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Biomedical subjects

G R Bock

Publications and source records attributed to G R Bock.

At least 37 records · Page 2Linked to original sources
PubMed1982

Preservation of central auditory function in the deafness mouse.

Deafness mice are profoundly deaf from birth as a result of genetically determined cochlear dysfunction. Evoked potentials in response to direct electrical stimulation of the cochlear nerve can readily be recorded in the inferior colliculus of deafness mice, and such responses are larger in amplitude than those in control mice. These observations indicate that at least some central connections become functional in the deafness central auditory pathway in the absence of peripheral stimulation, and are relevant to the general problem of restoring function by direct nerve stimulation in the profoundly deaf.

Animals↗
PubMed1980

The nature of inherited deafness in deafness mice.

Many mouse mutants have an apparent deficiency in their responsiveness to sound. Most of these mutants have other abnormalities in addition to their hearing deficit, and the only two which have been subjected to a detailed anatomical and physiological study, shaker-1 and Ames waltzer, also have motor abnormalities. The existence of such motor abnormalities throws some doubt on the usefulness of these two mutants as possible models for hereditary deafness in man, which is most frequently uncomplicated. Deol and Kocher have described the deafness mutation in which mice homozygous for the recessive deafness gene (dn/dn) were unresponsive to sound and had no significant behavioural abnormality. Cochlear hair cells in deafness mice develop normally and then degenerate, and the adult animals are completely deaf. We have now studied deafness mice in order to determine the nature of their inherited deafness. Our data indicate that stimulus-related cochlear potentials do not develop even though hair cells are present in the young animal. The endocochlear potential is present in the scala media, but behaves abnormally during anoxia.

Action Potentials↗
PubMed1979

Frequency selectivity in bird and man: a comparison among critical ratios, critical bands and psychophysical tuning curves.

The relative frequency selectivity of the internal auditory filters, as measured by critical bands or critical ratios, and psychophysical tuning curves, was compared in an avian species (parakeet) and human listeners. The results indicate that the critical band predicts the frequency selectivity of psychophysical tuning curves and vice versa. These findings suggest that there are similar mechanisms which contribute to the frequency selectivity measured by these two procedures and that these mechanisms operate in both the human and avian ear.

Adult↗
PubMed1979

Supra-normal susceptibility to acoustic trauma of the rat pup cochlea.

1 Young and adult rats were exposed to a continuous 120 dB SPL white noise for 30 min. 2 Animals exposed before the 40th postnatal day showed drastic and permanent threshold shifts (PTS) at high frequencies (between 6 and 20 kHz). 3 After 60 days of age, only temporary threshold shifts (TTS) were noticed, which lasted 7 days. 4 Thus the sensory structures of the rat cochlea showed a supra-normal susceptibility to acoustic trauma, during and just after their anatomical differentiation. 5 These results support previous data obtained on hamsters and guinea-pigs and are discussed in terms of anatomo-functional relationships.

Aging↗
PubMed1978

Frequency selectivity in the parakeet (Melopsittacus undulatus) studied with psychophysical tuning curves.

Seven parakeets were trained to avoid shock during pure-tone stimulation. A modified method of limits was used to measure detection thresholds of the pure tones. The intensity of masker tones, at numerous frequencies, was varied in order to measure the masked threshold of a probe-tone signal set at a fixed frequency and intensity. Masking curves were obtained for three probe tones (.63, 1.6, and 2.5 kHz) at each of five sensation levels (10, 20, 30, 40, and 50 dB). The masking curves from this procedure are frequently referred to as "psychophysical tuning curves" and provide an indication of frequency selectivity. The results are compared with analogous data in other species and suggest that frequency analysis in the parakeet ear is somewhat less accurate than in the mammalian ear.

Acoustic Stimulation↗
PubMed1978

Frequency selectivity in the parakeet (Melopsittacus undulatus) studied with narrow-band noise masking.

Narrow-band noise masking was studied in the parakeet (Melopsittacus undulatus) using a modified method of limits and an instrumental avoidance-conditioning procedure. Masked thresholds were obtained from five subjects at 10 frequencies between 0.5 and 5.0 kHz for each of four sensation levels (26, 46, 66, and 86 db) of a 1/3-octave band noise masker centered at 1.6 kHz. The amount of masking was found to be linearly related to noise level, and the shape of the masking curve was symmetrical on both sides of the center frequency of the masker. In all cases, the greatest threshold shift occurred at the center frequency of the masker. The relative symmetry of the parakeet narrow-band masking curves contrasts with masking results reported in mammals.

Acoustic Stimulation↗