An investigation of the effects of benzodiazepine receptor ligands and of scopolamine on conceptual priming

Abstract

Scopolamine and lorazepam both produce anterograde impairments of explicit memory but only lorazepam impairs implicit memory as assessed by perceptual priming tasks. The main aim of the two experiments reported in this article was to determine the effects of these drugs on conceptual priming. Experiment 1 compared the effects of lorazepam (1,2 mg PO) with scopolamine (0.3,0.6 mg SC) and placebo in a study with 60 healthy volunteers. Experiment 2 compared the separate and combined effects of lorazepam (2 mg PO) and flumazenil (2 mg IV) with placebo in a study with 48 healthy volunteers. We found that conceptual priming in category generation tasks was intact following lorazepam in both studies. This preservation of conceptual priming contrasted with lorazepam-induced impairments on explicit memory tasks. In conjunction with previous findings, these results are interpreted as providing further support for the notion that conceptual and perceptual priming are subserved by distinct memory systems, one based on the operations of semantic memory, the other possibly based on a perceptual representation system. That lorazepam impairs perceptual but not conceptual priming suggests that the neurochemical substrates of the two kinds of priming are distinct.

Functional MRI detection of pharmacologically induced memory impairment

“…Scopolamine is a potent antagonist of the muscarinic acetylcholine receptor and is thought to impair memory by blocking cholinergic transmission (10). Considerable work has been done to examine the effects of these medications on cellular physiology and animal behavior (11) and on human memory performance (12)(13)(14)(15). Both benzodiazepines and scopolamine have been shown to selectively impair the ability to encode new information, with relative sparing of semantic and procedural memory (13,16,17).…”

Effects of a benzodiazepine on free recall of semantically related words

“…The mid-list related words are already bound together in the semantic memory system and activation of semantic networks is considered to be an automatic process, as revealed for instance in studies of conceptual priming (see Smith et al, 1994), and not altered by BDZ (Bishop and Curran, 1998). But, even these related words were not fully recorded compared to the placebo condition.…”

The Nature of Recollection and Familiarity: A Review of 30 Years of Research

“…For example, like familiarity, conceptual implicit memory, as measured on tasks like the exemplar generation, increases with deep compared to shallow encoding (Hamann, 1990), picture naming compared to word reading (Vaidya & Gabrieli, 1996), word generation compared to word reading (Srinivas & Roediger, 1990), long compared to short study durations (Challis & Sidhu, 1993), and full compared to divided attention (e.g., Mulligan & Stone, 1999;Light, Prull, & Kennison, 2000). Moreover, like familiarity, conceptual implicit memory is not disrupted by lorazapam (Bishop & Curran, 1998) or by frontal lobe lesions (Gershberg, 1997). Note that although familiarity often appears to be preserved in aging, conceptual implicit memory results are mixed, indicating deficits in some cases and preserved performance in others (see Light, Prull, La Voie, & Healy, 2000).…”