Norma F. Besch

Effects of locus and size of septal lesion on consummatory behavior in the rat

Abstract There have been many reports of enhanced drinking following septal lesions in the rat. In order to designate more precisely the responsible area or structure, the present study was conducted in which the size (15, 30 or 60 millicoulombs of applied current) and vertical placement (dorsal or ventral septal lesion) of the lesion were varied. The more ventrally placed lesions produced the most frequent change. The most significant finding was that large increases in intake, whether transitory or persistent, were associated with damage to the paraventricular nucleus of the hypothalamus. No consistent relationship was demonstrated between postoperative water intake and damage to a given septal structure or group of septal structures.

Maze Learning by Secondary Reinforcement without Discrimination Training

An experiment was conducted to determine whether discrimination training is necessary to establish a neutral stimulus as a secondary reinforcer. Twenty rats were discrimination trained with 65 reward trials and 25 nonreward trials (black end-box positive, white end-box negative, and vice versa); 20 rats were single-stimulus trained to either a black or white end-box for 65 reward trials. T-maze test trials were given at a rate of 1 free choice and 3 forced-choice trials per day for 11 days. One-half of the Ss in each training group were given standard nonreward test trials; one-half of the Ss from each training condition were rewarded for both maze choices. The results showed that all 4 experimental groups performed significantly better than chance in the T maze. The successful test effects were attributed, in part, to the control of such factors as frustration and stimulus novelty. The data further suggest that discrimination training is not necessary for the production of secondary reinforcement effects.

The effects of familiarization training on the learning of paired adjectives

The effect of familiarizing Ss with English adjectives which subsequently appear as items in a paired-associate task was investigated in three experiments. In Exp. I, performance on nonfamiliarized pairs was significantly better than on pairs in which both the stimuli and responses had been given familiarization training. The two methods of familiarization, a card method and an anticipation method, produced the same effect. Experiment II replicated the results of Exp. I. It was also shown that stimulus articulation did not alter the effect of familiarization training. In Exp. III, better performance was shown for nonfamiliarized pairs in comparison to pairs given response familiarization and again for pairs given stimulus and response familiarization. Stimulus familiarization had no effect.

Stereotaxic tumor transplantation as an investigative tool

SummaryPreliminary studies on psychological observations on rats with stereotaxically placed tumor transplants in the midbrain structures are described. Although the reported results appear superficially to be inconclusive, they present some degree of clinico-pathologic correlation. It is felt that by introducing certain refinements and modifications, the technique may ultimately prove of value in the elucidation of problems pertaining to the functional localization in the central nervous system.