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A J Beauchamp

Publications and source records attributed to A J Beauchamp.

4 recordsLinked to original sources
PubMed1991

Associative processes in differentially reared rhesus monkeys (Macaca mulatta): blocking.

Nine isolate and 6 socially reared adult rhesus monkeys were examined in a standard blocking procedure. A tone was paired with a startle stimulus (US) during Phase 1. A tone-light compound CS was paired with a US during Phase 2. In Phase 3, the light was presented alone to test for blocking. Results showed that learning about the light was blocked in social controls, but not in isolates. These data suggest isolates processed information atypically, in that they developed an association to a redundant cue. A second group of isolates (n = 3) underwent the identical procedures. However, conditioned reactions to the tone were extinguished before testing. Test responding was significantly reduced in this group, that is, blocking was obtained. These data suggest the within-compound association developed during Phase 2 mediated the isolate blocking deficit. Together, these findings imply long-term intellectual consequences of early social impoverishment. Such deficits may be mediated by alterations in central dopamine systems.

Animals↗
PubMed1990

Long-term effects of early social isolation in Macaca mulatta: changes in dopamine receptor function following apomorphine challenge.

The hypothesis that early social isolation results in long-term alterations in dopamine receptor sensitivity was tested using older adult rhesus monkeys. Isolated and control monkeys were challenged with apomorphine (0.1 and 0.3 mg/kg), and the drug effects on spontaneous blink rate, stereotyped behavior, and self-injurious behavior were quantified using observational measures. Monoamine metabolites were quantified from cisternal CSF by HPLC-EC, prior to pharmacological challenge. Isolated and control monkeys did not differ in CSF concentrations of HVA, 5-HIAA, or MHPG. At the higher dose, apomorphine significantly increased the rate of blinking, the occurrence of whole-body stereotypies, and the intensity of stereotyped behavior (as measured by observer ratings) in isolated monkeys. The frequency of occurrence of self-injurious behavior was too low to allow for meaningful comparisons. These significant differences in response to apomorphine challenge support the hypothesis that long-term or permanent alterations in dopamine receptor sensitivity, as assessed by drug challenge, are a consequence of early social deprivation.

Animals↗
PubMed1988

Associative processes in differentially reared monkeys (Macaca mulatta): sensory preconditioning.

Past research has indicated that with regard to performance in formal learning test situations, early socially isolated rhesus monkeys display atypical reactions to noxious stimuli, deficits in response inhibition, slower adaptation to reinforcement contingencies, and lower performance on oddity tasks. Twelve adult rhesus monkeys (Macaca mulatta), 6 who had been reared in total isolation for the first 9 months of life 19 years earlier, and 6 socially reared, were tested in a sensory preconditioning paradigm. In phase I, two neutral stimuli (S1-S2) were paired in contiguous fashion; in phase II the S2 stimulus was conditioned to elicit a startle response; and in phase III the S1 stimulus was presented to assess whether an association between the two stimuli had been formed during the initial phase. Instead of a deficit, isolate subjects showed significantly more response transfer during phase III as compared to the controls. The superior performance displayed by isolates is viewed as resulting from a slower habituation to S1-S2 stimuli during preconditioning along with the perseveration of responses during testing. These findings support the notion that atypical cognitive processing across a lifespan is a consequence of early social impoverishment.

Animals↗