Meeting Abstract

P2.105  Sunday, Jan. 5 15:30  Expiratory muscle activity in a flexible mammalian vocal motor program. TRENT, S.*; SMOTHERMAN, M.; Texas A&M University; Texas A&M University strent@bio.tamu.edu

The main objective of this study is to investigate how respiratory muscle activity shapes the acoustic features of mammalian communication sounds. Mammalian vocalizations are generated by expiratory force which comes from coordinated actions of intercostal and abdominal muscles compressing the thoracic cavity to rapidly increase subglottic pressure. The acoustic properties of some mammalian vocalizations can be fine-tuned in a behavioral context by manipulating expiratory force. Echolocating bats demonstrate an exceptional level of vocal control and the abdominal musculature may play a central role in the bats’ ability to adjust the shape of outgoing echolocation pulses. Here we explore how bats manipulate muscle activity to produce different sounds. We used chronically-implanted wire electrodes for obtaining electromyograms (EMGs) from the external oblique muscle in awake and actively echolocating bats. By mapping the electrical activity of this muscle with concurrent ultrasound recordings, we were able to identify stereotyped patterns of external oblique muscle activity immediately preceding each echolocation pulse, showing the involvement and requirement of this muscle in sound production. From this data we can evaluate how the temporal dynamics of this muscle’s activity patterns relate to the spectrotemporal features of the bats’ echolocation pulses. These results provide important insight to the neural-motor transfer functions that create these highly stereotyped vocalizations. By ultimately linking changes in motor cortical activity to changes in this abdominal muscle force this project will offer new insights to how the brain controls vocal communication in mammals.