The number of neurons in the different laminae of the binocular and monocular regions of area 17 in the cat

The number of neurons in individual laminae of area 17 was determined separately for both the binocular and the monocular, regions in the left hemi‐sphere of six cats. The number of neurons/mm3 of tissue was obtained for each lamina by using the method of size‐frequency distribution applied to neuronal nuclei. The number of neurons per unit of cortical surface could then be calculated from measurements of layer, thickness. The number of neurons/mm3 of tissue for trie total cortical thickness is on the order of 48,000 to 50,000 neurons, with no statistically significant differences be‐tween binocular and monocular regions. There are no significant differences for any of the layers except layer IV, in which the numerical density is 20% higher in the monocular region. The thickness of the cortex and of many of its layers, however, do vary between the two regions. Consequently there are significant differences in the number of neurons under 1 mm2 the total cortical thickness there are significantly more (27%) neurons in the binocular (78,440) than in the monocular region (61,900). This overall difference is due to significant changes in layers II, IIIA, IVA, and especially in layers V and VIA where neurons are 40% more numerous in the binocular region. These findings could signify either that the binocular region contains additional interneurons specifically related to binocular interactions or that it has a greater number of neurons projecting to other cortical and subcortical areas, or both.

[1]  J. O'leary,et al.  Structure of the area striata of the cat , 1941 .

[2]  K. C. Richardson,et al.  Embedding in epoxy resins for ultrathin sectioning in electron microscopy. , 1960, Stain technology.

[3]  M. Colonnier.  THE TANGENTIAL ORGANIZATION OF THE VISUAL CORTEX. , 1964, Journal of anatomy.

[4]  B. Cragg.  The density of synapses and neurones in the motor and visual areas of the cerebral cortex. , 1967, Journal of anatomy.

[5]  E. Weibel.  Stereological principles for morphometry in electron microscopic cytology. , 1969, International review of cytology.

[6]  L. Palmer,et al.  An autoradiographic study of the projections of the dorsal lateral geniculate nucleus and the posterior nucleus in the cat. , 1974, Brain research.

[7]  C. Gilbert,et al.  The projections of cells in different layers of the cat's visual cortex , 1975, The Journal of comparative neurology.

[8]  H. H. Magalha˜es-Castro,et al.  Identification of corticotectal cells of the visual cortex of cats by means of horseradish peroxidase , 1975, Brain Research.

[9]  B. Cragg,et al.  The development of synapses in the visual system of the cat , 1975, The Journal of comparative neurology.

[10]  C. Gilbert,et al.  Laminar patterns of geniculocortical projection in the cat , 1976, Brain Research.

[11]  S. Sherman,et al.  Percentage of relay cells in the cat's lateral geniculate nucleus , 1977, Brain Research.

[12]  B. V. Updyke,et al.  Topographic organization of the projections from cortical areas 17, 18, and 19 onto the thalamus, pretectum and superior colliculus in the cat , 1977, The Journal of comparative neurology.

[13]  D. Ferster,et al.  The axonal arborizations of lateral geniculate neurons in the striate cortex of the cat , 1978, The Journal of comparative neurology.

[14]  G. Henry,et al.  Anatomical organization of the primary visual cortex (area 17) of the cat. A comparison with area 17 of the macaque monkey , 1979, The Journal of comparative neurology.

[15]  T. Wiesel,et al.  Morphology and intracortical projections of functionally characterised neurones in the cat visual cortex , 1979, Nature.

[16]  L. Palmer,et al.  Retinotopic organization of areas 18 and 19 in the cat , 1979, The Journal of comparative neurology.

[17]  David Ferster,et al.  Proportion of interneurons in the cat's lateral geniculate nucleus , 1979, Brain Research.

[18]  G. Henry,et al.  Laminar distribution of first-order neurons and afferent terminals in cat striate cortex. , 1979, Journal of neurophysiology.

[19]  L. Benevento,et al.  Extrageniculate thalamic projections to the primary visual cortex , 1980, Brain Research.

[20]  T. Powell,et al.  The basic uniformity in structure of the neocortex. , 1980, Brain : a journal of neurology.

[21]  A. M. Graybiel,et al.  Sensory maps in the claustrum of the cat , 1980, Nature.

[22]  E. Geisert,et al.  Cortical projections of the lateral geniculate nucleus in the cat , 1980, The Journal of comparative neurology.

[23]  C. P. Hughes,et al.  Afferent projections to the ventral lateral geniculate nucleus in the cat , 1981, Brain Research.

[24]  T. P. S. Powell,et al.  Similarity in number of neurons through the depth of the cortex in the binocular and monocular parts of area 17 of the monkey , 1981, Brain Research.

[25]  M. Colonnier,et al.  A laminar analysis of the number of neurons, glia, and synapses in the visual cortex (area 17) of adult macaque monkeys , 1982, The Journal of comparative neurology.