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Psychopharmacology (Berl). 2010 Oct;212(2):171-9. doi: 10.1007/s00213-010-1940-6. Epub 2010 Jul 14.

Transfer of the discriminative stimulus effects of Δ9-THC and nicotine from one operant response to another in rats.

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Department of Psychology, Saint Anselm College, 100 St Anselm Dr, Manchester, NH 03102, USA.



Transfer of the discriminative stimulus effects of two drugs from one operant (original-response) to a topographically different response (transfer-response) that was spared drug discrimination training was investigated.


Eight rats were trained in a counterbalanced one manipulandum (lever press and nose poke) drug discrimination procedure. Counterbalanced IP administered nicotine (0.3 mg/kg) or Δ(9)-tetrahydrocannabinol (3.0 mg/kg) functioned as discriminative stimuli. S(D) drugs occasioned sessions of food-reinforcement (variable-interval 30-s schedule); S(Δ) drugs occasioned non-reinforcement. The original-response (lever-pressing or nose-poking) was initially reinforced during 30-min S(D) drug sessions, and non-reinforced on the other alternating S(Δ)-drug sessions.


Two separate 5-min non-reinforcement tests, counterbalanced by drug order, revealed stimulus control over the original-response by both drugs, which transferred to the transfer-response. Subsequent extinction training of the transfer-response attenuated the original-response response rates with the S(D) drug conditions but had little impact on discriminative control. Discriminative control was reversed for the transfer-response but had little impact on the original-response but, again, reduced response rate.


These data demonstrate that (a) discriminative control by two distinct drug states can transfer and modulate a topographically different free-operant response and, (b) as is true for exteroceptive stimuli, drug states that function as antecedents embedded within the operant three-term contingency have differing relationships with the response and the primary reinforcer.

[Indexed for MEDLINE]

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