TY  - JOUR
A1  - Hechavarria, Julio C.
A1  - Macias, Silvio
A1  - Vater, Marianne
A1  - Mora, Emanuel C.
A1  - Kössl, Manfred
T1  - Evolution of neuronal mechanisms for echolocation specializations for target-range computation in bats of the genus Pteronotus
JF  - The journal of the Acoustical Society of America
N2  - 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.
Y1  - 2013
U6  - https://doi.org/10.1121/1.4768794
SN  - 0001-4966
VL  - 133
IS  - 1
SP  - 570
EP  - 578
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Hechavarria, Julio C.
A1  - Macias, Silvio
A1  - Vater, Marianne
A1  - Voss, Cornelia
A1  - Mora, Emanuel C.
A1  - Kossl, Manfred
T1  - Blurry topography for precise target-distance computations in the auditory cortex of echolocating bats
JF  - Nature Communications
N2  - 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.
Y1  - 2013
U6  - https://doi.org/10.1038/ncomms3587
SN  - 2041-1723
VL  - 4
IS  - 10
PB  - Nature Publ. Group
CY  - London
ER  -