Fixed-Ratio and Time-Out Changes on Behavior Maintained by Cocaine or Methohexital in Rhesus Monkeys: 1. Comparison of Reinforcing Strength

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28 Scopus citations

Abstract

Rhesus monkeys (Macaca mulatta) were exposed to fixed-ratio (FR) time-out (TO) schedules of cocaine or methohexital delivery under conditions in which either the FR or the TO value was increased periodically. Three doses of each drug were evaluated. Rates of responding increased and then decreased as a function of both FR and TO values and as a function of dose per injection. The FR and TO values that maintained maximum rates of responding increased as the dose per injection increased, and the dose per injection that maintained maximum rates of responding increased as the FR or TO values increased. Methohexital maintained lower maximum rates of responding than did cocaine with larger FR values, and these lower rates were not accounted for by drug accumulation, as demonstrated by increasing the TO values. This suggests that methohexital is less able than cocaine to maintain responding in the presence of high ratio values and is therefore a less effective reinforcer than is cocaine.

Original languageEnglish (US)
Pages (from-to)142-153
Number of pages12
JournalExperimental and Clinical Psychopharmacology
Volume1
Issue number1-4
DOIs
StatePublished - Oct 1993
Externally publishedYes

ASJC Scopus subject areas

  • Pharmacology
  • Psychiatry and Mental health
  • Pharmacology (medical)

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