Loss of the Kamin blocking effect in acute but not chronic schizophrenics.
Differences between research diagnostic criteria (RDC)-diagnosed acute and chronic schizophrenics and normal controls were studied using a Kamin blocking procedure. Blocking is an established animal learning procedure, thought by some researchers to reflect selective attention; decreased blocking indicates increased processing of irrelevant stimuli. It was predicted that this pattern would be obtained in acute schizophrenics, tested soon after admission, for two reasons: (1) evidence from previous clinical studies indicates that acute schizophrenics are more aware of nonsalient aspects of their environment than controls; and (2) blocking is disrupted in animals in a hyperdopaminergic state and restored by neuroleptic medication. This was the case: acute, but not chronic, schizophrenics showed disrupted blocking. This disruption was especially clear in those acute schizophrenics tested within 2 weeks of hospital admission. By the second test session (in a cross-over design), there was some evidence of normalization in performance in the acute schizophrenics. These findings are considered with regard to the dopamine hypothesis of schizophrenia.
Jones
S H
SH
Department of Psychology, University of London, England.
Gray
J A
JA
Hemsley
D R
DR
D000208:Acute Disease; D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001245:Association Learning / Q000187:drug effects / Q000502:physiology*; D001288:Attention / Q000187:drug effects / Q000502:physiology*; D002908:Chronic Disease; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects / Q000503:physiopathology*; D011337:Probability Learning; D011340:Problem Solving / Q000187:drug effects / Q000502:physiology; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D012559:Schizophrenia / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D012565:Schizophrenic Psychology
D014150:Antipsychotic Agents; D011954:Receptors, Dopamine; D004298:Dopamine