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At least 109 records · Page 6Linked to original sources
PubMed1990

Simulation of motion on the skin. IV. Responses of Pacinian corpuscle afferents innervating the primate hand to stripe patterns on the OPTACON.

1. To measure spatial acuity of Pacinian corpuscle (PC) afferents in the median and ulnar nerves of macaque monkeys, we displayed horizontal bar patterns spaced 1-13 mm apart on a computer-controlled OPTACON stimulator contacting the hand. Two-point resolution was measured by simultaneously pulsing pairs of rows at rates of 100, 50, and 25 Hz; each pair was shifted in tandem across the skin in 1.2-mm steps to simulate tangential motion at speeds of 30-120 mm/s. Single-fiber responses are reported from eight physiologically identified PC afferents innervating the fingers and palm in anesthetized monkeys. 2. Pacinian afferents differ in their sensitivity to stripe patterns moved across the hand. Bursting PCs fire bursts of two or three spikes/pulse when one of the bars is close to the field center and one spike/pulse when adjacent bars straddle the center. These bursts result in double-peaked response profiles at stripe spacings greater than or equal to 2.4 mm. The passage of individual stripes over the field center is therefore represented by bursts of impulses superimposed on a continuous spike train. Unfortunately, many of these fibers also demonstrate fluctuations in firing that appear unrelated to the stripe pattern and therefore obscure its clear representation. 3. The remainder of the PC population displays uniform-sensitivity responses that resemble those previously reported for rapidly adapting (RA) afferents. They fire one spike/pulse as long as at least one of the bars is contained within the field. They merge individual stripes spaced less than one field diameter apart and show a pause in firing at wider spacing. Spatial resolution of gaps in the stripe pattern is therefore determined by receptive-field diameters, which extend up to 9.6 mm when tested with the OPTACON. 4. PCs display poorer spatial resolution than RAs, because of their larger receptive fields and less regular firing patterns. Only two of eight PCs tested demonstrated a pause in activity representing the gap between bars spaced 4.8 mm apart, whereas 11 of 14 RAs ceased firing briefly between stripes. Resolution of the individual stripes by all of the PCs tested was observed only at bar spacings of 1 cm (8 rows) or more. Spatial resolution of stripes is further impeded by the tendency of PC afferents to summate inputs from stripes spaced less than 2.4 mm apart; this results in response profiles with a single, large-amplitude broad peak.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1988

[Possible role of the potential-dependent potassium channels in the generation of responses of the pacinian corpuscles].

Action of TEA (20 mM) and 4-AP (5 mM) on mechano- and electrically excitable membranes of the Pacinian corpuscles was studied by means of the air gap technique in constantly perfused preparations. Extracellular recordings of receptor and action potentials have shown that application of TEA causes prolongation of the receptor potential and inhibition of its amplitude by 40%. 4-AP has no effect on the mechanosensitive membrane. TEA and 4-AP induce a 2-3 fold increase of the action potential duration in the first Ranvier node. The computations based on the Dodge model help revealing that inhibition of voltage-sensitive potassium channels which participate in the first-order coding of the intact receptor accounts for this increase.

4-Aminopyridine↗
PubMed1991

Uncommon number and distribution of the Pacinian corpuscles in a human hand.

We describe some rare findings seen when dissecting the hands of a 65-year-old male cadaver. Very many lamellated (Pacinian) corpuscles were distributed all over the palms of both hands. They were normal in structure, but their size was greater (8 mms. in length and 5 mms. across) than the normal (2 mms. in length and 100-500 microns. across). Each lamellated corpuscle had only one nervous pedicle.

Aged↗
PubMed1985

Temporal summation by Pacinian corpuscles precludes entrainment at the detection threshold.

For rapidly adapting mechanoreceptor afferents, entrainment is defined as a response of one spike per stimulus cycle. For Pacinian corpuscles, the entrainment threshold and psychophysical detection threshold are similar. The psychophysical threshold, however, exhibits temporal summation, which proves that the psychophysical threshold and the physiological entrainment threshold cannot be identical.

Humans↗
PubMed1990

Immunohistochemical study of cat Pacinian corpuscles: co-localization of vimentin- and S-100 protein-like in the inner core.

