Stimulus generalization

TABLE 1. Results of stimulus generalization studies using racemic DOM as... 

RESPONSE This is what, propylhexedrine We have looked at propylhexedrine, and it does retain amphetamine-like activity, but it is less potent. In rats trained to discriminate 1.5 mg/kg of racemic MDMA from saline (ED5o=0.76 mg/kg), the ED50 values for stimulus generalization to MDE and N-OH MDA are 0.73 and 0.47 mg/kg, respectively (Glermon and Misenheimer, unpublished observations). 

Bufotenine has been found to be behaviorally inactive, or only weakly active, in most animal studies, although at 15 mg/kg, it did produce the head-twitch resonse in mice (43). It was also behaviorally active in experiments in which the blood-brain barrier was bypassed (78). Acylation of the polar hydroxy group of bufotenine increases its lipid solubility (65,74) and apparently enhances its ability to cross the blood-brain barrier (64). For example, O-acetylbufotenine (5-acetoxy-N,N-dimethyltryptamine 54) disrupted conditioned avoidance behavior in rodents (65) and produced tremorigenic activity similar to that elicited by DMT (37) or 5-OMeDMT (59) when administered to mice (64). In this latter study, a comparison of brain levels of bufotenine after administration of O-acetylbufotenine with those of DMT and 5-OMeDMT revealed bufotenine to be the most active of the three agents, based on brain concentration. The pivaloyl ester of bufotenine also appears to possess behavioral activity, since stimulus generalization was observed when this agent was administered to animals trained to discriminate 5-OMeDMT from saline (74). 

One of the interesting features in 3,4,5-substituted series is the dramatic enhancement of activity that occurs on modification of the 4-substituent (21). The absence of a 4-substituent (3,5-DMA Structure 5a) leads to little change in receptor affinity from that of 3,4,5-TMA (8), as measured in the rat fundus preparation (78). However, DOM-stimulus generalization to 3,5-DMA does not occur in rats (87). No human data have been reported for 3,5-DMA. 

Relative doses for stimulus generalization of psychostimulants (ED50)... 

Khat produces effects similar to those of other monoamine stimulants, (i.e., increases in mental stimulation, physical endurance, elevated mood) (Widler etal. 1994 Kalix 1994 Brenneisen etal. 1990). Stimulus generalization occurs between cathinone, amphetamine, and cocaine, suggesting similar subjective effects (Huang and Wilson 1986). Similar to other monoamine stimulants, cathinone causes dose-dependent reductions in eating and body weight (Islam et al. 1990 Zelger and Carlini 1980). Oral cathinone increases sexual arousal in rats, but does not affect erectile or ejaculatory responses (Taha et al. 1995). 

Stolerman IP (1989) Discriminative stimulus effects of nicotine in rats trained under different schedules of reinforcement. Psychopharmacology 97 131-138 Stolerman IP (1991) Measures of stimulus generalization in drug discrimination experiments, Behav Pharmacol 2 265-282... 

An example for stimulus generalization are responses of rats to stress-inducing odors. Laboratoiy rats of the Wistar strain respond to predator odors, specifically mercapto compounds in fox droppings, with stress reactions, for example avoidance behavior such as freezing and increased plasma corticosterone concentrations (Vemet-Mauiy et ah, 1984). The rats were trained to avoid water scented with a mercapto odorant that contained both a keto- and a sulfhydryl group (4-mercapto-4-methyl-2-pentanone). As the animals licked a waterspout, a mild electric shock was applied to their tongue. When different compounds were tested thereafter, the rats avoided compounds with similar... 

FIGURE 5.14 Stimulus generalization. Rats that experienced electric shocks when drinking water laced with compound 1, later also avoided compounds 5 and 6, which are structurally similar. The keto group was not necessary for the effect. 

Other examples of stimulus generalization are the alarm chemicals in salamanders (Mason and Stevens, 1981a) and behaviorally irrelevant pure odors (Braun and Marcus, 1969). 

Braun, J. J. and Marcus, J. (1969). Stimulus generalization among odorants by rats. Physiology and Behavior 4,245-248. 

Note the response of the senses to a continuous stimulus generally... 

Stimulus generalization an organism s tendency to respond to a similar stimuli with the similar response. If a salivation response had been conditioned to a tone of ip00 CPS, an 800 CPS tone will elicit a similar response. Or, in the second example, generalization will have occurred if any hospital, or even meeting a physician, comes to elicit nausea from the patient. 

Note that for a learning theorist, transference is just another instance of stimulus generalization... 

A) Anesthetic potency is quantitated by the minimum alveolar concentration (MAC) that causes 50% of subjects to fail to respond to a standardized painful stimulus General anesthesia is associated with increased blood pressure and total peripheral resistance... 

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