RECENT PRESENTATIONS

Chellaramani, R., McEvoy, L., Chung, S., Smith, M.E. & Gevins, A. (2001). Impact of Benzodiazepines on Behavioral and Neurophysiological Measures of Working Memory. Cognitive Neuroscience Society Eighth Annual Meeting. March, New York. [abstract]

ABSTRACT

Benzodiazepines are thought to act primarily on GABA receptors and might affect sustained attention and working memory (WM) by increasing GABA-mediated recurrent inhibition. Such enhancement of inhibitory mechanisms could disrupt the ability to sustain activation of task-relevant representations. In this study ten healthy adults received the benzodiazepine alprazolam (1mg) or a placebo in a within-subject double-blind fashion. EEG data were collected during two difficulty levels of an "n-back" spatial WM task and under resting conditions. Alprazolam impaired accuracy and slowed responses on the WM task, and produced marked subjective sedation. The drug also affected neurophysiological measures. Under placebo conditions, increased task difficulty was associated with an increase in power of the frontal midline theta EEG rhythm, and a widespread decrease in power in the alpha band. The acute effects of alprazolam eliminated these task-related changes. Across task conditions alprazolam increased power in the beta band, particularly over dorsolateral frontal regions. Alprazolam also affected attention-related components of the stimulus-locked ERP. Together the results suggest that, in conjunction with their sedating effect, benzodiazepines impair performance on WM tasks while changing the oscillatory properties of cortical neurons and disrupting their responsiveness to variations in WM task demands. Supported by the NIMH.