Effects of triazolam on brain activity during episodic memory encoding: a PET study

Area of Science:

• Neuroscience
• Pharmacology
• Cognitive Psychology

Background:

• Benzodiazepine hypnotics, like triazolam, are known to impair episodic memory encoding.
• Understanding the neuroanatomical basis of this impairment is crucial for assessing the drug's cognitive side effects.

Purpose of the Study:

• To investigate the neuroanatomical substrates underlying triazolam's impairment of episodic memory encoding.
• To examine regional cerebral blood flow (rCBF) changes associated with memory encoding under triazolam versus placebo.

Main Methods:

• A double-blind, within-subject design was employed with healthy adult volunteers.
• Positron emission tomography (PET) with 15O-H(2)O measured rCBF during semantic categorization, orthographic categorization, and visual fixation tasks.
• Episodic memory encoding-related rCBF was assessed by comparing orthographic and semantic categorization task rCBF.

Main Results:

• Placebo condition results replicated previous findings, showing activation in prefrontal cortex, cerebellum, anterior cingulate cortex, temporal cortex, and occipital cortex.
• Triazolam administration led to significantly impaired memory performance.
• Deactivation during encoding was observed in the anterior cingulate cortex, cerebellum, and precuneus under triazolam compared to placebo.

Conclusions:

• Triazolam impairs episodic memory encoding by deactivating specific brain regions involved in mnemonic processes.
• The findings suggest triazolam's effects may impact both mnemonic and attentional functions during memory encoding.