Anatomically discrete sex differences in neuroplasticity in zebra finches as reflected by perineuronal nets

PLoS One. 2015 Apr 7;10(4):e0123199. doi: 10.1371/journal.pone.0123199. eCollection 2015.


Large morphological sex differences in the vertebrate brain were initially identified in song control nuclei of oscines. Besides gross differences between volumes of nuclei in males and females, sex differences also concern the size and dendritic arborization of neurons and various neurochemical markers, such as the calcium-binding protein parvalbumin (PV). Perineuronal nets (PNN) of the extracellular matrix are aggregates of different compounds, mainly chondroitin sulfate proteoglycans, that surround subsets of neurons, often expressing PV. PNN develop in zebra finches song control nuclei around the end of the sensitive period for song learning and tutor deprivation, known to delay the end of the song learning sensitive period, decreases the numbers of PNN in HVC. We demonstrate here the existence in zebra finches of a major sex difference (males > females) affecting the number of PNN (especially those surrounding PV-positive cells) in HVC and to a smaller extent the robust nucleus of the arcopallium, RA, the two main nuclei controlling song production. These differences were not present in Area X and LMAN, the lateral magnocellular nucleus of the anterior nidopallium. A dense expression of material immunoreactive for chondroitin sulfate was also detected in several nuclei of the auditory and visual pathways. This material was often organized in perineuronal rings but quantification of these PNN did not reveal any sex difference with the exception that the percentage of PNN surrounding PV-ir cells in the dorsal lateral mesencephalic nucleus, MLd, was larger in females than in males, a sex difference in the opposite direction compared to what is seen in HVC and RA. These data confirm and extend previous studies demonstrating the sex difference affecting PNN in HVC-RA by showing that this sex difference is anatomically specific and does not concern visual or auditory pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avian Proteins / metabolism
  • Brain / cytology
  • Brain / metabolism
  • Female
  • Finches / anatomy & histology*
  • Male
  • Nerve Net / cytology
  • Nerve Net / metabolism*
  • Neuronal Plasticity*
  • Parvalbumins / metabolism
  • Sex Characteristics
  • Vocalization, Animal


  • Avian Proteins
  • Parvalbumins

Grants and funding

Funding for this work was provided by a grant from the Belgian Science Policy (BELSPO: SSTC PAI P7/17; url: to JB and CAC. CAC is Research Associate of the Fonds National de la Recherche Scientifique (F.R.S.-FNRS; url: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.