Zusammenfassung
Um das zeitliche Auflösungsvermögen kurzzeitiger Signalveränderungen zu erfassen, werden Untersuchungen zum Verhalten der kortikal evozierten Potentiale vorgestellt.
Für eine kurzzeitige Erhöhung bzw. Reduzierung der Intensität werden der Einfluß von Grad und Zeitdauer der Signalveränderung auf die Schwellenwerte der Zeitauflösung sowie das Verhalten der Reizantwortmuster (Erregungsamplitude, Latenz) im überschwelligen Bereich bestimmt.
Um ein reizspezifisches Potentialmuster zu evozieren, werden für Intensitätsänderungen von +3 dB Zeitkonstanten von etwa 16 ms benötigt. Für einen Intensitätssprung um +9 dB verringert sich dieser Wert auf 4–6 ms.
Eine kurzzeitige Intensitätserhöhung zeigt für gleiche Zeitkonstanten deutlich bessere Schwellenwerte und größere Erregungsamplituden im überschwelligen Bereich als entsprechende Reduzierungen der Intensität.
Die hier vorgestellten Ergebnisse bestätigen die aus psychoakustischen Untersuchungen ermittelten Zeitkonstanten, die wertvolle Hinweise zum Zeitauflösungsvermögen kurzzeitiger Signalveränderungen liefern.
Summary
Human cortical evoked potentials were monitored with scalp electrodes as an indicator of the ability to resolve brief changes in an auditory signal. For a brief period in the middle of a noise pulse its intensity was increased or decreased. The magnitude and duration of this change was varied to establish (1) the threshold for the cortical evoked potential and (2) the effect on the evoked response (amplitude, latency) in the suprathreshold region. To evoke a stimulus-specific potential pattern, durations of about 16 ms were required for intensity changes of +3 dB. With an intensity step of +9 dB, the threshold duration was reduced to 4–6 ms. A brief increase in intensity was more associated with distinctly lower thresholds and larger response amplitudes than an equivalent reduction in intensity, duration being equal. These results confirm the critical durations found in psychoacoustic studies that offer valuable evidence as to the ability to resolve brief changes in an auditory signal.
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Supported by the Minister für Wissenschaft und Forschung des Landes Nordrhein-Westfalen
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von Wedel, H. Cortical evoked potentials in response to brief modulation of signal amplitude. Arch Otorhinolaryngol 234, 235–243 (1982). https://doi.org/10.1007/BF00464327
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DOI: https://doi.org/10.1007/BF00464327