" Parietal region (fields 3, 3a, 2 , I , 40). The parietal region in the present parcel- lation is approximately coextensive with that of Krieg. Individual subdivisions are modified, however, to set apart the barrel field (Woolsey, '67; Woolsey and Van der Loos, '70; Welker, '71, '74; Welker and Woolsey, '74; Weller, '72) as a separate cytoarchitec tonic field. When reconstructed &om serial coronal sections in the present study, the configuration of the barrel field approximates that reconstructed by others from tangential sections (Woolsey and Van der Loos, '70). The number 3 is given to the barrel field because it lies at the inter- face of parietal and frontal cortex. As de- scribed by Woolsey and Van der Loos ('70) the barrels are not continuous through the medial limb of field 3. The interposed cor- tical sector without barrels corresponding to field 1 of Krieg ('46a,b) and the rostral portion of the adjacent parietal field desig- nated 7 by Krieg are architectonically sim- ilar. Collectively the area probably in- cludes the SmI representation of the trunk and proximal extremities (Woolsey, '67; Welker, '74) and has been joined in a sin- gle field, 1. " " Field 3 is the barrel field, the distinctive cytoarchitectonic configuration lying with- in layer IV described by Woolsey ('67) and Woolsey and Van der Loos ('70). As ob- served by these authors, the barrels are largest in the larger lateral-posterior re- gion; they are not well seen in the midpor- tion of the small medial limb. The general cellular and fiber characteristics of the parietal region are most fully developed in field 3. As described by Woolsey ('67) and Woolsey and Van der Loos ('70) the barrels are composed of central wide, relatively hypocellular hollows, bordered by narrow sides of densely packed small, darkly stain- ing cells (fig. 4A). Relatively cell-free septa lie between the sides of adjacent barrels. The grouping of cells into barrels is limited to layer IV. Layers I11 and V are not, ap- parently, involved in this cytoarchitectonic configuration. It is an additional feature of the fiber pattern in field 3 that fascicles of fibers may be seen in favorable sections to pass axially through the acellular septa between barrels (fig. 4b). In field 1, the cellularity of layer IV and overall fiber density are much less than in the adjacent barrel field caudally. The character of field 1, though distinctly parietal, is transi- tional in certain respects between parietal and occipital cortex. There is narrowing of overall cortical width, particularly at the expense of layers V and VI. Layer I1 becomes more conspicuous, layer IV and the hypocellular sublamina Va less con- spicuous. Field 3a is similar in its cell and fiber pattern to 3, though without barrels in layer 1V. The transition from 3a to 40 is marked by a general reduction in cell packing density. The granule cells of layer IV become more widely spaced and globular in a manner similar to layer IV of the cau- dally contiguous temporal region. Field 2 is more like field 3 because of the high cell density of layer IV, though this layer is narrower than in field 3. "
Summary:
This change is a minor edit.
Username: