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Subbarrel patterns of thalamocortical innervation in rat somatosensory cortical barrels: Organization and postnatal development
Author(s) -
Louderback Katherine M.,
Glass Christina S.,
ShamallaHannah Lorraine,
Erickson Susan L.,
Land Peter W.
Publication year - 2006
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.20969
Subject(s) - somatosensory system , biology , axon , neuroscience , barrel (horology) , barrel cortex , thalamus , anatomy , cytochrome c oxidase , serotonin transporter , cortex (anatomy) , immunohistochemistry , serotonin , microbiology and biotechnology , biochemistry , materials science , receptor , mitochondrion , composite material , immunology
Abstract Barrel hollows in the posteromedial barrel subfield of adult rat somatosensory cortex typically encompass two or three metabolically and structurally distinct regions, termed subbarrels. We used immunohistochemical staining for vesicular glutamate transporter 2 and the neuronal serotonin transporter, in conjunction with cytochrome oxidase (CO) histochemistry, to investigate the distribution of thalamocortical (TC) axon terminals in relation to subbarrel domains. We found, first, that CO‐dark subbarrels are more intensely immunoreactive for thalamocortical terminals than the CO‐light clefts that separate them. Second, during the first postnatal week, immunoreactivity for markers of TC terminals is relatively homogeneous throughout the barrel hollow; subbarrel patterns of distribution only become recognizable between P‐8 and P‐10. These observations extend previous findings that subbarrels denote barrel regions enriched in synaptic contacts. The data also indicate that allocation of TC terminals into subbarrel domains does not occur immediately upon thalamic axon ingrowth. Instead, refinement of TC arbors into subbarrels is a gradual process, the outcome of which is not manifest until the second week of postnatal life. J. Comp. Neurol. 497:32–41, 2006. © 2006 Wiley‐Liss, Inc.