The presence of vimentin and S-100 protein in cat Pacinian corpuscles of cat mesentery has been investigated immunohistochemically (streptavidin-biotin method) using monoclonal antibodies. A positive reaction for both vimentin- and S-100 protein-like was found only in the lamellae of the inner core. The presence of vimentin and the co-expression of vimentin/S-100 protein-like in sensory corpuscles is reported for the first time. The authors discuss the origin of the inner core and capsule of sensory corpuscles on the basis of their immunohistochemical characteristics.

Animals↗
PubMed1999

Clustering of Pacinian corpuscle afferent fibres in the human median nerve.

To further study the functional organisation of human peripheral nerves, the intrafascicular arrangement of afferent fibres supplying Pacinian corpuscles (PCs) was explored by percutaneous microneurography using thin-calibre, concentric needle electrodes. In normal adults, 20 PC afferents were identified in 13 recording sites. Low-amplitude (less than 30 microm) vibratory stimuli to the skin were applied with tuning forks oscillating at 128 Hz or 256 Hz and response patterns of individual PC units were studied. In many recording sites, two, sometimes even three, PC afferents with adjacent or overlapping receptive fields in the hand were clustered in the nerve. The observed incidence in the records containing a certain number of PC units was compared with the expected probability calculated according to the hypothesis that all nerve fibres are randomly organised in peripheral nerves. The results suggested that PC afferents are partially segregated in the nerve. In addition, PC afferents were neighbouring on slowly adapting type II (SAII) units and skin sympathetic activity in individual fascicles. SAII units often innervated the same skin area as PC units, but did not respond to vibration. The data provided additional information regarding the functional organisation of the human peripheral nerve and the mechanisms underlying the sense of vibration in man with special regard to population behaviour of neighbouring PC mechanoreceptors.

Adult↗
PubMed1984

Intensity and frequency characteristics of pacinian corpuscles. III. Effects of tetrodotoxin on transduction process.

This is the third in a series of three papers dealing with intensity and frequency characteristics obtained on pacinian corpuscles isolated from the cat mesentery (8, 9). The experimental results show that tetrodotoxin (TTX) affects not only regenerative action potentials but also the measured receptor (generator) potentials. Extracellularly recorded receptor and action potentials were simultaneously recorded in response to sinusoidal displacement stimuli. Receptor potentials measured in this manner responded with a time course similar to the driving frequency. Since the duration of the action potentials is long relative to the cycle period at high stimulus frequencies, the underlying receptor potentials can become obscured. To prevent this, TTX was applied through superfusion at a concentration of 6.0 microM. After about 30 min, the neural spikes were fully eliminated but the receptor potentials were also decreased in amplitude. Intensity characteristics relating receptor-potential amplitudes to probe displacement amplitudes showed that the percentage decrease in amplitude due to the application of TTX was constant regardless of stimulus intensity. Frequency characteristics relating probe displacement amplitudes to vibration frequency for a constant-response criterion showed an increase in the displacement amplitude required for the criterion response, across frequency, when TTX was applied. On average, the increase was a power function of vibration frequency.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1987

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

1. 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 85% 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 (greater than or equal to 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 phase-locked responses to high-frequency (greater than or equal to 100 Hz) vibration in the central neurones of dorsal column nuclei.

Action Potentials↗
PubMed1992

Effects of stimulus duration on the response properties of Pacinian corpuscles: implications for the neural code.

Based on physiological and psychophysical data, it has been suggested that the neural code for threshold detection in the P channel, mediated by Pacinian corpuscles (PCs), may be 2-4 neural impulses/stimulus (Bolanowski et al., 1988). To further test the efficacy of this code, responses from PCs were measured at different vibratory burst durations. Since it is known that the P channel has the capacity to summate vibratory stimuli temporally within the central nervous system, the effect should also be present in the physiological results. Temporal summation predicts a decrease in threshold at a rate of -3 dB/doubling of stimulus duration. Responses from single PCs were integrated by counting neural spikes over the entire burst duration. Furthermore, real-time responses were integrated with a low-pass filter, more accurately modeling the central process. For the spike-counting scheme, a criterion of 4 impulses/stimulus showed a decrease in stimulus amplitude for increases in duration similar to that obtained psychophysically. The amplitude-duration function obtained with the low-pass filter, however, resulted in a function which did not follow that obtained psychophysically, regardless of the number of impulses/stimulus. Since the P channel is known to have a central integrator, it has been concluded that activity of a single PC afferent probably is not sufficient to signal threshold in the P channel.

