Using event-related potentials to examine pharmacological effects on intervening cognitive functions in rats

Assessing toxicological and pharmacological effects on cognition using sensory evoked potentials and purposive behaviors as endpoints may limit testing to afferent activity and to populations able to follow directions. The present study uses a non-invasive method that does not require training or response to instruction to measure the brain's longer latency intervening cognitive response to stimulation. The averaged electrophysiological responses of 8 rat brains, Event-Related Potentials (ERPs), were recorded in 3 spatial dimensions and time while they experienced two time varying modes of auditory stimulation and anesthesia. Results show that both modes of stimulation elicited ERPs with similar magnitudes and latencies but with different electrophysiological patterns at each level of anesthesia. These results suggest anesthesia may not effect the brain's ability to detect and represent an input, but rather its ability to inhibit that input's decay over time so it can consolidate into a form able to benefit future processing. Anesthesia effected these events during the two modes of stimulation differently over time, suggesting this method of stimulation and recording may provide dependent variables sensitive to the brain's response at different dose levels.