Rats rock!

There are certain songs that make us feel this uncontrollable urge to dance – or at least to discreetly tap the foot to the beat. This phenomenon was thought to occur solely in humans until a new study by the University of Tokyo was published recently. They were able to observe the same behaviour in rats.

To investigate the “spontaneous beat synchronization in rats”, in other words how they instinctively move to music, the study connected their twenty human participants and ten Wistar rats to miniature accelerometers, which were used to measure even the slightest head movements. For the human volunteers, the accelerometers were attached to headphones, the rats had to surgically get a special holder fixed into their skulls. Accordingly to Science Advances, which published the results in detail, the experiment was conducted “in strict accordance with Guiding Principles for the Care and Use of Animals in the Field of Physiological Science” and the experimental protocol was approved by the Committee on the Ethics of Animal Experiments at the Graduate School of Information Science and Technology, the University of Tokyo.

In addition to the accelerometers, the scientists used video cameras to document the reactions of rats and humans to the exposure of different music pieces they were exposed to over the course of three days. In the first part of the experiment, short parts of Mozart’s Sonata for Two Pianos in D Major were played at four different speeds (75%,100%,200%, and 400% of the original speed).

For the next experiment, five different pieces of music were played twice each in no particular order. The chosen pieces were K.448 by Mozart, “Born This Way” by Lady Gaga, “Another One Bites the Dust” by Queen, “Beat It” by Michael Jackson, and “Sugar” by Maroon 5.

Before conducting the experiments, the hypothesis was that rats would prefer faster music since they are rather small and have a faster heartbeat than we do. Surprisingly though we seem to share the same preferences for beats with rats since they preferred music between 120-140 BPM. In addition to that the intensity of head jerking decreased the faster the music became in rats as well as in humans.

“Our results suggest that the optimal tempo for beat synchronization depends on the time constant in the brain,” said Dr. Hirokazu Takahashi of the University of Tokyo, which means that there could be a common preference in a diversity of species regarding music beats.

While this experiment might sound like the source of a new fun fact the importance of this discovery should not be underestimated. The team which was responsible for the study wants to go even further now by exploring how other musical elements such as melody and harmony influence the dynamics of the brain. With this knowledge, things like music therapy could be brought to the next level. “Also, as an engineer, I am interested in the use of music for a happy life,” said Takahashi.

Angelina Berndt

Sources:

SPIEGEL „Ratten nicken zu Mozart und Queen“

Science Advances „Spontaneous beat synchronization in rats: Neural dynamics and motor entrainment”

The Guardian “Slaves to the rhythm: rats can’t resist a good beat, researchers say”