Auditory brainstem responses to airborne sounds in the aquatic frog Xenopus laevis: correlation with middle ear characteristics

Abstract

In this study we recorded auditory brainstem responses to airborne sounds to determine the hearing sensitivity of Xenopus laevis frogs and correlated their hearing profiles with middle ear characteristics. In newly metamorphosed frogs (body mass 0.5-0.76 gm, snout-vent length 17-20 mm) best hearing sensitivities were measured in the 2.4-2.8 kHz range, whereas optimal hearing sensitivity of older adults (body mass 18-90 gm; snout-vent length 57-100 mm) ranged from 1.0 to 1.2 kHz. Middle ear volumes reconstructed from serial sections showed approximate volume of 0.002 cc and 0.04-0.07 cc in newly metamorphosed and older frogs, respectively. This inverse frequency-volume relationship is consistent with the properties of an acoustic resonator indicating that differences in best hearing sensitivity are at least in part correlated to variation in middle ear volumes for airborne sounds. These results are consistent with peak frequency vibrational velocity profiles of Xenopus tympanic disk that have been shown to be dependent on underlying middle ear volumes and corroborate the occurrence of peak amplitudes of otoacoustic emissions in the 1.0-1.2 kHz region in adult Xenopus frogs.

Assessing stimulus and subject influences on auditory evoked potentials and their relation to peripheral physiology in green treefrogs (Hyla cinerea)

“…We could determine no reason for the large difference at this single frequency. For brevity and consistency with previous studies in frogs (Katbamna et al, 2006a; Schrode et al, 2014; Zhang et al, 2012) and other animals (e.g. Brittan-Powell et al, 2010a; Lohr et al, 2013; Wysocki and Ladich, 2005b), we focused our statistical analysis on the audiogram determined from visually detected thresholds.…”

“…In both species, the peaks in sensitivity occur at the frequencies present in conspecific advertisement calls, and probably also represent the peak sensitivities of the AP and BP. Audiograms for African clawed frogs ( Xenopus laevis ; Katbamna et al, 2006a) and Emei music frogs ( Babina daunchina ; Zhang et al, 2012) both have a more U-like shape. That of the music frog is broad enough to encompass the frequencies containing most of the harmonic energy in male advertisement calls (Chen et al, 2011).…”

“…Though a handful of previous studies have measured brainstem potentials in anurans using methods that require surgery (Bibikov and Elepfandt, 2005; Carey and Zelick, 1993; Corwin et al, 1982; Hillery, 1984; Katbamna et al, 2006b; Seaman, 1991; Yu et al, 2006), recordings of ABRs in anurans using subcutaneous electrodes have been limited to just three previous studies (Katbamna et al, 2006a; Schrode et al, in press; Zhang et al, 2012). …”

“…Second, we sought to determine the extent to which ABR morphology and dependence on frequency and signal level correspond to the expected tuning of the green treefrog’s peripheral auditory system based on results from previous invasive studies (Capranica and Moffat, 1983; Ehret and Capranica, 1980; Lombard and Straughan, 1974). Finally, we sought to generate an ABR audiogram for comparison with previous behavioral (Megela-Simmons et al, 1985; Weiss and Strother, 1965) and neurophysiological (Lombard and Straughan, 1974; Miranda and Wilczynski, 2009b; Penna et al, 1992) audiograms from green treefrogs as well as ABR audiograms from Cope’s gray treefrog ( Hyla chrysoscelis ) (Schrode et al, 2014), the African clawed frog ( Xenopus laevis ) (Katbamna et al, 2006a), and the Emei music frog ( Babina daunchina ) (Zhang et al, 2012). …”

Objective threshold estimation and measurement of the residual background noise in auditory evoked potentials of goldfish

“…The technique remains popular for many reasons, but especially because it is a noninvasive and time-efficient means of measuring auditory system function. It has now become widely used in clinical and basic hearing research in both human and diverse vertebrate animal models ͓mammals ͑e.g., Boettcher, 2002͒, birds ͑e.g., Brittan-Powell et al, 2002͒, reptiles ͑e.g., Higgs et al, 2002͒, amphibians ͑e.g., Katbamna et al, 2006͒, and fishes ͑e.g., Kenyon et al, 1998͔͒. Most recently, AEP audiometry has been used to statistically test a wide variety of hypotheses on the function, development, and evolution of audition. Examples include the effect of chemical and noise exposure on auditory sensitivity ͑e.g., Lu and Tomchik, 2002;Le Prell et al, 2004;Popper et al, 2005;Porter et al, 2006;Cordova and Braun, 2007͒, ontogenetic changes in hearing abilities ͑e.g., Boettcher, 2002;Higgs et al, 2003;Song et al, 2006͒, or com-parative studies of closely related species ͑e.g., Ramcharitar and Popper, 2004;Ramcharitar et al, 2006͒.…”