In past experiments, researchers believed that the genes responsible for speech in humans did not exist in mice or if they did exist, they would be extremely limited. However, new studies show this to be untrue. Recent studies show that these same gens that regulate human speech are also found in mice.
The gene responsible for regulating speech is FOXP2. A mutation in this gene causes difficulty in producing complex speech in humans. An experiment was performed to see if a mutation in this gene would also cause complications in speech for mice.
Researchers did this by experimenting on male adult mice. They had a group of heterozygous mice with the FOXP2 mutation and a wildtype group with normal FOXP2. They exposed both of these groups to active wildtype female mice, the urine of female mice and sleeping female/male mice. After some tests, they saw that the wildtype mice who had normal FOXP2 had a different duration and sequence of ultrasonic vocalizations (USVs). USVs are high pitched sounds made by mice that is inaudible to humans.
New studies show that the mice with the FOXP2 mutation had difficulty producing complex vocalizations compared to how easy it was for the healthy wildtype mice. This was proven by measuring syllable length and amount of unique syllables over time. They also compared the vocal brain regions of the heterozygotes and wildtype and it was shown that the heterozygotes had neurons widly distributed while the wildtype had neurons packed together. This proved that the mutation in the FOXP2 gene also affected how the neurons were distributed in the vocal brain regions.
I think its amazing the many different similarities we keep discovering between humans and animals. The more technology improves, the more we get an insight on these similarities and I'm excited to see what research proves in the coming years.