4 research outputs found
Differential organization of cortical inputs to striatal projection neurons of the matrix compartment in rats
In prior studies, we described the differential organization of corticostriatal and
thalamostriatal inputs to the spines of direct pathway (dSPNs) and indirect
pathway striatal projection neurons (iSPNs) of the matrix compartment. In the
present electron microscopic (EM) analysis, we have refined understanding of
the relative amounts of cortical axospinous vs. axodendritic input to the two
types of SPNs. Of note, we found that individual dSPNs receive about twice as
many axospinous synaptic terminals from IT-type (intratelencephalically projecting)
cortical neurons as they do from PT-type (pyramidal tract projecting) cortical
neurons. We also found that PT-type axospinous synaptic terminals were about 1.5
times as common on individual iSPNs as IT-type axospinous synaptic terminals.
Overall, a higher percentage of IT-type terminals contacted dSPN than iSPN
spines, while a higher percentage of PT-type terminals contacted iSPN than
dSPN spines. Notably, IT-type axospinous synaptic terminals were significantly
larger on iSPN spines than on dSPN spines. By contrast to axospinous
input, the axodendritic PT-type input to dSPNs was more substantial than that
to iSPNs, and the axodendritic IT-type input appeared to be meager and
comparable for both SPN types. The prominent axodendritic PT-type input to
dSPNs may accentuate their PT-type responsiveness, and the large size of
axospinous IT-type terminals on iSPNs may accentuate their IT-type responsiveness.
Using transneuronal labeling with rabies virus to selectively label the cortical
neurons with direct input to the dSPNs projecting to the substantia nigra pars
reticulata, we found that the input predominantly arose from neurons in the upper
layers of motor cortices, in which IT-type perikarya predominate. The differential
cortical input to SPNs is likely to play key roles in motor control and motor
learning
Differential organization of cortical inputs to striatal projection neurons of the matrix compartment in rats
In prior studies, we described the differential organization of corticostriatal and
thalamostriatal inputs to the spines of direct pathway (dSPNs) and indirect
pathway striatal projection neurons (iSPNs) of the matrix compartment. In the
present electron microscopic (EM) analysis, we have refined understanding of
the relative amounts of cortical axospinous vs. axodendritic input to the two
types of SPNs. Of note, we found that individual dSPNs receive about twice as
many axospinous synaptic terminals from IT-type (intratelencephalically projecting)
cortical neurons as they do from PT-type (pyramidal tract projecting) cortical
neurons. We also found that PT-type axospinous synaptic terminals were about 1.5
times as common on individual iSPNs as IT-type axospinous synaptic terminals.
Overall, a higher percentage of IT-type terminals contacted dSPN than iSPN
spines, while a higher percentage of PT-type terminals contacted iSPN than
dSPN spines. Notably, IT-type axospinous synaptic terminals were significantly
larger on iSPN spines than on dSPN spines. By contrast to axospinous
input, the axodendritic PT-type input to dSPNs was more substantial than that
to iSPNs, and the axodendritic IT-type input appeared to be meager and
comparable for both SPN types. The prominent axodendritic PT-type input to
dSPNs may accentuate their PT-type responsiveness, and the large size of
axospinous IT-type terminals on iSPNs may accentuate their IT-type responsiveness.
Using transneuronal labeling with rabies virus to selectively label the cortical
neurons with direct input to the dSPNs projecting to the substantia nigra pars
reticulata, we found that the input predominantly arose from neurons in the upper
layers of motor cortices, in which IT-type perikarya predominate. The differential
cortical input to SPNs is likely to play key roles in motor control and motor
learning