Spiny cell local collaterals inputs GABA and peptide

Spiny cell local collaterals inputs (GABA and peptide) 

1988) in boutons presynaptic to striatal spiny neurons reveal similar distribution patterns. Such inputs are distributed on the cell soma or smooth proximal part of the dendrites, to interspine dendritic shafts or to the dendritic spines. In all cases, the morphological appearance and the distribution of spiny cell collaterals is similar to that of the dopaminergic input. Izzo and Bolam (1986) reported that substance P containing boutons make synaptic contact most often with the more proximal parts of the dendrites, both the soma and smooth parts and the proximal spiny portions. This is somewhat contrasted with the dopamine containing inputs that more frequently target more distal dendritic portions. 

As will be described in some detail, spiny neurons are subdivided into different subpopulations that are both connectionally and neurochemically distinct, although all share a common morphology and use GABA as a transmitter. Thus, it is of some interest whether the local collaterals of these neurons target neurons of their own subpopulation or those of another subset. Bolam and Izzo (1988) have directly demonstrated that substance P immunoreactive boutons make synaptic contact with striatonigral neurons 

Boutons immunoreactive for choline acetyltransferase (ChAT) make synaptic contacts with striatal spiny neurons as well as other striatal cells (Izzo and Bolam 1988). The cholinergic synapses are symmetric and make contact with the cell somata (20%) dendritic shafts (45%) and with dendritic spines (34%). As with the other symmetrical synapses on dendritic spines, these share the spine with an asymmetrical synapse, usually placed more distally on the spine, similar to afferents from the cerebral cortex and thalamus. 

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