Learn More
The enhanced locomotor and stereotypic responses of the rat to repeated amphetamine (AMPH) administration are considered to be an animal model of positive schizophrenic symptoms. In contrast, behaviors observed during withdrawal from repeated AMPH are believed to model depression or anxiety. In the present study, the authors tested whether AMPH withdrawal(More)
Latent inhibition (LI) is a behavioral phenomenon whereby repeated exposure to a non-reinforced stimulus retards subsequent conditioning to that stimulus. Deficits in LI may reflect an inability to ignore irrelevant stimuli and are studied as a model of the cognitive/attentional abnormalities found in schizophrenia. We recently determined that pretreatment(More)
Two experiments were carried out to evaluate the effects of amphetamine withdrawal in rats on spatial learning in the water maze. A schedule of repeated d-amphetamine administration lasting for 6 days, with three injections per day (1-5 mg/kg, i.p.), was employed. Experiment 1 demonstrated that amphetamine withdrawal did not impair the acquisition of the(More)
Latent inhibition, the process whereby pre-exposure to a conditioned stimulus without consequence impairs subsequent learning of an association between the conditioned stimulus and an unconditioned stimulus, is reportedly disrupted in both amphetamine-treated rats and in acute schizophrenics. This has led to the suggestion that disruptions in latent(More)
Administration of amphetamine (AMPH) can induce symptoms of psychosis in humans and locomotor sensitization in rats; in contrast, withdrawal from a period of AMPH intake is most often associated with symptoms of human endogenous depression. The aim of this study was to determine whether AMPH withdrawal produces a depressive-like state in rats. The present(More)
The use of hydromorphone and clonidine, delivered intrathecally by an implanted infusion pump, is described in a patient with intractable cancer pain. The patient was a 48-year-old woman with uterine cervical cancer-related pain that was poorly responsive to conventional oral narcotics. Hydromorphone was used because of the patient's history of morphine(More)
Rationale: Chronic intermittent administration of amphetamine and cocaine can precipitate psychotic episodes in humans and produce persistent behavioral changes (i.e. increased locomotion, stereotypy) in the rat. The psychostimulant sensitization model of psychosis holds that the repeated administration of drugs such as amphetamine and cocaine induces(More)
Psychomotor stimulants can induce psychotic states in humans that closely resemble those observed in patients with idiopathic schizophrenia. Attentional and sensorimotor gating impairments are observed in schizophrenic patients using the latent inhibition (LI) and prepulse inhibition (PPI) behavioral assays, respectively. Our previous studies demonstrated(More)
Dopamine transmission within the nucleus accumbens has been implicated as a neurochemical substrate of associative learning processes. It has been suggested that the acquisition of classically conditioned fear to a specific environment, or context, differs fundamentally from the development of conditioned fear to a discrete stimulus, such as a light or a(More)
The conditioned freezing response in rats has been much used both by psychologists and neuroscientists to investigate the behavioural effects of brain lesions and of changes in motivational state. The primary advantage of the freezing response is that it can be used without motivational manipulations such as food or water deprivation. Previously, freezing(More)