A brief history of EEG

A brief history of EEG

The early beginnings of Electroencephalography (EEG) can be traced back to the late 18th century, when the Italian Luigi Galvani (1737-1798), a biologist at the University of Bologna experimented on frog tissue. Accidentally, while cutting through a frog’s leg, Galvani’s scalpel touched the brass hook, which was holding the leg in place. This caused the dead frogs leg to twitch.

http://www.ssplprints.com/image/98857/unattributed-galvani-experiment-on-frogs-legs-late-18th-century
http://www.ssplprints.com/image/98857/unattributed-galvani-experiment-on-frogs-legs-late-18th-century

After long discussions with his peer Alessandro Volta (1755-1832), Galvani concluded from his experiment that electrical currents flow through the body and cause muscles to contract. The observed twitching of the leg must have been caused by an external stimulation of this electrical circuit. The study of Electrophysiology was born.

Many years, scientists and inventions later, the first EEG recordings were made by Richard Caton (1842-1926) at the Royal Infirmary, Liverpool. Using novel electrodes developed by Emil Du Bois-Reymond (1818-1896), he measured the EEG of everything he could get his hands on – cats, rabbits, even monkeys. Why did he not record human EEG you ask? His recordings were taken from the exposed brain and required the skull to be opened, which made it difficult to find human volunteers.

Although his EEG device was not as sophisticated as modern devices, he was able to show differences in EEG signals associated with sleep and wakefulness, anaesthesia and death. He even used EEG to identify brain regions and their associated functions. Caton is recognised as the discoverer of EEG and as the first EEG brain mapper.

In 1924, Hans Berger (1873-1941) was the first person to dare record the EEG of humans. He recorded from the cortex of a 17-year-old boy who had a trepanation (a hole in his skull) in preparation for surgery of a suspected tumour. However, Berger himself doubted the validity of his results.

http://commons.wikimedia.org/wiki/File%3AHansBerger_Univ_Jena.jpeg
Hans Berger at the University of Jena

He experimented with a number of different electrodes to optimise the signal from the recordings. On his son Karl, he tried out non-invasive scalp electrodes and on himself he experimented with silver needle electrodes.

In the year 1929 Berger finally published his discovery. The German medical and scientific establishment however largely ignored his findings or met them with derision and incredulity.

It wasn’t until 1934, when the British electrophysiologists Edgar Douglas Adam (1889-1977) and Sir Bryan H C Matthews (1906-1986) confirmed Bergers findings that he gained widespread recognition for his work.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s