13 research outputs found
Five to nine year follow-up results of arthroscopic synovectomy of the knee in rheumatoid patients
Five to nine year follow-up results of arthroscopic synovectomy of the knee in rheumatoid patients
The fate of motoneurons in the spinal cord after peripheral nerve repair: a quantitative study using the neural tracer horseradish peroxidase
Identification and control of pathogenic fungi in neotropical valued orchids (Laelia spp.)
Effects of nicotine and amphetamine on latent inhibition in human subjects
Latent inhibition (LI) is a phenomenon in which repeated non-reinforced exposure to a stimulus retards subsequent conditioning to that stimulus; it reflects a process whereby irrelevant stimuli become ignored, and has been the subject of study concerning attentional abnormalities in schizophrenia. Low doses of the indirect dopamine (DA) agonists, amphetamine and nicotine, disrupt LI in the rat. These drugs are believed to disrupt LI via DA release in the nucleus accumbens; LI in amphetamine- and nicotine-treated rats is reinstated by administration of the DA antagonist haloperidol. In human subjects, low doses of amphetamine abolish LI, and more recently haloperidol has been shown to potentiate LI. The present study investigated the effects of nicotine on LI in human subjects, and also attempted to replicate the abolition of LI by amphetamine. Nicotine failed to affect LI when administered either subcutaneously or by cigarette smoking. LI was, however, abolished in a group of subjects given 5 mg amphetamine 90 min before testing. Supplementary analyses of the data pooled from all three experiments showed that, in contrast to an earlier report, LI was no weaker in smokers than in nonsmokers