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.
Vercelli
Alessandro E
AE
Department of Anatomy, Pharmacology and Forensic Medicine, corso M. d'Azeglio 52, 10126 Torino, Italy. alessandro.vercelli@unito.it
Garbossa
Diego
D
Curtetti
Roberta
R
Innocenti
Giorgio M
GM
D000367:Age Factors; D000596:Amino Acids / Q000378:metabolism / Q000493:pharmacokinetics; D000818:Animals; D000831:Animals, Newborn; D001931:Brain Mapping; D002452:Cell Count / Q000379:methods; D003712:Dendrites / Q000378:metabolism / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D011726:Pyridinium Compounds / Q000493:pharmacokinetics; D051381:Rats; D014793:Visual Cortex / Q000166:cytology* / Q000254:growth & development; D014795:Visual Pathways / Q000378:metabolism
D000596:Amino Acids; D008869:Microtubule-Associated Proteins; D011726:Pyridinium Compounds; C098463:dolaisoleucine; C076868:4-(4-dihexadecylaminostyryl)-N-methylpyridium