Thomas S. Brown

Hippocampal lesions and learned taste aversion.

Rats with hippocampal lesions were compared with neocortical and sham-operated controls on a taste aversion learning task using an 8% sucrose solution (CS) and 2% body weight IP injection of.15 M lithium chloride (UCS). Hippocampally ablated animals acquired the taste aversion as rapidly as controls after a single CS-UCS pairing. No differences were found among the groups in terms of either the magnitude or extinction of the aversion. The results do not support a general loss of response inhibition interpretation of hippocampal function. Rather, the results confirm and extend a number of previous findings indicating that the enhanced perseverative tendencies frequently observed in rats with hippocampal lesions are absent in consummatory-type tasks.

Hippocampal lesions and shuttlebox avoidance behavior: A fear hypothesis☆

Abstract Rats with hippocampal damage were compared to cortically lesioned and normal controls in the acquisition of a shuttlebox avoidance task. It was hypothesized that animals with lesions of the hippocampus are superior to controls at this task because they are more fearful. Before avoidance training, all animals were allowed to lick at a drinking tube containing a highly palatable solution of glucose and saccharin. Following avoidance training, animals were returned to the drinking situation and the shuttlebox CS presented while the rat licked. The extent to which the CS suppressed licking provided an estimate of the fear transferred from the avoidance situation. According to this measure, animals with lesions of the hippocampus were more fearful than control animals. This result was interpreted in terms of heightened ACTH levels seen following damage to the hippocampus.

The impact of pre-employment integrity testing on employee turnover and inventory shrinkage losses

A major home improvement chain located primarily in the western United States initiated the use of thePersonnel Selection Inventory, a written integrity test, as part of its pre-employment hiring process. For two years only, those job applicants who passed this test and other pre-employment criteria were hired by the chain. Following the introduction of the inventory, there was: (1) a 50% reduction in the number of employee terminations for theft, illegal drug use, and violence over a five year period and (2) a savings in shrinkage losses that amounted to over two million dollars over a two year period.

Effectiveness of Personnel Selection Inventory in Reducing Drug Store Theft

The Personnel Selection Inventory was introduced as a component of the preemployment hiring procedures by a major retail drug chain in the southeastern United States. In the 3-yr. period following, two major results occurred. There was a significant increase in the proportion of employees who passed their annual routine polygraph examination and shrinkage losses were reduced sufficiently to reflect a savings of over one million dollars for the chain.

The effect of hippocampal lesions on the development and extinction of a learned taste aversion for a novel food

The effect of hippocampal lesions on the inhibition of eating was examined within a learned taste aversion paradigm. Rats with hippocampal lesions were tested on their ability to refrain from eating a novel tasting food that had been paired with the internal malaise produced by a.15-M IP injection of lithium chloride. The results showed that the rats with hippocampal lesions did not differ from normal rats on either the development or extinction of the aversion. These results extend previous findings which show that bilateral hippocampal lesions do not interfere with the normal modulation of consummatory behaviors.

Factors affecting sucrose preference behavior in rats with hippocampal lesions

Abstract Rats with hippocampal lesions were compared to rats with neocortical lesions and to normal unoperated animals on tests of sucrose preference in both a short (5 min) and a long (24 hr) test session. Sucrose preference behavior was examined on a seven point solution range which extended from water to 48% sucrose. Rats with hippocampal lesions failed to show any preference for sucrose in the 5-min test session, whereas the same animals were identical to controls in the 24-hr test. Additional groups with comparable lesions were also compared on tests of sucrose preference under conditions of both food and water deprivation. The hippocampally-ablated animals showed none or a markedly attenuated preference for sucrose when water deprived. The same animals were identical to the control groups when sucrose preference was tested under food deprivation. Under both deprivation conditions, however, the rats with hippocampal lesions changed significantly more often between the members of the test solution pairs. No differences were found between the cortical and normal unoperated control groups.

Behaviors emitted by rats with limbic lesions during feeding

Spontaneous behavior was monitored during a short feeding session in male and female rats with lesions of either the hippocampus or amygdala. Behavior was time-sampled every 10 sec for 10 min daily for 8 days. Male rats with hippocampal lesions reared less frequently but showed elevated levels of drinking and locomotion compared to control males. Female rats with hippocampal lesions were similar to controls along all measures. Amygdala lesions were without effect in rats of either sex. It was concluded that the hippocampal lesion interacts with sex in affecting spontaneous behavior.

Chronic intermittent ethyl alcohol inhalation and avoidance learning

Weanling male and female rats were chronically exposed to alcohol for 50 days using an intermittent inhalation technique which does not cause alcohol dependency. After 17 days of no exposure to alcohol, animals began two-way active avoidance testing. Results indicated that males were impaired on this task and females were not while at the same time males had reduced body weights. The male weight reduction was not responsible for the avoidance impairment. It was concluded that impaired avoidance learning following chronic esposure to alcohol is not specific to dependency models of animal alcoholism.

Effects of Desalivation on Schedule-Induced Polydipsia in the Rat.

The development and magnitude of schedule-induced polydipisa (SIP) were examined in desalivate and control rats in two experiments. In Experiment 1 animals were placed on a noncontingent fixed time (FT) 60-sec schedule for 24 days. Results indicate speeded development but asymptotically lower levels of SIP in desalivate rats compared to controls. Home cage consumption, however, was elevated in desalivate rats. In Experiment 2 schedule length, pellet size, and the percentage of body weight were manipulated. Desalivate rats consumed less fluid during each schedule condition relative to controls, but the pattern of results across schedules was similar to controls. It was concluded that (a) desalivation attenuates SIP; (b) SIP is a learned phenomenon; (c) dry mouth theories of SIP appear inadequate; and (d) the developmental aspect of the SIP phenomenon deserves additional research attention.

Limbic lesions and consummatory behavior in the rat

The consummatory behavior of normal rats and rats with lesions of the hippocampus, neocortex, entorhinal cortex or transections of the fornix was compared during 3 days of ad-lib feeding. The results showed that none of the groups differed on the mean amount of food or water consumed. However, the rats with lesions of the hippocampus dropped a significantly larger portion of their food ration through the wire mesh floors of the cages. The results are discussed in terms of a possible confounding which could occur when rats with hippocampal lesions are maintained on fixed rations of food and housed in wire mesh cages.