Snakes on a Brain

In October, 2013 ScienceNews put out a press release describing an article published by researchers from UC Davis and U Toyama (Japan) advancing the “Snake Detection Theory.” They measured the responses of pulvinar neurons to visual stimuli, including a hand, face, geometric shape, and a snake. They report that they found a specific response to the snake as a visual stimulus, and that it supports the notion that the primate brain evolved under evolutionary pressure from living alongside snakes as competitors and predators.

The pulvinar neurons are located in the thalamus (in humans, the pulvinar nucleus, or cluster or neurons, is the largest in this structure). The thalamus is a structure that is deep in the vertebrate brain and it relays sensory and motor signals to the cerebral cortex, it regulates consciousness, sleep, alertness. This group of neurons receives input from crossed optic fibers (that is, the right part receives input from the left eye), which then relays information to the cortex of the occipital lobe. They also communicate with other regions, but that is the path of visual stimuli. Continue reading