Biomedical subjects

Diego Garbossa

Publications and source records attributed to Diego Garbossa.

4 recordsLinked to original sources

PubMed2005

Differential distribution of NADPH-diaphorase histochemistry in human cerebral cortex.

Beta-nicotinamidedinucleotide phosphate diaphorase (NADPH-d) colocalizes with NOS in the central nervous system. Two types of NADPH-d-positive neurons are present in the primate cerebral cortex: type 1, intensely and Golgi-like labeled neurons, a subset of GABAergic interneurons; type 2, lightly labeled neurons (divided into two subclasses, a first one having a lightly stained cell body bearing only one short process, and a second one showing intense NADPH-d staining with short processes extending radially). We have analyzed the distribution of NADPH-d activity in human frontal, temporal, and occipital cortical areas, finding remarkable laminar and interareal differences in cell size and distribution of the different cell types. There was a clear bias for type 1 neurons in infragranular layers in all areas considered; both in supra- and infragranular layers, their density was highest in frontal, and lowest in temporal cortex. The density of type 2 neurons was lower supragranularly in temporal cortex and infragranularly in occipital cortex. The overall density of type 2 cells was remarkably higher in occipital cortex than in the temporal and frontal ones. Type 1 neurons were significantly larger than type 2, and were smaller in the supragranular than in the infragranular subzone in occipital and temporal cortex. Type 1 cells were significantly larger in frontal cortex than in occipital and temporal cortex, and type 2 cells were significantly smaller in occipital than in temporal and frontal cortex. These area-related differences might reflect differences between heterotypic and homotypic cortex in the regulation of cortical blood flow.

Axons↗

PubMed2004

Somatodendritic minicolumns of output neurons in the rat visual cortex.

The apical dendrites of the pyramidal neurons of the cerebral cortex form radial bundles in all species and areas. Using microtubule-associated protein (MAP)2 immunostaining and Voronoi tessellation analysis in the rat visual cortex, we obtained objective criteria to define dendritic bundles in tangential sections: in supragranular layers of the rat visual cortex we found bundles of 6-6.4 dendrites, at a density of 1929 bundles/mm(2) and a centre-to-centre distance of 27 micro m. Using lipophilic tracers to label different pyramidal cell populations, based on the same criteria as in MAP2-immunostained material, we found that in the rat visual cortex the bundles consist of neurons with specific targets. Neurons projecting to the ipsi- or contralateral cortex form bundles together and with neurons projecting to the striatum, but not with those projecting to the superior colliculus, dorsal division of the lateral geniculate nucleus or through the cerebral peduncle. The latter neurons form bundles with neurons projecting to the striatum. Thus, the cerebral cortex is organized in minicolumns of output neurons visible at the earliest ages studied (P3), which might have a higher probability of being interconnected than those outside.

Age Factors↗

PubMed2003

Experimentally-induced microencephaly: effects on cortical neurons.

Genetic and epigenetic factors may alter the normal development of cerebral cortex, producing laminar and cellular abnormalities and heterotopiae, major causes of juvenile, drug-resistant epilepsy. Experimentally-induced migration disorders provide interesting insights in the mechanisms of the determination of neuronal phenotype and connectivity, of congenital cortical dysgenesis and the pathophysiology of associated neurological disorders, such as epilepsy. We investigated the effects of E14 administration of methylazoxymethanol acetate (MAM), which induces microencephaly by ablating dividing cells. Brains from newborn and adult rats were reacted for NADPH-d and CO histochemistry. Moreover, callosally-projecting neurons were retrogradely labeled with DiI at P9 or with BDA in adults. MAM-treated rats displayed a remarkable reduction in cortical thickness, mainly due to reduction in layer IV and in supragranular layers. Heterotopic nodules appeared in the supragranular layers and in the hippocampus. CO-positive barrels in somatosensory cortex were almost absent. The distribution of NADPH-d-positive neurons was regular, but they were rare in heterotopic nodules. Callosally-projecting neurons displayed abnormal orientation of the apical dendrite and increase in the basal dendritic length. Alterations in the dendritic arborization of pyramidal neurons may be one of the substrates for the increased sensitivity to drugs which induce epileptic seizures in these animals.

Animals↗

PubMed2002

Development of dendritic bundles of pyramidal neurons in the rat visual cortex.

The apical dendrites of pyramidal neurons in the cerebral cortex form vertical bundles whose distribution and density vary across species and areas. To understand their relationships with cortical columns, we labeled retrogradely neurons from the white matter underlying the visual cortex with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) at P3 and P10 and with biotinylated dextran amine at P30. We also mapped the distribution of apical dendrites in tangential sections, immunostained for microtubule-associated proteins (MAP2). Their composition and distribution were studied with Neurolucida and NeuroExplorer software. The apical dendrites of pyramidal neurons formed different bundle types: at P3 we found bundles formed (a) by neurons located in cortical plate; (b) by layer V neurons; and (c) by upper layer V neurons and cortical plate neurons. At P10, the amount of supragranular neurons participating in the bundles increased. The inter-dendritic and inter-bundle distances increased with age. These findings confirm that dendritic bundles are present in the rat visual cortex early in development and are formed by neurons belonging to different cortical layers. The existence of different types of bundles relative to the layer of location of their parent neurons suggests that they are heterogeneous from each other in nature and in the pattern of connectivity.

Animals↗