Original Paper

Cytoarchitecture of Vocal Control Nuclei in Nestling Budgerigars: Relationships to Call Development
William S. Hall, Kelly K. Cookson, James T. Heaton, Todd F. Roberts, Stephen D. Shea, Stuart K. Amateau, Steven E. Brauth

Department of Psychology, University of Maryland, College Park, Md., USA

Address of Corresponding Author

Brain Behav Evol 1999;53:198-226 (DOI: 10.1159/000006595)

  Key Words

• Parrot vocal development
• Vocal learning
• Brain development
• Cytoarchitectural development
• Budgerigars
• Call development
• Vocal control nuclei

  Abstract

Changes in the cytoarchitecture of vocal control nuclei were investigated in nestling budgerigars (Melopsittacus undulatus) from hatching to fledging (five to six weeks) in relation to changes in vocalizations produced by nestlings during this period. The nuclei investigated were the hypoglossal nucleus, dorsomedial nucleus of the intercollicular midbrain, central nucleus of the archistriatum, central nucleus of the lateral neostriatum, oval nucleus of the hyperstriatum ventrale, medial division of the oval nucleus of the anterior neostriatum, and magnocellular nucleus of the lobus parolfactorius. These nuclei have been shown to form functional circuits in adults related to vocal learning. Consistent with previously reported results, we found that call development could be described in terms of five different phases based on changes in the duration and segmentation of single and multiple segment foodbegging calls and the appearance of the first socially learned contact calls around the time of fledging. We also found that call segment duration exhibited an inverted U-shaped developmental function during the nestling period, as has been found for total call duration. Cytoarchitectonic studies revealed striking changes in the cellular architecture of vocal control nuclei during the first four weeks posthatching. At hatching the hypoglossal nucleus exhibits adult-like cytoarchitecture, and the central nucleus of the archistriatum and the central nucleus of the lateral neostriatum are distinguishable from surrounding fields. By one week posthatch, the central nucleus of the archistriatum exhibits an adult-like appearance, while other telencephalic vocal control nuclei do not exhibit adult-like cytoarchitecture until three to four weeks posthatching. By two weeks posthatching, the dorsomedial nucleus of the intercollicular midbrain also exhibits adult-like cytoarchitecture. We observed substantial decreases in the thickness of ventricular proliferation zones during this period, with decreases in ventricular zones occurring at about the same point that nuclei at corresponding levels come to exhibit adult-like cytoarchitectonic features. Of interest is the fact that cytoarchitectural development occurs asynchronously in different brain regions, with the appearance of adult-like characteristics in the hindbrain and midbrain occurring before the appearance of adult-like cytoarchitectonic characteristics in telencephalic nuclei. These results are consistent with recent lesion studies indicating that neither auditory feedback nor telencephalic vocal control nuclei are necessary for the production of foodbegging and other nestling calls until three to four weeks posthatching.

  Author Contacts

William S. Hall, PhD
Department of Psychology, University of Maryland
College Park, MD 20742 (USA)
Tel. 301-405-5788, Fax 301-405-5869
E-Mail hall@bss3.umd.edu

  Article Information

Abbreviations

Budgerigar

A = archistriatum

AAc = central nucleus of the anterior archistriatum

AAcd = dorsal subdivision of AAc

AAcv = ventral subdivision of AAc

DM = dorsomedial nucleus of the intercollicular midbrain

DMm = magnocellular nucleus of the dorsomedial thalamus

DMP = nucleus dorsomedialis posterior

HV = hyperstriatum ventrale

HVo = oval nucleus of the ventral hyperstriatum

MLd = lateral dorsal mesencephalic nucleus

LFS = superior frontal lamina

LH = hyperstriatal lamina

LMD = dorsal medullary lamina

LPO = lobus parolfactorius

LPOm = magnocellular nucleus of the lobus parolfactorius

N = neostriatum

NAo = oval nucleus of the anterior neostriatum

NAom = medial division of the oval nucleus of the anterior neostriatum

NL = lateral neostriatum

NLc = central nucleus of the lateral neostriatum

nXII = nucleus nervi hypoglossi

nXIIts = tracheosyringeal portion of the hypoglossal nucleus

PA = paleostriatum augmentatum

SGP = substantia grisea et fibrosa periventricularis

Zebra Finch

Area X = area X of the paraolfactory lobe

DLM = medial portion of the dorsolateral portion of the thalamic nucleus

DMP = posterior portion of the dorsomedial thalamic nucleus

HVC = high vocal center

pHVC = paraHVC

IMAN = lateral magnocellular nucleus of the anterior neostriatum

mMAN = medial magnocellular nucleus of the anterior neostriatum

RA = robust nucleus of the archistriatum

Number of Print Pages : 29
Number of Figures : 16, Number of Tables : 4, Number of References : 45