Primacy and recency effects in rhesus monkeys (Macaca mulatta) using a serial probe recognition task I. Effects of diazepam

Abstract

In this study, we evaluated the effects of diazepam (0.2, 0.8, 1.6 and 3.2 mg/kg; IM) on the primacy and recency memory effects in four rhesus monkeys trained on a six-item serial probe recognition (SPR) task. Only the highest dose of diazepam (3.2 mg/kg) consistently affected the shape of the monkeys' serial position curves. Accuracy on the probe trials was disrupted for list items which occurred in the middle portion and recency memory component of the serial position curve, without affecting the primacy component. Diazepam, however, also produced several nonspecific effects on SPR performance. Both the 1.6 and 3.2 mg/kg diazepam doses disrupted accuracy on the non-matching probe trials, and the 3.2 mg/kg dose caused an increase in response latencies which were unrelated to any one component of the serial position curve. This is the first demonstration in nonhuman primates showing that the primacy and recency memory effects can be differentiated on the basis of diazepam dose.

Treatment with the Noradrenergic Alpha-2 Agonist Clonidine, But Not Diazepam, Improves Spatial Working Memory in Normal Young Rhesus Monkeys

“…Diazepam (1.0 mg/kg) impaired performance and responding on a delayedmatch-to-sample task in rhesus monkeys (Hudzik and Wenger 1993). In monkeys, 3.2 mg/kg diazepam has impaired a serial probe recognition task (Castro 1995) but only 10 mg/kg diazepam impaired a delayed alternation task (Bradley and Nicholson 1984), suggesting that spatial working memory tasks such as that in the current study need higher doses for impairment to be seen. As both clonidine and diazepam have effects such as producing sedation (Wayner et al 1989), relieving natural and drug-induced anxiety anxiety (Charney et al 1983;Dawson et al 1995), and reducing LC firing, the very different cognitive profiles produced by these compounds suggests that these effects do not underlie the cognitive improvement seen with clonidine treatment.…”

An Experimental Analysis of Memory Processing

“…These SPFs show primacy and recency effects and were the first evidence of both these characteristic signatures of human list memory. These signatures of serial list memory have been replicated many times since with a variety of species including: apes (Buchanan, Gill, & Braggio, 1981), rhesus monkeys (Castro, 1995(Castro, , 1997Castro & Larsen, 1992;Sands & Wright 1980a, b;Wright, Santiago, & Sands, 1984;Wright, Santiago, Sands, Kendrick, & Cook, 1985), squirrel monkeys (Roberts & Kraemer, 1981), capuchin monkeys (Wright, 1999b), rats (Bolhuis & van Kampen, 1988;Harper, McLean, & Dalrymple-Alford, 1993;Kesner & Novak, 1982;Reed, Croft, & Yeomans, 1996), and pigeons Wright et al, 1985). Thus, a variety of animals show at least some of the important characteristics of list memory as humans do.…”

Primacy Versus Recency in a Quantitative Model: Activity Is the Critical Distinction

“…Conversely, damage to the medial temporal lobes, which includes the hippocampal formation and surrounding cortices, severely impairs LTM formation (i.e., anterograde amnesia) and also disrupts the primacy effect (Milner 1970). Importantly, disruption of one system has little effect on the performance of the other (Shallice and Vallar 1990;Castro 1995Castro , 1997, indicating that the systems are distinct and largely independent, and that the formation of LTM does not require prior processing in STM.…”