Number and laminar distribution of neurons in a thalamocortical projection column of rat vibrissal cortex.
This is the second article in a series of three studies that investigate the anatomical determinants of thalamocortical (TC) input to excitatory neurons in a cortical column of rat primary somatosensory cortex (S1). Here, we report the number and distribution of NeuN-positive neurons within the C2, D2, and D3 TC projection columns in P27 rat somatosensory barrel cortex based on an exhaustive identification of 89,834 somata in a 1.15 mm(3) volume of cortex. A single column contained 19,109 ± 444 neurons (17,560 ± 399 when normalized to a standard-size projection column). Neuron density differences along the vertical column axis delineated "cytoarchitectonic" layers. The resulting neuron numbers per layer in the average column were 63 ± 10 (L1), 2039 ± 524 (L2), 3735 ± 905 (L3), 4447 ± 439 (L4), 1737 ± 251 (L5A), 2235 ± 99 (L5B), 3786 ± 168 (L6A), and 1066 ± 170 (L6B). These data were then used to derive the layer-specific action potential (AP) output of a projection column. The estimates confirmed previous reports suggesting that the ensembles of spiny L4 and thick-tufted pyramidal neurons emit the major fraction of APs of a column. The number of APs evoked in a column by a sensory stimulus (principal whisker deflection) was estimated as 4441 within 100 ms post-stimulus.
Department of Cell Physiology, Max Planck Institute for Medical Research, D-69120 Heidelberg, Germany. Hanno-S.Meyer@mpimf-heidelberg.mpg.de
Hanno S
HS
Meyer
Verena C
VC
Wimmer
M
M
Oberlaender
Christiaan P J
CP
de Kock
Bert
B
Sakmann
Moritz
M
Helmstaedter
D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count / Q000379:methods; D000229:Dependovirus / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005968:Glutamate Decarboxylase / Q000378:metabolism; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000145:classification / Q000166:cytology / Q000502:physiology*; D009716:Numerical Analysis, Computer-Assisted; D018408:Patch-Clamp Techniques / Q000379:methods; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000033:anatomy & histology*; D020651:Ventral Thalamic Nuclei / Q000166:cytology* / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation*
D008164:Luminescent Proteins; C413663:fluorescent protein 583; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D010751:Phosphopyruvate Hydratase