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The representation of auditory space in the auditory cortex of anesthetized and awake mice
The representation of auditory space in the auditory cortex of anesthetized and awake mice
The ability to localize sounds is of profound importance for animals, as it enables them to detect prey and predators. In the horizontal plane, sound localization is achieved by means of binaural cues, which are processed and interpreted by the ascending auditory pathway. The auditory cortex (AC), as its primary cortical relay station, has traditionally been thought to broadly and stationary represent the contralateral hemifield of auditory space. Because prior research on space representation in the mammalian AC heavily relied on anesthetized preparations, the manner in which anesthesia influences this representation has remained elusive. Performing chronic two-photon-calcium imaging in the AC of awake and anesthetized mice, I characterized the effects of anesthesia on auditory space representation. First, anesthesia was found to impair the spatial sensitivity of neurons. Second, anesthesia constantly suppressed the representation of frontal locations biasing spatial tuning to the contralateral side. In both conditions (awake and anesthetized), the population of neurons endured a stable representation of auditory space, while single-cell spatial tuning was found to be extremely dynamic. Importantly, under both conditions no evidence for a topographical map of auditory space was found. This study is the first to chronically probe spatial tuning in the AC and likewise the first to directly assess effects of anesthesia on single-cell spatial tuning and the population code emphasizing the need for a shift towards awake preparations.
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Gumbert, Matthias
2022
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Gumbert, Matthias (2022): The representation of auditory space in the auditory cortex of anesthetized and awake mice. Dissertation, LMU München: Graduate School of Systemic Neurosciences (GSN)
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Abstract

The ability to localize sounds is of profound importance for animals, as it enables them to detect prey and predators. In the horizontal plane, sound localization is achieved by means of binaural cues, which are processed and interpreted by the ascending auditory pathway. The auditory cortex (AC), as its primary cortical relay station, has traditionally been thought to broadly and stationary represent the contralateral hemifield of auditory space. Because prior research on space representation in the mammalian AC heavily relied on anesthetized preparations, the manner in which anesthesia influences this representation has remained elusive. Performing chronic two-photon-calcium imaging in the AC of awake and anesthetized mice, I characterized the effects of anesthesia on auditory space representation. First, anesthesia was found to impair the spatial sensitivity of neurons. Second, anesthesia constantly suppressed the representation of frontal locations biasing spatial tuning to the contralateral side. In both conditions (awake and anesthetized), the population of neurons endured a stable representation of auditory space, while single-cell spatial tuning was found to be extremely dynamic. Importantly, under both conditions no evidence for a topographical map of auditory space was found. This study is the first to chronically probe spatial tuning in the AC and likewise the first to directly assess effects of anesthesia on single-cell spatial tuning and the population code emphasizing the need for a shift towards awake preparations.