✍ Scribed by Manley, Geoffrey A.
No coin nor oath required. For personal study only.
A comparative analysis of the frequency response of the inner and middle ear of Gekko gecko is described. Tungsten microelectrodes were used to isolate single auditory neurons in the cochlear nucleus in order to study their frequency selectivity and sensitivity.
Neurons were detected with characteristic frequencies up to 5 kHz, and tuning curves were similar to those of mammalian systems. The single neuron responses were strongly frequency selective, as was expected from the presence of a well‐differentiated basilar membrane. The sensitivity of this hearing system compares favorably with that of birds and mammals and is the most sensitive of those reptiles yet studied with neurophysiological techniques.
The middle‐ear response was studied with the Mössbauer system and shows a typical non‐mammalian response. Amplitude of the drum or columella is constant up to 1 kHz, then falls off rapidly at higher frequencies. A lever action between drum and columella presumably aids impedance matching. The overall ear sensitivity function was corrected for middle ear response and reveals a true inner‐ear sensitivity curve. Analysis of the single‐unit data is aided by a knowledge of the middle‐ear response, and somewhat different conclusions are reached after correction of the data to constant columella amplitude.
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