Afferent Pathways↗
PubMed1993

Reinnervation of denervated Pacinian corpuscles: ultrastructural observations in rats following free nerve grafts.

Nerve transection and immediate free nerve grafts using rat sciatic nerves were employed to observe the morphologic changes in periodical denervation and reinnervation of Pacinian corpuscles located on the interosseous membrane between the fibula and tibia. During periods of from 2 weeks to 20 months after the surgery, a total of 28 corpuscles were obtained under an operating microscope and processed for morphologic analysis using light and electron microscopes. Based on our morphologic findings, normal corpuscles were composed of an axon terminal and inner and outer cores. The axon terminal disappeared within 2 weeks after the nerve grafts, but the original inner and outer core cells remained for up to 20 months. In addition, a small number of collagen fibrils was observed between the inner and outer core cells. After 4 months, multiple axon terminals began to regenerate in the inner core. From 7 to 20 months, these axon terminals in some corpuscles developed a structure resembling that of normal terminals. Some of these terminals were located in the center of the inner core, but a few were in contact with the outside of the inner core. The production of collagen fibrils in denervated corpuscles was periodically activated in the intercellular spaces. These findings suggest that the morphologic changes in denervated corpuscles correspond to those in denervated nerves. Inner core cells, which are continuous with Schwann cells, remain in their original condition in denervated corpuscles until regenerating nerves enter the inner core and are essential for corpuscle regeneration, because they may produce some trophic substances that induce the regeneration of multiple axon terminals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Effects of anaesthetics on reflexes elicited in the sudomotor system by stimulation of Pacinian corpuscles and of cutaneous nociceptors.

Sudomotor neurones supplying sweat glands in the hairless skin of the cat's paws can be activated by the cutaneous afferent inputs deriving from vibrational receptors (Pacinian corpuscles) in the paws and from cutaneous nociceptors. Both reflexes probably have separate spinal pathways. In the present investigation the effects of the anaesthetics ketamine, methohexital, chloralose, halothane and Althesin on both types of sudomotor reflexes were examined. For this purpose the skin potentials were recorded from the hairless skin of the paws with Ag--AgCl-electrodes. Before application of any anaesthetic the cats were in a state of light ketamine anaesthesia. The following results were obtained: (1) the resting activity in the sudomotor system and the synchronization of the activity between both hindpaws and between hind- and forepaws were depressed by all anaesthetics to a variable degree. After chloralose application large synchronous potentials of low frequency appeared; (2) ketamine (18--25 mg/kg injected intramuscularly) enhanced the reflexes on vibrational stimulation and depressed the reflexes on noxious stimulation of skin; (3) methohexital (3--10 mg/kg injected intramuscularly) mostly depressed the reflexes on vibrational stimulation and enhanced the reflexes on noxious cutaneous stimuli; (4) chloralose (4.5--20 mg/kg injected intraperitoneally) enhanced both types of reflexes; (5) halothane (1--1.5 vol. %) and Althesin (2.5--5 mg/kg injected intramuscularly) depressed both types of reflexes; (6) in chronic spinal cats ketamine, methohexital and chloralose had a slightly depressive effect on the resting activity of the sudomotor system, but practically no influence on the reflexes induced by cutaneous stimuli; and (7) these results argue that the effects of anaesthetics on the sudomotor system depend on the type of reflex tested and the type of anaesthetic used. They indicate furthermore that the anaesthetics affect largely supraspinal structures and influence the spinal reflex pathways via descending spinal pathways.

Adrenergic Fibers↗
PubMed1981

The effect of sympathetic nerve stimulation on responses of cutaneous pacinian corpuscles in the cat.

