You are here:
PFIESTERIA PISCICIDA-INDUCED COGNITIVE EFFECTS: VISUAL SIGNAL DETECTION PERFORMANCE AND REVERSAL.
Citation:
Rezvani, A H., P J. Bushnell, H. Glasgow, N. DeamerMelia, J. Burkholder, AND E. D. Levin. PFIESTERIA PISCICIDA-INDUCED COGNITIVE EFFECTS: VISUAL SIGNAL DETECTION PERFORMANCE AND REVERSAL. Presented at Society of Toxicology, San Francisco, CA, 3/25-29/2001.
Description:
Humans exposed to Pfiesteria piscicida report cognitive impairment. In a rat model, we showed that exposure to Pfiesteria impaired learning a new task, but not performance of previously-learned behavior. In this study, we characterized the behavioral effects of Pfiesteria in rats using a visual signal detection task designed to assess attention, and then reversed the response contingencies of the task to assess learning. Female Sprague-Dawley rats (N = 24) were trained to earn food by pressing one lever after a visual signal and a second lever if no signal was given. Signal intensities ranged from barely to clearly detectable. The proportion of correct responses increased with signal intensity (positive slope). After training, the rats were injected (sc) with water containing 0; 35,600 or 106,800 cells of Pfiesteria per kg of rat body weight. Signal detection testing continued for 2 weeks after treatment, after which the signal-response contingencies were reversed. After the discrimination was re-estab-lished, the rats received the same dose of Pfiesteria again, were tested for two weeks, and a second reversal was imposed. Pfiesteria exposure did not affect performance of the task prior to reversal. However, Pfiesteria altered the reversal-induced shift in responding: over 12 sessions of reversal training, the slope of the function relating accuracy to signal intensity changed from negative toward positive more slowly in the high-dose group than in the controls. This finding is consistent with previous studies in which Pfiesteria-treated rats learned new responses more slowly than controls, but performed previously-acquired response patterns normally. (Supported by the U.S. EPA, NOAA, Duke University and the State of North Carolina. This abstract may not reflect EPA policy.)