Rapid Contractions and Associated Potentials in a Sand-Dwelling Anemone

1969 ◽  
Vol 51 (2) ◽  
pp. 513-528
Author(s):  
PETER E. PICKENS
Keyword(s):  
Maximum Size ◽  
Mechanical Stimulus ◽  
Retractor Muscle ◽  
Mechanical Stimuli ◽  
Nerve Impulses ◽  
Electrical Potentials ◽  
Spread Of Excitation ◽  
Electrical Stimuli ◽  
Withdrawal Response ◽  
Muscle Potential

1. Two kinds of electrical potentials can be recorded from the surface of the. retractor muscle of the anemone, Calamactis, during rapid contraction. These are large muscle action potentials and smaller pulses which are thought to be nerve spikes The latter resemble nerve impulses of higher organisms in that they are all-or-none and of short duration. 2. A nerve spike follows each of a pair of electrical stimuli, but the muscle potential and contraction occur only after the second shock, indicating that facilitation is required at the neuromuscular junction. 3. The size of the muscle potential and of the contraction are correlated with the interval between paired electrical stimuli. Maximum size is reached when stimuli are zoo msec. apart even though the minimum effective interval is 30 msec. 4. A muscle potential precedes contraction only along the upper part of the retractor muscle and this is the part that contracts rapidly during the withdrawal response. The lower retractor does not contract. 5. Conduction velocity along the upper retractor is higher than along the lower. The histological correlate of rapid conduction is a nerve net with large, long, longitudinally oriented fibres. 6. The refractory period of the conducting system of the upper retractor is shorter than that of the lower retractor. Consequently, spread of excitation toward the aboral end is limited if paired stimuli are further apart than 250-300 msec. 7. A mechanical stimulus which is just strong enough to elicit a withdrawal response evokes a single muscle potential of maximum size, suggesting that two nerve impulses closer together than 200 msec. precede the muscle potential. Stronger mechanical stimuli evoke a burst of muscle potentials.

The initiation of nerve impulses by mesenteric Pacinian corpuscles

1950 ◽  
Vol 137 (886) ◽  
pp. 96-114 ◽  
Keyword(s):  
Conditioning Stimulus ◽  
Mechanical Stimulus ◽  
Constant Current ◽  
Mechanical Stimuli ◽  
Pacinian Corpuscles ◽  
Nerve Impulses ◽  
A Value ◽  
Test Shock ◽  
Long Duration ◽  
Refractory State

A preparation of a single Pacinian corpuscle in the cat’s mesentery has been used to study the initiation of nerve impulses in sensory endings. The minimum movement of a mechanical stimulator required to excite a single corpuscle has been found to be 0⋅5 μ in 100 μ sec. It has been difficult to produce repetitive discharges with rectangular pulses of long duration, either mechanical or of constant current. The latency between a mechanical stimulus and the initiation of an impulse has a value around 1⋅5 msec, for threshold stimuli, and this decreases to a minimum value around 0⋅5 msec, as the stimulus is increased; it is altered only slightly, if at all, by changes in the duration of the maintained displacement of the mechanical stimulator. Subthreshold mechanical stimuli have been shown to facilitate stimulation by electrical test shocks. The return of excitability at the ending is independent of the nature of the conditioning stimulus and varies but little with the nature of the test shock. The value of the latency at threshold is unaffected by the relatively refractory state. The relations of these results to various hypotheses are discussed, and it is suggested that these results can all be accounted for in terms of the known properties of axons.

scholarly journals The Excitation of Nematocysts

1942 ◽  
Vol 19 (3) ◽  
pp. 294-310 ◽  
Author(s):  
C. F. A. PANTIN
Keyword(s):  
Mechanical Stimulus ◽  
Solid Food ◽  
Natural Food ◽  
Mechanical Stimuli ◽  
Contact Sensitization ◽  
Anemonia Sulcata ◽  
Spread Of Excitation ◽  
Surface Active ◽  
Contact Discharge ◽  
Active Substances

