Anthony Moore
Psych 303-01
Dr. Katilius-Boydstun
May 1, 2007
Annotated Bibliography

Stressors and Their Effects on Exploratory Behavior

Good, Mark, and R. C. Honey. "Dissociable Effects of Selective Lesions to Hippocampal Subsystems on Exploratory Behavior, Contextual Learning, and Spatial Learning." Behavioral Neuroscience 111 (1997): 487-493. PsychARTICLES. EBSCO. Saint Xavier University, Chicago. 24 Apr. 2007. Keyword: Exploratory behavior. The aims of this test were to assess the effect of hippocampal lesions applied to rats on both exploratory behavior and contextual freezing, and to examine the idea that neural mechanisms are shared in contextual learning and spatial learning. There were three groups in the experiment: a control group (14 rats), a group that was given lesions of the hippocampus proper (10 rats), and one that received lesions of the entorhinal cortex (8 rats). For the first part of the experiment, the rats were placed in a chamber and were given half-second footshocks every 30 seconds after being observed for three minutes. For the second part, for the first six days, rats were placed in a water maze at a randomized position and swam to a hidden platform in the pool (this was a “training” period). For half of each of the groups, the platform was placed in the northwest quadrant of the pool, and for the other half it was placed in the southeast quadrant. On day seven, the platform was removed and the time each rat spent in each quadrant of the pool was recorded. The results of the first experiment showed that the hippocampal group was less likely to freeze than the control and entorhinal groups. The results of the second experiment showed that control rats preferentially swam in the training quadrant of the pool, while lesioned rats showed no significant preference to swim in the training quadrants. This implies that cortical influences that culminate in the hippocampus proper might be the basis for contextual freezing, and that the spatial learning and contextual freezing have different origins.

Kleen, Jonathan K., Matthew T. Sitomer, Peter R. Killeen, and Cheryl D. Conrad. "Chronic Stress Impairs Spatial Memory and Motivation for Reward Without Disrupting Motor Ability and Motivation to Explore." Behavioral Neuroscience 120 (2006): 842-851. PsychARTICLES. EBSCO. Saint Xavier University, Chicago. 24 Apr. 2007. Keyword: Exploratory behavior. This experiment was conducted to answer three questions: 1. Does chronic stress have selective effects on mnemonic ability? 2. Do such well-documented effects account for what appear to be memory problems, or are those independent of chronic stress? 3. Might chronic stress affect cognition, motivation, and motor ability along different time courses? The first experiment used 18 male rats, which was changed to 12 after removing the three top and bottom performers after operant training. The rats were placed in a chamber or a Y maze, and their behaviors recorded. In the chamber, the control group was allowed food immediately while the stressed rats were required to wait three hours. Each session was based on a variation of this method. In the Y-maze, the rats were tested using varying paths to test long-term spatial memory and spatial working memory. The results showed that chronic restraint influenced motivation without altering memory or motor ability. Stressed rats performed worse than the control group in the Y maze, although they were statistically similar when entries of the maze were examined. As stress persisted, motivation decreased, but there was no significant change in memory or motor ability.

