TY  - JOUR
A1  - Mora, Emanuel C.
A1  - Macias, S.
A1  - Vater, Marianne
A1  - Coro, Frank
A1  - Kossl, Manfred
T1  - Specializations for aerial hawking in the echolocation system of Molossus molossus (Molossidae, Chiroptera)
N2  - While searching for prey, Molossus molossus broadcasts narrow-band calls of 11.42 ms organized in pairs of pulses that alternate in frequency. The first signal of the pair is at 34.5 kHz, the second at 39.6 kHz. Pairs of calls with changing frequencies were only emitted when the interpulse intervals were below 200 ms. Maximum duty cycles during search phase are close to 20%. Frequency alternation of search calls is interpreted as a mechanism for increasing duty cycle and thus the temporal continuity of scanning, as well as increasing the detection range. A neurophysiological correlate for the processing of search calls was found in the inferior colliculus. 64% of neurons respond to frequencies in the 30- to 40-kHz range and only in this frequency range were closed tuning curves found for levels below 40 dB SPL. In addition, 15% of the neurons have double-tuned frequency-threshold curves with best thresholds at 34 and 39 kHz. Differing from observations in other bats, approach calls of M. molossus are longer and of higher frequencies than search calls. Close to the roost, the call frequency is increased to 45.049.8 kHz and, in addition, extremely broadband signals are emitted. This demonstrates high plasticity of call design
Y1  - 2004
SN  - 0340-7594
ER  - 
TY  - JOUR
A1  - Koessl, M.
A1  - Hechavarria, J. C.
A1  - Voss, C.
A1  - Macias, S.
A1  - Mora, E. C.
A1  - Vater, Marianne
T1  - Neural maps for target range in the auditory cortex of echolocating bats
JF  - Current opinion in neurobiology : reviews of all advances ; evaluation of key references ; comprehensive listing of papers
N2  - Computational brain maps as opposed to maps of receptor surfaces strongly reflect functional neuronal design principles. In echolocating bats, computational maps are established that topographically represent the distance of objects. These target range maps are derived from the temporal delay between emitted call and returning echo and constitute a regular representation of time (chronotopy). Basic features of these maps are innate, and in different bat species the map size and precision varies. An inherent advantage of target range maps is the implementation of mechanisms for lateral inhibition and excitatory feedback. Both can help to focus target ranging depending on the actual echolocation situation. However, these maps are not absolutely necessary for bat echolocation since there are bat species without cortical target-distance maps, which use alternative ensemble computation mechanisms.
Y1  - 2014
U6  - https://doi.org/10.1016/j.conb.2013.08.016
SN  - 0959-4388
SN  - 1873-6882
VL  - 24
SP  - 68
EP  - 75
PB  - Elsevier
CY  - London
ER  -