1. The nature of the stimulus which causes discharge of the cnidae (nematocysts and spirocysts) in the tentacles of Anemonia sulcata has been studied. 2. The cnidoblasts behave as independent effectors. Contact with solid food or electric stimuli cause only local discharge. Repetitive electric stimulation at various frequencies causes spread of excitation far down the nerve net of the tentacle but the cnida discharge remains localized under the stimulating electrode. There is no physiological evidence for any connexion ofcnidoblasts with the nervous system. 3. The stimulus to the cnidoblast is primarily due to direct mechanical contact. Discharge is easily effected by solid food. It can also be effected by inert solids provided the mechanical stimulus is sufficiently intense. 4. The normal stimulus to the cnidoblast is not a directly chemical one. Most food solutions and solutions of food derivatives do not cause a discharge. Some strong food solutions cause a few scattered cnidae to discharge. This differs from the intense local discharge to solid food. 5. Immersion in solutions of certain surface-active substances, such as the lower fatty acids, bile salts and saponin, causes an immediate general discharge of all the cnidae. This differs from the normal discharge to solid food. 6. Although natural food solutions do not normally cause a discharge, the cnidae are easily discharged by contact when they are present. That is, food solutions sensitize the cnidoblasts to mechanical stimuli. 7. The sensitizing substance is not protein. But it is strongly adsorbed on to protein. It cannot be extracted with ethyl ether. But it can be extracted with ethyl alcohol or acetone. Alcohol extracts of food are very active in sensitizing the cnidoblasts to mechanical disturbance. 8. Water insoluble foods can sensitize cnidoblasts with which they come in contact. Sensitization by contact is almost instantaneous. It is suggested that normally sensitization is due to some surface active lipoid directly transferred to the cnidoblast by contact.

Identification of Mechanoafferent Neurons in Terrestrial Snail: Response Properties and Synaptic Connections

2002 ◽  
Vol 87 (5) ◽  
pp. 2364-2371 ◽  
Author(s):  
Aleksey Y. Malyshev ◽  
Pavel M. Balaban
Keyword(s):  
Avoidance Behavior ◽  
Receptive Fields ◽  
Dorsal Surface ◽  
Mechanical Stimulus ◽  
Terrestrial Snail ◽  
Mechanosensory Neurons ◽  
Intracellular Stimulation ◽  
Pleural Ganglion ◽  
Withdrawal Response ◽  
Stimulation Of

In this study, we describe the putative mechanosensory neurons, which are involved in the control of avoidance behavior of the terrestrial snail Helix lucorum. These neurons, which were termed pleural ventrolateral (PlVL) neurons, mediated part of the withdrawal response of the animal via activation of the withdrawal interneurons. Between 15 and 30 pleural mechanosensory neurons were located on the ventrolateral side of each pleural ganglion. Intracellular injection of neurobiotin revealed that all PlVL neurons sent their axons into the skin nerves. The PlVL neurons had no spontaneous spike activity or fast synaptic potentials. In the reduced “CNS-foot” preparations, mechanical stimulation of the skin covering the dorsal surface of the foot elicited spikes in the PlVL neurons without any noticeable prepotential activity. Mechanical stimulus-induced action potentials in these cells persisted in the presence of high-Mg2+/zero-Ca2+ saline. Each neuron had oval-shaped receptive field 5–20 mm in length located on the dorsal surface of the foot. Partial overlapping of the receptive fields of different neurons was observed. Intracellular stimulation of the PlVL neurons produced excitatory inputs to the parietal and pleural withdrawal interneurons, which are known to control avoidance behavior. The excitatory postsynaptic potentials (EPSPs) in the withdrawal interneurons were induced in 1:1 ratio to the PlVL neuron spikes, and spike-EPSP latency was short and highly stable. These EPSPs also persisted in the high-Mg2+/high-Ca2+ saline, suggesting monosynaptic connections. All these data suggest that PlVL cells were the primary mechanosensory neurons.

scholarly journals Epithelial Conduction in Hydromedusae

1968 ◽  
Vol 52 (3) ◽  
pp. 600-621 ◽  
Author(s):  
G. O. Mackie ◽  
L. M. Passano
Keyword(s):  
Nervous System ◽  
Spontaneous Activity ◽  
Nervous Activity ◽  
The Other ◽  
Refractory Periods ◽  
Spread Of Excitation ◽  
Composite Events ◽  
Waves Propagation ◽  
Excess Mg ◽  
Electrical Stimuli

