Machine Telepathy: Speech Reconstructed From Brain Waves

Scientists are a a step closer to broadcasting our inner thoughts to the world without us speaking.

Via New Scientist: 

...How the brain converts speech into meaningful information is a bit of a puzzle. The basic idea is that sound activates sensory neurons, which then pass this information to different areas of the brain where various aspects of the sound are extracted and eventually perceived as language. Pasley and colleagues wondered whether they could identify where some of the most vital aspects of speech are extracted by the brain.

The team presented spoken words and sentences to 15 people having surgery for epilepsy or a brain tumour. Electrodes recorded neural activity from the surface of the superior and middle temporal gyri – an area of the brain near the ear that is involved in processing sound. From these recordings, Pasley's team set about decoding which aspects of speech were related to what kind of brain activity.

Sound is made up of different frequencies which are separated in the brain and processed in different areas. "Simply put, one spot [of neurons] might only care about a frequency range of 1000 hertz and doesn't care about anything else. Another spot might care about a frequency of 5000 hertz," says Pasley. "We can look at their activity and identify what frequency they care about. From that we can assume that when that spot's activity is increasing there was a sound that had that frequency in it."

Frequency isn't the only information you can extract. Other aspects of speech, such as the rhythm of syllables and fluctuations of frequencies are also important for understanding language, says Pasley.... Read more here...