Abstract
We assessed the structure–function relationship of the human cholinergic system and hypothesized that structural measures are associated with short-latency sensory afferent inhibition (SAI), an electrophysiological measure of central cholinergic signal transmission. Healthy volunteers (n = 36) and patients with mild cognitive impairment (MCI, n = 20) underwent median nerve SAI and 3T structural MRI to determine the volume of the basal forebrain and the thalamus. Patients with MCI had smaller basal forebrain (p < 0.001) or thalamus volumes (p < 0.001) than healthy volunteers. Healthy SAI responders (> 10% SAI) had more basal forebrain volume than non-responders (p = 0.004) or patients with MCI (p < 0.001). More basal forebrain volume was associated with stronger SAI in healthy volunteers (r = 0.33, p < 0.05) but not patients with MCI. There was no significant relationship between thalamus volumes and SAI. Basal forebrain volume is associated with cholinergic function (SAI) in healthy volunteers but not in MCI patients. The in-vivo investigation of the structure–function relationship could further our understanding of the human cholinergic system in patients with suspected or known cholinergic system degeneration.
Highlights
We assessed the structure–function relationship of the human cholinergic system and hypothesized that structural measures are associated with short-latency sensory afferent inhibition (SAI), an electrophysiological measure of central cholinergic signal transmission
Basal forebrain volumes decline in ageing humans and are severely reduced in patients with dementia due to Alzheimer’s disease (AD), a neurodegenerative disease associated with a loss of cholinergic brain structure and their cholinergic projection neurons[4,5,6]
Cholinergic pathways can be examined in-vivo using short-latency sensory afferent inhibition (SAI), a transcranial magnetic stimulation (TMS) paradigm that non-invasively measures the effect on motor cortex (M1) excitability of a preceding, conditioning sensory afferent electrical stimulus given to a peripheral mixed nerve above its motor threshold[7]
Summary
We assessed the structure–function relationship of the human cholinergic system and hypothesized that structural measures are associated with short-latency sensory afferent inhibition (SAI), an electrophysiological measure of central cholinergic signal transmission. Healthy volunteers (n = 36) and patients with mild cognitive impairment (MCI, n = 20) underwent median nerve SAI and 3T structural MRI to determine the volume of the basal forebrain and the thalamus. More basal forebrain volume was associated with stronger SAI in healthy volunteers (r = 0.33, p < 0.05) but not patients with MCI. Basal forebrain volume is associated with cholinergic function (SAI) in healthy volunteers but not in MCI patients. Basal forebrain volumes decline in ageing humans and are severely reduced in patients with dementia due to Alzheimer’s disease (AD), a neurodegenerative disease associated with a loss of cholinergic brain structure and their cholinergic projection neurons[4,5,6]. We expected to find less basal forebrain volume in patients with MCI since atrophy in this population is well r ecognized[9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
