Inside our heads, there’s a flurry of electrical activity messages going from brain cell to brain cell, creating our conscious and unconscious experience. For about a century, scientists have been able to record such signals using electroencephalography (EEG) and they have allowed researchers to understand our inner workings at an incredible level.
What Is EEG?
EEG is a method to record the electrical signals happening in the brain by placing sensors on the scalp. It is used in both medical assessments and in research studies pertinent to brain and cognition. And it is not invasive, making it very useful and versatile.
The sensors are measuring the voltage fluctuation between neurons, the brain's cells. These fluctuations are caused by currents that, unlike those you get from batteries, change over time.
Focusing on its power of diagnosis, EEG can be used to diagnose epilepsy, but also sleep disorders, brain tumors, dementia, and it can assess the state of a comatose patient. It is also the way brain death is assessed. That’s when there is a complete loss of brain function, even involuntary ones. EEG has also been used to assess the effects of COVID-19 on the brain.
The scientific importance of EEG spans beyond the realm of medicine and has allowed us to better understand our brains, our consciousness, and even some human functions such as swallowing. It is an incredible tool.
"EEG represents one of the best ways of measuring whole-brain neural activity on a sub-second timescale. For those of us interested in how dynamic neural processes support cognition, this temporal precision makes the technique incredibly useful,” neuroscientist Dr Duncan Astle, Programme Leader at the MRC Cognition and Brain Sciences Unit at the University of Cambridge, told IFLScience.
“Furthermore, the technique is relatively inexpensive and can be used with participants of all ages, from infants to the elderly. These features make it incredibly practical too," Dr Astle continued.
Hans Berger, Telepathy, And The Creation Of THE EEG
Electrical signals were first measured in non-human animals by British physician Richard Caton in 1875, but it wasn’t until almost half a century later that German psychiatrist Hans Berger demonstrated this in humans.
The spurring factor in Berger's studies was surprisingly not a very scientific one. He set out to find a physiological base for psychic energy. This came from a curious incident that happened in his youth. During a year of service in the cavalry, after he abandoned his studies, Berger was thrown off his horse and fell into the path of a horse-drawn cannon. The driver was able to stop in time and Berger was left shaken but not seriously injured.
Far away from the place of the accident, his sister, unaware of what had happened, felt that he was in danger and urged their father to telegram him at once. This incident convinced him that he had somehow communicated with her using only his mind.
“This was a case of spontaneous telepathy in which at a time of mortal danger as I contemplated certain death, I transmitted my thoughts, while my sister, who was particularly close to me, acted as the receiver," Berger wrote about the experience.
As his military service ended, he went back to his studies. And after several decades, in 1924, he was able to conduct the first successful EEG. He was the one who coined the term electroencephalography.
While his scientific contribution is undeniable, his legacy will be forever tarnished by his collaboration with the Nazi regime, supporting the Schutzstaffel (SS) as well as taking part in the Nazi genetic health higher courts, where the forced sterilization of neuropsychiatric patients was decided.