Abstract
Betz cells—the gigantopyramidal neurons found in high amount in the primary motor cortex—are among of the most characteristic neuronal cells. A part of them contains the calcium-binding protein parvalbumin (PV) in primates. However, less is known about these cells in the human motor cortex despite their important role in different neurological disorders. Therefore, the aim of our study was to investigate the neurochemical features and perisomatic input properties of Betz cells in control human samples with short post-mortem interval. We used different microscopic techniques to investigate the primary motor cortex of both hemispheres. The soma size and density, and expression of PV of the Betz cells were investigated. Furthermore, we used confocal fluorescent and electron microscopy to examine their perisomatic input. The soma size and density showed moderate variability among samples and hemispheres. Post-mortem interval and hemispherical localization did not influence these features. Around 70% of Betz cells expressed PV, but in less intensity than the cortical interneurons. Betz neurons receive dense perisomatic input, which are mostly VIAAT- (vesicular inhibitory amino acid transporter) and PV immunopositive. In the electron microscope, we found PV-immunolabelled terminals with asymmetric-like synaptic structure, too. Terminals with morphologically similar synaptic specialisation were also found among vGluT2- (vesicular glutamate transporter type 2) immunostained terminals contacting Betz cells. Our data suggest that Betz cells’ morphological properties showed less variability among subjects and hemispheres than the density of them. Their neurochemical and perisomatic input characteristics support their role in execution of fast and precise movements.
Highlights
Motor control is crucial for reaction and survival in the environment, and the primary motor cortex (Brodmann’s area 4—BA 4) plays a major role in it
We have examined the morphological features and input characteristics of the Betz cells in the area of the human primary motor cortex, approximately in the somatotopic upper limb area of the motor homunculus (Penfield and Boldrey 1937)
We have checked the samples in two subjects, which were immunostained with SMI32 and counterstained by Cresyl violet (Nissl staining) whether all giant pyramidal neurons are immunolabelled for PV with our fixation method, too
Summary
Motor control is crucial for reaction and survival in the environment, and the primary motor cortex (Brodmann’s area 4—BA 4) plays a major role in it. One study in pig-tailed macaques showed that the primary motor cortex produces around 50% of the corticospinal projections originating from the frontal lobe (Dum and Strick 1991). This region differs from other areas of the neocortex in some peculiar features. According to Brodmann, it is found in the caudal part of the precentral gyrus in the human brain (Brodmann 1909) This region Brodmann’s area 4 (BA 4) receives input from several motor and sensory areas (e.g. postcentral sulcus or superior parietal lobule), and subcortical structures as well (e.g. ventrolateral (VL) nucleus of the thalamus, as a significant
Sign-in/Register to view highlights & summary 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.