Sarsia, Euphysa, and other hydromedusae have been studied by electrophysiological techniques and are found to have nonnervous conducting epithelia resembling those described earlier for siphonophores. Simple, nonmuscular epithelia fire singly or repetitively following brief electrical stimuli. The pulses recorded with suction electrodes are biphasic, initially positive, and show amplitudes of 0.75–2.0 mv, durations of 5–15 msec, and velocities of 15–35 cm/sec with short refractory periods. In the swimming muscle (myoepithelium) 2.0–4.0 mv composite events lasting 150–300 msec are associated with contraction waves. Propagation in nonnervous epithelia is typically all-or-none, nondecremental, and unpolarized. The subumbrellar endoderm lamella conducts independently of the adjacent ectoderm. The lower regions of the tentacles do not show propagated epithelial events. The spread of excitation in conducting epithelia and associated effector responses are described. Examples are given of interaction between events seemingly conducted in the nervous system and those in nonnervous epithelia. Either system may excite the other. Spontaneous activity, however, appears to originate in the nervous system. Conduction in nonnervous tissues is unaffected by excess Mg++ in concentrations suppressing presumed nervous activity, although this may not be a wholly adequate criterion for distinguishing components of the two systems. Evidence from old work by Romanes is considered in the light of these findings and the general significance of epithelial conduction is discussed.

Parallel processing of tactile information in the cerebral cortex of the cat: effect of reversible inactivation of SI on responsiveness of SII neurons

1992 ◽  
Vol 67 (2) ◽  
pp. 411-429 ◽  
Author(s):  
A. B. Turman ◽  
D. G. Ferrington ◽  
S. Ghosh ◽  
J. W. Morley ◽  
M. J. Rowe
Keyword(s):  
Phase Locking ◽  
Receptive Fields ◽  
Mechanical Stimulus ◽  
Glabrous Skin ◽  
Mechanical Stimuli ◽  
Sinusoidal Vibration ◽  
Response Level ◽  
Reversible Inactivation ◽  
Stimulus Response ◽  
Cortical Cooling

1. Localized cortical cooling was employed in anesthetized cats for the rapid reversible inactivation of the distal forelimb region within the primary somatosensory cortex (SI). The aim was to examine the responsiveness of individual neurons in the second somatosensory area (SII) in association with SI inactivation to evaluate the relative importance for tactile processing of the direct thalamocortical projection to SII and the indirect projection from the thalamus to SII via an intracortical path through SI. 2. Response features were examined quantitatively before, during, and after SI inactivation for 29 SII neurons, the tactile receptive fields of which were on the glabrous or hairy skin of the distal forelimb. Controlled mechanical stimuli that consisted of l-s trains of either sinusoidal vibration or rectangular pulses were delivered to the skin by means of small circular probes (4- to 8-mm diam). 3. Twenty-three of the 29 SII neurons (80%) showed no change in response level (in impulses per second) as a result of SI inactivation. These included seven neurons activated exclusively or predominantly by Pacinian corpuscle (PC) receptors, six that received hair follicle input, four activated by convergent input from hairy and glabrous skin, and six driven by dynamically sensitive but non-PC inputs from the glabrous skin. 4. Six SII neurons (20%), also made up of different functional classes, displayed a reduction in response to cutaneous stimuli when SI was inactivated. 5. Stimulus-response relations, constructed by plotting response level in impulses per second against the amplitude of the mechanical stimulus, showed that the effect of SI inactivation on individual neurons was consistent over the whole response range. 6. The reduced response level seen in 20% of SII neurons in association with SI inactivation cannot be attributed to direct spread of cooling from SI to the forelimb area of SII, as there was no evidence for a cooling-induced prolongation in SII spike waveforms, an effect that is known to precede any cooling-induced reduction in responsiveness. 7. As SI inactivation produced a fall in spontaneous activity in the affected SII neurons, we suggest that the inactivation removes a source of background facilitatory influence that arises in SI and affects a small proportion of SII neurons. 8. Phase-locking and therefore the precision of impulse patterning were unchanged in the responses of SII neurons to vibration during SI inactivation. This was the case whether response levels of neurons were reduced or unchanged by SI inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

Involvement of the dorsolateral funiculus in the descending spinal projections responsible for diffuse noxious inhibitory controls in the rat

1986 ◽  
Vol 56 (4) ◽  
pp. 1185-1195 ◽  
Author(s):  
L. Villanueva ◽  
D. Chitour ◽  
D. Le Bars
Keyword(s):  
Receptive Fields ◽  
Conditioning Stimulus ◽  
Mechanical Stimuli ◽  
Diffuse Noxious Inhibitory Controls ◽  
Strong Reduction ◽  
Inhibitory Processes ◽  
C Fiber ◽  
Dorsolateral Funiculus ◽  
Electrical Stimuli ◽  
Descending Projections

