High Frequency Resonance Mechanisms in the Electrical Activity of the Cat Inferior Colliculus

Abstract

The previous report on the dynamics of spontaneous and evoked activities of the substructures within the cat inferior colliculus (IC) has been extended in order further to demonstrate the high frequency resonance phenomena in the IC. Steady-state evoked potentials, which were recorded by repetitive acoustical stimulation, proved the fact that high frequency oscillatory components of the evoked potentials (EPs) resulted from a real resonance phenomenon. The changes in the electrical activities following local lesions further helped us to decide that the high frequency oscillatory components of the EPs reflected unique activity of a neural net of spatially confined populations. By quantifying two parameters, namely the primary peak seen in the cross-covariance functions and the degree of synchronization as measured from the cross-power spectra of two simultaneously recorded spontaneous activity from a localized neural net in the IC, it was possible to show some dynamic patterns as associated with the spontaneous activity of the net. The behavior of these measured parameters as a function of external inputs exhibited a hysteresis which is of interest in the theory of short-term memory. Some interpretations of the high frequency resonance activities in terms of neuroanatomic structure of the IC were also made briefly.

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Notes on contributors

Atila Gönder

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.