In the cat electrical stimulation of the distal segments of transected sympathetic nerves to the forelimb produces either an increase or a decrease in the responsiveness of the Pacinian corpuscles under the glabrous skin of th forepaw when the corpuscles are stimulated with high frequency mechanical vibration. The minimum latency of the change in Pacinian response is about 1-2 sec. As these effects could be stimulated by reduction in the forelimb blood supply it is probable that the changes in cutaneous corpuscle responsiveness following sympathetic stimulation are caused by local changes in blood flow.

Animals↗
PubMed1989

Immunohistochemical study of Pacinian corpuscles using monoclonal antibodies for neurofilament protein, glial fibrillary acidic protein and S-100 protein.

The presence of neurofilament protein (NFP), glial fibrillary acidic protein (GFAP) and S-100 protein has been investigated in Pacinian corpuscles from cat's mesentery by means of immunohistochemical methods. The NFP-like positivity was found in the central axon of the corpuscles; the GFAP- and S-100 protein-like immunoreactivities were shown in the innermost layers of the differentiated cell of the inner core. No positive reaction was detected in the capsule. The authors discuss these findings.

Animals↗
PubMed1984

Intensity and frequency characteristics of pacinian corpuscles. II. Receptor potentials.

Intensity characteristics that relate receptor- (generator) potential amplitude to vibration amplitude and frequency characteristics that relate either the stimulus intensity required for a criterion response or the phase angle between the stimulus and the receptor potential to vibration frequency have been obtained from isolated pacinian corpuscles removed from cat mesentery. The intensity characteristics of signal-averaged receptor potentials in response to sinusoidal displacements were found to be linear at low stimulus levels and to saturate at higher ones. At the higher levels, an asymmetric full-wave rectification was often found, the degree of which varied among receptors. The receptor-potential waveforms showed a time-dependent hysteresis in response to every stimulus cycle at moderate and high stimulus levels. An average intensity characteristic is given. The measured amplitude-frequency characteristics for a constant magnitude of the receptor potential below the neural spike threshold were found to be U-shaped functions. The averaged (n = 7) amplitude-frequency characteristic generated at a constant criterion response had a best frequency of 370 Hz and a bandwidth of Q3 dB equal to 0.8. The phase-frequency characteristics of the receptor potentials below spike threshold exhibited two populations of responses. Both populations underwent phase changes of about 300 degrees as the vibration frequency was increased from 20 Hz to 1.0 kHz but were separated by 180 degrees. An average (n = 8) phase-frequency characteristic is shown. For a constant neural firing rate, the relationship between receptor-potential amplitude and stimulus frequency was also U-shaped. Several qualitative physiological models are presented in relation to previously reported anatomical evidence (14, 18, 19, 32, 45). For the intensity domain, it is suggested that the cytoplasmic extensions that protrude from the unmyelinated portion of the corpuscle axon into the hemilamellar clefts are responsible for the asymmetric full-wave rectification and the response polarity in the phase-frequency characteristics. It is the asymmetric full-wave rectification and consequent receptor-potential waveforms that produce the 2 spikes/stimulus cycle plateaus in the characteristics relating firing rate to stimulus intensity described in the preceding paper (5). An additional model, based on the recovery of spike threshold, suggests how the plateaus in the firing rate-intensity characteristics (5) are produced. For the frequency domain, three filters in cascade can account for the frequency characteristic obtained with a constant firing rate criterion (see Ref. 5).(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1977

[Effect of acetylcholine and cholinolytics on the activity of Pacinian corpuscles].

The effect of acetylcholine and cholinergic antagonists (atropine, d-tubocurarine, hexamethonium) was studied as applied to isolated decapsulated preparations. Acetylcholine (10(-5)-10(-4) g/ml) enhanced the sensitivity of the receptors to mechanical stimuli due to increased excitability of the Ranvier node. The amplitude of the receptor potential decreased. Cholinergic drugs did not block the responses of receptors to mechanical stimuli. The results provide evidence against the role of acetylcholine as a transmitter in the Pacinian corpuscles.

Acetylcholine↗
PubMed1966

Mechanical transmission in a Pacinian corpuscle. An analysis and a theory.