Recordings were made from convergent neurons in the lumbar dorsal horn of the spinal cord of the rat. These neurons were activated by both innocuous and noxious mechanical stimuli applied to their excitatory receptive fields located on the extremity of the hindpaw. Transcutaneous application of suprathreshold 2-ms square-wave electrical stimuli to the center of the excitatory field, resulted in responses to C-fiber activation being observed. This type of response was inhibited by applying a noxious thermal conditioning stimulus on the muzzle. The immersion of the muzzle in a 52 degrees C waterbath resulted in a strong reduction of the response during the application of the noxious conditioning stimulus and this was followed by long lasting poststimulus effects. Such inhibitory processes have been termed diffuse noxious inhibitory controls (DNIC). The effects on these inhibitions of lesions including the dorsolateral funiculus (DLF) were investigated in acute experiments: tests were performed before and at least 30 min after the DLF lesion. A lesion including the DLF ipsilateral to the neuron under study completely abolished the inhibitory processes triggered from the muzzle. Concomitantly, a facilitation of C-fiber responses was observed. Nevertheless, DNIC was still impaired even using a juxtathreshold current to elicit a weak C-fiber response. To ascertain further the main, if not entire, participation of the ipsilateral DLF in the descending projections responsible for the heterotopic inhibitory processes, the effects of a lesion of the contralateral DLF were investigated. Neither the inhibitory processes nor the unconditioned C-fiber responses were altered by this procedure. Again, a second lesion including the ipsilateral DLF induced a blockade of DNIC. It is concluded that the descending projections involved in the triggering of DNIC are mainly, if not entirely, confined to the DLF ipsilateral to the neuron under study. The contralateral DLF did not appear to play a role in these processes.

A comparative study of the changes in receptive-field properties of multireceptive and nocireceptive rat dorsal horn neurons following noxious mechanical stimulation

1989 ◽  
Vol 62 (4) ◽  
pp. 854-863 ◽  
Author(s):  
J. M. Laird ◽  
F. Cervero
Keyword(s):  
Dorsal Horn ◽  
Mechanical Stimulation ◽  
Receptive Fields ◽  
Mechanical Stimulus ◽  
Mechanical Stimuli ◽  
Dorsal Horn Neurons ◽  
Mechanical Threshold ◽  
Before And After ◽  
Low Threshold ◽  
Noxious Mechanical Stimulation

1. Single-unit electrical activity has been recorded from 42 dorsal horn neurons in the sacral segments of the rat's spinal cord. The sample consisted of 20 multireceptive (class 2) cells with both A- and C-fiber inputs and 22 nocireceptive (class 3) cells. All neurons had cutaneous receptive fields (RFs) on the tail. 2. The RF sizes of the cells and their response thresholds to mechanical stimulation of the skin were determined before and after each of a series of 2-min noxious mechanical stimuli. Up to five such stimuli were delivered at intervals ranging from 10 to 60 min. In most cases, only one cell per animal was tested. 3. The majority of neurons were tested in barbiturate-anesthetized animals. However, to test whether or not this anesthetic influenced the results obtained, experiments were also performed in halothane-anesthetized and decerebrate-spinal preparations. The results from these experiments are considered separately. 4. All of the neurons responded vigorously to the first noxious pinch stimulus and all but one to the rest of the stimuli in the series. The responses of the neurons varied from stimulus to stimulus, but there were no detectable trends in the two groups of cells. 5. The RFs of the class 2 cells showed large increases (624.3 +/- 175.8 mm2, mean +/- SE) after the application of the pinch stimuli. The RFs of the class 3 neurons, which were initially smaller than those of the class 2 cells, either did not increase in size or showed very small increases after the pinch stimuli (38.3 +/- 11.95 mm2, mean +/- SE). 6. Some cells in both groups (6/10 class 2 cells and 7/16 class 3 cells) showed a decrease in mechanical threshold as a result of the noxious mechanical stimulus, but none of the class 3 cells' thresholds dropped below 20 mN into the low-threshold range. 7. The results obtained in the halothane-anesthetized and decerebrate-spinal animals were very similar to those seen in the barbiturate-anesthetized experiments, with the exception that in the decerebrate-spinal animals, the RFs of the class 2 cells were initially larger and showed only small increases.(ABSTRACT TRUNCATED AT 400 WORDS)

