Diversity of Cortico-descending Projections: Histological and Diffusion MRI Characterization in the Monkey.
Cereb Cortex
; 29(2): 788-801, 2019 02 01.
Article
em En
| MEDLINE
| ID: mdl-29490005
ABSTRACT
The axonal composition of cortical projections originating in premotor, supplementary motor (SMA), primary motor (a4), somatosensory and parietal areas and descending towards the brain stem and spinal cord was characterized in the monkey with histological tract tracing, electron microscopy (EM) and diffusion MRI (dMRI). These 3 approaches provided complementary information. Histology provided accurate assessment of axonal diameters and size of synaptic boutons. dMRI revealed the topography of the projections (tractography), notably in the internal capsule. From measurements of axon diameters axonal conduction velocities were computed. Each area communicates with different diameter axons and this generates a hierarchy of conduction delays in this order a4 (the shortest), SMA, premotor (F7), parietal, somatosensory, premotor F4 (the longest). We provide new interpretations for i) the well-known different anatomical and electrophysiological estimates of conduction velocity; ii) why conduction delays are probably an essential component of the cortical motor command; and iii) how histological and dMRI tractography can be integrated.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Tratos Piramidais
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Imagem de Difusão por Ressonância Magnética
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Imagem de Tensor de Difusão
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Córtex Motor
Limite:
Animals
Idioma:
En
Revista:
Cereb Cortex
Assunto da revista:
CEREBRO
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Suécia