Creating Pink Floyd with Your Brain??

A friend shared an article with me today that I found absolutely fascinating, so I am sharing it with my readers. First the citation and then my thoughts:

Bellier, L., Llorens, A., Marciano, D., Gunduz, A., Schalk, G., Brunner, P., & Knight, R. T. (2023). Music can be reconstructed from human auditory cortex activity using nonlinear decoding models. PLoS Biol 21(8): e3002176. https://doi.org/10.1371/journal.pbio.3002176 . You can also find a summary of the article on the New York Times website.

The researchers used intracranial electroencephalography and statistical analysis to recreate "Another Brick in the Wall" outside of the brain. Now, that's a mouthful! Let me break that down. 

First, what is an intracranial electroencephalography (iEEG)? And why is it important? You may be familiar with the abbreviated EEG – electroencephalography where wires with electrodes are placed at various points of the head to trace brain activity. EEGs are primarily used to diagnose epilepsy, and in fact, 29 epileptic patients participated in this study. The iEEG is more invasive as the electrodes go below the surface of the skull to look at brain function. The iEEG is most often used to plan surgery on the brain, particularly in epileptic patients. Of course, iEEG is not used on all epileptic patients – only those whose condition is severe enough to require an alteration of some sort to the brain. So, you can still imagine wires being attached to the head, but think of these wires attached to the actual brain through skull incisions.

The incisions were made throughout the front and sides of the brain (the cerebrum). OUCH! It is also important to point out that this study was only done on epileptic patients requiring surgery, those who were drug-resistant. The risks to those not needing such invasive tactics would be too great for an average healthy human being. After the electrodes were attached to the brain, participants listened to the entire song of “Another Brick in the Wall, Part 1” through headphones.

Statistical analysis. Wow, this is a doozy! I just finished statistics, and there is terminology that you may never understand. But to simplify, these researchers analyzed the results of the iEEG to see where the brain activity was when patients listened to Pink Floyd’s “Another Brick in the Wall”. Can you imagine having wires touching your brain as you listen to music? It almost sounds like something from a science fiction movie, but we are able to do this now! With the information gathered, researchers looked at similarities in brain function, the actual volume (hertz) of the music’s affect on the brain. Even without speaking, the patients were responding to the music.

Now, let me take a brief segue – Stephen Hawking is a perfect example to explain a little bit of what is happening. He couldn’t speak on his own, but his brainwaves combined with his eye contact on letters allowed him to share his wisdom with the world. The researchers in this Pink Floyd study used this knowledge plus research from similar sources in their study; however, this time, they used music, questioning whether the music like words could be spoken or played by the brain. Such a result would further reinforce the connection of music to speech.

Pink Floyd’s “Another Brick in the Wall” was a perfect element for this study. If you listen to the song, you can hear the complexity of the melody and the rhythm. And, in fact, this music was used with a normal EEG attempting to find this same result. What would be the difference between that study and this iEEG study?

The intracranial EEG found a new area of the brain! Specifically, the area within the Superior Temporal Gyrus that responded to rhythm – now this was what excited me the most about this study! I know, more complicated terminology, but that is why I provided a link to the Superior Temporal Gyrus and showed a picture of its location in the brain!

Within the Superior Temporal Gyrus, the brain can differentiate between timbre, pitch, melody, harmony, and rhythm. And that helped the researchers focus on three areas of the Superior Temporal Gyrus – bilateral (on both sides of the brain) superior temporal gyri (STG), bilateral (on both sides of the brain) sensorimotor cortices (SMC), and the inferior (bottom of Superior Temporal Gyrus) frontal gyrus (IFG). Each of these areas within the Superior Temporal Gyrus responded to the music as you can see in the graphic below.

Because the brain was responding to the rhythm of the song, there was significance, and the sound the brain activity produced was remarkable!

There were two different reconstructions made of the brain’s response to the music. The first, called a linear reconstruction, showed

“strong rhythmic cues on the presence of foreground elements (vocals syllables and lead guitar notes); a sense of spectral structure underlying timbre and pitch of lead guitar and vocals; a sense of harmony (chord progression moving from Dm to F, C, and Dm); but limited sense of the rhythm guitar pattern.”

(Bellier et al., 2023)

The second, called a non linear reconstruction, showed

“a recognizable song… [where] pitch and timbre were especially improved, and phoneme identity was perceptible. There was also a stronger sense of harmony and an emergence of the rhythm guitar pattern”

(Bellier et al., 2023)

So what? In all of this study, we learned that the brain can play the music it has heard! You can hear the result here. Of course, this was just classic rock. I wonder how the brain might play Hip Hop?

_{*All images except for brain activity in the superior temporal gyrus are free to share and use. The image of the brain activity in the superior temporal gyrus is taken from the research study.}