1. An analysis is made of the transmission of mechanical forces through the Pacinian corpuscle. In particular, forces are analysed which produce pressure differences at the centre of the corpuscle and lead to excitation of the sensory nerve ending.2. The main structural elements in force transmission through the corpuscle are the lamellae, their interconnexions, and the interlamellar fluid. The two former provide the elastic elements and constraint for the fluid; and the latter, the viscous elements. The mechanical equivalent incorporating these elements is a system of dashpots (the lamellar surfaces and the interlamellar fluid) and springs (the lamellae and their interconnexions); it is a mechanical filter which suppresses low frequencies. The dynamic and static patterns of lamella displacements in the equivalent are in close agreement with those observed in Pacinian corpuscles.3. Steady-state and transient pressure fields were determined for the equivalent. Under static compression, only elastic forces exist in the corpuscle. Analysis shows that such forces are transmitted poorly from periphery to centre through the lamellated structure. The compliance of the lamellar interconnexions is so high in relation to that of the lamellae themselves, that most of the pressure load is carried by the outer lamellae. As a result, only a small fraction of the steady-state pressure at the outer surface reaches the centre of the corpuscle where the sensory ending is located. This is the mechanical basis of receptor adaptation.4. Under dynamic compression, viscous forces develop in the corpuscle; and these account for most of the pressure at times too early for development of elastic deformations. Analysis shows that such forces are transmitted well. For example, if a typical corpuscle of 500mu diameter is compressed by 20mu linearly during 2 msec, the pressure differences near to the centre of the corpuscle are initially as high as at the periphery, and stay within the same order throughout the process of compression. In general, pressure at the centre increases steeply with velocity of compression. This explains the marked velocity dependence of the generator response of the sensory ending.If, in the foregoing example, the 20mu compression is held fixed after 2 msec, the pressure differences at the centre fall abruptly to near zero with the onset of the static phase. The duration of pressure transients at the centre approximates that of the ;active' phase of the generator current of the sensory ending derived from experiments, as expected in a causal relationship: pressure difference --> generator current. Taken together with the earlier experimental finding of marked prolongation of generator response in corpuscles partially stripped of lamellae (Loewenstein & Mendelson, 1965), this result warrants the conclusion that the mechanical filter action of the corpuscle is the rate-limiting factor in generator response adaptation.5. When the corpuscle is released from compression, energy stored in the elastic elements during compression is released and consumed in viscous flow. Thus, viscous pressure is produced anew. The magnitude of this pressure depends on the velocity of release. The pressure distribution is rotated by 90 degrees with respect to that in compression; i.e. during release, compression occurs once again, but this time at right angles to the direction of initial compression. Experiments show that the sensory ending does not discriminate such a rotation; the polarity and order of magnitude of the generator response to compression in one plane are the same as in another. Analysis shows that considerable pressure differences may be developed at the centre of the corpuscle during releases at physiological velocities. For instance, in a passive return from a compression of 20mu, the pressure difference at the centre (and the generator current) is of the same order of magnitude as that in a compression of the velocity in 4. This accounts for the ;off'-response of the sensory ending in purely mechanical terms.

Biophysical Phenomena↗
PubMed2005

Bcl-2 immunoreactivity in human cutaneous Meissner and Pacinian corpuscles.

The occurrence and distribution of Bcl-2, a protein involved in the death-life cell pathways, was investigated in the peripheral sensory nervous system of healthy adult humans, including lumbar dorsal root ganglia, nerve trunks and glabrous skin (to analyze sensory corpuscles) using Western blot and immunohistochemistry. The antibody used labelled a protein of 26 kDa of estimated molecular weight corresponding with Bcl-2. Immunohistochemistry showed that only a neuronal population in dorsal root ganglia, some axons in peripheral nerves and the axon supplying Meissner and Pacinian corpuscles contained Bcl-2, whereas peripheral glial cells (i.e. satellite glial cells, Schwann cell, and lamellar cells of sensory corpuscles) did not. These results suggest that in normal conditions, Bcl-2 is only present in some neuronal, but not glial, elements of the sensory peripheral nervous system. The functional significance, if any, of these results remains to be determined.

Adult↗