An MRI scan of a person listening to music shows brain locations that react. (This scan wasn’t part of the research study comparing humans and monkeys.)
What sounds like music to us might just be noise to a macaque monkey.
That’s since a monkey’s brain appears to do not have critical circuits that are highly sensitive to a noise’s pitch, a group reported Monday in the journal Nature Neuroscience.
The finding recommends that humans may have established brain locations that are sensitive to pitch and tone in order to process the noises related to speech and music.
” The macaque monkey does not have the hardware,” states Bevil Conway, a detective at the National Institutes of Health. “The question in my mind is, what are the monkeys hearing when they listen to Tchaikovsky’s 5th Symphony?”
The study began with a bet between Conway and Sam Norman-Haignere, who was a graduate student at the time.
Norman-Haignere, who is now a postdoctoral researcher at Columbia University, belonged to a group that found proof that the human brain responds to a sound’s pitch.
” I resembled, well if you see that and it’s a robust finding you see in humans, we’ll see it in monkeys,” Conway says.
However Norman-Haignere believed monkey brains might be various.
” Truthfully, I wasn’t sure,” Norman-Haignere states. “I suggest that’s typically an indication of a great experiment, you know, when you do not know what the result is.”
So the 2 scientists and several coworkers used a special type of MRI to monitor the brains of six individuals and five macaque monkeys as they listened to a variety of sounds through earphones.
Some of the sounds were more like music, where changes in pitch are obvious.
Other noises were more like sound.
And Conway states it didn’t take long to understand he ‘d lost his bet.
” In human beings you see this lovely company, pitch predisposition, and it’s clear as day,” Conway says. In monkeys, he states, “we see absolutely nothing.”
That shocked Conway since his own research had actually revealed that the two types are almost identical when it concerns processing visual information.
” When I look at something, I’m pretty sure that the monkey is seeing the exact same thing that I’m seeing,” he states. “But here in the acoustic domain it appears basically different.”
The study didn’t try to explain why noises would be processed differently in a human brain. However one possibility involves our exposure to speech and music.
” Both speech and music are highly complicated structured sounds,” Norman-Haignere states, “and it’s absolutely possible that the brain has actually established regions that are extremely tuned to those structures.”
That tuning could be the outcome of “something in our hereditary code that triggers those regions to establish the way they are and to be situated where they are,” Norman-Haignere states.
Or, he says, it might be that these brain areas develop as kids listen to music and speech.
Regardless, subtle changes in pitch and tone appear to be critical when individuals want to convey emotion,” Conway says.
” You can know whether I’m mad or sad or questioning or confused, and you can get practically all of that significance just from the tone,” he states.