to their brains, a search for functional alterations in such animals would seem to be particularly challenging.

Sound-induced seizures in long-surviving prenatally x-irradiated rats

Abstract Twelve rats which had been exposed to 250 r of x-radiation in utero, on either the eighteenth or nineteenth day of pregnancy, were tested for their susceptibility to sound-induced seizures at a median age of 21 I 2 months. No significant association between incidence of seizures and prenatal x-irradiation was found. Some indication that x-irradiation in utero enhanced the reactivity of seizure-susceptible animals (whatever the causal factor for such susceptibility might be) was adduced from the findings. Contrary to the findings of others, it was concluded that audiogenic seizure susceptibility cannot be considered either a long-term or a sensitive indicator of the effect of x-irradiation upon the central nervous system.