Hi everyone. This video looks at some of  the historical highlights in the history

of neuroscience. I happen to like history,  but I understand that not all students do.

But I think we have some interesting  things to share with you in this video.

The history of neuroscience parallels  the history of the technological advances

providing us opportunities to study the brain and  nervous system. We also see a series of advances,

steps backward, and dead ends, ultimately  leading to the knowledge we have today.

We take many bits of knowledge for granted,  such as knowing that the brain is responsible

for awareness and thought. But ask yourself,  how would anyone know this? As far back as

seven thousand years ago, people drilled holes in  the skulls of living humans for purposes we don't

fully understand. This might have been a religious  ritual or intended to cure demonic possession or

some other affliction. Regardless, it suggests  some understanding of the importance of the head

to behavior. The ancient Egyptians demonstrated  a more sophisticated understanding. They knew

that nervous system damage was permanent and that  damage to the right side of the head would affect

feeling and movement on the left side of the  body. They compared the convolutions of the brain,

in the upper left, to molten copper, in the lower  left. 4th Century BCE Greek scholars understood

that the brain was the organ of sensation.  Hippocrates understood that seizures were

caused by the brain, even though they appeared  outwardly as muscular convulsions. Galen,

a Greek who administered to Roman gladiators,  made an interesting mistake that lasted another

1500 years. Galen believed that the fluid in  the ventricles of the brain played an important

part of transmitting messages. It does not. True  scientific reasoning blossomed in the Renaissance,

led by thinkers like Renee Descartes. Descartes  proposed a philosophy of mind called dualism,

which sees the body as mechanical and subject  to scientific exploration while the mind is not.

This contrasts with modern neuroscience which is  monistic rather than dualistic. You will sometimes

see people try to separate mind and body, such as  asking if addiction is physical or psychological.

The neuroscientist does not make this distinction.  The mind is completely physical. The mind is what

the brain does. Descartes also continued Galen's  mistake by proposing a hydraulic or fluid model of

the brain. In spite of such errors, the remarkable  Age of Reason gave birth to the science we benefit

from today. Neuroscience benefited from a  huge technical boost from the invention of the

light microscope in 1674 in the Netherlands.  The subsequent refinement of lenses by the

Germans opened whole new worlds to scientists.  This, along with the relaxation of religious

restrictions regarding the study of cadavers,  allowed scientists to make great strides in

their study of the structure and function of the  nervous system. Discoveries followed discoveries

at a fast and furious pace. The nervous system  communicates using electricity, a discovery

that piqued the imagination of Mary Shelley,  who wrote Frankenstein. Nerves for sensation

and movement might travel together but they're  separate, not two-way streets for information.

Significant misunderstanding persisted, though.  As late as the beginning of the 20th century,

scientists were still debating whether the  nervous system, like other organ systems,

was made up of single cells. Neurons can have  branches measured in feet and do not fit neatly

on a microscopic slide. Their transparency  makes it difficult to see important features.

It wasn't until 1906 that Santiago Ramon y Cajal  won the Nobel Prize for his Neuron Doctrine,

the idea that the nervous system is made up  of single cells. His rival, Camilla Golgi,

had maintained that the nervous system was  instead a connected reticulum, which is Latin for

fisherman's net. Ironically, Cajal used a stain  developed by Golgi to prove that Golgi was wrong,

and much to Cajal's dismay, he had to share  his Nobel prize money with Golgi as a result.

Another odd zigzag in the path to knowledge was  the concept of phrenology. Although the basic

premise of phrenology, that we can read the bumps  in people's skulls to understand their character,

appears ridiculous today, the phrenologists helped  to demystify the brain as the organ of the mind.

They were also correct in their thinking that  functions were localized in the brain, but not

quite the way they envisioned it. Many terms in  our modern language originated from phrenology.

Phrenology was the source of terms like high  brow or low brow, getting your head examined,

or being well-rounded. We even owe our use of the  term shrink for a psychiatrist to the phrenology

movement. Progress accelerated in the 19th century  as scientists localized language in the brain and

determined that information about a touch on  the toe takes longer to reach the brain than

a touch on the thigh. Electrically stimulating  one side of the brain would produce movement on

the opposite side of the body, confirming early  Egyptian principles. The brain was presented as

a hierarchy with more sophisticated processes  being carried out by the cerebral cortex. You

might have heard that you have a reptilian brain  hidden under your cortex based on this model.

In the 20th century, neuroscientists gained  remarkable insight into neural signaling.

Continued improvements in technology and imaging  in particular have caused an explosion in

knowledge. In 1969, the Society for Neuroscience  boasted 500 members. Current membership is around

40 000 members in 90 countries and counting. Where  will Neuroscience go from here? Again, we can look

to developments in technology and particularly  in artificial intelligence for clues about that.