Dr. Cornelia Voß , geb. Hagemann
Lecturer (Wissenschaftliche Assistentin)

Sensory organs enable mammals to identify and analyse their environment. While the sense of vision dominates the cognitive capabilities of most mammals and humans, bats (Microchiroptera) possess the exceptional ability to orientate themselves in complete darkness with the help of echolocation. These echolocation or echo perception capabilities require bats to have an extremely well-developed auditory system. Bats achieve these capabilities by hypertrophy of the auditory system, while the composition of their sound processing centre is not fundamentally different from other mammals not using echolocation. The physiology of auditory centres in mammals is already well examined and characterized. However, little is known about the ontogenetic development of the auditory system in bats.

Therefore, my research is focused on the maturing process of the auditory system at the cortical level in the FM bat Carollia perspicillata. Similar to analyses of the auditory cortex (AC) in adult animals, the AC is being examined and mapped electrophysiologically in animals across age groups. My focus is on the frequency organization in the auditory cortex during the ontogenesis of Carollia perspicillata.

Juvenile (3rd day, left) and adult Carollia perspicillata (right)

Other publications have shown for the CF-FM bat Pteronotus parnellii, for example, that the AC can be separated into different areas (primary & secondary cortex) within the first few postnatal weeks. Neurons, which analyse the frequency of the CF-components, are located in the primary auditory cortex. In the CF/CF region there are neurons, which respond to a certain combination of two CF components. In the FM/FM region, neurons respond to certain FM/FM combinations with a defined time interval (delay). With the help of these specific sound-echo delays an efficient acoustic ranging on neural level is guaranteed. Such delay-sensitive neurons are also assumed in the auditory cortex of Carollia perspicillata.

In my graduation work I examined the AC of Carollia perspicillata from an electrophysiological perspective and focused on delay sensitive neurons. So the description of the processing mechanism of the auditory cortex in detail is possible. It is interesting that delay sensitive neurons in Pteronotus parnellii are thought to be essential for detecting insects. However, since Carollia perspicillata is a frugivore it may be concluded that delay-tuned neurons are needed for general orientation purposes.

Further readings:

Eiermann, A., Esser K.-H., (2000): Auditory responses from the frontal cortex in the short-tailed fruit bat Carollia perspicillata. Neuroreport, 11(2):421-5.
Esser K.-H., Eiermann A. (1999): Tonotopic organization and parcellation of auditory cortex in the FM-bat Carollia perspicillata. Eur. J. Neuros., 11:3669-3682.
Esser K.-H., Eiermann A. (2004): Processing of frequency-modulated sound in the Carollia auditory and frontal cortex. In: Thomas J., bats. J. Exp. Zoology, 89:475-490.
Kössl, M., Vater, M. (1990): Tonotopic organization of the cochlear nucleus of the mustache bat, Pteronotus parnellii. J. Comp. Physiol. A, 166:695-709.
Sterbing, S. J., Schmidt, U., Rübsamen, R. (1994): The postnatal development of fre-quency-place code and tuning characteristics in the auditory midbrain of the phyllostomid bat, Carollia perspicillata. Hear. Res., 76:133-146.

Publications:

Hagemann, C.; Vater, M.; Kössl, M. (2011) Comparison of properties of cortical echo delay-tuning in the short-tailed fruit bat and the mustached bat. J Comp Physiol A 197:605-613.

 Schlenther D., Voss C., Kössl M. (2011): Cubic and quadratic distortion-product otoacoustic emissions (DPOAE) in awake and anesthetized short-tailed fruit bats. 9th Göttingen Meeting of the German Neuroscience Society: T17-6A

Hagemann, C; Esser, K.H.; Kössl, M. (2010) A chronotopically organized target-distance map in the auditory cortex of the Short-tailed Fruit Bat. J Neurophysiol 103:322-333.

Hagemann, C; Kössl, M. (2010) Postnatal development of frequency-representation in the auditory cortex of the Short-Tailed Fruit Bat. FNES Abstract 5, 112.20.

Hagemann, C.; Esser, K.H.; Kössl, M. (2009):
Chronotopic organization in the auditory cortex of the FM bat Carollia perspicillata.
Assoc Res Otolaryngol Abs 145: 392

Kössl, M.; Hagemann, C.; Foeller, E.; Mora, E.; Macias, S.; Vater, M. (2009):
Cortical delay-tuning in young mustached bats.
Assoc Res Otolaryngol Abs 296: 658

Hagemann, C.; Esser, K.H.; Kössl, M. (2009):
Delay-sensitive neurons in the auditory cortex of the Phyllostomid bat, Carollia perspicillata.
8th Göttingen Meeting of the German Neuroscience Society: T18-1A

Müller, B.; Glösmann, M.; Peichl, L.; Knop, G.C.; Hagemann, C.; Ammermüller, J. (2009):
Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors.
PLoS ONE 4:e6390.