Nicotine effects on default mode network during resting state

Abstract

Rationale The default mode network (DMN), one of several resting-state networks (RSN) in the brain, is thought to be involved in self-referential thought, awareness, and episodic memories. Nicotine improves cognitive performance, in part by improving attention. Nicotinic agonists have been shown to decrease activity in regions within DMN 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 nicotine 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 nicotine or placebo patch. Group independent component analysis was performed. The DMN component was identified by spatial correlation with a reference DMN mask. A visual attention component was identified by spatial correlation with an extra-striate mask. Analyses were conducted using statistical parametric mapping. Results Nicotine was associated with decreased activity in regions within the DMN and increased activity in extra-striate regions. Conclusions Suppression of DMN and enhancement of extra-striate resting-state activity in the absence of visual stimuli or effortful processing suggest that nicotine’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.

Neurobiological Impact of Nicotinic Acetylcholine Receptor Agonists: An Activation Likelihood Estimation Meta-Analysis of Pharmacologic Neuroimaging Studies

“…Conversely, nicotine administration leads to activity increases within the lateral parietal and prefrontal cortices, thalamus, and dorsal anterior cingulate cortex (ACC), which also accompany behavioral improvements among smokers performing a sustained attention task (19, 21). Suggesting that such activity decreases and/or increases are not constrained to task-, participant- or drug-specific manipulations, similar modulations have been observed when considering alternative cognitive domains (18), nonsmokers (22), or varenicline administration (23). As such, aggregating the corpus of pharmacological neuroimaging results regarding nAChR agonists affords the opportunity to identify common functional brain changes that may be related to the pro-cognitive effects of these drugs.…”

Cannabis, cigarettes, and their co-occurring use: Disentangling differences in default mode network functional connectivity

“…Although research has explored the acute effects of Δ9-tetrahydrocannabinol (THC), the psychoactive component of cannabis (Gaoni and Mechoulam, 1971), and nicotine, the primary component of tobacco cigarettes, on rsFC (Hong et al, 2009; Klumpers et al, 2012; Lerman et al, 2014; Sutherland et al, 2013; Tanabe et al, 2011; van Hell et al, 2011), research examining rsFC of the DMN and its connections among individuals with CUD or TUD is sparse. One resting state fMRI study compared the DMN and other neural networks associated with self-referential processes (i.e., Insula network) in heavy cannabis users compared to healthy controls and found that cannabis users showed increased functional connectivity in the core nodes of the DMN and Insula networks and reduced functional connectivity in areas overlapping with other brain networks (Pujol et al, 2014).…”

Overview of potential procedural and participant- related confounds for neuroimaging of the resting state

“…107 In comparisons between nicotine and placebo, these cognitive effects have been linked to deactivation of the DMN in response to tasks 108 in conjunction with increases in activity in other attention-related regions. 109 In addition to such task-related changes in the DMN, a similar pattern of changes in response to nicotine administration (i.e., a reduction in DMN activity and an increase in activity in attention networks) has been observed in an fMRI resting-state study, 110 along with changes in fMRI functional connectivity between subregions of the DMN and other brain regions. 111 Similarly, a recent EEG study found that resting EEG measures in nonsmokers were altered by nicotine administration; specifically an increase in left frontal α2 power was reported.…”