Quantitative Analyses of Dynamic Strain Sensitivity in Human Skin Mechanoreceptors

2004 ◽  
Vol 92 (6) ◽  
pp. 3233-3243 ◽  
Author(s):  
Benoni B. Edin
Keyword(s):  
Discharge Rate ◽  
Receptive Fields ◽  
Dynamic Strain ◽  
Strain Sensitivity ◽  
Power Functions ◽  
Discharge Rates ◽  
Response Onset ◽  
Quantitative Analyses ◽  
The Mean ◽  
Skin Mechanoreceptors

Microneurographical recordings from 24 slowly adapting (SA) and 16 fast adapting (FA) cutaneous mechanoreceptor afferents were obtained in the human radial nerve. Most of the afferents innervated the hairy skin on the back of the hand. The afferents' receptive fields were subjected to controlled strains in a ramp-and-hold fashion with strain velocities from 1 to 64% · s−1, i.e., strain velocities within most of the physiological range. For all unit types, the mean variation in response onset approached 1 ms for strain velocities >8% · s−1. Except at the highest strain velocities, the first spike in a typical SAIII unit was evoked at strains <0.5% and a typical SAII unit began to discharge at <1% skin strain. Skin strain velocity had a profound effect on the discharge rates of all classes of afferents. The “typical” peak discharge rate at the highest strain velocity studied was 50–95 imp/s−1 depending on unit type. Excellent fits were obtained for both SA and FA units when their responses to ramp stretches were modeled by simple power functions ( r2 > 0.9 for 95% of the units). SAIII units grouped with SAII with respect to onset latency and onset variation but with SAI units with respect to dynamic strain sensitivity. Because both SA and FA skin afferents respond strongly, quickly, and accurately to skin strain changes, they all seem to be able to provide useful information about movement-related skin strain changes and therefore contribute to proprioception and kinesthesia.

scholarly journals Assessing watershed hydrological response to climate change based on signature indices

2021 ◽  
Author(s):  
Atiyeh Fatehifar ◽  
Mohammad Reza Goodarzi ◽  
Seyedeh Sima Montazeri Hedesh ◽  
Parnian Siahvashi Dastjerdi
Keyword(s):  
Climate Change ◽  
Discharge Rate ◽  
Baseline Period ◽  
Future Climate Change ◽  
Hydrological Response ◽  
High Discharge ◽  
Discharge Rates ◽  
Segment Volume ◽  
The Mean ◽  
Hydrological Signatures

Abstract Due to the fact that one of the important ways of describing the performance of basins is to use the hydrological signatures, the present study is to investigate the effects of climate change using the hydrological signatures in Azarshahr Chay basin, Iran. To this end, Canadian Earth system model (CanESM2) is first used to predict future climate change (2030–2059) under two Representative Concentration Pathways (RCP2.6 and RCP8.5). Six signature indices were extracted from flow duration curve (FDC) as follows: runoff ratio (RR), high-segment volume (FHV), low-segment volume (FLV), mid-segment slope (FMS), mid-range flow (FMM), and maximum peak discharge (DiffMaxPeak). These signature indices act as sorts of fingerprints representing differences in the hydrological behavior of the basin. The results indicate that the most significant changes in the future hydrological response are related to the FHV and FLV and FMS indices. The BiasFHV index indicates an increase in high discharge rates under RCP8.5 scenario, compared to the baseline period and the RCP2.6 scenario, as well. The mean annual discharge rate, however, is lower than the discharge rate under this scenario. Generally, for the RCP8.5 scenario, the changes in the signature indices in both high discharges and low discharges are significant.

Comparison of the responses to moving texture patterns of simple and complex cells in the cat's area 17

1995 ◽  
Vol 74 (3) ◽  
pp. 1271-1286 ◽  
Author(s):  
C. Casanova ◽  
T. Savard ◽  
J. P. Nordmann ◽  
S. Molotchnikoff ◽  
K. Minville
Keyword(s):  
Striate Cortex ◽  
Discharge Rate ◽  
Receptive Fields ◽  
Sine Wave ◽  
T Test ◽  
Visual Noise ◽  
C Cells ◽  
Noise Pattern ◽  
Optimal Velocity ◽  
The Mean

