Functional capacities of tactile afferent fibres in neonatal kittens

1987

SUMMARY1. Recordings were made in decerebrate cats from gracile and cuneate neurones responding to vibration-induced inputs from Pacinian corpuscle (P.c.) receptors of the hind-limb and forelimb footpads. The two groups of neurones were compared, in particular for their capacities for responding to cutaneous vibration with phaselocked impulse patterns.2. In both nuclei the P.c. neurones were most sensitive to vibration in the range 80 to > 600 Hz. Stimulus-response relations were similar for the two groups, as were measures derived from these relations such as response levels, absolute thresholds and the dynamic range (defined as the vibration amplitude range over which responses were graded).

Section: Identification Of Dorsal Column Nuclei Neuronesmentioning

confidence: 99%

“…1 and 2) whereas individual P.c. fibres often reach a response plateau at 5-10 /tm (Talbot et al 1968;Ferrington & Rowe, 1980b).…”

Section: Neurones To Cutaneous Vibrationmentioning

confidence: 99%

Temporal patterning in the responses of gracile and cuneate neurones in the cat to cutaneous vibration.

Ferrington

Horniblow

1987

“…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

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.

“…receptors and their associated P.c. sensory fibres (Janig, Schmidt & Zimmermann, 1968;Talbot, Darian-Smith, Kornhuber & Mountcastle, 1968;Iggo & Ogawa, 1977;Ferrington & Rowe, 1980b). Over their whole frequency range, the P.c.…”

Section: Introductionmentioning

confidence: 99%

Phase coherence in vibration‐induced responses of tactile fibres associated with Pacinian corpuscle receptors in the cat.

Greenstein

Kavanagh

1987

SUMMARY1. In pentobarbitone-anaesthetized cats, responses were recorded in peripheral nerves or cervical dorsal columns from sensory fibres associated with Pacinian corpuscle (P.c.) receptors in the forelimb footpads. Factors affecting the phase of response to cutaneous vibration in individual P.c. fibres, and the extent of phase coherence in the responses of different P.c. fibres were examined when sinusoidal vibratory stimuli at 100-400 Hz were delivered using a 1 mm diameter probe.2. Increases in vibration amplitude from the absolute to the 1 : 1 threshold for the P.c. fibre led to phase advances in the response, often of about 60 deg, in over 850 of fibres tested at 200 and 300 Hz, but further increases had little effect.3. Variations in stimulus position within the receptive field led to unpredictable changes in the response phase that ranged from minimal change to shifts of 180 deg. As the response phase was unrelated to the distance from the point of peak sensitivity it is likely that at high vibration frequencies ( > 100 Hz) the recruited population of P.c. fibres will respond over the whole range of phase angles.4. The calculated phase of spike initiation in different pairs of P.c. fibres that shared coincident points of best sensitivity on the skin ranged from near synchrony to maximum asynchrony indicating that there is little phase coherence even in the subpopulation of somatotopically related P.c. fibres recruited by high-frequency cutaneous vibration.5. Paired recordings from P.c. fibres within the cervical dorsal columns revealed a broad range of phase discrepancies in the responses of P.c. fibres to vibration at 200 and 300 Hz.6. Several hypotheses are considered to explain the known presence of phaselocked responses to high-frequency ( > 100 Hz) vibration in the central neurones of dorsal column nuclei.