Uncrossed cortico-muscular projections in humans are abundant to facial muscles of the upper and lower face, but may differ between sexes

Fischer, Urs; Hess, Christian W; Rösler, Kai M (2005). Uncrossed cortico-muscular projections in humans are abundant to facial muscles of the upper and lower face, but may differ between sexes. Journal of neurology, 252(1), pp. 21-6. Heidelberg: Steinkopff-Verlag 10.1007/s00415-005-0592-7

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It is a popular concept in clinical neurology that muscles of the lower face receive predominantly crossed cortico-bulbar motor input, whereas muscles of the upper face receive additional ipsilateral, uncrossed input. To test this notion, we used focal transcranial magnetic brain stimulation to quantify crossed and uncrossed cortico-muscular projections to 6 different facial muscles (right and left Mm. frontalis, nasalis, and orbicularis oris) in 36 healthy right-handed volunteers (15 men, 21 women, mean age 25 years). Uncrossed input was present in 78% to 92% of the 6 examined muscles. The mean uncrossed: crossed response amplitude ratios were 0.74/0.65 in right/left frontalis, 0.73/0.59 in nasalis, and 0.54/0.71 in orbicularis oris; ANOVA p>0.05). Judged by the sizes of motor evoked potentials, the cortical representation of the 3 muscles was similar. The amount of uncrossed projections was different between men and women, since men had stronger left-to-left projections and women stronger right-to-right projections. We conclude that the amount of uncrossed pyramidal projections is not different for muscles of the upper from those of the lower face. The clinical observation that frontal muscles are often spared in central facial palsies must, therefore, be explained differently. Moreover, gender specific lateralization phenomena may not only be present for higher level behavioural functions, but may also affect simple systems on a lower level of motor hierarchy.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology

UniBE Contributor:

Fischer, Urs; Hess, Christian Walter and Rösler, Kai Michael

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0340-5354

ISBN:

15654551

Publisher:

Steinkopff-Verlag

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 15:05

Last Modified:

22 Oct 2019 22:07

Publisher DOI:

10.1007/s00415-005-0592-7

PubMed ID:

15654551

Web of Science ID:

000226322100004

BORIS DOI:

10.7892/boris.28423

URI:

https://boris.unibe.ch/id/eprint/28423 (FactScience: 120706)

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