Physiology and morphology of intratelencephalically projecting corticostriatal-type neurons in pigeons as revealed by intracellular recording and cell filling

Anton Reiner, E. A. Stern, C. J. Wilson

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Much of the Wulst and dorsal ventricular ridge (DVR) in birds, which together make up the part of the avian telencephalon functionally resembling mammalian cerebral cortex, projects to the striatum. Those connections arise from neurons projecting additionally to the brainstem as well as from neurons projecting only within the telencephalon. As part of an effort to further characterize corticostriatal-type projection neurons in birds, we recorded intracellularly from neurons of the outer DVR, identified neurons projecting to the striatum by antidromic stimulation from the ipsilateral rostromedial striatum or subsequently by their axonal projection, characterized these neurons physiologically and then filled them with biocytin. As neurons in the outer DVR only project within telencephalon, neurons within it projecting to the striatum are of the intratelencephalically projecting (IT) type. Our studies suggest that: (1) the membrane potentials of avian IT-type neurons fluctuate between two preferred subthreshold values, and action potentials occur only in the 'up' state, (2) avian IT-type neurons show a time-dependent inward rectification in response to hyperpolarization and regular firing in response to constant current injection, (3) the conduction velocity of avian IT-type neurons is slow (about 0.2 m/s), (4) avian IT-type neurons possess radially disposed densely spiny dendrites but no apical dendrite, (5) avian IT-type neurons have local and distant collateral projections within the DVR, and (6) individual avian IT-type neurons give rise to an extensive terminal field within the striatum. Aside from the shape of their dendritic tree, IT-type neurons in birds closely resemble IT-type corti-costriatal neurons in mammals in these various aspects, although it is presently uncertain whether this neuron type has been inherited in common by birds and mammals from stem amniotes.

Original languageEnglish
Pages (from-to)101-114
Number of pages14
JournalBrain, Behavior and Evolution
Volume58
Issue number2
DOIs
StatePublished - 2001
Externally publishedYes

Funding

FundersFunder number
National Institute of Neurological Disorders and StrokeR01NS020743

    Keywords

    • Basal ganglia
    • Birds
    • Cortex
    • Evolution
    • Pigeons
    • Striatum
    • Telencephalon

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