Cytoarchitectonic mapping of the human dorsal extrastriate cortex

C. & O. Vogt Institute for Brain Research, University of Düsseldorf, Düsseldorf, Germany.
Brain Structure and Function (Impact Factor: 5.62). 02/2012; 218(1). DOI: 10.1007/s00429-012-0390-9
Source: PubMed


The dorsal visual stream consists of several functionally specialized areas, but most of their cytoarchitectonic correlates have not yet been identified in the human brain. The cortex adjacent to Brodmann area 18/V2 was therefore analyzed in serial sections of ten human post-mortem brains using morphometrical and multivariate statistical analyses for the definition of areal borders. Two previously unknown cytoarchitectonic areas (hOc3d, hOc4d) were detected. They occupy the medial and, to a smaller extent, lateral surface of the occipital lobe. The larger area, hOc3d, is located dorso-lateral to area V2 in the region of superior and transverse occipital, as well as parieto-occipital sulci. Area hOc4d was identified rostral to hOc3d; it differed from the latter by larger pyramidal cells in lower layer III, thinner layers V and VI, and a sharp cortex-white-matter borderline. The delineated areas were superimposed in the anatomical MNI space, and probabilistic maps were calculated. They show a relatively high intersubject variability in volume and position. Based on their location and neighborhood relationship, areas hOc3d and hOc4d are putative anatomical substrates of functionally defined areas V3d and V3a, a hypothesis that can now be tested by comparing probabilistic cytoarchitectonic maps and activation studies of the living human brain.

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Available from: Simon B Eickhoff, Jan 23, 2014
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    • "Handedness of the subjects was unknown. For the current analysis, 9 of the 10 brains from earlier anatomical studies of the visual cortex were used (Amunts et al. 2000; Rottschy et al. 2007; Caspers, Zilles, et al. 2013; Kujovic et al. 2013). One brain had to be replaced by another case because of artifacts in the respective histological sections through the region of interest. "
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    ABSTRACT: Areas of the fusiform gyrus (FG) within human ventral temporal cortex (VTC) process high-level visual information associated with faces, limbs, words, and places. Since classical cytoarchitectonic maps do not adequately reflect the functional and structural heterogeneity of the VTC, we studied the cytoarchitectonic segregation in a region, which is rostral to the recently identified cytoarchitectonic areas FG1 and FG2. Using an observer-independent and statistically testable parcellation method, we identify 2 new areas, FG3 and FG4, in 10 human postmortem brains on the mid-FG. The mid-fusiform sulcus reliably identifies the cytoarchitectonic transition between FG3 and FG4. We registered these cytoarchitectonic areas to the common reference space of the single-subject Montreal Neurological Institute (MNI) template and generated probability maps, which reflect the intersubject variability of both areas. Future studies can relate in vivo neuroimaging data with these microscopically defined cortical areas to functional parcellations. We discuss these results in the context of both large-scale functional maps and fine-scale functional clusters that have been identified within the human VTC. We propose that our observer-independent cytoarchitectonic parcellation of the FG better explains the functional heterogeneity of the FG compared with the homogeneity of classic cytoarchitectonic maps.
    Full-text · Article · Oct 2015 · Cerebral Cortex
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    • "Regions of interest ( ROIs ) were taken from the literature ( Geyer et al . , 1999 , 2000 ; Amunts et al . , 2000 ; Binkofski et al . , 2000 ; Rademacher et al . , 2001 ; Rottschy et al . , 2007 ; Scheperjans et al . , 2008 ; Caspers et al . , 2010 , 2013 ; Kolster et al . , 2010 ; Kujovic et al . , 2013 ) ; they were defined as 6 - mm radius spheres in both hemispheres . We included 15 seeds to assess functional connectivity ( Table 2 , Figure 1 ) . These seeds were selected within the occipital cortex ( i . e . , V1 , V2 , hOC3V , hOC3D , hOC4V , hOC4D , MT / V5 , and fusiform gyrus ) , parietal cortex ( S1 , lateral BA5 , anterior BA"
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    ABSTRACT: There is ample evidence that congenitally blind individuals rely more strongly on non-visual information compared to sighted controls when interacting with the outside world. Although brain imaging studies indicate that congenitally blind individuals recruit occipital areas when performing various non-visual and cognitive tasks, it remains unclear through which pathways this is accomplished. To address this question, we compared resting state functional connectivity in a group of congenital blind and matched sighted control subjects. We used a seed-based analysis with a priori specified regions-of-interest (ROIs) within visual, somato-sensory, auditory and language areas. Between-group comparisons revealed increased functional connectivity within both the ventral and the dorsal visual streams in blind participants, whereas connectivity between the two streams was reduced. In addition, our data revealed stronger functional connectivity in blind participants between the visual ROIs and areas implicated in language and tactile (Braille) processing such as the inferior frontal gyrus (Broca's area), thalamus, supramarginal gyrus and cerebellum. The observed group differences underscore the extent of the cross-modal reorganization in the brain and the supra-modal function of the occipital cortex in congenitally blind individuals.
    Full-text · Article · Jul 2015 · Frontiers in Neuroanatomy
    • "Zilles & Amunts, 2010). The following areas were considered: primary and secondary visual cortex: areas hOc1, hOc2 (corresponding to V1, V2; or BA 17 and 18 accordingly; Amunts et al., 2000); ventral extrastriate areas hOc3v, hOc4v (corresponding to V3v, V4; Rottschy et al., 2007); dorsal extrastriate areas hOc3d, hOc4d (V3d, V3A; Kú jovic et al., 2013); as well as extrastriate area hOc5 (V5; Malikovic et al., 2007), and the posterior fusiform areas FG1, FG2 (Caspers et al., 2013). "
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    ABSTRACT: Transcallosal fibers of the visual system have preferential target sites within the occipital cortex of monkeys. These target sites coincide with vertical meridian representations of the visual field at borders of retinotopically defined visual areas. The existence of preferential target sites of transcallosal fibers in the human brain at the borders of early visual areas was claimed, but controversially discussed. Hence, we studied the distribution of transcallosal fibers in human visual cortex, searching for an organizational principle across early and higher visual areas. In-vivo high angular resolution diffusion imaging data of 28 subjects were used for probabilistic fiber tracking using a constrained spherical deconvolution approach. The fiber architecture within the target sites was analyzed at microscopic resolution using 3D polarized light imaging in a post-mortem human hemisphere. Fibers through a seed in the splenium of the corpus callosum reached the occipital cortex via the forceps major and the tapetum. We found target sites of these transcallosal fibers at borders of cytoarchitectonically defined occipital areas not only between early visual areas V1 and V2, V3d and V3A, and V3v and V4, but also between higher extrastriate areas, namely V4 (ventral) and posterior fusiform area FG1 as well as posterior fusiform area FG2 and lateral occipital cortex. In early visual areas, the target sites coincided with the vertical meridian representations of retinotopic maps. The spatial arrangement of the fibers in the 'border tuft' region at the V1/V2 border was found to be more complex than previously observed in myeloarchitectonic studies. In higher visual areas, our results provided additional evidence for a hemi-field representation in human area V4. The fiber topography in posterior fusiform gyrus indicated that additional retinotopic areas might exist, located between the recently identified retinotopic representations phPITv/phPITd and PHC-1/PHC-2 in lateral occipital cortex and parahippocampal gyrus. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · Jan 2015 · Cortex
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