We suspected that "bird brain" might lose some force as an insult due to studies that show how smart crows can be or that western scrub jays call their friends to funerals for their dead. But researchers at the University of Chicago Medical Center have taken things to a new level: they have proven that a structure in birds' brains is built from the same cells that scientists believe make mammals smart.
In mammalian brains, the neocortex forms the outermost layer of brain tissue, and is thought to be the structure that processes higher-order thoughts -- that is the part that makes us mammals so smart. Bird brains do not have a neocortex, but they do have a structure called the dorsal ventricular ridge (DVR).Both the DVR and the neocortex start their growth from the same place in the early embryonic stages of development. Scientists such as Harvey Karten investigated the DVR's neural inputs and outputs already in the 1960's, and hypothesized that the DVR might function similarly to the neocortex, even though they look not at all similar in their mature forms.
Clifton Ragsdale, Jennifer Dugas-Ford, and Joanna Rowell of U. Chicago studied chicken and zebra finches to find proof that the DVR has a lot in common with the neocortex. They were able to use molecular markers to identify the types of cells in the DVR, and found that the cells in a bird brain match two layers -- the input and output neurons -- of the neocortex.
Finding that different structures may have evolved to perform the same tasks will lead to many areas of research. Scientists will have new avenues to research cures for neurological damage related to paralysis, blindness, or other conditions. Learning the advantages and disadvantages of the varying structures may further help scientists understand how the brain performs the awesome processing that supports language, self-awareness, and intelligence.