Clever Corvids: due to neuron number and design (Introduction)

by David Turell , Tuesday, June 14, 2016, 15:52 (3084 days ago) @ David Turell

The latest research shows that bird brains have more neurons in the frontal area than monkeys and a primate-like design pattern of the neuron networks:-https://www.sciencedaily.com/releases/2016/06/160613153411.htm-"The first study to systematically measure the number of neurons in the brains of birds has found that they have significantly more neurons packed into their small brains than are stuffed into mammalian and even primate brains of the same mass. -"The macaw has a brain the size of an unshelled walnut, while the macaque monkey has a brain about the size of a lemon. Nevertheless, the macaw has more neurons in its forebrain -- the portion of the brain associated with intelligent behavior -- than the macaque.-"That is one of the surprising results of the first study to systematically measure the number of neurons in the brains of more than two dozen species of birds ranging in size from the tiny zebra finch to the six-foot-tall emu, which found that they consistently have more neurons packed into their small brains than are stuffed into mammalian or even primate brains of the same mass.-***-"Scientists were left with a generally unsatisfactory fallback position: Avian brains must simply be wired in a completely different fashion from primate brains. Two years ago, even this hypothesis was knocked down by a detailed study of pigeon brains, which concluded that they are, in fact, organized along quite similar lines to those of primates.-***-"'We found that birds, especially songbirds and parrots, have surprisingly large numbers of neurons in their pallium: the part of the brain that corresponds to the cerebral cortex, which supports higher cognition functions such as planning for the future or finding patterns. That explains why they exhibit levels of cognition at least as complex as primates," said Herculano-Houzel, who recently joined the Vanderbilt psychology department.-"That is possible because the neurons in avian brains are much smaller and more densely packed than those in mammalian brains, the study found. Parrot and songbird brains, for example, contain about twice as many neurons as primate brains of the same mass and two to four times as many neurons as equivalent rodent brains.-"Not only are neurons packed into the brains of parrots and crows at a much higher density than in primate brains, but the proportion of neurons in the forebrain is also significantly higher, the study found.-"'In designing brains, nature has two parameters it can play with: the size and number of neurons and the distribution of neurons across different brain centers," said Herculano-Houzel, "and in birds we find that nature has used both of them."-***-"One of the important implications of the study, the neuroscientist said, is that it demonstrates that there is more than one way to build larger brains. Previously, neuroanatomists thought that as brains grew larger neurons had to grow bigger as well because they had to connect over longer distances. "But bird brains show that there are other ways to add neurons: keep most neurons small and locally connected and only allow a small percentage to grow large enough to make the longer connections. This keeps the average size of the neurons down," she explained."-Comment: Brain size as a measure of intellectual function is out the window. It is a matter of neuron-packing and a more advanced network design.