Search PubMed⌕ Search

Biomedical subjects

D B Moody

Publications and source records attributed to D B Moody.

68 records · Page 4Linked to original sources
PubMed1971

Auditory generalization gradients for response latency in the monkey.

Two monkeys were trained to press and hold a response key in the presence of a light and to release it at the onset of a pure tone. Initially, all responses with latencies shorter than 1 sec were reinforced without regard to the frequency of the pure tone, and the intensity of the pure tone that resulted in equal latencies at each frequency was determined. The second stage of the experiment consisted of discrimination training, during which releases to one pure-tone frequency (positive stimulus) were reinforced and releases to a second frequency (negative stimulus) were extinguished. Median latencies to the negative stimulus slowly increased as did the variability of the latency distribution for the negative stimulus. There was no evidence of a concurrent decrease in latencies to the positive stimulus indicative of behavioral contrast. The third part of the experiment consisted of determining maintained generalization gradients by increasing the number of nonreinforcement stimuli. The gradients that eventually resulted showed approximately equal latencies to all frequencies of the negative stimulus and shorter latencies to the positive stimulus frequency.

Animals↗
PubMed1969

Evoked potentials and auditory reaction time in monkeys.

Monkeys with bipolar stimulating and recording electrodes in primary auditory cortex were trained to release a key to the onset of a pure tone. Substitution of direct cortical stimulation for the pure tone resulted in a reduction of 15 milliseconds In the latency of the behavioral response. This changed latency agreed with the latency of the primary evoked potential recorded from the animals. Systematic related changes in the amplitude of the central response and in the latency of the behavioral response followed changes in the intensity and frequency of the acoustic stimulus.

Animals↗
PubMedDate not supplied

Permanent threshold shift and cochlear hair cell loss in the kanamycin-treated guinea pig.

The differential contribution of the inner hair cells (IHC) and the outer hair cells (OHC) in the mammalian cochlea to hearing sensitivity was assessed in six behaviorally-trained guinea pigs by comparing audiograms preadministration and postadministration of kanamycin, an antibiotic that predominantly destroys guinea pig OHC while leaving the IHC structurally unchanged. The results support the hypothesis that only the IHC of the cochlea responds to tones approximately 50 to 60 dB above the threshold of the intact cochlea.

Animals↗
PubMedDate not supplied

Hearing loss and cochlear pathology in monkeys after noise exposure.

Old World monkeys were exposed to octaveband noise from 0.5 to 8 kHz at 120 dB SPL, 8 hours daily for 20 days. Restricted permanent threshold shifts and localized loss of outer hair cells were produced, which were reasonably well correlated with the exposure frequencies. There was also a loss of both inner and outer hair cells at the extreme basal end of Corti's organ, regardless of the exposure frequency. Implications for human inner ear pathology are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

The patas monkey as a model for dihydrostreptomycin ototoxicity.

Although the cochlear toxicity of dihydrostreptomycin (DHSM) is well-recognized in man, it has always proved difficult to demonstrate in animals. Hearing thresholds in M. nemestrina monkeys remained essentially unchanged after DHSM 100 mg/kg im daily for 8 months, but E. patas monkeys were severely deafened by DHSM 20 mg/kg for 90 days, a regimen formerly used in treating human tuberculosis. The patas monkey may prove to be the animal model of choice for evaluating aminoglycoside ototoxicity.

Animals↗