Glutamatergic thalamopallial projections in the pigeon identified by retrograde labeling and expression of vGluT2 mRNA

• Published in: Neuroscience research 2014-07, Vol.84, p.43-46
• Main Authors: Atoji, Yasuro, Karim, Mohammad Rabiul
• Format: Article
• Language: English
• Subjects: Animals; Bird; Cholera Toxin - metabolism; Columbidae; Entopallium; Field L2; Globus Pallidus - cytology; Glutamic Acid - metabolism; Homology; Layer 4; Neocortex - metabolism; Neurons - metabolism; Receptors, AMPA - genetics; Receptors, AMPA - metabolism; RNA, Messenger - metabolism; Thalamus - cytology; Vesicular Glutamate Transport Protein 2 - genetics; Vesicular Glutamate Transport Protein 2 - metabolism
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/j.neures.2014.03.002

•Neurons in the rotundo-entopallial projection are glutamatergic.•Neurons in the ovoido-field L2 projection are glutamatergic.•Glutamatergic thalamopallial projections support a neocortical hypothesis on homology between nidopallium and neocortex. A neocortical hypothesis as to homology of certain nuclear components of the avian brain proposes that the entopallium and field L2 are homologous to layer 4 of mammalian extrastriate and auditory neocortex, respectively. However, the hypothesis lacks support from the neurochemistry of thalamopallial projections. We investigated whether these projections are glutamatergic by injecting cholera toxin B into either the entopallium or field L2 in combination with in situ hybridization. Retrogradely labeled neurons in nucleus rotundus and nucleus ovoidalis were found to express vesicular glutamate transporter 2 mRNA, showing that the thalamopallial projections are glutamatergic. The results are consistent with the neocortical hypothesis.