1. Whether complex (C) cells are the only truly texture-sensitive units in the cat's primary visual cortex remains controversial. In view of the strong physiological significance of having putatively only one class of cells sensitive to visual noise in the striate cortex, we reinvestigated this issue. Sensitivities of simple (S) and C cells to noise were quantitatively studied and compared in order to clearly document the response properties of cells in the striate cortex to visual noise and to establish whether one can unequivocally segregate S from C cells on the basis of those specific properties. 2. Receptive fields were stimulated with all relevant stimuli, i.e., drifting sine-wave gratings, electronically generated noise pattern of 256 x 256 elements (ratio 1:1 of dark and light elements), and flashing and moving bars (both bright and dark). 3. A total of 60 S cells out of 85 (70.6%) and 90 C cells out of 101 (81.8%) responded to the motion of visual noise. Responses of most C cells were sustained, i.e., their discharge rate was maintained at a constant level throughout presentation of the stimulus. On the other hand, responses of the majority of S cells were characterized by several bursts of discharges. On average, optimal firing rates were greater for gratings than for noise. 4. For practically all cells, responses to noise varied as a function of direction of motion. The mean direction bandwidths were, respectively, 43 +/- 24 degrees and 48 +/- 23 degrees (mean +/- SD) for S and C cells. In both groups, neurons were more broadly tuned for the direction of noise than that of gratings (t-test, P < 0.001). We rarely observed bimodal tuning curves for noise, with each peak lying on either side of the orientation curve. These results could be expected if one considers texture stimuli not in the space domain (as dot patterns) but in the frequency domain, i.e., patterns containing all spatial frequencies and orientations. 5. In general, the direction indexes of S and C cells were similar whether they were stimulated by drifting noise or gratings. S cells had a slight tendency to be more direction selective for noise than for gratings. 6. For all S and C cells tested, responses to noise varied as a function of drift velocity. The mean optimal velocity was 12.9 and 10.2 degrees/s for S and C cells, respectively (t-test, P > 0.05). Most cells were band-pass with mean bandwidths of 2.2 and 2.7 octaves for S and C cells, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals In vivo responses of cutaneous C-mechanosensitive neurons in mouse to punctate chemical stimuli that elicit itch and nociceptive sensations in humans

2012 ◽  
Vol 107 (1) ◽  
pp. 357-363 ◽  
Author(s):  
C. Ma ◽  
H. Nie ◽  
Q. Gu ◽  
P. Sikand ◽  
R. H. LaMotte
Keyword(s):  
Time Course ◽  
Discharge Rate ◽  
Receptive Fields ◽  
Mechanical Stimuli ◽  
Nociceptive Neurons ◽  
Electrophysiological Recordings ◽  
The Mean ◽  
Chemical Stimuli ◽  
Temporal Profiles

Native cowhage spicules, and heat-inactivated spicules containing histamine or capsaicin, evoke similar sensations of itch and nociceptive sensations in humans. In ongoing studies of the peripheral neural mechanisms of chemical itch and pain in the mouse, extracellular electrophysiological recordings were obtained, in vivo, from the cell bodies of mechanosensitive nociceptive neurons in response to spicule stimuli delivered to their cutaneous receptive fields (RFs) on the distal hindlimb. A total of 43 mechanosensitive, cutaneous, nociceptive neurons with axonal conduction velocities in the C-fiber range (C-nociceptors) were classified as CM if responsive to noxious mechanical stimuli, such as pinch, or CMH if responsive to noxious mechanical and heat stimuli (51°C, 5 s). The tips of native cowhage spicules, or heat-inactivated spicules containing histamine or capsaicin, were applied to the RF. Heat-inactivated spicules containing no chemical produced only a transient response occurring during insertion. Of the 43 mechanosensitive nociceptors recorded, 20 of the 25 CMHs responded to capsaicin, and of these, 13 also responded to cowhage and/or histamine. In contrast, none of the 18 CMs responded to any of the chemical stimuli. The time course of the mean discharge rate of CMHs was similar in response to each type of spicule and generally similar, although reaching a peak earlier, to the temporal profiles of itch and nociceptive sensations evoked by the same stimuli in humans. These findings are consistent with the hypothesis that the itch and nociceptive sensations evoked by these punctuate chemical stimuli are mediated at least in part by the activity of mechanoheat-sensitive C-nociceptors. In contrast, activity in mechanosensitive C-nociceptors that do not respond to heat or to pruritic chemicals is hypothesized as contributing to pain but not to itch.

