Retrograde Amnesic Effect of Audiogenic Seizure on the Reversal of a Maze Response

Two groups of mice were given acquisition trials followed by reversal training in a water maze. Experimental Ss were convulsed with a single audiogenic seizure immediately following the last reversal trial. 50% of the latter Ss showed retention of the initial response, but retrograde amnesia for the reversed maze habit. Control Ss all showed retention of the reversed response. The data tend to support the conclusion that audiogenic seizure is partially effective in disrupting the consolidation of the memory trace.

Reduction of retroactive effects of interpolated maze training in hypothermic mice

In two experiments the retroactive effect of maze training interpolated between an initial acquisition phase and a testing phase was determined in mice. In the first experiment a retroactive inhibitory effect was demonstrated in animals given interpolated training for the reversal of an acquired maze response. In the second experiment the interpolated activity was either habit reversal, overtraining, or practice swimming. When the interpolated activity was initiated in the presence of hypothermia habit reversal did not occur, no retroactive inhibition was shown, and facilitation of performance from overtraining or practice swimming was negated. The data support the hypothesis that hypothermia maintained during maze training reduces the negative (retroactive inhibition) as well as positive (facilitation) effects that such training has upon the performance of a previously acquired maze habit. maze learning in mice; maze acquisition during hypothermia; hypothermia and interpolated maze training; animal behavior; learning in hypothermic animals; hypothermia and maze acquisition Submitted on January 16, 1964

Body temperature as a determinant in maze acquisition by mice

The effect of increasing the number of training trials and spacing training sessions on acquisition of a simple water-escape response was investigated in mice during a moderate reduction in colonic temperature. Hypothermia was produced by treatment of the animals with 50 mg/kg 2,4-dichlorophenoxyacetic acid (2,4-D) (i.p.) and a 30-min exposure to cold air (2.0 ± 0.5 C). Control animals received 2,4-D and were maintained in a thermoneutral environment (32.0 ± 1 C) to preclude loss of body temperature. Following these procedures, all animals were given four training trials spaced at 15-min intervals. Two days later, the procedures were repeated and four more training trials were given. Acquisition of the escape response occurred within five training trials for animals in which colonic temperatures were reduced 2.6–4.8 C during training. Control animals demonstrated acquisition of the maze habit within two training trials. These data suggest that extending the training trials over an expanded period of time was effective in allowing for acquisition in hypothermic mice and that a reduction in body temperature affects acquisition rate. animal behavior; learning in hypothermic animals; hypothermia and maze acquisition Submitted on March 6, 1963

Maze acquisition and retention in hypothermic mice

Three experiments were carried out to demonstrate the relation between learning and retention as affected by a reduction of colonic temperature in mice. Animals rendered hypothermic (T Ε = 3.3 C, 3.4 C) by treatment with 2,4-dichlorophenoxyacetic acid and exposure to cold air (2.0±0.5 C) did not acquire a simple escape response from a water maze within ten training trials. Saline-treated control animals demonstrated acquisition within four trials under similar conditions. Retention of the maze habit was a function of acquisition during training. Retention scores, as well as performance measures, were not affected by a comparable reduction in colonic temperature. Note: (With the Technical Assistance of J. R. Blumstein and D. Pennec) Submitted on January 22, 1962