Summary: The new findings reveal that mice can move their heads to the rhythm of music, showing that the animals have an innate synchronization of the pulse.
source: University of Tokyo
Precisely moving into a musical rhythm was thought to be a skill unique to humans. However, new research now shows that mice also have this ability.
The optimal rhythm for gesturing is found to depend on the constant time in the brain (the speed at which our brains can respond to something), which is similar across all species. This means that the ability of our auditory and motor systems to interact and transition to music may be more widespread across genres than previously thought.
This new discovery not only offers more insight into the animal’s mind, but also provides insight into the origins of our music and dance.
Can you move into the rhythm, or is your left foot? Apparently, how well we can adjust the timing of our movement to music depends to some extent on our innate genetic ability, and this skill was previously thought to be a uniquely human trait.
While animals also react to auditory noises, may make rhythmic sounds, or are trained to respond to music, this is different from the complex neural and motor processes that work together to enable us to naturally recognize the rhythm of a song, respond to it or even anticipate it. This is referred to as pulse synchronization.
Only recently, research studies (and home videos) have shown that some animals share our desire to go into the groove. A new research paper by a team from the University of Tokyo provides evidence that mice are one of them.
Associate Professor Hirokazu Takahashi of the institute explained that “rats instinctively – that is, without any training or prior exposure to music – outperform synchrony more clearly within 120-140 beats per minute (beats per minute), which humans also show clear synchronization of impulses.” . Graduate School of Information Science and Technology.
“The auditory cortex, an area in our brain that processes sound, was also set at 120-140 beats per minute, which we were able to explain using our mathematical model of brain conditioning.”
But why play music to mice in the first place?
“Music exerts a strong attraction to the brain and has profound effects on emotion and cognition. To make effective use of music, we need to unravel the neural mechanism underlying this experimental fact,” Takahashi said.
“I’m also an electrophysiologist, which is concerned with electrical activity in the brain, and I’ve studied the auditory cortex of mice for many years.”
The team had two alternative hypotheses: the first was that the optimal musical tempo for tempo synchronization would be determined by the body’s time constant. This varies between species and is much faster for small animals than for humans (think of how fast mice can roll over).
The second is that the optimal cadence will instead be determined by the brain’s time constant, which is surprisingly similar across species.
“After conducting our research with 20 human participants and 10 rats, our results indicate that the optimal rhythm of beat synchronization depends on the constant time in the brain,” Takahashi said.
“This shows that the animal brain can be useful in elucidating the sensory mechanisms of music.”
Mice were fitted with miniature wireless accelerometers, which could measure the slightest head movements.
The human participants also wore accelerometers on headphones. They were then played to one-minute excerpts from Mozart’s Sonata for Two Pianos at D Major, K. 448, at four different tempos: seventy-five percent, 100%, 200% and 400% of the original speed.
The original rhythm was 132 beats per minute and the results showed that the synchronization of the rats’ beats was clearest in the range of 120-140 beats per minute.
The team also found that both mice and humans shook their heads to the beat with a similar rhythm, and that the level of head shaking decreased as the speed of the music increased.
“To our knowledge, this is the first report of innate beat synchrony in animals that was not achieved through training or musical presentation,” Takahashi said.
“We also hypothesized that short-term adaptation in the brain was involved in tempo-tuning in the auditory cortex. We were able to explain this by fitting our neural activity data with a mathematical model of the adaptation.”
Furthermore, our adaptive model showed that in response to a sequence of random clicks, the highest hit prediction performance occurred when the average inter-stimulus interval (the time between the end of one stimulus and the start of another) was about 200 milliseconds (one thousandth of a second).
“This matches internal period statistics in classical music, suggesting that an adaptive property of the brain underlies the perception and creation of music.”
In addition to being a fascinating insight into the animal mind and the development of our own rhythmic synchrony, researchers also see it as an insight into the creation of music itself.
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“Next, I would like to reveal how other musical characteristics such as melody and harmony are related to brain dynamics. I am also interested in how, why and what brain mechanisms create human cultural fields such as fine art, music, science, technology, and religion,” Takahashi said.
I think this question is the key to understanding how the brain works and developing the next generation of artificial intelligence (AI). Also, as an engineer, I am interested in using music for a happy life.”
Financing: This work was supported in part by JSPS KAKENHI (20H04252, 21H05807) and JST Moonshot R&D software (JPMJMS2296).
About this music and news of neuroscience research
author: Joseph Krecher
source: University of Tokyo
Contact: Joseph Krecher – University of Tokyo
picture: The image is in the public domain
original search: open access.
“Synchronization of spontaneous beats in rats: neural dynamics and motor impulsivityWritten by Hirokazu Takahashi et al. Translational Medicine Sciences
Summary
Synchronization of spontaneous beats in rats: neural dynamics and motor impulsivity
Pulse perception and synchronization within 120 to 140 beats/minute (BPM) is common in humans and is frequently used in musical composition. Why tempo synchrony is uncommon in some species and the mechanism for determining the optimal tempo is unclear.
Here, we examined bodily movements and neural activities in mice to determine the sensitivity of their impulses.
Close examination of head movements and neural recordings revealed that the mice showed prominent synchronization and pulse activity in the auditory cortex at 120 to 140 beats per minute. Mathematical modeling suggests that short-term adaptation underlies this stroke tuning.
Our results support the hypothesis that the optimal rhythm of beat synchronization is determined by the time constant of neural dynamics conserved across species, rather than the species specific time constant for bodily movements. Thus, the underlying neural propensity for auditory motor interference may provide the basis for a more widespread human entry than is currently thought.
More studies comparing humans and animals will provide insight into the origins of music and dance.