The HVC microcircuit: the synaptic basis for interactions between song motor and vocal plasticity pathways.

Published

Journal Article

Synaptic interactions between telencephalic neurons innervating descending motor or basal ganglia pathways are essential in the learning, planning, and execution of complex movements. Synaptic interactions within the songbird telencephalic nucleus HVC are implicated in motor and auditory activity associated with learned vocalizations. HVC contains projection neurons (PNs) (HVC(RA)) that innervate song premotor areas, other PNs (HVC(X)) that innervate a basal ganglia pathway necessary for vocal plasticity, and interneurons (HVC(INT)). During singing, HVC(RA) fire in temporally sparse bursts, possibly because of HVC(INT)-HVC(RA) interactions, and a corollary discharge can be detected in the basal ganglia pathway, likely because of synaptic transmission from HVC(RA) to HVC(X) cells. During song playback, local interactions, including inhibition onto HVC(X) cells, shape highly selective responses that distinguish HVC from its auditory afferents. To better understand the synaptic substrate for the motor and auditory properties of HVC, we made intracellular recordings from pairs of HVC neurons in adult male zebra finch brain slices and used spike-triggered averages to assess synaptic connectivity. A major synaptic interaction between the PNs was a disynaptic inhibition from HVC(RA) to HVC(X), which could link song motor signals in the two outputs of HVC and account for some of the song playback-evoked inhibition in HVC(X) cells. Furthermore, single interneurons made divergent connections onto PNs of both types, and either PN type could form reciprocal connections with interneurons. In these two regards, the synaptic architecture of HVC resembles that described in some pattern-generating networks, underscoring features likely to be important to singing and song learning.

Full Text

Duke Authors

Cited Authors

  • Mooney, R; Prather, JF

Published Date

  • February 23, 2005

Published In

Volume / Issue

  • 25 / 8

Start / End Page

  • 1952 - 1964

PubMed ID

  • 15728835

Pubmed Central ID

  • 15728835

Electronic International Standard Serial Number (EISSN)

  • 1529-2401

Digital Object Identifier (DOI)

  • 10.1523/JNEUROSCI.3726-04.2005

Language

  • eng

Conference Location

  • United States