Fixation cells in monkey superior colliculus. I. Characteristics of cell discharge

1993 ◽  
Vol 70 (2) ◽  
pp. 559-575 ◽  
Author(s):  
D. P. Munoz ◽  
R. H. Wurtz
Keyword(s):  
Superior Colliculus ◽  
Visual Stimulation ◽  
Discharge Rate ◽  
Receptive Fields ◽  
Visual Cells ◽  
Cell Discharge ◽  
Target Spot ◽  
Saccade Onset ◽  
The Mean ◽  
Mean Time

1. We studied the role of the superior colliculus (SC) in the control of visual fixation by recording from cells in the rostral pole of the SC in awake monkeys that were trained to perform fixation and saccade tasks. 2. We identified a subset of neurons in three monkeys that we refer to as fixation cells. These cells increased their tonic discharge rate when the monkey actively fixated a visible target spot to obtain a reward. This sustained activity persisted when the visual stimulation of the target spot was momentarily removed but the monkey was required to continue fixation. 3. The fixation cells were in the rostral pole of the SC. As the electrode descended through the SC, we encountered visual cells with foveal and parafoveal receptive fields most superficially, saccade-related burst cells with parafoveal movement fields below these visual cells, and fixation cells below the burst cells. From this sequence in depth, the fixation cells appeared to be centered in the deeper reaches of the intermediate layers, and this was confirmed by small marking lesions identified histologically. 4. During saccades, the tonically active fixation cells showed a pause in their rate of discharge. The duration of this pause was correlated to the duration of the saccade. Many cells did not decrease their discharge rate for small-amplitude contraversive saccades. 5. The saccade-related pause in fixation cell discharge always began before the onset of the saccade. The mean time from pause onset to saccade onset for contraversive saccades and ipsiversive saccades was 36.2 and 33.0 ms, respectively. Most fixation cells were reactivated before the end of contraversive saccades. The mean time from saccade terminatioN to pause end was -2.6 ms for contraversive saccades and 9.9 ms for ipsiversive saccades. The end of the saccade-related pause in fixation cell discharge was more tightly correlated to saccade termination, than pause onset was to saccade onset. 6. After the saccade-related pause in discharge, many fixation cells showed an increased discharge rate exceeding that before the pause. This increased postsaccadic discharge rate persisted for several hundred milliseconds. 7. The discharge rate of fixation cells was not consistently altered when the monkey actively fixated targets requiring different orbital positions. 8. Fixation cells discharged during smooth pursuit eye movements as they did during fixation. They maintained a steady tonic discharge during pursuit at different speeds and in different directions, provided the monkey looked at the moving target.(ABSTRACT TRUNCATED AT 400 WORDS)

Quantitative analysis of visual receptive fields of neurons in nucleus of the optic tract and dorsal terminal nucleus of the accessory optic tract in macaque monkey

1989 ◽  
Vol 62 (2) ◽  
pp. 416-428 ◽  
Author(s):  
K. P. Hoffmann ◽  
C. Distler
Keyword(s):  
Discharge Rate ◽  
Receptive Fields ◽  
Optic Tract ◽  
Macaque Monkey ◽  
Response Strength ◽  
Ongoing Activity ◽  
Stimulus Movement ◽  
The Mean ◽  
Rightward Movement ◽  
The Right

1. The visual receptive field properties of neurons in the nucleus of the optic tract (NOT) in the pretectum and the dorsal terminal nucleus (DTN) of the accessory optic tract were analyzed quantitatively in anesthetized, paralyzed macaque monkeys. 2. Visual latencies to reversals in direction of stimulus movement ranged from 40 to 80 ms [61 +/- 13.5 (SD) ms]. 3. All neurons increased their discharge rate during ipsiversive movement and decreased their ongoing activity during contraversive movement of single stimuli or whole-field random dot patterns. The population of neurons in the left NOT-DTN was excited most strongly by leftward movement pointing 4 degrees down; neurons in the right NOT-DTN were excited most strongly by rightward movement pointing 6 degrees down. The mean angle between the directions yielding the highest and the lowest discharge rate in the two populations of NOT-DTN neurons was 177 degrees. 4. The deviation of the preferred excitatory directions from the horizon in individual neurons varied with recording depth. Within the first 500 microns below the midbrain surface, neurons preferred near-horizontal directions, whereas neurons recorded more deeply preferred more oblique directions of stimulus movement. 5. The tuning widths of NOT-DTN neurons in the preferred excitatory direction were very broad. The mean halfwidth defined as the range of directions eliciting responses greater than 50% of the maximum was 127 +/- 25 degrees. 6. Moving a random dot pattern and a single bar of light simultaneously but in opposite directions caused NOT-DTN neurons to increase their discharge rate as soon as one of the two stimuli moved in the ipsiversive direction. The reduction in overall discharge rates when two stimuli moved in opposite directions indicates mainly inhibitory interactions. 7. All NOT-DTN neurons could be activated from both eyes. Interactions between the two eyes were modest and unspecific. Misalignment of the visual axes of the two eyes had no influence on response strength. 8. Optimal speeds of stimulus movement varied widely for different NOT-DTN neurons. The effective range of speeds to elicit direction-selective responses in the total population was very broad (0.1400 degrees/s. With oscillating horizontal stimulation, NOT-DTN neurons followed repetition rates up to 4 Hz at excursions of 40 degrees. Speeds greater than 500 degrees/s were either not effective or resulted in a suppression of ongoing activity in all directions of movement.(ABSTRACT TRUNCATED AT 400 WORDS)