Maho, Catherine, Gérard Dutrieux, and Martine Ammassari-Teule. "Parallel Modifications of Spatial Memory Performances, Exploration Patterns, and Hippocampal Theta Rhythms in Fornix-Damaged Rats: Reversal by Oxotremorine." Behavioral Neuroscience 102 (1988): 601-604. PsychARTICLES. EBSCO. Saint Xavier University, Chicago. 24 Apr. 2007. Keyword: Exploratory behavior. The purpose of this experiment was twofold. One, it was designed to define eventual variations of theta rhythms in rats in relation to modifications of exploratory schemas associated with performance deficits in a radial maze; two, to examine the possibility of modulating electrophysiological and behavioral parameters with injections of postsynaptic cholinergic agonist oxotremorine. 32 male rats were placed in a maze individually for five minutes each, for three consecutive days. Then, surgery was performed on the hippocampus. Two recording electrodes were placed in two sections of the brain. A second hole was drilled to make fornix sections. The rats were then placed in their home cages for a recovery period of one week. Theta recordings were made before the surgery and EEG readings were taken during conditions of locomotion and alert immobility. They were then separated into two groups. One received dorsal fornix sections using lesions, while the other was given a sham-style. They were then separated into four subgroups of 8 animals that were given injections of oxotremorine or an equivalent amount of saline. For 10 days, each rat was placed in the maze again and made 8 runs, all paths previously having been baited. The oxotremorine was shown to improve maze performance, while animals with lesions made less unrepeated path choices than did the sham-operated rats. This confirms previous reports of a close dependence of spatial learning, organization of exploratory schemas, and hippocampal functioning. Oxotremorine injections in sham-operated animals decrease theta frequencies do not improve choice accuracy, but strongly reduce the degree of divergence exploratory patterns.

Myhrer, Trond. "Exploratory Behavior and Reaction to Novelty in Rats: Effects of Medial and Lateral Septal Lesions." Behavioral Neuroscience 103 (1989): 1226-1233. PsychARTICLES. EBSCO. Saint Xavier University, Chicago. 24 Apr. 2007. Keyword: Exploratory behavior. There were two purposes for this study: One, it was intended to examine the different effects of two types of lesions—medial septal and lateral septal—on exploratory behavior. Two, it was intended to compare the results to a previous test so that damage to certain hippocampal regions could be compared. 20 male rats were randomly assigned to three groups: control (7 rats), MS lesions (6 rats), and LS lesions (7 rats). Testing was conducted in a Plexiglas cage containing three identical wooden cubes on one side, and three novel objects on another. For training, each rat was allowed to explore the empty apparatus for 25 minutes. For phase I, the rats each spent 10 minutes in the cage with the neutral objects, and their behavioral data was recorded. In phase II, one of the neutral objects was replaced with a novel object and the same behavioral data was recorded. Two more sessions followed with a neutral object being replaced by a novel object each time (a smaller object or a cube of cheese). The results showed that both lesion groups showed a reduced preference for novelty in comparison to the control group in phase I. In phase II, the LS group differed significantly from the control and MS groups, exploring the neutral objects more.

Rosellini, Robert A., and David R. Widman. "Prior Exposure to Stress Reduces the Diversity of Exploratory Behavior of Novel Objects in the Rat (Rattus Norvegicus)." Journal of Comparative Psychology 103 (1989): 339-346. PsychARTICLES. EBSCO. Saint Xavier University, Chicago. 24 Apr. 2007. Keyword: Exploratory behavior. The primary goal of this test was to find out how stress affects animals’ exploration. The test consisted of 32 male rats. The rats were exposed to the test environment before testing began. The test for exploration was not administered until 48 hours after the stress exposure in order to limit direct transfer of activity-lowering effects of stress. There were four phases: Preexposure to the arena, stress exposure, recovery, and object exploration test. On days 1 and 2, the rats were exposed to the arena to lessen the fear from the training environment to the test environment and to replicate the procedures used by Renner (1987). On day 3, shock training was conducted. The rats were assigned to one of two conditions (stress vs. no stress) and were placed in the chambers for equal periods of time. Next, the rats were placed in their home cages undisturbed for 48 hours for the recovery period. On days 6, 7, and 8, the same procedure as phase I was conducted. The objects were novel, but did not change over the course of the final testing phase. The results showed that while there was no significant difference in general arena activity, there was a difference in object interaction measures. Animals not exposed to stress spent progressively less time with the object across the three days, while the animals exposed to stress spent approximately the same amount of time with the object across the three testing days. Also, the no shock group exhibited an increase in diverse behaviors on the first test day and decreases across the final two days. In contrast, the stressed group exhibited more diverse behavior across the last two days and a decrease on the first. This essentially means that stress may not have a powerful effect on the initiation of exploration, but it does appear to influence the investigation of a novel object.