Psychophysical and neurophysiological hearing thresholds in the bat Phyllostomus discolor

Absolute hearing thresholds in the spear-nosed bat Phyllostomus discolor have been determined both with psychophysical and neurophysiological methods. Neurophysiological data have been obtained from two different structures of the ascending auditory pathway, the inferior colliculus and the auditory cortex. Minimum auditory thresholds of neurons are very similar in both structures. Lowest absolute thresholds of 0 dB SPL are reached at frequencies from about 35 to 55 kHz in both cases. Overall behavioural sensitivity is roughly 20 dB better than neural sensitivity. The behavioural audiogram shows a first threshold dip around 23 kHz but threshold was lowest at 80 kHz (−10 dB SPL). This high sensitivity at 80 kHz is not reflected in the neural data. The data suggest that P. discolor has considerably better absolute auditory thresholds than estimated previously. The psychophysical and neurophysiological data are compared to other phyllostomid bats and differences are discussed.

[1]  Lutz Wiegrebe,et al.  The absence of spatial echo suppression in the echolocating bats Megaderma lyra and Phyllostomus discolor , 2006, Journal of Experimental Biology.

[2]  K. Esser,et al.  Tonotopic organization and parcellation of auditory cortex in the FM‐bat Carollia perspicillata , 1999, The European journal of neuroscience.

[3]  Susanne Radtke-Schuller,et al.  A stereotaxic method for small animals using experimentally determined reference profiles , 1986, Journal of Neuroscience Methods.

[4]  C. Moss,et al.  The role of the external ear in vertical sound localization in the free flying bat, Eptesicus fuscus. , 2007, The Journal of the Acoustical Society of America.

[5]  Hearing in American leaf-nosed bats. I: Phyllostomus hastatus , 2002, Hearing Research.

[6]  Hans-Ulrich Schnitzler,et al.  Behavioural audiograms from the bat,Rhinolophus ferrumequinum , 2004, Journal of comparative physiology.

[7]  Uwe Firzlaff,et al.  Spectral directionality of the external ear of the lesser spear-nosed bat, Phyllostomus discolor , 2003, Hearing Research.

[8]  K. Esser,et al.  Detection of frequency modulation in the FM-bat Phyllostomus discolor , 1996, Journal of Comparative Physiology A.

[9]  K. Esser,et al.  Discrimination of sinusoidally frequency-modulated sound signals mimicking species-specific communication calls in the FM-bat Phyllostomus discolor , 1997, Journal of Comparative Physiology A.

[10]  William M. Hartmann,et al.  Psychoacoustics: Facts and Models , 2001 .

[11]  J. Simmons,et al.  Spectral cues and perception of the vertical position of targets by the big brown bat, Eptesicus fuscus. , 2000, The Journal of the Acoustical Society of America.

[12]  J A Simmons,et al.  Echolocation in bats: the external ear and perception of the vertical positions of targets. , 1982, Science.

[13]  J. Ostwald,et al.  Anesthesia changes frequency tuning of neurons in the rat primary auditory cortex. , 2001, Journal of neurophysiology.

[14]  G. Schuller.  A cheap earphone for small animals with good frequency response in the ultrasonic frequency range , 1997, Journal of Neuroscience Methods.

[15]  H. Heffner,et al.  Hearing in American leaf-nosed bats. II: Carollia perspicillata , 2003, Hearing Research.

[16]  A. Grinnell.  Comparative auditory neurophysiology of neotropical bats employing different echolocation signals , 1970, Zeitschrift für vergleichende Physiologie.

[17]  Alan D. Grinnell,et al.  THE SENSITIVITY OF ECHOLOCATION IN BATS , 1958 .

[18]  Manfred Kössl,et al.  Cochlear sensitivity in the lesser spear-nosed bat, Phyllostomus discolor , 2004, Journal of Comparative Physiology A.

[19]  Auditory sensitivity and frequency selectivity in greater spear-nosed bats suggest specializations for acoustic communication , 2004, Journal of Comparative Physiology A.

[20]  D. Clarençon,et al.  Spectrum of neural electrical activity in guinea pig cochlea: Effects of anaesthesia regimen, body temperature and ambient noise , 2006, Hearing Research.

[21]  K. Esser,et al.  Hearing in the FM-bat Phyllostomus discolor: a behavioral audiogram , 1996, Journal of Comparative Physiology A.

[22]  R. Rübsamen,et al.  The postnatal development of frequency-place code and tuning characteristics in the auditory midbrain of the phyllostomid bat, Carollia perspicillata , 1994, Hearing Research.

[23]  Z. Fuzessery,et al.  Monaural and binaural spectral cues created by the external ears of the pallid bat , 1996, Hearing Research.

[24]  A. Greenhall,et al.  A review of the bats of Trinidad and Tobago : descriptions, rabies infection, and ecology. Bulletin of the AMNH ; v. 122, article 3 , 1961 .

[25]  K. Esser,et al.  Behavioral auditory thresholds in neonate lesser spear-nosed bats,Phyllostomus discolor , 1990, The Science of Nature.

[26]  H. Heffner,et al.  Hearing in American leaf-nosed bats. III: Artibeus jamaicensis , 2003, Hearing Research.

[27]  E. Evans,et al.  On the functional relationship between the dorsal and ventral divisions of the cochlear nucleus of the cat , 1973, Experimental Brain Research.

[28]  Uwe Firzlaff,et al.  Object-Oriented Echo Perception and Cortical Representation in Echolocating Bats , 2007, PLoS biology.

[29]  U. Firzlaff,et al.  A Neural Correlate of Stochastic Echo Imaging , 2006, The Journal of Neuroscience.

[30]  J. Siegel,et al.  Cochlear basal and apical differences reflected in the effects of cooling on responses of single auditory nerve fibers , 1994, Hearing Research.

[31]  Uwe Schmidt,et al.  Der Einfluß visueller Information auf die Echoortung bei Phyllostomus discolor (Chiroptera) , 1981 .

[32]  Lutz Wiegrebe,et al.  Classification of natural textures in echolocation. , 2004, Proceedings of the National Academy of Sciences of the United States of America.