Charles Bonnet b1720 Swiss naturalist

Charles Bonnet was a swiss lawyer turned naturalist. He was the first to describe the phenomenon of visual release hallucinations in his aging father in the 18th century. The tonic inhibition of the visual cortex by visual input from the environment when removed creates a denervation hypersensitivity that can occur anywhere along the visual pathway (from the granular layer to higher order integration areas), thus excessive cortical activity about the occipital lobe and beyond originally inhibited is now "released" and the patient experiences a wide ranging assemblage of visual hallucinations.

This above picture was a drawing by a patient described in this case report who also experienced these visual hallucinations.

Later in his life, Bonnet set out to the Swiss countryside to write. In my opinion his intuition regarding the nervous system as a modifiable feedback loop with the environment first, correctly identified the chief mechanism believed to underlie the development of memory in organisms, that repeated environmental stimuli create nerve approximations that are favored because that have less resistance (or could be said to be more likely to refire). And second, created the central dogma for approaching an understanding of how nervous tissue functions (much the way Newton reorganized bodies in motion) Genius!!!

The following excerpt is taken from his 1760 essay on the faculties of the heart Essai analytique sur les facultes de l'ame (i think).

"All knowledge originates in sensations; sensations follow vibrations in the nerves appropriate to each; the nerves are made to vibrate by external physical stimulus. A nerve once set in motion by a particular object tends to reproduce that motion; so that when it a second time receives an impression from the same object it vibrates with less resistance. The sensation accompanying this increased flexibility in the nerve is, the condition of moemory. That which puts [the mind] into activity is pleasure or pain. When the active element of the mind is applied to the acquisistion and combination of sensations, those abstract ideas are formed which, though generally distinguished from , are thus merely sensations in combination only."