Characteristics of responses from receptors from the flexor longus digitorum muscle and the adjoining interosseous region of the cat

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.

Section: Resultsmentioning

confidence: 99%

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

Greenstein

Kavanagh

Rowe

1987

“…The estimated conduction latencies for hind limb (horizontal shading) and forelimb (vertical shading) were calculated from conduction velocity values derived for P.c. fibres supplying the hind limb (59 + 8 m s-1; Hunt & McIntyre, 1960;Janig et al 1968) and forelimb (54 + 8 m s-'; Greenstein et al 1987) and allowing for a 25 % slowing in conduction speed over the central portion of the conduction path (Brown, 1968). The conduction path lengths used in these estimates, 80 and 45 cm, from the appropriate footpads to the gracile and cuneate nuclei respectively, were based on measurements from 4 kg cats.…”

Section: Capacity Of Pc Neurones For Phase-locked Response To Vibramentioning

confidence: 99%

“…6) on 286 VIBRATION CODING IN GRACILE AND CUNEATE CELLS conduction distances from hind-limb and forelimb footpads to the dorsal column nuclei and reported conduction velocity values for P.c. fibres in hind limb and forelimb (Hunt & McIntyre, 1960;Janig et al 1968;Greenstein et al 1987). Allowance was made for an estimated 25 % slowing in conduction velocity over the central portion of the axons (Brown, 1968).…”

Section: Capacity Of Pc Neurones For Phase-locked Response To Vibramentioning

confidence: 99%

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

Ferrington

Horniblow

Rowe

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).

“…In all the four cases the interosseous branch (cf. Hunt & McIntyre, 1960) In two experiments the interosseous nerve was dissected for separate stimulation. Figure 12 shows that an IPSP having the same time course as in Fig.…”

Section: T Hongo and Othersmentioning

confidence: 99%

post‐synaptic excitation and inhibition from primary afferents in neurones of the spinocervical tract

Hongo¹,

Jankowska²,

Lundberg³

1968

145

SUMMARY1. Intra-and extracellular recordings were made from cells of the spinocervical tract in the lumbosacral spinal cord. A convergence of monosynaptic excitatory post-synaptic potentials (EPSPs) and disynaptic inhibitory post-synaptic potentials (IPSPs) was a general pattern of effects from the low threshold cutaneous fibres. Unitary IPSPs, probably mediated via the same disynaptic path, were evoked by light touch of hairs, which was also the adequate stimulus for exciting the cells. The receptive field for unitary IPSPs was closely related to the excitatory receptive field but was eccentric, not of a surround type.2. EPSPs, IPSPs, or both, were evoked from the flexor reflex afferents in the great majority of neurones. Disynaptic IPSPs may be evoked from the interosseous nerve. No effects were produced by volleys in group I muscle afferents.3. It is suggested, on the basis of the spatial organization of the excitatory and inhibitory receptive skin fields, that the spinocervical tract may give information regarding the direction of tactile stimuli.