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In the chapter written by Professor Hallowell Davis the clinical use of ERA (Electric Response Audiometry) in audiology is described in full detail including the early response (BERA) and the perstimulatory DC-shift. Hence, this most important subtopic of the auditory evoked responses can be omitted here. We therefore feel that our contribution in this handbook should deal with all those questions and solutions — as far as they have been elaborated — which are related to explanations from a neurophysiological background. Thus, it should be obvious that a response as complex as the auditory evoked potential must be looked at under a great variety of aspects. Even then our present knowledge does not allow us to get more than a feeling about possible avenues of the basic physiological principles involved.

Using the 31-Phosphorus pulsed NMR-technique by FFT information processing it was possible to obtain the following results: The phosphorus compounds were measured as time function in the course of 24 h in isolated skeletal and cardiac muscle of rana temporaria in a dynamic NMR experiment. The shift of the observed resonance lines by increasing intracellular H+ concentration during anoxic conditions will be described in this paper in accordance with the NMR literature. The time course of the beta group of ATP (which is representative for ATP) has been found not to decrease monotonically but rather periodically in a half-hour periodicity until finally a complete fading of ATP in the NMR spectrogram occurs. Besides the resonances described in the literature it was possible to record two additional unknown resonance lines 1.6 and 4.6 ppm apart from the classical alpha- and beta ATP peaks. The peak area of this up to now unknown substance followed a periodic law, regarding the first 2-3 h after preparation. Afterward the concentration dropped to zero. Some shift of the resonance lines of the NMR spectrum could be observed dependent upon the fact that in the muscle cell the ATP normally occurs as a complex with Mg++ ions (MgATP). After separation of Mg++ ions from ATP at low intracellular pH values the resonance lines shifted by some 1-4 ppm. This was tested by test solutions containing MgATP as a complex of free ATP. Although this observation could not sufficiently explain the two as yet unknown lines in the NMR spectra, this result gave rise to further exploration of the phenomenon. To explain the unknown resonance lines, the spectra of the heart and skeletal muscle were compared with that of an adenosine tetraphosphate solution. Based upon the fact that the frequencies of the lines under discussion are identical with those of the adenosine tetraphosphate, one can conclude with a high degree of probability that the as yet unknown lines are originated by adenosine tetraphosphate. If this hypothesis is correct, the concentration of adenosine tetraphosphate could be determined in the order of 1 mM, thus being one third or one quarter of the concentration of the adenosine triphosphate. To give better evidence for the clarification of the newly found substance it will be necessary to record under identical experimental conditions 1H and 13C NMR spectra during the time course of deterioration of the skeletal and cardiac muscle.(ABSTRACT TRUNCATED AT 400 WORDS)

There have been many efforts to help completely deaf people with prostheses which would allow them to communicate verbally with other people. All the requirements for such a type of auditory prosthesis have so far not been fulfilled, however. One of the main reasons for this failure is the great complexity of the auditory stimuli used by nature for conveying spoken information from one subject to another. The language phonemes, as they have been labeled, are not only remarkably complex with respect to their frequency distribution, but they also change in time and intensity with respect to the different components of the sound spectra used as stimuli for speech communication. One of the first to clearly show the complexity of auditory stimuli of this type was Licklider (1951). He gave an example of a spoken word in a three-dimensional plot where the abscissa indicates time, the rear ordinate the frequency, increasing from front to rear, and the third ordinate, perpendicular in direction, the intensity of each component. Such a figure looks like the skyline of Manhattan and makes very clear the extreme complexity of a spoken phoneme or word.

To deal with the systems for perception of vibratory stimuli in man one must look at tactile mechanoreception by means of a special filter: the dynamic and periodic ways of perceiving the Umwelt (surroundings) (Geldard and Sherrick 1966–1981; Keidel 1956).