Sensitizing effects of bradykinin on the heat responses of the visceral nociceptor

1991 ◽  
Vol 66 (6) ◽  
pp. 1819-1824 ◽  
Author(s):  
T. Kumazawa ◽  
K. Mizumura ◽  
M. Minagawa ◽  
Y. Tsujii
Keyword(s):  
Discharge Rate ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Impulse Generation ◽  
Heat Stimulation ◽  
Discharge Rates ◽  
Low Concentrations ◽  
Heat Response ◽  
The Mean

1. Whether bradykinin (BK), which is known as an endogenous pain-producing substance, induces augmentation of the discharges of polymodal receptors evoked by heat stimulation was investigated in in vitro canine testis-superior spermatic nerve preparations. 2. The heat response was significantly augmented by pretreatments with BK at concentrations greater than 0.094 nM, whereas BK induced significant increases in the mean discharge rates at concentrations above 9.4 nM. Both effects increased in a concentration-dependent manner. The augmenting effect of BK on the heat response diminished within 10 min after application of BK, regardless of concentration. 3. When 9.4 nM BK was applied in a mixture with 940 nM NPC349, a B2 receptor antagonist, the averaged mean discharge rate evoked by BK and the averaged augmenting effect were both significantly suppressed compared with those induced by BK given alone. 4. The augmenting effect of BK on the heat response of polymodal receptors could be observed even in the absence of BK-evoked discharges per se in several cases in which low concentrations of BK or BK plus B2 antagonists were given. 5. These findings suggest that the augmenting effects of BK on the heat response depend on B2 receptor-mediated intracellular processes acting in parallel to, but not directly on, the impulse-generation mechanism of the heat response of the polymodal receptor.

scholarly journals Laboratory modelling of the effects of temporal changes of estuarine-fresh-water discharge rates on the propagation speed of oceanographic coastal currents

2010 ◽  
Vol 664 ◽  
pp. 337-347
Author(s):  
PETER J. THOMAS ◽  
P. F. LINDEN
Keyword(s):  
Discharge Rate ◽  
Water Discharge ◽  
Propagation Speed ◽  
Current Speed ◽  
Discharge Condition ◽  
Kelvin Wave ◽  
Coastal Currents ◽  
Discharge Rates ◽  
The Mean ◽  
Fresh Water Discharge

In this paper, results of laboratory experiments simulating buoyancy-driven coastal currents produced by estuarine discharges into the ocean, are discussed. The responses of the propagation speeds of the currents to increases and decreases of the volumetric discharge rate at the source are investigated. For increasing discharge rate, we find that the mean speed of the current head displays a sharp rise some time after the source discharge condition has changed. In contrast, a decrease of the current speed following a decreasing discharge rate proceeds gradually. The current speed after acceleration or deceleration is found to be equal to the speed that would be expected had the discharge been at the higher or lower rate from the start of the experiment. The relative speed at which the information of the changed discharge condition at the source approaches the advancing current head from upstream, for both increasing and decreasing discharge rates, is found to be approximately one to three times the mean speed of the current. Further, we find that this transmission speed is 0.82±0.20 times the propagation speed of a linear, long interfacial Kelvin wave.

The ENT emergency clinic: does senior input matter?

