The Human Pyramidal Tract II. A Numerical Investigation of the Betz Cells of the Motor Area.

Lassek, A. M.

doi:10.1097/00005053-194108000-00026

Cited by 21 publications

(34 citation statements)

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“…With respect to the total number of Betz cells per hemisphere, the values reported by Campbell (1905), Lassek (1940), and Lassek and Wheatley (1945) represent underestimates by a factor of 3.6 in comparison to our results. These considerable discrepancies can be explained by the differences in the techniques used.…”

Section: Characteristics Of Betz Cells Vs Layer V Pyramidal Cellscontrasting

confidence: 98%

“…9H and I), corresponding generally to the previously described "hand-knob" region (Yousry et al, 1997;Boroojerdi et al, 1999;. Interestingly, this analysis also demonstrates that while the area of maximal clustering occurs in blocks 3 and 4, the region of area 4 where Betz cells are most numerous corresponds to the representation of the leg (blocks 1 and 2), in agreement with Lassek's earlier findings (Lassek, 1939(Lassek, , 1940(Lassek, , 1954 (Fig. 9).…”

Section: Tessellation Maps and Coefficient Of Clusteringsupporting

confidence: 90%

“…The fact that the largest Betz cells were located in the medial portion of the primary motor cortex (Figs. 8A and 9H) corroborates the observation that the size of the Betz cells is larger in the areas representing the foot and leg (Lassek, 1940;Zilles, 1990). Depending on their location in the primary motor cortex, the Betz cells exhibited morphological variability.…”

Section: Stereologic Assessment Of Cell Numbers and Volumessupporting

confidence: 82%

“…This size reduction appears to be related to motor somatotopy: the largest cells are found in the region of foot and leg representation, where efferent axons project the farthest along the corticospinal tract. The values reported in early studies for the total number of Betz cells in one human hemisphere range from 25,000 (Campbell, 1905), to 34,370 (Lassek, 1940;Lassek and Wheatley, 1945;Blinkov and Glezer, 1968), and up to 40,000 (Scheibel and Scheibel, 1978). Lassek (1940) demonstrated that the numerical distribution of Betz cells is related to somatotopy, with 75% of all Betz cells being in the leg area, 17.9% in the arm region, and 6.6% in the head area.…”

mentioning

confidence: 99%

“…The values reported in early studies for the total number of Betz cells in one human hemisphere range from 25,000 (Campbell, 1905), to 34,370 (Lassek, 1940;Lassek and Wheatley, 1945;Blinkov and Glezer, 1968), and up to 40,000 (Scheibel and Scheibel, 1978). Lassek (1940) demonstrated that the numerical distribution of Betz cells is related to somatotopy, with 75% of all Betz cells being in the leg area, 17.9% in the arm region, and 6.6% in the head area. However, his functional demarcation was not based on visible cytoarchitectural differences that could permit a precise definition of functional motor zones.…”

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confidence: 99%

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Stereologic characterization and spatial distribution patterns of Betz cells in the human primary motor cortex

et al. 2003

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Betz cells are giant motoneurons located in layer Vb of the primate primary motor cortex. We conducted stereological analyses of Betz cells and neighboring pyramidal cells from the brains of six neurologically normal elderly humans to determine their volume, total number, and spatial distribution, and to relate these data to functional localization. The distribution of cellular volumes exhibits a bimodal pattern, delineating two different subpopulations. Betz cell volumes follow a mediolateral gradient, the largest Betz cells being located on the most medial part of the motor cortex. Additionally, the shape of Betz cells varies between the rostral and caudal parts of the primary motor cortex, supporting the notion that there are anatomically distinct zones in primary motor cortex. The total number of Betz cells per hemisphere accounts for about one-tenth of the total number of pyramidal cells in layer Vb. Analysis of spatial distribution using Voronoi tessellation revealed maximal clustering of Betz cells in a zone situated two-thirds from the midline along the mediolateral axis of the primary motor cortex. These data suggest that Betz cells have a discrete subregional distribution that may correspond to certain aspects of the functional parcellation of area 4. These results may offer a histological correlate of functional imaging studies and are relevant in the context of neurodegenerative diseases such as amyotrophic lateral sclerosis, progressive supranuclear palsy, and Guamanian amyotrophic lateral sclerosis/Parkinsonism-dementia, and in studies of normal brain aging. Anat Rec Part A 270A: 137-151, 2003. © 2003 Key words: amyotrophic lateral sclerosis; area 4; Betz cells; cytoarchitecture; human neocortex; motoneurons; stereologyThe human neocortex is characterized by regional and laminar specific distributions of a variety of neuronal subtypes and distinct afferent and efferent connections. The neocortex can be parcellated into a large number of more or less distinct fields according to microscopic architecture. Identification of the primary motor cortex and its boundaries, however, has been particularly contentious. Brodmann (1903Brodmann ( , 1909 originally described area 4 as an agranular zone, delineated by the presence of Betz cells, a subpopulation of giant infragranular pyramidal neurons in cortical layer V, located on its rostral border and buried in the depth of the anterior wall of the central sulcus. This definition has since been criticized (Zeki, 1979), and Brodmann's original delineation of the primary motor cortex has been revised by other investigators, who described an intermediate precentral area, an area precentralis A, area

