An analysis of the learning deficit following hyoscine administration to man

Abstract

Summary1. Twelve volunteer subjects completed a free-recall word learning test, a number-colour association test, and a scanning task after the following treatments: saline 1 ml, hyoscine 04 mg, or atropine 0-6 mg, administered by intravenous injection.2. Performance on all three tests was not significantly impaired after atropine. 3. Performance on the two learning tests but not on the scanning task, was significantly impaired after hyoscine. 4. Analysis of the results of the free-recall word learning test indicates that impairment of learning following hyoscine does not affect recall over intervals of a few seconds, but affects that portion of the learning curve which has been attributed to long-term (or secondary) rather than short-term (or primary) memory. 5. The results suggest that hyoscine 04 mg may impair learning processes, without significantly depressing other psychological functions, and that the impairment of learning following hyposcine does not affect recall over intervals memory.

Blockade of Central Cholinergic Receptors Impairs New Learning and Increases Proactive Interference in a Word Paired-Associate Memory Task.

“…This may be one factor that has contributed to the apparently inconsistent findings between studies that have and those that have not used active placebos in their control groups when studying the effects of scopolamine on attention, working memory, and item and associative memory (Beatty et al, 1986;Caine et al 1981;Crow & Grove-White, 1973;Ghoneim & Mewaldt, 1977;Grober et al, 1989;Mintzer & Griffiths, 2001Robbins et al, 1997;Safer & Allen, 1971;Sherman et al, 2003). Scopolamine injection has been found to significantly impair paired-associate memory for free recall of number-color associations (Crow & Grove-White, 1973), and cued recall of name in face-name associations (Sperling et al, 2002), but not for cued recall of digit in symbol-digit associations (Beatty et al, 1986), cued recall of self-generated (i.e., generated by free association with a given cue) and well-rehearsed semantic and phonemic word paired associates (Caine et al, 1981), or cued recall of colored pattern in colored pattern-spatial location associations (Robbins, et al, 1997). However, it is important to note that both Beatty et al (1986) and Caine et al (1981) combined active placebo (glycopyrrolate or methylscopolamine) and inactive placebo (saline) groups to obtain their control groups used for comparison to their scopolamine groups.…”

“…In addition, short-term memory phenomena such as the recency component of a serial position curve (Crow & Grove-White, 1973;Frith et al, 1984) and digit span (Beatty et al, 1986;Drachman, 1978) are also spared. Recently, studies have shown that scopolamine may impact recognition memory processes by affecting both recollection and familiarity (Mintzer & Griffiths, 2001Sherman, Atri, Hasselmo, Stern, & Howard, 2003).…”

Free recall and recognition in a network model of the hippocampus: simulating effects of scopolamine on human memory function

“…Only a few studies have addressed the effects of scopolamine on paired associates. Scopolamine impaired encoding of paired associates in section VI of the Wechsler memory scale [29] encoding of number-color associations [22], and memory for self-generated paired associates [30]. A recent study using very strong pre-existing category associations showed no impairment [31].…”

Scopolamine and Pavlovian Fear Conditioning in Rats Dose-Effect Analysis

“…Using muscarinic receptor antagonists (scopolamine or atropine), pervasive impairments of learning have been demonstrated in humans (Crow and Grove-White 1973), monkeys (Aigner et al 1991), rabbits (Harvey et al 1983, and rodents (Levin et al 1990). In many behavioral paradigms, the deficits produced by muscarinic-cholinergic antagonism are similar to the effects produced by hippocampal lesions (Watts et al 1981;Anagnostaras et al 1995), while in others they are more general (Hagan et al 1986;Rudy 1996;Paylor and Rudy 1990).…”