The effects of changing the number of choices in the first response on “psychological refractoriness” were found to be partially consistent with intermittency theory but modifications may be needed to explain the results when the number of choices in the second response is increased.

Nineteen healthy volunteer subjects who regularly administered cocaine to themselves were given placebo and 10 and 25 milligrams of cocaine hydrochloride intravenously and intranasally. A dose of 100 milligrams of cocaine was administered only by the intranasal route. By this route 10 milligrams of cocaine produced no changes different from placebo, and 25 milligrams of cocaine produced physiologic changes only in systolic blood pressure. The 100-milligram dose given intranasally and all of the doses given intravenously produced significant dose-related physiologic and subjective responses.

No abstract

We examined naloxone-precipitated withdrawal as a means for rapid opiate detoxification and induction onto naltrexone. In 29 patients dependent on methadone (5 to 20 mg/day), abstinence was precipitated by an injection of naloxone. Repeated injections of naloxone were given subsequently until symptoms of abstinence were no longer induced. Successive injections induced less intense withdrawal assessed by vital signs and ratings on abstinence scales. The most rapid procedure consisted of 1.2 mg naxolone every 30 min for 3 to 6 hr, for 3 to 6 hr, followed by hourly increasing doses of naltrexone. This procedure allowed transition from opiate dependence to naltrexone maintenance (50 to 100 mg/day) within 48 hr. The results are consistent with assumptions that antagonists actively displace opiates from receptor sites.

A new technique in which elicited behavior of the freely moving rat is used to measure the poststimulation excitability cycle of the central neurons mediating that behavior has been adapted from accepted methods of neurophysiology. A continuous train of pairs of brief pulses was delivered to pain systems in the midbrain. Rate of lever pressing to achieve 3-second rests from this stimulation was measured as a function of the interval separating the pulses within pairs. Evidence for latent addition, absolute refractory period, temporal summation, and adaptation was demonstrated. Obtained relationships suggested that three sets of fibers may carry the aversive signal and that synaptic integration of pain in the brain may be related to Stevens' power law functions.