|
LESF00
|
Literature
38 records
|
excitatory spiny neurons in layer 4 of the rat barrel cortex.
particularly prominent in the "barrel" field of the somatosensory
cortex. Here we describe the morphology of two classes of synaptically coupled
excitatory neurons in layer 4 of the barrel cortex, spiny stellate, and star
pyramidal cells, respectively. Within a single barrel, their somata tend to be
organized in clusters. The dendritic arbors are largely confined to layer 4,
except for the distal part of the apical dendrite of star pyramidal neurons
that extends into layer 2/3. In contrast, the axon of both types of neurons
spans the cortex from layer 1 to layer 6. The most prominent axonal
projections are those to layers 4 and 2/3 where they are largely restricted to
a single cortical column. In layers 5 and 6, a small fraction of axon
collaterals projects also across cortical columns. Consistent with the dense
axonal projection to layers 4 and 2/3, the total number and density of boutons
per unit axonal length was also highest there. Electron microscopy combined
with GABA postimmunogold labeling revealed that most (>90%) of the synaptic
contacts were established on dendritic spines and shafts of excitatory neurons
in layers 4 and 2/3. The largely columnar organization of dendrites and axons
of both cell types, combined with the preferential and dense projections
within cortical layers 4 and 2/3, suggests that spiny stellate and star
pyramidal neurons of layer 4 serve to amplify thalamic input and relay
excitation vertically within a single cortical column.
