The Same Vision for All Primates: Revealed by World's Smallest Primate
upstart writes in with an IRC submission for Runaway1956:
For more than a century, the visual system of primates has been intensely studied. These studies uncovered that unlike other mammals such as rodents, visual information is processed by small dedicated computing units located in the visual cortex. "As the different primate species cover a wide range of sizes, we were led to wonder whether this basic computing unit scales with body or brain size. Is it simplified or miniaturized, for example, in the world's smallest primate, the gray mouse lemur," asks Daniel Huber, professor in the Department of Fundamental Neurosciences at the UNIGE Faculty of Medicine?
[...] To answer this question, the visual system of the mouse lemur was studied using an optical brain imaging technique. Geometrical shapes representing lines of various orientations were presented to the lemurs and the activity of the neurons responding to the visual stimuli was imaged. The repetition of such measurements gradually allowed them to determine the size of the minimal units processing form information. "We expected to see a unit of tiny size, proportional to the small size of the lemur, but our data revealed that they measure more than half a millimeter in diameter," says Daniel Huber.
In collaboration with the Max Planck Researchers, Huber compared hundreds of these units imaged in the tiny mouse lemur brain with the data obtained for the visual circuits of other, much larger primate species. The team made a surprising discovery: not only was the basic processing unit almost identical in size in the 60-gram mouse lemur, as in larger monkeys such as macaques weighing about seven kilograms, or even larger primates such as us humans.
They also found that the way the units are arranged across the brain was totally indistinguishable, following the same rules with mathematical precision. The researchers also found that the number of nerve cells per visual unit was almost identical in all primates studied so far.
Journal Reference:
Chun Lum Andy Ho, Robert Zimmermann. et. al.,Orientation Preference Maps in Microcebus murinus Reveal Size-Invariant Design Principles in Primate Visual Cortex, Current Biology (DOI: 10.1016/j.cub.2020.11.027)
Read more of this story at SoylentNews.