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Biomedical subjects

P Finkenzeller

Publications and source records attributed to P Finkenzeller.

At least 19 recordsLinked to original sources
PubMed1988

Unanswered questions concerning the indication for cochlear implant.

In a discussion of the function of cochlear implant (CI), the following criteria should be mentioned: (1) If possible, all deaf persons (including the prelingually deaf and children) should benefit from CI. (2) Since the number of patients with late deafness is doubtlessly decreasing with better prevention and medical care (elimination of ototoxic damage, decrease of iatrogenic deafness), the percentage distribution of the deaf will be displaced in favor of the prelingually deaf. At present, the ratio of cases of late deafness to those of prelingual deafness among our CI candidates is 1:3. (3) The objective of CI must be to provide the advantage of the procedure to children as early as possible. This means that under certain circumstances a technique that is as low in risks as possible and with a handy implement should already have been used in patients at the age of 3 to 4 years.

Adaptation, Psychological↗
PubMed1983

The resolution of brief interaural time-difference changes: recordings from primary auditory cortical projection field AI of the cat.

The ability of the auditory organ to resolve brief changes in an acoustic signal presented either monaurally or binaurally is not only of great importance in the processing of speech, it is also involved in the localization of sound stimuli and in selective listening. In the latter context, the electric activity of the primary auditory cortical projection field AI of the cat has been studied with the aim of evaluating specific response patterns evoked by brief changes in interaural time difference. The differences in response of the neuron populations sampled by two recording electrodes indicate that, within this area, there are significant differences in temporal resolution ability. Whereas click stimuli elicit distinct potential patterns at the two sites, with a brief change in interaural time difference, a marked response is recorded by only one of the electrodes. This response is characterized by a decrease in amplitude as the interaural time difference is reduced and as the duration of the time-shift stimulus decreases.

Animals↗
PubMed1980

Auditory prostheses--a challenge for neurophysiology.

To achieve speech discrimination with prosthetic stimulation, pre-processing of speech adapted to the function to be replaced is indispensable. This is demonstrated using the example of a phase-conserving frequency transposition for a more efficient use of residual hearing. The intelligibility of transposed speech was investigated by employing simulated residual hearing. Long-term implanted electrodes in the auditory nerve of the cat permitted both the measurement of the natural activity of fibres and the application of corresponding stimulus currents. Phase reversal of the acoustic input was used to isolate a phasic response with a topographically differing proportional or differential behaviour. This suggests a periodicity analysis of the sound in the auditory pathway. In acoustic and electrical stimulation, additionally implanted, cortical control electrodes revealed largely corresponding potentials; the dynamic stimulation ranges, however, differed greatly. Finally, the possibility of assessing speech perception by measuring speech-evoked potentials is discussed.

Cochlear Implants↗
PubMed1979

Grafting and electrical stimulation of the auditory nerve in cats.

The effect of implanting wire electrodes into the cochlea is limited by the deficit of nerve fibers in most diseases of the cochlea. Therefore, in a series of experiments it was tried, for the first time, to direct new outspreading nerve fibres into the afferent acoustic nerve by grafting a motor nerve to it. A second series of experiments should demonstrate the possibility of direct electrical stimulation of the eighs nerve by implanting wire electrodes via the transoccipital approach. The electrically evoked potentials, recorded at the auditory cortex, were compaired to potentials evoked by auditory stimulation. The answers to acoustic or electric stimulation showed no significant difference.

Acoustic Stimulation↗