title: Central cholinergic pathway involvement in the regulation of pupil diameter, blink rate and cognitive function.
abstract: Anticholinergic medications can exert their effects by acting on muscarinic receptors, which mediates the function of acetylcholine in the central nervous system. Acetylcholine plays a number of roles, particularly in regard to the control of muscle activity and normal cognitive functioning. Eighteen subjects were recruited into the human, double-blind, placebo-controlled, four-way crossover study. Pupil diameter and blink rate were assessed at rest while eye tracking technology recorded eye characteristics. Thereafter a cognitive task was performed, where pupil size and blink rate were once again measured. Assessments were performed pre-ingestion, 0.5h and 2h following the ingestion of a strong centrally acting anticholinergic (promethazine hydrochloride), a moderate centrally acting anticholinergic (hyoscine hydrobromide), an anticholinergic devoid of central effects (hyoscine butylbromide) and placebo. At rest, hyoscine hydrobromide was the only medication to increase pupil diameter and no drug intervention influenced blink rate. During performance of the cognitive task, hyoscine hydrobromide increased pupil diameter and promethazine increased blink rate. Promethazine was the only medication to influence the modified attention network test (ANT) by increasing the conflict effect and grand mean reaction time (RT). Pupil diameter and blink rate were both influenced by the central anticholinergics during performance of the cognitive test, thus highlighting the importance of central cholinergic pathways in the control of pupil diameter and blink rate. The collective effects of central anticholinergics on the modified ANT and on pupil diameter and blink rate during its performance, conveys the importance of central cholinergic pathways in cognitive function.
authors.affiliation: Menzies Health Institute, Griffith University, Gold Coast, Queensland, Australia; School of Pharmacy, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Preshanta
authors.initials: P
authors.lastname: Naicker
authors.affiliation: Menzies Health Institute, Griffith University, Gold Coast, Queensland, Australia; School of Pharmacy, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Shailendra
authors.initials: S
authors.lastname: Anoopkumar-Dukie
authors.affiliation: Menzies Health Institute, Griffith University, Gold Coast, Queensland, Australia; School of Pharmacy, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Gary D
authors.initials: GD
authors.lastname: Grant
authors.affiliation: Menzies Health Institute, Griffith University, Gold Coast, Queensland, Australia; School of Applied Psychology, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: David L
authors.initials: DL
authors.lastname: Neumann
authors.affiliation: Menzies Health Institute, Griffith University, Gold Coast, Queensland, Australia; School of Allied Health Sciences, Griffith University, Gold Coast, Queensland, Australia. Electronic address: j.kavanagh@griffith.edu.au.
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Kavanagh
mesh_terms: D001288:Attention / Q000187:drug effects / Q000502:physiology; D001767:Blinking / Q000187:drug effects* / Q000502:physiology; D002086:Butylscopolammonium Bromide / Q000494:pharmacology; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D018680:Cholinergic Antagonists / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects* / Q000502:physiology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism; D009483:Neuropsychological Tests; D009929:Organ Size; D011398:Promethazine / Q000494:pharmacology; D011680:Pupil / Q000187:drug effects* / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012146:Rest; D012601:Scopolamine / Q000494:pharmacology; D013997:Time Factors; D055815:Young Adult
chemical_list: D018680:Cholinergic Antagonists; D002086:Butylscopolammonium Bromide; D012601:Scopolamine; D011398:Promethazine
keywords: anticholinergic; attention; blink rate; eye tracker; motor control; pupil diameter