Jhr. Maes et al., Effects of d-amphetamine on the performance of rats in an animal analogue of the A-X Continuous Performance Test, J PSYCHOPH, 15(1), 2001, pp. 23-28
Schizophrenia patients subjected to the A-X Continuous Performance Test (A-
X CPT) show cognitive deficits that are thought to reflect impaired represe
ntation and maintenance of context information, An issue deserving attentio
n is to what extent the acute amphetamine model of schizophrenia also model
s these cognitive deficits. The present experiment examined the effect of a
cute d-amphetamine (AMP) on the performance of rats in an animal analogue o
f the A-X CPT, Subjects first learned to solve an A --> X +, B --> X -, A -
-> Y- discrimination task, with A and B representing visual features; X and
Y designating auditory target stimuli; --> signifying a serial presentatio
n; and + and - referring to food reinforcement and nonreinforcement, respec
tively. Frequency of food-magazine visits was the dependent measure. After
mastering the discrimination, rats received test trials under either saline
or 0.5 mg/kg AMP (s.c.). At test, the interval between feature and target
presentation was varied; reinforcement contingencies were maintained. AMP s
ignificantly impaired performance on the A --> X +/ B --> X - discriminatio
n by increasing the response level on 13 --> X - trials. AMP did not signif
icantly affect performance on the A --> X +/ A --> Y - discrimination. Howe
ver, AMP also increased magazine responding in the absence of the presentat
ion of features and targets. A parsimonious conclusion based on these preli
minary results is that acute AMP does not affect processing of context info
rmation provided by the visual features in this procedure. It rather has a
more nonspecific response-enhancing effect, especially with respect to stim
uli associated with the delivery of food.