title: Nicotinic antagonist effects on functional attention networks.
abstract: Cholinergic neurotransmission has been implicated in memory and attention. We investigated the effect of the non-competitive nicotinic antagonist mecamylamine on three components of attention processes (i.e. alerting, orienting and executive control) in 12 healthy male subjects whilst performing the Attention Network Task (ANT) in a magnetic resonance imaging (MRI) scanner. Participants received 15 mg mecamylamine in a single blind and placebo- controlled randomized procedure 90 min prior to obtaining functional MRI data. Our results confirm previous reports of beneficial effects of cueing (alerting and orienting) and detrimental effects of conflict (executive control) on reaction times when performing the ANT. The functional MRI data confirmed distinct neural networks associated with each of the three attention components. Alerting was associated with increased left temporal lobe activation while orienting increased bilateral prefrontal, right precuneus and left caudate activation. Executive control activated anterior cingulate and precuneus. Mecamylamine slowed overall response time and down-regulated brain activation associated with orienting and to some extent brain activation associated with executive control when compared to placebo. These findings are consistent with nicotinic modulation of orienting attention by cueing and executive control when responding to conflicting information. The latter nicotine antagonist effect may be mediated via cholinergic modulation of dopamine neurotransmission in mesolimbic pathways.
authors.affiliation: Centre for Rural and Remote Mental Health, University of Newcastle, Australia. renate.thienel@newcastle.edu.au
authors.forename: Renate
authors.initials: R
authors.lastname: Thienel
authors.forename: Bianca
authors.initials: B
authors.lastname: Voss
authors.forename: Thilo
authors.initials: T
authors.lastname: Kellermann
authors.forename: Martina
authors.initials: M
authors.lastname: Reske
authors.forename: Sarah
authors.initials: S
authors.lastname: Halfter
authors.forename: Abigail J
authors.initials: AJ
authors.lastname: Sheldrick
authors.forename: Katrin
authors.initials: K
authors.lastname: Radenbach
authors.forename: Ute
authors.initials: U
authors.lastname: Habel
authors.forename: Nadim Jon
authors.initials: NJ
authors.lastname: Shah
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schall
authors.forename: Tilo
authors.initials: T
authors.lastname: Kircher
mesh_terms: D000328:Adult; D001288:Attention / Q000187:drug effects* / Q000502:physiology*; D018592:Cross-Over Studies; D006801:Humans; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D009415:Nerve Net / Q000187:drug effects* / Q000502:physiology*; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D016037:Single-Blind Method; D055815:Young Adult
chemical_list: D018733:Nicotinic Antagonists; D008464:Mecamylamine