XXXX effects on default mode network during resting state.

@entity1233 @entity1239
RATIONALE: The default mode network ( @entity1233 ), one of several resting-state networks (RSN) in the brain, is thought to be involved in self-referential thought, awareness, and episodic memories. @entity1239 improves cognitive performance, in part by improving attention. Nicotinic agonists have been shown to decrease activity in regions within @entity1233 and increase activity in regions involved in visual attention during effortful processing of external stimuli. It is unknown if these pharmacological effects also occur in the absence of effortful processing. OBJECTIVES: This study aims to determine if @entity1239 suppresses activity in default mode and enhances activity in extra-striate RSNs in the absence of an external visual task. METHODS: Within-subject, single-blinded, counterbalanced study of 19 non-smoking subjects who had resting functional MRI scans after 7 mg @entity1239 or placebo patch. Group independent component analysis was performed. The @entity1233 component was identified by spatial correlation with a reference @entity1233 mask. A visual attention component was identified by spatial correlation with an extra-striate mask. Analyses were conducted using statistical parametric mapping. RESULTS: @entity1239 was associated with decreased activity in regions within the @entity1233 and increased activity in extra-striate regions. CONCLUSIONS: Suppression of @entity1233 and enhancement of extra-striate resting-state activity in the absence of visual stimuli or effortful processing suggest that @entity1239 's cognitive effects may involve a shift in activity from networks that process internal to those that process external information. This is a potential mechanism by which cholinergic agonists may have a beneficial effect in diseases associated with altered resting-state activity.
