AUDITORY CORTEX ACTIVATION IN A VOCAL LEARNING MAMMAL: AN IMMEDIATE EARLY GENE STUDY
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2017-07-01
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en
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As social animals, language and communication are important traits for humans. These are complex abilities that involve the combination of diverse cognitive processes in order to succeed in understanding and transmitting a meaningful message. Vocal production learning (VPL), the ability to learn and modify sounds, is an important aspect of vocal plasticity and a key ability to human language. Identifying key structures and circuits of VPL could contribute to the understanding of biological and genetic underpinnings necessary for language and communication. The use of animal models helps with investigating these points. Most animal research in this area has focused on making models of birds’ VLP. However, this is not enough to fully understand human language. The similarity in vocal communication between some vocal learning bat species and humans provides a unique opportunity to study neuronal mechanisms underlying communication. Neuronal commonalities such as a 6-layered cortical surface may provide results in bats that are easier to translate in humans compared to birds. We were interested in investigating the bats’ auditory cortex (AC) and its function with respect to communication. This brain area is fundamental for integration of auditory information. Given its relevance for social interactions, this area might be specialized in terms of processing of communication sounds. To investigate the regions of the AC involved in communication vocalizations, bats of the species Phyllostomus discolor were exposed to either communication sounds, echolocation sounds or a silence control condition. Immediately after exposure to these conditions, the brains were collected and RNA in situ hybridization was used to analyze c-FOS expression levels. c-FOS is an immediate early gene that rapidly expresses when brain areas are active. We then determined the density of c-FOS expression for different areas of the AC (left, right, front, back, top and bottom areas). The results on differences between conditions (echolocation, communication and control) were non-conclusive due to limited sample size. Nonetheless, this research found interesting differences between dorsal and ventral areas as well as symmetry of left and right AC activation that could be studied in future research projects. Furthermore, we developed a method to approximate the location and area of the AC in order to eliminate individual differences in brain size and brain morphology. Bats and humans are social animals that highly rely in communication for their social interactions. The ability to modify and learn sounds is a key ability to communication for these species. The detection of immediate early genes is a useful indicator of brain activity that has a resolution at the cellular-level. This provided an opportunity to look at separate areas of the AC and how they might respond to specific stimuli. With the study of bats’ neurobiological and genetic mechanisms, we might identify of key elements necessary for communication and human language.
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Faculteit der Sociale Wetenschappen