TY  - JOUR
A1  - Kössl, Manfred
A1  - Mora, Emanuel C.
A1  - Coro, Frank
A1  - Vater, Marianne
T1  - Two-toned echolocation calls from Molossus molossus in Cuba.
Y1  - 1999
SN  - 0022-2372
ER  - 
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  - Vater, Marianne
A1  - Foeller, Elisabeth
A1  - Mora, Emanuel C.
A1  - Coro, Frank
A1  - Russell, Ian J.
A1  - Kössl, Manfred
T1  - Postnatal maturation of primary auditory cortex in the mustached bat, pteronotus parnellii
N2  - The primary auditory cortex (AI) of adult Pteronotus parnellii features a foveal representation of the second harmonic constant frequency (CF2) echolocation call component. In the corresponding Doppler-shifted constant frequency (DSCF) area, the 61 kHz range is over-represented for extraction of frequency-shift information in CF2 echoes. To assess to which degree AI postnatal maturation depends on active echolocation or/and reflects ongoing cochlear maturation, cortical neurons were recorded in juveniles up to postnatal day P29, before the bats are capable of active foraging.At P1-2, neurons in posterior AI are tuned sensitively to low frequencies (22-45 dB SPL, 28-35 kHz). Within the prospective DSCF area, neurons had insensitive responses (>60 dB SPL) to frequencies <40 kHz and lacked sensitive tuning curve tips. Up to P10, when bats do not yet actively echolocate, tonotopy is further developed and DSCF neurons respond to frequencies of 51-57 kHz with maximum tuning sharpness (Q(10dB)) of 57. Between P11 and 20, the frequency representation in AI includes higher frequencies anterior and dorsal to the DSCF area. More multipeaked neurons (33%) are found than at older age. In the oldest group, DSCF neurons are tuned to frequencies close to 61 kHz with Q(10dB) values <= 212, and threshold sensitivity, tuning sharpness and cortical latencies are adult-like. The data show that basic aspects of cortical tonotopy are established before the bats actively echolocate. Maturation of tonotopy, increase of tuning sharpness, and upward shift in the characteristic frequency of DSCF neurons appear to strongly reflect cochlear maturation.
Y1  - 2010
UR  - http://jn.physiology.org/
U6  - https://doi.org/10.1152/jn.00517.2009
SN  - 0022-3077
ER  -