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G E Wolfe

Publications and source records attributed to G E Wolfe.

6 recordsLinked to original sources
PubMed1978

Multivalued stimulus-response relation in isolated elasmobranch utricles.

The relation between a maintained spatial orientation and the corresponding fully adapted discharge rate was multivalued in all the afferents tonically sensitive to maintained spatial orientation observed in isolated utricles of Rhinobates productus. The spread of rate values was of the order of changes produced by natural tilts. The occurrence of multivaluedness in isolated receptors indicated that peripheral issues are sufficient. Two factors contributed: firstly, the side from which the orientation had been reached (i.e. "hysteresis"): higher adapted rates occurred when the preceding orientation was characterized by lower rates and when the corresponding transition caused acceleration; secondly, "spontaneous" rate variations, some of which resembled markedly, and interacted with, the effects of tilts. It was not possible to identify the basic mechanisms underlying these factors. The multivaluedness in the coding of maintained position, because of its constancy and magnitude, cannot be ignored. It, as well as the sensitivity to fast transients, must be taken into account in utricular models, in evaluations of information transmission, and in psychophysical explorations.

Action Potentials↗
PubMed1975

Response of the elasmobranch utricle to maintained spatial orientation, transitions and jitter.

1. The spike discharges of single first order afferents from the utricle were recorded in the isolated head of the guitarfish and tested for responses to maintained spatial orientation, to transitions and to a small positional jitter representing natural perturbations. Sensitivity to maintained orientation is referred to as "tonic", and to transitions and jitter as "phasic". 2. Most responsive cells were either phasically, or phasically and tonically sensitive. A few were exclusively tonic. Tonic responsiveness implied that maintained orientation was associated with a stationary discharge which differed from one position to another; it sometimes differed also from one station to another at the same position. Transitions from one position to another evoked a rate change that later adapted to the level of the tonic response. Opposite transitions evoked rate changes in the opposite sense. The phasic rate change was usually larger for transitions that increased the rate. Many units were non-responsive. The prevalence of phasic over tonic sensitivity is stressed, and the remarkable heterogeneity of utricular afferents confirms that the macula is not uniform, probably coding a wide variety of head accelerations. 3. The jitter increased the ongoing scatter of intervals and binrates, changing, complicating, or abolishing their periodicity. The jitter could influence the effects of maintained orientation, increasing, decreasing, inverting or even revealing directional sensitivity. It could also force previously independent units into an orientation-dependent correlation; hence, between-cell correlation is potentially useful in coding of spatiel orientation. Naturally occurring perturbations may sonstitute a significant issue of normal operation. 4. Certain afferents from the horizontal semicircular canal showed a slow tonic response to maintained spatial orientation.

Action Potentials↗