@article{MoraMaciasVateretal.2004, author = {Mora, Emanuel C. and Macias, S. and Vater, Marianne and Coro, Frank and Kossl, Manfred}, title = {Specializations for aerial hawking in the echolocation system of Molossus molossus (Molossidae, Chiroptera)}, issn = {0340-7594}, year = {2004}, abstract = {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}, language = {en} } @article{KoesslMoraCoroetal.1999, author = {K{\"o}ssl, Manfred and Mora, Emanuel C. and Coro, Frank and Vater, Marianne}, title = {Two-toned echolocation calls from Molossus molossus in Cuba.}, issn = {0022-2372}, year = {1999}, language = {en} } @article{VaterFoellerMoraetal.2010, author = {Vater, Marianne and Foeller, Elisabeth and Mora, Emanuel C. and Coro, Frank and Russell, Ian J. and K{\"o}ssl, Manfred}, title = {Postnatal maturation of primary auditory cortex in the mustached bat, pteronotus parnellii}, issn = {0022-3077}, doi = {10.1152/jn.00517.2009}, year = {2010}, abstract = {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.}, language = {en} } @article{HechavarriaMaciasVateretal.2013, author = {Hechavarria, Julio C. and Macias, Silvio and Vater, Marianne and Mora, Emanuel C. and K{\"o}ssl, Manfred}, title = {Evolution of neuronal mechanisms for echolocation specializations for target-range computation in bats of the genus Pteronotus}, series = {The journal of the Acoustical Society of America}, volume = {133}, journal = {The journal of the Acoustical Society of America}, number = {1}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0001-4966}, doi = {10.1121/1.4768794}, pages = {570 -- 578}, year = {2013}, abstract = {Delay tuning was studied in the auditory cortex of Pteronotus quadridens. All the 136 delay-tuned units that were studied responded strongly to heteroharmonic pulse-echo pairs presented at specific delays. In the heteroharmonic pairs, the first sonar call harmonic marks the timing of pulse emission while one of the higher harmonics (second or third) indicates the timing of the echo. Delay-tuned units are organized chronotopically along a rostrocaudal axis according to their characteristic delay. There is no obvious indication of multiple cortical axes specialized in the processing of different harmonic combinations of pulse and echo. Results of this study serve for a straight comparison of cortical delay-tuning between P. quadridens and the well-studied mustached bat, Pteronotus parnellii. These two species stem from the most recent and most basal nodes in the Pteronotus lineage, respectively. P. quadridens and P. parnellii use comparable heteroharmonic target-range computation strategies even though they do not use biosonar calls of a similar design. P. quadridens uses short constant-frequency (CF)/frequency-modulated (FM) echolocation calls, while P. parnellii uses long CF/FM calls. The ability to perform "heteroharmonic" target-range computations might be an ancestral neuronal specialization of the genus Pteronotus that was subjected to positive Darwinian selection in the evolution.}, language = {en} } @article{HechavarriaMaciasVateretal.2013, author = {Hechavarria, Julio C. and Macias, Silvio and Vater, Marianne and Voss, Cornelia and Mora, Emanuel C. and Kossl, Manfred}, title = {Blurry topography for precise target-distance computations in the auditory cortex of echolocating bats}, series = {Nature Communications}, volume = {4}, journal = {Nature Communications}, number = {10}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/ncomms3587}, pages = {11}, year = {2013}, abstract = {Echolocating bats use the time from biosonar pulse emission to the arrival of echo (defined as echo delay) to calculate the space depth of targets. In the dorsal auditory cortex of several species, neurons that encode increasing echo delays are organized rostrocaudally in a topographic arrangement defined as chronotopy. Precise chronotopy could be important for precise target-distance computations. Here we show that in the cortex of three echolocating bat species (Pteronotus quadridens, Pteronotus parnellii and Carollia perspicillata), chronotopy is not precise but blurry. In all three species, neurons throughout the chronotopic map are driven by short echo delays that indicate the presence of close targets and the robustness of map organization depends on the parameter of the receptive field used to characterize neuronal tuning. The timing of cortical responses (latency and duration) provides a binding code that could be important for assembling acoustic scenes using echo delay information from objects with different space depths.}, language = {en} } @article{KoesslVossMoraetal.2012, author = {K{\"o}ssl, Manfred and Voss, Cornelia and Mora, Emanuel C. and Macias, Silvio and F{\"o}ller, Elisabeth and Vater, Marianne}, title = {Auditory cortex of newborn bats is prewired for echolocation}, series = {Nature Communications}, volume = {3}, journal = {Nature Communications}, number = {2}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/ncomms1782}, pages = {7}, year = {2012}, abstract = {Neuronal computation of object distance from echo delay is an essential task that echolocating bats must master for spatial orientation and the capture of prey. In the dorsal auditory cortex of bats, neurons specifically respond to combinations of short frequency-modulated components of emitted call and delayed echo. These delay-tuned neurons are thought to serve in target range calculation. It is unknown whether neuronal correlates of active space perception are established by experience-dependent plasticity or by innate mechanisms. Here we demonstrate that in the first postnatal week, before onset of echolocation and flight, dorsal auditory cortex already contains functional circuits that calculate distance from the temporal separation of a simulated pulse and echo. This innate cortical implementation of a purely computational processing mechanism for sonar ranging should enhance survival of juvenile bats when they first engage in active echolocation behaviour and flight.}, language = {en} }