The FOXP2 gene encodes a transcription factor associated with vocal learning in mice, bats, birds, and humans. In humans, loss-ofDigging Into Data Enhanced Spatial Learning Ability in Mice with an Autism Mutation Autism is a neurobiological disorder with a range of symptoms that include impaired social interactions and stereotyped patterns of behavior such as hand-flapping or rocking. A relatively high proportion of autistic people—around 10 percent—have an extraordinary skill or talent such as greatly enhanced memory. Mutations in neuroligin 3, an adhesion protein (Section 3.3) that connects brain cells to one another, have been associated with autism. One mutation changes amino acid 451 from arginine to cysteine. Mouse and human neuroligin 3 are very similar. In 2007, Katsuhiko Tabuchi and his colleagues genetically modified mice to carry the same arginine-to-cysteine substitution in their neuroligin 3. The mutation caused an increase in transmission of some types of signals between brain cells. Mice with the mutation had impaired social behavior, and, unexpectedly, enhanced spatial learning ability (Figure 10.15).
1. In the first test, how many days did unmodified mice need to learn to find the location of a hidden platform within 10 seconds?
2. Did the modified or the unmodified mice learn the location of the platform faster in the first test?
3. Which mice learned faster the second time around?
4. Which mice had the greatest improvement in memory? Figure 10.15 Enhanced spatial learning ability in mice engineered to carry a particular mutation in neuroligin 3 (R451C), compared with unmodified (wild-type) mice. Credits:
(a) Courtesy of Dr. S. Thuret, Kings College London;
(b) © Cengage Learning. Days of training required to reach platform in 10 sec 6 5 4 3 0 2 1 First test Second test wild-type R451C function mutations in FOXP2 result in severe speech and language disorders. In mice, they hamper brain function and vocalizations. The chimpanzee, gorilla, and rhesus FOXP2 proteins are identical; the human version differs in only 2 amino acids, an evolutionary change that may have contributed to the development of spoken language. Mice genetically engineered to carry the human version of FOXP2 show changes in vocal patterns, and more growth and greater adaptability of neurons involved in memory and learning. Biologists do not anticipate that a similar experiment with FOXP2 in chimpanzees would confer the ability to speak, because spoken language is a polygenic trait. However, if future genetic engineering research produces a talking chimp, how do you think the debate about using animals for research would change?
