Von Economo Neurons in Indian Green Ring Neck Parrot (Psittacula Krameri): Possible Role in Vocal Learning

Only a few vertebrates communicate acoustically, notably the three birds' group - songbirds, hummingbirds, and parrots; and some mammals – cetaceans, bats, elephants, seals, and hominids are able to produce elaborate patterns of vocalization. Vocal learning and Imitation is a rare trait and one of the highest forms of social learning. Here detailed anatomical investigation of the brain of Indian parrot - an exclusive imitator, reveal that brain wiring of parrot is unique with specialized cells and lacking multilayered cortical structure. We encounter an unusual neuronal type, known as Von Economo Neurons (VENs) in parrot – those have been noticed to date only in a few groups of mammals like humans, elephants, cetaceans, pinnipeds, and a few primates. Almost all are vocal learners. Functionally these neurons are associated with intelligence, cognition, emotion, facial expression as well as autonomic visceral, olfactory and gustatory functions. The presence of VENs in vocal counterparts of parrot pallium especially in the nidopallium caudolaterale (callopallial anterior region), lemnopallial region - the dorsolateral corticoid area (CDL), and in Arcopallium, indicate that parrot brain is restricted with compact nuclei and diversity of neural subtypes. Except VENs, Fork neurons and enveloping neurons have also been noticed in these regions. Strikingly similar Neuroarchitecture of vocal control areas of parrot brain to upper layer of mammalian neocortex provide clues of involvement of these neurons in the processing of vocal communication and imitation. These findings are important to understand the common blueprint of brain wiring of high-level cognition during evolution and related neurodegenerative disorders.