Both, the sensory organs themselves and the central nervous system with its decoding functions for perception of sensory stimuli influence drastically the human ability for social communication especially with respect to the exchange of speech information. Severe hearing loss, e. g., may inhibit the motivation for the continuation of existing social contacts considerably in aging human beings. Additionally the drop of elasticity within the eye's lense influences negatively the visual human interaction with increasing age. Similarly the performance of the somesthetic, the olfactory and the gustatory sensory may drop simultaneously. Since also the physiological conditions for information storage and retrieval are altered in the senium the wellknown social problems of aged people seem to be due rather to the central parts of the sensory channels than to the sensory organs per se. In this context it is of great importance for the avoidance of problems of the human interrelations between older subjects to keep the human brain intellectually trained as long as intensive as possible (E. Jalavisto). The neurophysiological changes within the CNS, therefore, are discussed in this paper as a function of age and in context with the more somato-physiological changes of the circulatory and metabolic processes including humoral, hormonal and biocybernetical transitions between the second and "Third" section of the human life. During senium, as a conclusion, emphasis should be given to the behavioral selection both of contact persons and of intellectual and emotionally loaded topics of interest to improve the quality of this last part of the life under the aspect that "multum" can be more than "multa", "universalistic" filtering of the life's events more than "encyclopedistic" knowledge (Th. Heuss).

Die Untersuchung der einzelnen Horbahnkerngebiete mit Mikroelektroden liefert eine grose Zahl charakteristischer Entladungsmuster, die sich besonders ubersichtlich in Histogrammschreibweise darstellen lassen. Aus den reizzugeordneten Entladungsmustern der einzelnen Neurone lassen sich z. T. Schlusse hinsichtlich funktioneller Leistungen im Rahmen der Informationsverarbeitung ziehen, wahrend man in anderen Fallen zunachst nur die Entladungsmuster beschreiben kann, ohne ihre funktionelle Bedeutung fur die Informationsverarbeitung zu erkennen.

Das menschliche Auge wird haufig mit einer fotografischen Kamera verglichen. Gemeinsam ist beiden als Konstruktionsprinzip die geometrisch optische Abbildung der Umwelt mittels eines geeigneten brechenden Systems auf der fotografischen Platte bzw. auf der Netzhaut. Der Vergleich ist jedoch nur zum Teil berechtigt. Einerseits besteht namlich ein grundsatzlicher Unterschied zwischen beiden Systemen darin, das die Netzhaut nicht wie eine fotografische Platte als Ebene ausgebildet ist. Vielmehr ist sie gekrummt und ist praktisch in Halbkugelform vom Sinnesepithel bedeckt. Zum anderen ist beim fotografischen Objektiv die Brechkraft in einem Linsensystem mit hoherem Brechungsindex zusammengefast. Dieses „fotografische Objektiv“ befindet sich dabei in Luft, und zwar vor und hinter diesem Linsensystem. Beim Auge dagegen sind vom Hornhautscheitel an bis zur Netzhaut Medien von unterschiedlicher Brechkraft fur das Licht vorhanden. In der vorderen Augenkammer befindet sich das Kammerwasser mit dem Brechungsindex praktisch von Wasser. Die bikonvexe elastische und verformbare Linse des Auges hat einen hoheren Brechungsindex als das Kammerwasser. Der anschliesende Glaskorper besitzt wieder einen etwas niedrigeren, aber doch immerhin betrachtlich hoheren Brechungsindex als die Luft (Abb. 69).

The present paper dealt with auditory evoked responses, especially with their temporal and local aspect, according to the criteria of von Kries. It further discussed the problem of specificity and, finally, reported on a novel technique for registering a dc-potential in response to, and during the course of, long-lasting sound signals. Possible applications of this technique and its importance for objective audiometry are being discussed.

Welche der genannten Grosen wirken als adaquate Reize auf das Bogengangsorgan? a) alle Bewegungen im Schwerefeld der Erde b) die Flussigkeitsdrucke von Endo- und Perilymphe c) lineare bzw. Progressiv-Beschleunigungen d) Winkelbeschleunigungen e) uber eine bestimmte Zeit konstante Winkelgeschwindigkeiten

While in the visual system the role of the cortex for the decoding processes is well known, and even highly sophisticated neurons have been detected (Hubel and Wiesel), the organizational structure within the auditory system seems to differ markedly in so far as obviously quite large parts of the decoding functions in audition are located within the medial geniculate. We do not know what in detail the cortex adds by its performance to that basic function at thalamic level. But it can be speculated that it is rather the great storage capability of the auditory cortex than its additional decoding processes which make it up.