ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary In 46 isolated and 4in situ preparations of perioral skin, afferent impulse patterns, leading from cutaneous mechanoreceptors and responding to orthogonal square as well as sine-wave stimuli, were investigated in selachians (Scyliorhinus canicula). 1. Two distinct classes of specific mechanoreceptors could be differentiated: pressure- and tension-sensitive units, excited only in either the pressure or the tension phase of standard steps. Both populations yielded PD-transfer functions with predominating D-components and slow adaptation. The pressure units (majority of trigeminal skin afferents) usually revealed lower thresholds than the tension type. 2. Receptive areas (with a considerable portion of overlapping) and local discrimination thresholds were determined. A comparison with values of the dorsolateral region showed a twofold higher sensitivity in perioral skin. Several response parameters, such as overshoot and latency, were proved to be a function of the distance between focus and stimulus, as well as of the hydromechanical pressure bias of the skin. 3. Under biologically relevant conditions, the focal transformation characteristics and amplitude-frequency responses of 78 cutaneous afferents were measured for low-frequency vibration. Increasing skin pressure resulted in a significant amplitude and frequency shift of different synchronization thresholds. 4. In addition to specific responses, afferent discharges of unspecific units, sensitive to touch as well as cold, were also recorded. Most of these fibres revealed spontaneous activity, which could be modulated by superimposed mechanical stimulation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00663614
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