Short-Term Memory Resists the Depressant Effect of the Nonimmobilizer 1-2-Dichlorohexafluorocyclobutane (2N) More than Long-Term Memory

Abstract

The nonimmobilizer 1,2-dichlorohexafluorocyclobutane (2N, also termed F6) does not suppress movement to noxious stimuli but does suppress learning of fear-potentiated startle. The mechanism whereby 2N suppresses this learning is unknown. Herein, we report the effect of 2N on suppression of two other forms of learning, fear conditioning to context and to tone. Because 2N does not cause sedation, we could study the effect of 2N on short-term memory (memory for fear conditioning measured during or immediately after training) as well as on long-term memory (measured 24 h after training). The EC50 for suppression of long-term memory (the concentration decreasing memory by 50%) of fear conditioning to context was 2.00% ± 0.01% (mean ± sem), and for fear conditioning to tone was 3.45% ± 0.26%, (P 50