Javier Vila

Retroactive interference after discrimination reversal decreases following temporal and physical context changes in human subjects.

One experiment was conducted to test the additive effects of physical context changes and the passage of time on a retroactive interference task in human subjects. Participants learned a discrimination in a symbolic matching to sample situation within a specific context. The discrimination was subsequently reversed. The context in which the reversal occurred was combined factorially with the passage of time before the test. All testing was conducted in the context in which the original discrimination was acquired. Participants had received the discrimination reversal in either a context different from that in which the original discrimination was acquired, or in the same context. Half of each of the groups mentioned above received testing immediately after reversal training and the other half received testing 48 h later. Both manipulations, changing the context after the reversal and the passage of time following the reversal, led to a recovery of the original discrimination performance. Participants that received both a context change and retention interval showed the largest recovery.

Tolerance to Pentabarbitaland Sensitation to Amphetamine Due to Assoctative Processes

It has been suggested that drug tolerance is arnenable to an analysis based on Par’lovian conditioning processes. Conditioned tolerance has been demonstrated with several dru gr. ami the role of contextttal stimuli in the establishment of conditioned tolerance has been discussed extensively.The present stndy demonstrated conditioned tolerance as a function of the type of contextual stirnuli; it also assessed the effects of amphetamine on subjects tolerant to pentobarbital. In Experitnent 1, rats received 20 pentobarbital injectons in the presence of dsstmncttve contex tttal stitnult Then, they were given two tolerance tests of the sedative effects of pentobarbital (30 and 50 ntg/kg). These tests were condztcted itt the presence of contextual stimuli associated with drug injections and satine inlections. Rats tested under dr-ug-associated contextual sti,nuli showed tolerance, but they were not tolerant when tested under saline-associated contextual stitnuli. Itt Experintent 2, rats were trained to drinh evaporated ntilk. Then, they were given seven pentobarbital injections itt a dis¬tintive environntent and seven satine injections itt a different environ,nent. Titen, they were given three tnilk consuntption tests. During tite first test tite rats were allowed to drink without tite effects of drugs; during the second test sessions tite rats were injected tite 4 mg/hg of amphetamine and were tested under the presence of stimuli associated witit pentobarbital injections; the iart was conducted under the effects of tite sorne dore of a,npitetamine ?mt itt tite presence of stimuli.

Efectos de la anfetamina sobre un estimulo inhibidor de la tolerancia condicionada al pentobarbital

Los efectos de dos ambientes explicitamente pareados y no pareados con la administraci6n de pentobarbital, fueron evaluados sobre la actividad producida en ratas por inyecciones de anfetamina. La actividad producida por el estimulante fue menor en Ia presencia de los estimulos no pareados al pentobarbital que ante los pareados con la droga. Los resultados son coherentes con el modelo de tolerancia condicionada de Siegel.