The excitatory thalamo-"cortical" projection within the song control system of zebra finches is formed by calbindin-expressing neurons

Raphael Pinaud, Colin J. Saldanha, Ryan D. Wynne, Peter V. Lovell, Claudio V. Mello

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

The learning and production of vocalizations in songbirds are controlled by a system of interconnected brain nuclei organized into a direct vocal motor pathway and an anterior forebrain (pallium-basal ganglia-thalamo-pallial) loop. Here we show that the thalamo-pallial ("thalamo-cortical") projection (from the medial part of the dorsolateral thalamic nucleus to the lateral magnocellular nucleus of the anterior nidopallium - DLM to LMAN) within the anterior forebrain loop is composed of cells positive for the calcium-binding protein calbindin. We show that the vast majority of cells within DLM express calbindin, based both on immunocytochemistry (ICC) for calbindin protein and in situ hybridization for calb mRNA. Using a combination of tract-tracing and ICC we show that the neurons that participate in the DLM-to-LMAN projection are calbindin-positive. We also demonstrate that DLM is devoid of cells expressing mRNA for the GABAergic marker zGAD65. This observation confirms that the calbindin-expressing cells in DLM are not GABAergic, in accordance with previous electrophysiological data indicating that the DLM-to-LMAN projection is excitatory. Furthermore, we use ICC to determine the trajectory of the fibers within the DLM-to-LMAN projection, and to demonstrate a sex difference in calbindin expression levels in the fibers of the DLM-to-LMAN projection. Our findings provide a clear-cut neurochemical signature for a critical projection in the songbird vocal control pathways that enable song learning.

Original languageEnglish (US)
Pages (from-to)601-618
Number of pages18
JournalJournal of Comparative Neurology
Volume504
Issue number6
DOIs
StatePublished - Oct 20 2007

Keywords

  • Calbindin
  • DLM
  • LMAN
  • Projection
  • Songbird
  • Thalamo-cortical
  • Vocal learning

ASJC Scopus subject areas

  • Neuroscience(all)

Fingerprint Dive into the research topics of 'The excitatory thalamo-"cortical" projection within the song control system of zebra finches is formed by calbindin-expressing neurons'. Together they form a unique fingerprint.

  • Cite this