On the nature of vibration receptors in the hind limb of the cat

317

SUMMARY1. The functional characteristics of cutaneous receptors in the squirrel monkey were determined by recording discharges of single myelinated afferent fibres in peripheral nerves with micro-electrodes or from fine filaments prepared by dissection. One hundred and sixty-nine fibres of the posterior femoral cutaneous nerve and 209 of the superficial radial nerve with conduction velocities between 4 and 88 m/sec were classified according to the nature of the most effective stimulus, discharge characteristics, adaptation rate and organization of the receptive field.2. Twenty per cent of the fibres innervating either hairy or glabrous skin required strong mechanical stimuli for activation; thresholds ranged from moderate to overtly damaging pressures. This class showed little or no sensitivity to thermal changes including noxious heat. Their receptive fields consisted of numerous, mechanically-excitable points or spots. All such fibres gave higher impulse frequencies to noxious than to innocuous mechanical stimuli and a large fraction were considered to be nociceptors because they responded only to noxious deformation. The conduction velocities of nociceptors were distributed between 5 and 28 m/sec.3. All but a few of the other fibres encountered responded vigorously to innocuous stimuli and were readily identified as corresponding to one of the receptor types known to exist in either the primate or the cat. These sensitive receptors were systematically tested by intense cutaneous stimuli; their response to injurious stimuli always could be mimicked by innocuous ones.4. Therefore, in the primate a particular class of slowly-conducting myelinated fibres is partially responsible for signalling mechanicallyinduced cutaneous damage. The probable relation between such afferent fibres and certain kinds of cutaneous pain is explored.

Section: Resultsmentioning

confidence: 99%

Myelinated afferent fibres innervating the primate skin and their response to noxious stimuli

Perl¹

1968

317

“…Electrophysiological investigations have shown that the mammalian Pacinian corpuscle is a phasic mechanoreceptor of great sensitivity to vibration (Gray & Malcolm, 1950;Gray & Matthews, 1951;Hunt, 1961;McIntyre, 1962). However, little information has yet been published about the properties of the somewhat similar Herbst corpuscle of birds (Quilliam & Armstrong, 1961, 1963Munger, 1971), although the behavioural studies of Schwartzkopff (1948Schwartzkopff ( , 1949) and a brief report by Skoglund (1960) PATRICIA K. DOR WARD AND A. K. McINTYRE suggest that Herbst corpuscles are vibration-sensitive, like their mammalian counterparts.…”

Section: Introductionmentioning

confidence: 99%

Responses of vibration‐sensitive receptors in the interosseous region of the duck's hind limb

Dorward¹,

McIntyre²

1971

1. Responses of receptors with fibres in the interosseous nerve of the duck's leg have been studied by recording unit discharges in filaments dissected from the sciatic nerve. 2. Seventy‐two of the ninety‐four units examined served highly phasic, vibration‐sensitive mechanoreceptors in the interosseous region interpreted as being Herbst corpuscles. Receptor types for most of the other units could not be determined, but some were slowly adapting mechanoreceptors. 3. Rheobase threshold values for the most sensitive vibration‐receptors were similar to those of mammalian Pacinian corpuscles. 4. Threshold—frequency relationships for the vibration receptors showed a wider range of low frequency cut‐off values, and a greater capacity to signal high frequencies, than is the case with Pacinian corpuscles. 5. Fibres of the vibration‐receptors had calculated diameters ranging from 5 to 10 μm and account for the bulk of the larger fibres in the interosseous nerve. 6. It is suggested that Herbst corpuscles in the legs of birds might act as a warning device by detecting vibratory disturbances of the ground or other supporting surface.

“…fibres up to 800-1000 Hz (Hunt, 1961;Talbot et al 1968;Ferrington & Rowe, 1980b;Ferrington, Hora & Rowe, 1984), the behaviour of the dorsal column nuclei neurones nevertheless parallels the steep decline observed in the subjective capacity for vibration frequency discrimination (von Bekesy, 1962;Goff, 1967;Rothenberg, Verrillo, Zahorian, Brachman & Bolanowski, 1977). The Weber fraction, Af/f, for frequency discrimination increases steeply above 100-200 Hz, its value being about 03-0{4 at 200 Hz (Goff, 1967;Rothenberg et al 1977) whereas in the range 350-450 Hz, von Bekesy (1962) reported that doubling the vibration frequency no longer raised the pitch, a finding that implies a Weber fraction > 1.…”

Section: Integrative Processing In Dorsal Column Nucleimentioning

confidence: 99%

Integrative processing of vibratory information in cat dorsal column nuclei neurones driven by identified sensory fibres.

Ferrington

Rowe

Tarvin

1987

SUMMARY1. In decerebrate or anaesthetized cats, the vibration-induced responses of dorsal column nuclei neurones were examined, first, when their input came from simultaneously recorded pairs or other combinations of identified Pacinian corpuscle (P.c.) afferent fibres of the interosseous nerve, and secondly, when different convergent sets of P.c. fibres were engaged by footpad vibration.2. Suprathreshold actions were observed on individual dorsal column nuclei neurones from two or more identified P.c. fibres. Recruitment of these convergent fibres usually led to summation in the dorsal column nuclei neurone as reflected in higher response levels compared with those evoked by single-fibre inputs.3. When the input was increased from one to two or more identified P.c. fibres the dorsal column nuclei neurones could retain a single, dominant phase of response to high-frequency (> 100 Hz) vibration even though these fibres, in isolation, evoked responses in the target neurone at substantially different latencies. However, on average, phase locking was significantly tighter in response to single-fibre input than to multiple P.c.-fibre input.4. Dorsal column nuclei neurones were also able to retain phase-locked responses to high-frequency vibration when phase differences between different convergent inputs were systematically introduced to alter the degree of synchrony in the activity arriving over convergent, identified P.c. fibres.5. When the input to dorsal column nuclei neurones came from the skin it was found that with the recruitment of two converging sets of P.c. fibres the dorsal column nuclei neurones were able to retain phase-locked responses to high-frequency vibration even when phase shifts were introduced between the two sets of P.c. inputs.6. In conclusion, the observed integrative processing by dorsal column nuclei neurones of vibration-induced inputs arriving over identified, convergent P.c. fibres, or sets of P.c. fibres, is consistent with our hypothesis that the retention of phase-locked responses to vibration at frequencies > 100 Hz may reflect the functional domination of the target neurone by just one or a few of its convergent input fibres.