The Efects of Dose and Time of Administration of Pentylenetetrazol on a Visual Discrimination Task
The problem: The purpose of this study was to determine if a given range of pentylenetetrazol doses differentially affected retention of a visual discrimination task in the rat as a function of time of administration after training was completed. Procedure: Using food reinforcement, 36 rats were trained to perform a brightness discrimination in a Y-maze until they reached a criterion of nine out of ten correct responses. They were then injected with either 10.0, 12.5 or 15.0 mg/kg pentylenetetrazol at intervals of either 0,5 or 15 minutes after completion of training. Twenty-four hours later a test of retention was given. This consisted of counting the number of errors made by each rat in 15 additional trials run under identical conditions in the Y-maze as on the previous day. Using the number of errors made by each rat as the dependent variable, the data was analyzed by a two-factor completely randomized analysis of variance. Findings: The results of this study indicated that the number of errors wsde by the rats was dependent upon the dosage of drug and the time intervals after training at which it was administered. Overall, pentylenetetrazol was shown to facilitate retention of the brightness discrimination task. In addition, it was found that the effectiveness of the drug in facilitating retention decreased linearly with increasing delay of injection. Conclusion: It was concluded that although pentylenetetrazol in the range of doses investigated facilitates retention for a learned task, there exists a critical period after training has been completed after which injections of the drug lose their utility in facilitating retention. Within this critical period, there is a linear decrement in the drug's effectiveness with increasing delay of injection after completion of training. Recommendations: It is recommended that procedural guidelines and a system for the standardization of variables be formulated and adhered to when conducting experiments of this sort. This would most likely serve to eliminate various discrepancies, both major and minor, now found in the results of these experiments.