Tolerance to Behavioral Effects of Physostigmine under Interval Schedules of Positive or Negative Reinforcement.

摘要

The present experiments examined whether the rate and type of events maintaining responding help determine physostigmine's behavioral effects. The two experiments examined the acute and chronic effects of physostigmine, respectively, on lever pressing of rats under variable-interval schedules of food presentation. The third examined the chronic effects of physostigmine on lever pressing under random-interval schedules of shock avoidance. Baseline rates of responding were directly related to the scheduled rate of food delivery or shock avoidance. Acute administration of physostigmine sulfate produced monotonic decreases in overall response rate under all schedules of food presentation. Large doses suppressed the rate of food delivery. When initially administered, physostigmine salicylate also suppressed avoidance response rates and per cent shocks avoided. Tolerance developed the effects of this dose of physostigmine salicylate on pellet or shock-avoidance frequency more rapidly than to effects on overall response rate. Blood acetylcholinesterase levels showed no recovery during chronic physostigmine. Tolerance is discussed in terms of the reinforcement-loss hypothesis. Reprints. (AW)