Every once in a while, we hear of amazing scientific feats about how some new drug successfully reduces weight without dieting or exercise in monkeys, or how scientists slowed aging in worms and doubled their lifespans. These studies are often a cause for ridicule in the media, which reduces their significance and validity by implying that mice, flies, birds—any animal really—is not a true representation of the human condition.
While disease and physiological processes in humans may be very different from those in other species, animal models are not only relevant in learning more about the human condition – they are essential. Kate recently introduced a study about how songbirds learn and correct errors during song acquisition. You might ask, why would anyone be interested in studying anything in songbirds? Let’s take a close look.
Learning and generating vocal sounds during development is not a uniquely human feature. Songbirds, or Bengalese finches, learn to imitate vocal patterns of an adult during a sensitive period of development, much like a human baby learning to speak a language. Two MIT neuroscientists extensively review these animals, highlighting their use and validity in learning and language studies (Fee and Sharff, 2010). Instead of phonetic sounds that make up words as we know them, songbirds use individual notes structured into a stereotyped series of acoustic sounds, modulated over a wide range of time scales. Like a toddler beginning to make incoherent sounds after listening to the words of a parent, a young songbird begins to sing a variable, unstructured song after a sensory stage of listening to the vocalization of adult birds. Just like humans learning to speak, songbirds use auditory feedback to correct errors and further refine their songs. This study is relevant in elucidating how we are able to partake on a similar process during language acquisition, how the brain learns language, and potentially inform vocal rehabilitation therapies for various disorders.
Songbirds are able to learn songs like humans can learn language. This is in part due to a brain network that includes auditory, striatal, and pre-motor pathways that process vocal sounds. These anatomical correlates allow scientists to study language learning at the circuit level, in addition to cellular and molecular processes required for this amazing feature. Moreover, genetic analysis of songbirds have identified key genes that are important for song, speech, and language learning. Some of these genetic sequences are 80-90% identical to human genes!
Sure, songbirds can’t speak. But their songs are a kind of language, and songbird vocal learning has strikingly similar behavioral, neural, and genetic processes to human language learning. Therefore, studies in these animals inform us about how our brains can perform this complex task while we are developing. Animal models, like the songbird, can also help to study speech deficiencies of complex disorders like in Autism Spectrum Disorders, or even after recovering from stroke. As it turns out, animal models need not fully replicate the human condition to be relevant and useful. We may not be able to understand each other, but songbirds can tell us so much about ourselves.
~Fee M.S. & Scharff C. The songbird as a model for the generation and learning of complex sequential behaviors., ILAR journal / National Research Council, Institute of Laboratory Animal Resources, PMID: 21131713 Warren W.C., Clayton D.F., Ellegren H., Arnold A.P., Hillier L.W., Künstner A., Searle S., White S., Vilella A.J., Fairley S. & Heger A. (2010). The genome of a songbird, Nature, 464 (7289) 757-762. DOI: 10.1038/nature08819 Panaitof S.C. (2012) A songbird animal model for dissecting the genetic bases of autism spectrum disorder. Disease markers, DOI: 10.3233/DMA-2012-0918 Images adapted from Corbis (songbird, musical note), and Simonyan K., Horwitz B. & Jarvis E.D. (2012). Dopamine regulation of human speech and bird song: A critical review, Brain and Language, 122 (3) 142-150. DOI: 10.1016/j.bandl.2011.12.009