[Extracochlear prosthesis in acute experiment]. / Ekstrakokhlearnoe protezirovanie v ostrom éksperimente.

Whether the transfer of coded sound intensity is possible was studied in acute experiments on cats with acquired deafness, using an original transducer of the signals with extracochlear position of the electrodes. The stimulation results were compared to intracochlear prosthesis. The type of the stimulation was not essential for threshold values of the total electric impact. In extracochlear position of the electrodes and the duration of potential 0.2 msec its amplitude increment was the highest, while the dynamic range turned out the lowest. With the impulse duration 0.5 msec, these differences disappeared. When compared to extracochlear, intracochlear bipolar stimulation proved superior.

[Response of cortical evoked potentials to electric stimulation of the acoustic nerve in animals with damaged cochlea]. / Korkovye vyzvannye potentsialy na élektricheskoe razdrazhenie slukhovogo nerva u zhivotnykh s povrezhdennoi ulitkoi.

Evoked potentials of the auditory cortex during the electrical stimulation of the cochlea were studied in acute experiments on cats. A series of electric pulses of short duration and different frequency delivered to the streptomycin-damaged cochlea were used as a stimulus. It has been shown that an amplitude and latency of electrical cortex responses depended on the number of pulses in series and on the interpulse intervals. Amplitudes of evoked responses increased with the growth of the number of stimuli. Latent periods changed in a narrower stimulation frequency band. Dependence of the induced potentials' amplitude growth on the increase in the number of electric pulses changed as a result of the two-fold enhancement of the stimulation amplitude.

[Effect of low-energy laser irradiation on the functional state of the acoustic analyzer (experimental study)]. / Vliianie izlucheniia nizkoenergeticheskogo lazera na funktsional'noe sostoianie slukhovogo analizatora (eksperimental'noe issledovanie).

The acoustic function of guinea-pigs (in terms of ERA) before and after middle ear laser treatment (LHe-75, radiation intensity 15-17 mW, total dose 63 J/cm2, number of exposures 14) was investigated. The experiment was carried out using three groups of animals. Group 1 included healthy young animals. Group 2 consisted of adult animals with no signs of otitis media suppurativa. Group 3 involved adult guinea-pigs with chronic suppurative otitis media. After laser treatment all the animals showed increase of amplitudes of all ERA peaks, specifically of the first peak, an increase of the A1/A4 ratio, and an insignificant shortening of L1 at low sound intensities in group 1 and group 2 animals. This may suggest a greater excitation of the first component of the acoustic system. The group 3 animals exhibited a greater L1; this indicates that laser therapy of an untreated cavity during chronic otitis media may aggravate the pathological process. This pathology requires pretreatment of the middle ear cavity and laser therapy in combination with other therapeutic measures. None of the treated animals showed changes of the second time interval, whereas the third time interval (central time of conduction) became shorter, particularly on the side exposed to laser treatment. Our findings demonstrated differences in responses of adult and young animals to laser treatment (distinct shortening of the central time of conduction in those latter) which obviously needs further study.

[Morphologic basis for cochlear implantation in the cat]. / Morfologicheskoe obosnovanie implantatsii ulitki koshki.

The cat cochlear structure has been studied in 20 temporal bones. Owing to the preparations of the osseous cochleae investigated, certain anatomical parameters have been revealed; a detailed anatomo-topographic analysis on relations of the cochlear coils with the cochlear fenestra, the vestibular fenestra is presented. This gives a spatial notion on arrangement of the internal cochlear structures. The data obtained makes it possible to choose a precise place for electrode introduction and direction for their course along the coils. In its turn, this prevents trauma of the functional elements of the cochlea and, thus, contributes to stimulation effect.