Frequency tuning and intensity coding of sound in the auditory periphery of the lake sturgeon, Acipenser fulvescens

Abstract

SUMMARYAcipenser fulvescens, the lake sturgeon, belongs to one of the few extant non-teleost ray-finned (bony) fishes. The sturgeons (family Acipenseridae) have a phylogenetic history that dates back about 250 million years. The study reported here is the first investigation of peripheral coding strategies for spectral analysis in the auditory system in a non-teleost bony fish. We used a shaker system to simulate the particle motion component of sound during electrophysiological recordings of isolated single units from the eighth nerve innervating the saccule and lagena. Background activity and response characteristics of saccular and lagenar afferents (such as thresholds, response-level functions and temporal firing) resembled the ones found in teleosts. The distribution of best frequencies also resembled data in teleosts (except for Carassius auratus, goldfish) tested with the same stimulation method. The saccule and lagena in A. fulvescens contain otoconia, in contrast to the solid otoliths found in teleosts, however, this difference in otolith structure did not appear to affect threshold, frequency tuning, intensity-or temporal responses of auditory afferents. In general, the physiological characteristics common to A. fulvescens, teleosts and land vertebrates reflect important functions of the auditory system that may have been conserved throughout the evolution of vertebrates.

Coding of sound direction in the auditory periphery of the lake sturgeon,Acipenser fulvescens

“…Because these differences are important for the interpretation of the physiological data presented, we will summarize them briefly. The reader should refer to Popper (1978) and Lovell et al (2005) regarding general morphology and hair cell orientation and to Meyer et al (2010) regarding innervation and recording site for a more detailed description.…”

“…All of these units showed directional selectivity and strongly phase-locked to the stimulus waveform (Z Ն 20). For 170 of these directional units, we also obtained frequency responses (Meyer et al 2010). The BF of those units ranged between 100 and 330 Hz.…”

“…For a detailed description of the methods, see Meyer et al (2010). Fish were lightly anesthetized in a bath containing 0.05% buffered 3-aminobenzoic acid methane-sulfonate salt (Sigma, St. Louis, MO) dissolved in tank water and after that were immobilized with an intramuscular injection of gallamine triethiodide in goldfish Ringer solution (43 g/g body mass).…”

Auditory sensitivity of larval zebrafish (Danio rerio) measured using a behavioral prepulse inhibition assay

“…1ms -2 at 100Hz (Fay et al, 1994)], sturgeon [Acipenser fulvescens; −90 to −33dB re. 1ms -2 at 100Hz (Meyer et al, 2010)] and goldfish [Carassius auratus; −90 to −8dB re. 1ms -2 at 140Hz (Fay, 1984)].…”

Comparative Hearing: Honoring Dick Fay

“…Michaela pointed out that the Fay shaker table represents a carefully controlled stimulus device simulating water particle motion. This work showed that peripheral coding mechanisms for spatial and spectral analysis of sound in sturgeon appear similar to those of teleost fish, such as the goldfish (Meyer et al, 2010;Meyer et al, 2012).…”