by Gooly (Li Yang Ku)
Cats contributed a lot to the development of internet, but they also play an important role in the field of understanding vision. Around the 60’s scientist started a series of researches on understanding how brains process visual inputs from eye. Cats, which have a relative sharp vision, were their major subjects.
One of the series of researches that lead to a Nobel Prize was done by Hubel and Wiesel. In 1958 they accidentally discovered neurons in Cats that respond to edges with different orientation; they named these neurons “simple cells“. These neurons was later discovered to be in orientation columns and has profound impact on many computer vision algorithms such as the Gabor filter.
The following video explains how the experiment was made. They first implanted a sensor in a certain area in the cat’s visual cortex. The cat’s head is then fixed to face the projector screen. Different patterns are shown to the cat while the electrode sensor records the response. (The cat is anesthetized during the whole experiment.)
A further experiment was done by Hubel and Wiesel to understood whether the ability to see is innate or acquired. The experiment is done by suturing one of the eyes of a newborn kitten and reopen it after a certain period. Surprisingly kittens with one eye deprived of vision for the first 3 month remain blind on that eye for their whole life.
Another cat experiment done by Blakemore and Cooper gave an even clearer result. Two special cylinders are made, one with only vertical stripes inside and the other with only horizontal stripes. Newborn kittens are placed in one of the cylinders the first few month. Kittens that only perceive vertical lines for the first few month of birth could only see vertical lines not horizontal lines for the rest of their life. The following video explains more in detail.
These experiments show that vision from the most basic line detection to complex scene recognition are all learned and largely depend on the environment one experienced.
Hubel, David H., and Torsten N. Wiesel. “Receptive fields of single neurones in the cat’s striate cortex.” The Journal of physiology 148.3 (1959): 574-591.
Hubel, David H., and Torsten N. Wiesel. “The period of susceptibility to the physiological effects of unilateral eye closure in kittens.” The Journal of physiology 206.2 (1970): 419.