ZFIN ID: ZDB-PUB-070409-3
Asymmetric innervation of the habenula in zebrafish
Hendricks, M., and Jesuthasan, S.
Date: 2007
Source: The Journal of comparative neurology   502(4): 611-619 (Journal)
Registered Authors: Hendricks, Michael, Jesuthasan, Suresh
Keywords: habenula afferent, asymmetry, eminentia thalami, pallium, habenula commissure, neuropil
MeSH Terms:
  • Afferent Pathways/anatomy & histology*
  • Afferent Pathways/physiology
  • Animals
  • Axons/physiology
  • Axons/ultrastructure*
  • Brain Mapping
  • Carbocyanines
  • Diencephalon/anatomy & histology
  • Diencephalon/physiology
  • Functional Laterality/physiology
  • Habenula/anatomy & histology*
  • Habenula/physiology
  • Telencephalon/anatomy & histology
  • Telencephalon/physiology
  • Zebrafish/anatomy & histology*
  • Zebrafish/physiology
PubMed: 17394162 Full text @ J. Comp. Neurol.
The habenular complex is a paired structure found in the diencephalon of all vertebrates, linking the forebrain and midbrain. Habenulae are asymmetrical and may contribute to lateralized behavior. Recent studies in zebrafish have characterized molecular pathways that give rise to the habenular asymmetry and the distinct projections of the left and right habenula to the midbrain. However, it is unclear whether there are asymmetries in habenula afferents from the forebrain. By lipophilic dye tracing, we find that axons innervating the habenula derive primarily from a region in the lateral diencephalon containing migrated neurons of the eminentia thalami (EmT). EmT neurons terminate in neuropils in both ipsilateral and contralateral habenula. These axons, together with axons from migrated neurons of the posterior tuberculum and pallial neurons, cross the midline via the habenular commissure. Subsets of pallial neurons terminate only in the medial right habenula, regardless of which side of the brain they originate from. These include an unusual type of forebrain projection: axons that cross the midline twice, at both the anterior and habenular commissures. Our data establish that there is asymmetric innervation of the habenula from the telencephalon, suggesting a mechanism by which habenula asymmetry might contribute to lateralized behavior.