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Behav Brain Res. 2008 May 16;189(1):170-9. doi: 10.1016/j.bbr.2007.12.032. Epub 2008 Jan 20.

A sensitizing regimen of amphetamine that disrupts attentional set-shifting does not disrupt working or long-term memory.

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Section of Biopsychology, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8.


Exposure to an intermittent, escalating dose of amphetamine induces a sensitized state that, both behaviourally and neurochemically, mirrors several features linked to the positive symptoms of schizophrenia. Increasingly it is being realized that cognitive deficits are a core component of schizophrenia; therefore we sought to assess the effects of inducing an amphetamine-sensitized state on memory (working and long-term) and cognitive flexibility, two cognitive domains impaired in schizophrenia. Rats were exposed to a sensitizing regimen of amphetamine (1-5 mg/kg; three times per week for 5 weeks; escalating at 1mg/kg per week) or saline. In experiment 1, animals were tested on an operant delayed non-match to position task (working memory). Experiment 2 used a standard fixed-platform location water maze task (long-term memory), while experiment 3 used a variable-platform location water maze task (long-term memory and working memory). Amphetamine-sensitized animals were not impaired on any of these tasks. In experiment 4, animals were assessed on a strategy selection task in which they were first required to learn to locate a food reward using a particular learning strategy (place or response) then to learn to shift to an alternate learning strategy (response or place). Amphetamine-sensitized animals were not impaired on this task. In the final experiment animals were found to be impaired in performance of the extra-dimensional shift component of an attentional set-shifting task. These results suggest that while amphetamine sensitization does not produce memory impairments similar to those seen in schizophrenia, it does produce strong impairments in set-shifting, suggesting changes in prefrontal function similar to those seen in schizophrenia.

[Indexed for MEDLINE]

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