Comparison of stimulants and hallucinogens on shuttle avoidance in rats

Influencing of Spatial Memory in Rats by DSP-4 and Mescaline

Behavioural effects of two experimental neurotoxins, mescaline and DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine), on retention of spatial orientation were studied in the T - maze. The stereotaxic administration of both neurotoxins into the selected brain structures was chosen to reveal this effect. The intensity and time course of the neurotoxic effect were dependent on the brain area administered. Nevertheless, the lengthening of the latencies in reaching the goal was generally more marked after mescaline in comparison with DSP-4.

MDA effects on classical appetitive conditioning of the rabbit jaw movement response

We determined MDA's effects on: (a) conditioning of the rabbit's jaw movement response (JMR) (Experiment 1); and (b) nonassociative JMRs and unconditioned JMRs (Experiment 2). Rabbits were administered 3,4-methylenedioxyamphetamine (MDA; 0, 2, or 4 mg/kg) into the marginal ear vein 20-30 min prior to each of 10 daily sessions. Experiment 1 involved 30 daily training trials of 15 tone- and 15 light-conditioned stimuli (CSs) paired with a 1-ml squirt of water, as the unconditioned stimulus (UCS), injected into the oral cavity. The study revealed that MDA impaired conditioned response (CR) acquisition to tone-CS trials while augmenting CRs to light-CSs. In Experiment 2, the animals received 15 tone- and 15 light CS-alone and 30 UCS-alone presentations daily. The study revealed that MDA produced a modest increase in nonassociative responses over days that interacted with CS modality. Accordingly, these nonassociative effects could not account for MDA's influences on CR acquisition. Moreover, MDA's decrementing and enhancing of CRs to tone- and light-CSs, respectively, appears to be attributable to the drug's enhancing or decrementing tone- and light-CS intensity.

Effects of MDA on classical conditioning of the rabbit nictitating membrane response

In Experiment 1, classical conditioning of the rabbit's nictitating membrane response (NMR) was accomplished by pairing tone and light conditioned stimuli (CSs) with a shock unconditioned stimulus (UCS). MDA impaired the acquisition of conditioned responses (CR) to a tone-CS, while significantly enhancing CR acquisition to a light-CS. Experiment 2, employing explicitly unpaired CS, UCS training, revealed no reliable effects of MDA upon nonassociative processes. Subsequent efforts determined if MDA's CR acquisition effects resulted from alterations in sensory processing of the CS, UCS, and/or UCR motor functioning. Specifically, it was determined that MDA: (a) increased the tone-CS intensity threshold for eliciting CRs (Experiment 3); (b) attenuated the tone-induced reflex modification of the unconditioned NMR (Experiment 4); and (c) enhanced UCR frequency at varying UCS intensities (Experiment 5). It was concluded that MDA's effect upon CR acquisition reflected the drug's effect upon CS and UCS/UCR processing and thereby altered the ability of these components of conditioning to enter into associative learning.