Jovo Tosevski

Occipital sulci of the human brain: variability and morphometry

The external morphology of the occipital lobe was investigated in 15 human post-mortem brains (30 hemispheres) fixed in formalin. We identified, described and measured the lengths of nine major human occipital sulci and five variable ones, comparing both types between individuals and hemispheres. Morphological variability of human occipital sulci is related to interindividual and interhemispheric differences in their presence, origin, type, segmentation, intersection and length. The major occipital sulci, particularly the parieto-occipital, the calcarine, the inferior lateral occipital and the anterior occipital sulci, as well as two points of their intersections (cuneal point and intersection of the transverse occipital and superior occipital sulcus) may be used as reliable anatomical landmarks for the location of architectonically and functionally defined human visual areas (V1, V2, V3, V3A, V5/MT+, LO1 and LO2) and during less invasive neurosurgical procedures in the cases of focal lesions within the occipital lobe. Two lateral occipital sulci (inferior and superior) were defined on the lateral surface of the occipital lobe. The variable lunate sulcus was studied and combining our results with those from histological and functional imaging studies, we suggest that the lunate sulci of human and nonhuman primates are not homologous.

Types of neurons and some dendritic patterns of basolateral amygdala in humans--a golgi study.

Classification of the neurons in the human basolateral amygdala is performed on preparations impregnated by the Golgi technique. Three different neuronal types are found in the nuclei of the basolateral amygdala: Type I--Pyramidal cells, with numerous dendritic spines and two subtypes (slender and squat); Type II--Modified pyramidal cells, sparsely spinous with rare dendritic spines and two subtypes (single apical and double apical) and; Type III--Non-pyramidal cells, with few dendritic spines and three subtypes (bipolar, multipolar and gliaform). The analysis of the primary dendritic branches pointed out the occasional presence of dendritic bundles (fascicular dendritic arrangement) with their predomination in the parvicellular division of the basal nucleus and paralaminar nucleus. Additionally, the presence of dendrodendritic contacts, indicated by light microscopy, was also found in the parvicellular division of the basal nucleus and especially in the paralaminar nucleus.

Neurons of human nucleus accumbens.

BACKGROUND/AIM Nucleus accumbens is a part of the ventral striatum also known as a drug active brain region, especially related with drug addiction. The aim of the study was to investigate the Golgi morphology of the nucleus accumbens neurons. METHODS The study was performed on the frontal and sagittal sections of 15 human brains by the Golgi Kopsch method. We classified neurons in the human nucleus accumbens according to their morphology and size into four types: type I--fusiform neurons; type II--fusiform neurons with lateral dendrite, arising from a part of the cell body; type III--pyramidal-like neuron; type IV--multipolar neuron. The medium spiny neurons, which are mostly noted regarding to the drug addictive conditions of the brain, correspond to the type IV--multipolar neurons. RESULTS Two regions of human nucleus accumbens could be clearly recognized on Nissl and Golgi preparations each containing different predominant neuronal types. Central part of nucleus accumbens, core region, has a low density of impregnated neurons with predominant type III, pyramidal-like neurons, with spines on secondary branches and rare type IV, multipolar neurons. Contrary to the core, peripheral region, shell of nucleus, has a high density of impregnated neurons predominantly contained of type I and type IV--multipolar neurons, which all are rich in spines on secondary and tertiary dendritic branches. CONCLUSION Our results indicate great morphological variability of human nucleus accumbens neurons. This requires further investigations and clarifying clinical significance of this important brain region.

Fractal analysis of dendritic arborization patterns of pyramidal neurons in human basolateral amygdala

Background It is well known that there is important role of amygdala in emotional-cognitive processes, i.e. in emotional and associative learning, fear acquisition and emotional memory [1]. We investigated dendritic branching patterns of pyramidal neurons which are believed to be excitatory. According to our earlier findings pyramidal neurons in human basolateral amygdala have two subtypes pyramidal slender and pyramidal squat neurons [2]. Fractal analysis, which comes from Mandelbrots fractal geometry [3], is used as a tool for differentiation of the complexity of neuronal dendritic branching patterns. The measure of dendritic branching represents the fractal dimension of the neuron. In performing this study, we have applied the fractal analysis to the images of neurons, in order to investigate its capability to distinguish between subtypes.

The neurons of the human magnocellular septal nuclei: A Golgi study

The morphology of neurons in the magnocellular septal nuclei (medial septal and diagonal band nucleus) were studied in frontal sections of 15 human brains by means of the Golgi method. We classified neurons in the diagonal band nucleus according to their size and morphology into four types: type I--multipolar neurons, type II--fusiform neurons, type III--triangular neurons and type IV--fusiform multipolar neurons. The neurons of the medial septal nucleus we classified into two types: type I--multipolar neurons and type II--fusiform neurons. Our results indicated greater morphological variability of neurons in the human diagonal band nucleus than in the medial septal nucleus.