Convergence of excitatory synaptic inputs to caudate spiny neurons.

Intracellular recordings were obtained from cat caudate nucleus neurons. These cells responded with convergent, monosynaptic EPSPs to cerebral cortex, intralaminar thalamus, and substantia nigra stimulation. Intracellular injection of horseradish peroxidase into these electrophysiologically defined neurons shows that they represent the spiny neuron of the caudate based upon somadendritic morphology. The axons of these cells are appreciably longer than previous reports indicate. Several lines of evidence are discussed to question the intrinsic nature of these neurons.