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Section: Characteristics Of Betz Cells Vs Layer V Pyramidal Cellscontrasting

confidence: 98%

Section: Tessellation Maps and Coefficient Of Clusteringsupporting

confidence: 90%

Section: Stereologic Assessment Of Cell Numbers and Volumessupporting

confidence: 82%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Stereologic characterization and spatial distribution patterns of Betz cells in the human primary motor cortex

et al. 2003

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Neurochemical, morphologic, and laminar characterization of cortical projection neurons in the cingulate motor areas of the macaque monkey

et al. 1996

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The primate cingulate gyrus contains multiple cortical areas that can be distinguished by several neurochemical features, including the distribution of neurofilament protein-enriched pyramidal neurons. In addition, connectivity and functional properties indicate that there are multiple motor areas in the cortex lining the cingulate sulcus. These motor areas were targeted for analysis of potential interactions among regional specialization, connectivity, and cellular characteristics such as neurochemical profile and morphology. Specifically, intracortical injections of retrogradely transported dyes and intracellular injection were combined with immunocytochemistry to investigate neurons projecting from the cingulate motor areas to the putative forelimb region of the primary motor cortex, area M1. Two separate groups of neurons projecting to area M1 emanated from the cingulate sulcus, one anterior and one posterior, both of which furnished commissural and ipsilateral connections with area M1. The primary difference between the two populations was laminar origin, with the anterior projection originating largely in deep layers, and the posterior projection taking origin equally in superficial and deep layers. With regard to cellular morphology, the anterior projection exhibited more morphologic diversity than the posterior projection. Commissural projections from both anterior and posterior fields originated largely in layer VI. Neurofilament protein distribution was a reliable tool for localizing the two projections and for discriminating between them. Comparable proportions of the two sets of projection neurons contained neurofilament protein, although the density and distribution of the total population of neurofilament protein-enriched neurons was very different in the two subareas of origin. Within a projection, the participating neurons exhibited a high degree of morphologic heterogeneity, and no correlation was observed between somatodendritic morphology and neurofilament protein content. Thus, although the neurons that provide the anterior and posterior cingulate motor projections to area M1 differ morphologically and in laminar origin, their neurochemical profiles are similar with respect to neurofilament protein. This suggests that neurochemical phenotype may be a more important unifying feature for corticocortical projections than morphology.

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Comparative morphology of gigantopyramidal neurons in primary motor cortex across mammals

Jacobs

Garcia

Shea‐Shumsky

et al. 2017

J of Comparative Neurology

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Gigantopyramidal neurons, referred to as Betz cells in primates, are characterized by large somata and extensive basilar dendrites. Although there have been morphological descriptions and drawings of gigantopyramidal neurons in a limited number of species, quantitative investigations have typically been limited to measures of soma size. The current study thus employed two separate analytical approaches: a morphological investigation using the Golgi technique to provide qualitative and quantitative somatodendritic measures of gigantopyramidal neurons across 19 mammalian species from 7 orders; and unbiased stereology to compare the soma volume of layer V pyramidal and gigantopyramidal neurons in primary motor cortex between 11 carnivore and 9 primate species. Of the 617 neurons traced in the morphological analysis, 181 were gigantopyramidal neurons, with deep (primarily layer V) pyramidal (n = 203) and superficial (primarily layer III) pyramidal (n = 233) neurons quantified for comparative purposes. Qualitatively, dendritic morphology varied considerably across species, with some (sub)orders (e.g., artiodactyls, perissodactyls, feliforms) exhibiting bifurcating, V-shaped apical dendrites. Basilar dendrites exhibited idiosyncratic geometry across and within taxonomic groups. Quantitatively, most dendritic measures were significantly greater in gigantopyramidal neurons than in superficial and deep pyramidal neurons. Cluster analyses revealed that most taxonomic groups could be discriminated based on somatodendritic morphology for both superficial and gigantopyramidal neurons. Finally, in agreement with Brodmann, gigantopyramidal neurons in both the morphological and stereological analyses were larger in feliforms (especially in the Panthera species) than in other (sub)orders, possibly due to specializations in muscle fiber composition and musculoskeletal systems.

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The Human Pyramidal Tract II. A Numerical Investigation of the Betz Cells of the Motor Area.

Cited by 21 publications

References 0 publications

Stereologic characterization and spatial distribution patterns of Betz cells in the human primary motor cortex

Stereologic characterization and spatial distribution patterns of Betz cells in the human primary motor cortex

Neurochemical, morphologic, and laminar characterization of cortical projection neurons in the cingulate motor areas of the macaque monkey

Comparative morphology of gigantopyramidal neurons in primary motor cortex across mammals

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