Analysis of nerve fibers and their distribution in histologic sections of the human brain

Abstract

The field of quantitative analysis and subsequent mapping of the cerebral cortex has developed rapidly. New powerful tools have been applied to investigate large regions of complex folded gyrencephalic cortices in order to detect structural transition regions that might partition different cortical fields of disjunct neuronal functions. We have developed a new mapping approach based on axoarchitectonics, a method of cortical visualization that previously has been used only indirectly with regard to myeloarchitectonics. Myeloarchitectonic visualization has the disadvantage of producing strong agglomerative effects of closely neighbored nerve fibers. Therefore, single and neurofunctional-relevant parameters such as axonal branchings, axon areas, and axon numbers have not been determinable with satisfying precision. As a result, different staining techniques had to be explored in order to achieve a suitable histologic staining for axon visualization. The best results were obtained after modifying the Naoumenko-Feigin staining for axons. From these contrast-rich stained histologic sections, videomicroscopic digital image tiles were generated and analyzed using a new fiber analysis framework. Finally, the analysis of histologic images provided topologic ordered parameters of axons that were transferred into parameter maps. The axon parameter maps were analyzed further via a recently developed traverse generating algorithm that calculated test lines oriented perpendicular to the cortical surface and white matter border. The gray value coded parameters of the parameter maps were then transferred into profile arrays. These profile arrays were statistically analyzed by a reliable excess mass approach we recently developed. We found that specific axonal parameters are preferentially distributed throughout granular and agranular types of cortex. Furthermore, our new procedure detected transition regions originally defined by changes of cytoarchitectonic layering. Statistically significant inhomogeneities of the distribution of certain axon quantities were shown to indicate a subparcellation of areas 4 and 6. The quantification techniques established here for the analysis of spatial axon distributions within larger regions of the cerebral cortex are suitable to detect inhomogeneities of laminar axon patterns. Hence, these techniques can be recommended for systematic and observer-supported cortical area mapping and parcellation studies.

Quantitative architectural analysis: a new approach to cortical mapping

“…Algorithm-based mapping procedures are not limited to the analysis of cytoarchitectonic images, but can be applied to all architectural modalities which reveal a quantifiable, laminar cortical pattern. Typical examples are specimens stained for acetylcholinesterase (AChE; Hackett et al 2001), receptorarchitecture (Geyer et al 1996;Morosan et al 2004b) and myeloarchitecture (Annese et al 2004;Schmitt et al 2004). Recently, Fatterpekar et al (2002) depicted the laminar pattern in some neocortical areas using MR-microscopy in post mortem, fixed human brains.…”

“…In a myeloarchitectural study, the traditional optical density measurement (e.g. Hopf 1968a) has been extended to structural parameters such as fibre density and orientation (Schmitt et al 2004). …”

Examining brain microstructure using structure tensor analysis of histological sections

“…Since the identical parameters are derived from structure tensor analysis of histological sections, direct comparisons between the two modalities were straightforward. ST analysis is a widely used technique in the realm of digital image and video processing (Bigun et al, 2004) and has previously been applied to human tissue sections (Schmitt and Birkholz, 2010;Schmitt et al, 2004). The application of ST analysis using a local neighborhood (i.e.…”

Three-dimensional cytoarchitectonic analysis of the posterior bank of the human precentral sulcus

“…However, other investigators have observed distinct rostral-occipital differences, which were designated as FB , FC (B) and FC region (von Economo and Koskinas 1925); 6a, 6, 6p and 6op regions (Sarkissov et al 1955); 39bL, 38b, 39bb, 39c, 40b, 40L, 42d-L and 44a regions (Ngowyang 1934); 6aa, 6ab, 6ba and 6bb regions (Vogt and Vogt 1919;Foerster 1931); the frontomotoric zone of Sanides consists of five sub-regions: 37-42 (Sanides 1962) ( Table 1). Descriptive myeloarchitectonic investigations differentiated up to eight areas (Vogt 1910: area 38-44, 55) (Strasburger 1937: 37-39, 41a, 42, 44, and 55b) and a quantitative mapping study (Schmitt et al 2004a) provided evidence of a subdivision of BA 6 into rostrooccipital parts. At the very least, pigmentarchitectonic findings present a convincing argument for the existence of a homogeneous region (Braak 1980).…”