Biomedical subjects

Julia Fisher

Publications and source records attributed to Julia Fisher.

4 recordsLinked to original sources

PubMed2006

Midazolam amnesia and short-term/working memory processes.

We examined whether midazolam impairs short-term/working memory processes. We hypothesize that prior dissociations in midazolam's effects on short-term/working memory tasks and episodic memory tasks arise because midazolam has a larger effect on episodic memory processes than on short-term/working memory processes. To examine these issues, .03 mg/kg of participant's bodyweight of midazolam was administered in a double-blind placebo-controlled within-participant design. Performance on the digit span and category generation/recall tasks was examined. The results of Experiment 1 demonstrated that: (1) midazolam impaired performance on the digit span task; (2) midazolam did not impair performance on the category generation task; (3) midazolam impaired performance on the category recall task; and (4) midazolam's effect on category recall was four times as large as its effect on digit span. The results of Experiment 2 demonstrated that midazolam did not impair digit span performance when the digit span task was administered at a later time. These results suggest that midazolam can impair short-term/working memory processes, but these effects are substantially smaller than midazolam's effect on episodic memory processes. Moreover, they demonstrate that conscious awareness of materials during study is not sufficient to produce episodic memory.

Adult↗

PubMed2003

Midazolam amnesia and retrieval from semantic memory: Developing methods to test theories of implicit memory.

Studies of organic anterograde amnesia have been central to the development of theories of implicit memory. Pharmacological amnesia provides an additional method for exploring implicit memory, allowing for the experimental manipulation of amnesia and the testing of more participants. A significant concern with pharmacological amnesia is whether its cognitive effects are specific to explicit memory. The current research examines the effects of the benzodiazepine, midazolam, on retrieval from semantic memory and encoding in explicit memory. We focus on midazolam because it holds significant advantages over other benzodiazepines in inducing pharmacological amnesia and prior research suggests it may be useful for testing theories of implicit memory. Our results demonstrate that midazolam does not impair accuracy of retrieval from semantic categories, even when it produces anterograde amnesia for retrieved category items on a later recall test. These results suggest ways midazolam can be used to help test theories of implicit memory.

Adult↗

PubMed2003

The effect of midazolam on conscious, controlled processing: evidence from the process-dissociation procedure.

The benzodiazepine midazolam produces a dense anterograde amnesia. Recent findings (see, e.g., Hirshman, Passannante, & Arndt, 2001) have demonstrated that midazolam produces larger impairments on explicit memory tests such as free recall and recognition memory than on implicit memory tests such as perceptual identification and free association. Such findings suggest that midazolam impairs conscious, controlled memory processes. In the present experiments, we used Jacoby's (1991, 1998) process-dissociation procedure to examine this hypothesis. Our results demonstrate that midazolam increases the production of old items on the exclusion task and reduces the production of old items on the inclusion task. Moreover, generation effects, hypothesized to arise from conscious processes, are reduced by midazolam on both tasks. Analyses using both independence and redundancy models of the process-dissociation procedure confirm the conclusion that midazolam impairs conscious memory processes.

Consciousness↗

PubMed2003

The effect of dehydroepiandrosterone (DHEA) on recognition memory decision processes and discrimination in postmenopausal women.

In this article, the theoretical distinction between recognition memory decision and discrimination processes is used to explore the effect of dehydroepiandrosterone (DHEA) in postmenopausal women. DHEA is an adrenal steroid that diminishes with aging. It has enhanced memory in laboratory animals. An 8-week placebo-controlled, double-blind experiment in which 30 women (ages 39-70) received a 50-mg/day oral dose of DHEA for 4 weeks demonstrated that DHEA made subjects more conservative (i.e., less likely to call test items "old") in their recognition memory decisions and enhanced recognition memory discrimination for items presented briefly. The former result may reflect an empirical regularity (Hirshman, 1995) in which recent strong memory experiences make participants more conservative. The latter result may reflect the effect of DHEA on visual perception, with consequent effects on memory. These results suggest the methodological importance of focusing on decision processes when examining the effects of hormones on memory.

Administration, Oral↗