The rats that ‘dance’ by Lady Gaga

Humans are eminently musical primates because we can anticipate. We are able to predict the blows, beats and turns of a song, in what we understand as rhythm. That is where the mathematics behind all music was born and which dictates what ‘sounds good’ or has a certain communicative intention. From there to dancing there is only one step. But what if other animals like rats also dance?

New research shows that the laboratory rodents also have this ability. The rats dance by moving their heads slightly at the optimal tempo to make the typical nodding gesture. A bit like the cat meme that, with its eyes half open, seems to follow the beat of a song (‘cat vibes to…’).

In ‘dancing rats’, a team from the University of Tokyo (Japan) found that the tempo for nodding was dependent on the time constant in the brain. That is, the speed at which a brain can respond to something. This is something common to almost all species, including humans. We have a kind of metronome in our heads.

Rats dance to Mozart, Queen or Lady Gaga

The experiment was as follows: They equipped rats with miniature accelerometers with wireless connection. Thanks to them they could measure the slightest movements of the head. Because although we are saying here that ‘rats dance’, it is not really that they stand up and start clicking their heels.

In parallel, they convened human participants who also wore accelerometers in headphones. One-minute excerpts from Mozart’s Sonata for Two Pianos in D Major, K. 448, were then played. Not at the same rate. At 75%, 100%, 200% and 400% of the original speed.

The original tempo is 132 beats per minute (bpm). Well, if you are human, what is expected is that your foot or head goes at that rate. 132 taps per minute. Rats were also found to make slight head movements at a rate between 120 and 140 bpm.

The team also found that both rats and humans shook their heads in time at a similar rate. But the level of head shaking decreased the more the music was sped up. That also happens to us sapiens. In highly accelerated music, such as bakalaowhich can exceed 600 bpm, we choose the integer divisor that gives us a result closest to 120 bpm (200, for example). Basically, so as not to get too dizzy when shaking repeatedly. And also because it is, more or less, at the rate at which our brain’s natural ‘metronome’ goes. Our neurons usually synchronize to that frequency.

The team had the rats stand on two legs, giving them a drink at the top of the cage, to see if the head waddling was more evident than on all fours. And although the sway was not very evident, it was there. The rats dance their way with their heads. They tried classical music, but it also worked with Lady Gaga, with. Michael Jackson and with Queen. As long as the song was in the tempo range of 120 to 140 bpm (specifically, Born This Way, beat it Y Another One Bites the Dust).

Music is not just for humans

Does this mean that rats have a sense of rhythm? No, it assures Hirokazu Takahashi of the Graduate School of Information Sciences and Technologies. “They don’t have the ability to predict the song”, but they do innately perceive its rhythm at a neural level.

To test this hypothesis, Takahashi’s team made them, on the one hand, a magnetic resonance to sedated rats. On the other hand, they monitored a group of neurons that reacted to sound stimuli (through a graft). Then they played the song snippets at different speeds.

The neurons were found to synchronize their activity in the range of 120 to 140 bpm, as occurs in humans. “To the best of our knowledge, this is the first study on the innate rhythm synchronization in animals that was not achieved through training or musical exposure”, explains the professor, who has published the results in Science Advances.

In humans, it is released dopamine –that is, pleasure– when just an instant before we anticipate that there will be a new measure of song. When the expected pattern is broken, brain activity is unleashed. But there isn’t much difference between listening to a song and humming in your head when there is silence

This discovery implies that the ability of our auditory and motor systems to interact and move to the rhythm of music may be more widespread among species than previously thought. This new discovery offers not only a greater understanding of the animal mind, but also the origins of our own music and dance.

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The rats that ‘dance’ by Lady Gaga