Document Type
Journal Article
Publication Title
Journal of Neuroscience Research
PubMed ID
36353842
Publisher
Wiley
School
School of Medical and Health Sciences
RAS ID
56448
Funders
Coopers Brewery Foundation Incorporated Trust / National Health and Medical Research Council of Australia / Parkinson's South Australia / Rebecca L. Cooper Medical Research Foundation / University of South Australia / University of Sydney / Australian Research Council
Grant Number
ARC Number : DE180100741
Grant Link
http://purl.org/au-research/grants/arc/DE180100741
Abstract
Substantia nigra (SN) hyperechogenicity, viewed with transcranial ultrasound, is a risk marker for Parkinson's disease. We hypothesized that SN hyperechogenicity in healthy adults aged 50 – 70 years is associated with reduced short-interval intracortical inhibition in primary motor cortex, and that the reduced intracortical inhibition is associated with neurochemical markers of activity in the pre-supplementary motor area (pre-SMA). Short-interval intracortical inhibition and intracortical facilitation in primary motor cortex was assessed with paired-pulse transcranial magnetic stimulation in 23 healthy adults with normal (n = 14; 61 ± 7 yrs) or abnormally enlarged (hyperechogenic; n = 9; 60 ± 6 yrs) area of SN echogenicity. Thirteen of these participants (7 SN − and 6 SN+) also underwent brain magnetic resonance spectroscopy to investigate pre-SMA neurochemistry. There was no relationship between area of SN echogenicity and short-interval intracortical inhibition in the ipsilateral primary motor cortex. There was a significant positive relationship, however, between area of echogenicity in the right SN and the magnitude of intracortical facilitation in the right (ipsilateral) primary motor cortex (p = .005; multivariate regression), evidenced by the amplitude of the conditioned motor evoked potential (MEP) at the 10 – 12 ms interstimulus interval. This relationship was not present on the left side. Pre-SMA glutamate did not predict primary motor cortex inhibition or facilitation. The results suggest that SN hyperechogenicity in healthy older adults may be associated with changes in excitability of motor cortical circuitry. The results advance understanding of brain changes in healthy older adults at risk of Parkinson's disease.
DOI
10.1002/jnr.25145
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Comments
Todd, G., Rae, C. D., Taylor, J. L., Rogasch, N. C., Butler, J. E., Hayes, M., ... & Double, K. L. (2023). Motor cortical excitability and pre‐supplementary motor area neurochemistry in healthy adults with substantia nigra hyperechogenicity. Journal of Neuroscience Research, 101(2), 263-277. https://doi.org/10.1002/jnr.25145