2012 ◽  
Vol 127 (1) ◽  
pp. 15-19 ◽  
Author(s):  
A Mirza ◽  
L McClelland ◽  
M Daniel ◽  
N Jones
Keyword(s):  
Quality Of Care ◽  
Discharge Rate ◽  
Surrogate Marker ◽  
Operating Theatre ◽  
Number Of Children ◽  
Discharge Rates ◽  
Time Period ◽  
Number Of Patients

AbstractBackground:Many ENT conditions can be treated in the emergency clinic on an ambulatory basis. Our clinic traditionally had been run by foundation year two and specialty trainee doctors (period one). However, with perceived increasing inexperience, a dedicated registrar was assigned to support the clinic (period two). This study compared admission and discharge rates for periods one and two to assess if greater registrar input affected discharge rate; an increase in discharge rate was used as a surrogate marker of efficiency.Method:Data was collected prospectively for patients seen in the ENT emergency clinic between 1 August 2009 and 31 July 2011. Time period one included data from patients seen between 1 August 2009 and 31 July 2010, and time period two included data collected between 1 August 2010 and 31 July 2011.Results:The introduction of greater registrar support increased the number of patients that were discharged, and led to a reduction in the number of children requiring the operating theatre.Conclusion:The findings, which were determined using clinic outcomes as markers of the quality of care, highlighted the benefits of increasing senior input within the ENT emergency clinic.

New analytical solution for the study of hydraulic interaction between Alpine tunnels and groundwater

2003 ◽  
Vol 174 (5) ◽  
pp. 441-448 ◽  
Author(s):  
Jean-Christophe Maréchal ◽  
Pierre Perrochet
Keyword(s):  
Analytical Solution ◽  
Surface Waters ◽  
Discharge Rate ◽  
Water Discharge ◽  
Rate Condition ◽  
Type Curves ◽  
Discharge Rates ◽  
The Alps ◽  
Surface Monitoring ◽  
Tunnel Discharge

Abstract The present paper addresses two major problems encountered during tunnel drilling and related to the hydraulic interaction with surrounding groundwater bodies. The first one is the prediction of water discharge into the tunnel, as a function of the geometric and hydrogeological data. The second problem is related to the assessment of the draining effects on surface waters (springs, lakes, wetlands). Surface monitoring campaigns are costly and evaluating their duration is a sensitive question. Both problems are tightly related and depend on aquifer dynamics. It is shown that in a geological context with steeply dipping structures, nearly vertical, inducing series of aquifers and aquicludes such as in the Alps, the drainage of the aquifer by the tunnel can be modelled by the analytical solution of Jacob and Lohman [1952] for artesian wells. First developed for horizontal, confined unsteady flow towards a vertical well with constant drawdown, it is adapted here to a horizontal tunnel by a rotation of π/2. The main difference between this solution and more classical Theis’ solutions is that a constant drawdown condition replaces the constant discharge rate condition. Hence, a relation is obtained for the time-dependent discharge rate Q(t) detected at the tunnel after drilling, as a function of aquifer transmissivity (T), storage coefficient (S), initial drawdown (so) and tunnel radius (ro). This analytical solution is compared to a finite-elements model simulating a draining tunnel in a simplified 2D vertical cross-section. The comparisons show that the decay of the tunnel discharge can be divided into two periods. During the first period, radial drawdown develops around the tunnel and there is excellent match between analytical and numerical results. Tunnel discharge results from the decompression of rock and water (storage effects) as a response to the sudden initial drawdown at the tunnel location. During the second period, the drawdown cone reaches the aquifer limits (lateral and upper) and numerical discharge rates decrease faster than analytical rates because of hydraulic heads decline at the aquifer limits. In the Alps, such trends were observed for the discharge rates into the Simplon and Mont-Blanc tunnels, and the analytical solution of Jacob and Lohman [1952] was applied to the first discharge period to evaluate aquifer transmissivity and storage coefficients. As indicated by the simulations, and corroborated by field observations, the analytical solution is only valid during a first period after tunnel opening, the duration of which scaling with the inverse of the aquifer diffusivity (T/S). In the second part of the paper, dimensionless type-curves are presented to enable rapid evaluation of the time where a given drawdown is observed at a given distance from the tunnel. Accounting for tunnel geometry (radius and depth) and aquifer parametres (T and S), these curves could for instance help in practice to determine when surface waters would start to be affected by a draining tunnel underneath. Although neglecting the boundary effects discussed in the first part of the paper, these type-curves demonstrate the great inertia of mountain aquifers, and could be used to adjust the duration of surface monitoring campaigns according to the specific tunnel/aquifer settings.

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