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Abstract:
Normal participants (n=5) having no experience with
antipsychotic drugs and medicated participants (n=5) having
clinical experience with chronic low doses of haloperidol (3-10
mg/day for 2-4 months) in the treatment of neuroses were evaluated
for the effects of inter-trial interval (ITI) feedback on a
discrete-trials peak-interval timing procedure. Feedback was
presented during the ITI in the form of a histogram showing the
distribution of responses made on the previous trial plotted on a
relative time scale. As feedback concerning the accuracy and
precision of duration reproduction (e.g, 7-s and 14-s) becomes more
remote in time, reproduced intervals gradually lengthen in
duration. This rightward horizontal shift in peak time increases as
a function of the probability of feedback and is enhanced by
chronic treatment with haloperidol in a manner proportional to
signal duration. Our interval timing data suggest a gradual change
in the underlying memory representation of the signal duration as a
function of the remoteness of ITI feedback that is dependent upon
both changes in working memory and the speed of the internal clock
used to time durations in the seconds-to-minutes range. In
addition, dopamine agonists can reverse these haloperidol-induced
deficits in a manner consistent with the involvement of D1
receptors in the prefrontal cortex.
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