Enhancement of latent inhibition in patients with chronic schizophrenia.
OBJECTIVE
Latent inhibition (LI) refers to the retarding effects of inconsequential stimulus preexposure on subsequent conditioning to that stimulus, and reflects the organism's capacity to ignore irrelevant stimuli. LI is disrupted in schizophrenia patients, due to faster learning of the association between the conditioned stimulus (CS) and an unconditioned stimulus (US). It was recently proposed that LI has an additional pole of abnormality indicated by LI persistence.


METHODS
Two experiments were performed to test this hypothesis. Both experiments applied a new within-subject, visual recognition LI procedure in which the association between a cue (CS) and the target (US) is acquired. In Exp 1 the task was applied to healthy volunteers (n=21). In Exp 2 chronic schizophrenia patients (n=19) were compared to control subjects (n=20).


RESULTS
In Exp 1 the subjects showed LI in the initial trials of cue-target pairings, and an attenuation of the phenomenon at later trials. In Exp 2 control subjects showed a pattern of response comparable to the subjects of Exp 1, while the patients showed LI only on the later trials of the task.


CONCLUSIONS
This result suggests that patients with chronic schizophrenia showed LI persistence. The possible advantages of the new LI paradigm are discussed.
Gal
Gilad
G
School of Behavioral Sciences, The Academic College of Tel-Aviv-Yaffo, Tel-Aviv, Israel.
Barnea
Yael
Y
Biran
Lior
L
Mendlovic
Shlomo
S
Gedi
Tamir
T
Halavy
Michal
M
Feldon
Joram
J
Fennig
Shmuel
S
Levkovitz
Yechiel
Y
D000328:Adult; D000704:Analysis of Variance; D001245:Association Learning / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D016022:Case-Control Studies; D002908:Chronic Disease; D003214:Conditioning, Classical / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D005364:Field Dependence-Independence; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D012016:Reference Values; D012559:Schizophrenia / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D055815:Young Adult