Summary
The effect of physostigmine on EEG activity and conditioning was studied in rats. Theta activity develops in the hippocampus of curarized or freely moving unanesthetized animals 3–7 min after i.p. injection of 1 mg/kg physostigmine salicylate, attains maximum after 10 min and disappears after 30–60 min. Gradual impairment of learning corresponds to the development of theta waves. One-trial acquisition of a passive avoidance reaction (avoiding a compartment with electrifiable floor) is completely suppressed 10 min after application of 1.0 or 0.5 mg/kg physostigmine and to a lesser extent even after 0.2 mg/kg physostigmine. No retention of this reaction was found 24 h after onetrial learning when physostigmine (0.5 mg/kg) was applied 8 min before the retention test. On the contrary the same physostigmine dose does not impair the retention of an overtrained (four times) passive avoidance reaction. Also retention of an overlearned active avoidance reaction (running to the safe part of the apparatus is not affected by 0.5 mg/kg physostigmine and only partly impaired by 1 mg/kg physostigmine. The functional significance of the hippocampal theta activity is discussed.
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Bureš, J., Bohdanecký, Z. & Weiss, T. Physostigmine induced hippocampal theta activity and learning in rats. Psychopharmacologia 3, 254–263 (1962). https://doi.org/10.1007/BF00411366
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DOI: https://doi.org/10.1007/BF00411366