INK-JET PRINTED STRETCHABLE SENSORS FOR CELL MONITORING UNDER MECHANICAL STIMULI: A FEASIBILITY STUDY

2019 ◽  
Vol 19 (06) ◽  
pp. 1950049 ◽  
Author(s):  
SARAH TONELLO ◽  
MICHELA BORGHETTI ◽  
NICOLA F. LOPOMO ◽  
MAURO SERPELLONI ◽  
EMILIO SARDINI ◽  
...  
Keyword(s):  
Cyclic Strain ◽  
Mechanical Stimulus ◽  
Research Field ◽  
Stretchable Electronics ◽  
Present System ◽  
Mechanical Stimuli ◽  
Ink Jet ◽  
Cell Monitoring ◽  
Cell Concentrations ◽  
Stretchable Sensors

Impedance-based sensors represent a promising tool for cell monitoring to improve current invasive biological assays. A novel research field is represented by measurements performed in dynamic conditions, monitoring cells (e.g., myocytes) for which the mechanical stimulus plays an important role for promoting maturation. In this picture, we applied printed and stretchable electronics principles, developing a system able to evaluate cells adhesion during substrate cyclic strain. Cytocompatible and stretchable sensors were ink-jet printed using carbon-based ink on crosslinked poly([Formula: see text]-caprolactone) electrospun mats. Moreover, a customized stretching device was produced, with a complete user interface to control testing condition, validated in order to correlate impedance changes with myoblasts — i.e., myocytes precursors — adhesion. Overall system sensitivity was evaluated using three different cell concentrations and DAPI imaging assay was performed to confirm myoblast adhesion. Preliminary results showed the possibility to correlate an average increase of impedance magnitude of 1[Formula: see text]k[Formula: see text] every 15,000 cells/cm2 seeded, suggesting the possibility to discriminate between different cell concentrations, with a sensitivity of 80[Formula: see text]m[Formula: see text]/(cells/cm2). In conclusion, the present system might be generalized in the development of future applications, including the differentiation process of cardiac myocytes with the aid of mechanical stimuli.

A High Throughput System for Long Term Application of Intermittent Cyclic Hydrostatic Pressure on Cells in Culture

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Markus Rottmar ◽  
Sabine Ackerknecht ◽  
Peter Wick ◽  
Katharina Maniura-Weber
Keyword(s):  
Cell Proliferation ◽  
Hydrostatic Pressure ◽  
Cell Fate ◽  
High Throughput ◽  
Cell Response ◽  
Mechanical Stimulus ◽  
Bone Alkaline Phosphatase ◽  
Cell Counting ◽  
Present System ◽  
Mechanical Stimuli

The process of bone remodeling is governed by mechanical stresses and strains. Studies on the effects of mechanical stimulation on cell response are often difficult to compare as the nature of the stimuli and differences in parameters applied vary greatly. Experimental systems for the investigation of mechanical stimuli are mostly limited in throughput or flexibility and often the sum of several stimuli is applied. In this work, a flexible system that allows the investigation of cell response to isolated intermittent cyclic hydrostatic pressure (icHP) on a high throughput level is shown. Human bone derived cells were cultivated with or without mechanical stimulus in the presence or absence of chemical cues triggering osteogenesis for 7–10 days. Cell proliferation and osteogenic differentiation were evaluated by cell counting and immunohistochemical staining for bone alkaline phosphatase as well as collagen 1, respectively. In either medium, both cell proliferation and level of differentiation were increased when the cultures were mechanically stimulated. These initial results therefore qualify the present system for studies on the effects of isolated icHP on cell fate and encourage further investigations on the details behind the observed effects.

Habituation in a Protozoan Vorticella Conyallaria

Behaviour ◽  
1973 ◽  
Vol 45 (3-4) ◽  
pp. 304-311 ◽  
Author(s):  
David J. Patterson
Keyword(s):  
Response Curve ◽  
Deionized Water ◽  
Mechanical Stimuli ◽  
Response Curves ◽  
Sodium Salts ◽  
Electrical Stimuli

AbstractThe response of Vorticella convallaria to electrical and mechanical stimuli was investigated. It was shown that: (I) V. convallaria becomes habituatcd independently to both mechanical and electrical stimuli if these are repeated at I0 sec. intervals. (2) The habituation is more rapid to lower intensities of stimuli. (3) The form of the response curve is similar for both types of stimulus. (4) No habituation was obtained when the animals were stimulated while in deionized water. No response was obtained while they were placed in a solution of CaCl2 but continuous contraction was induced in a solution of KOH. Other potassium and sodium salts in deionized water gave response curves similar to those obtained under normal conditions.

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