scholarly journals Quantitative characterization reveals three types of dry-sensitive corneal afferents: pattern of discharge, receptive field, and thermal and chemical sensitivity

2012 ◽  
Vol 108 (9) ◽  
pp. 2481-2493 ◽  
Author(s):  
Harumitsu Hirata ◽  
Nathan Fried ◽  
Michael L. Oshinsky
Keyword(s):  
Receptive Fields ◽  
High Sensitivity ◽  
Stimulus Onset ◽  
High Threshold ◽  
Heat Sensitivity ◽  
Noxious Heat ◽  
External Temperature ◽  
Wide Range ◽  
Highly Correlated ◽  
Discharge Patterns

This study reveals that the cold-sensitive (CS) + dry-sensitive (DS) corneal afferents reported in a previous study consist of two types: 1) low threshold (LT)-CS + DS neurons with <1°C cooling sensitivity, and 2) high threshold (HT)-CS + DS neurons with a wide range of cooling sensitivities (∼1–10°C cooling). We also found DS neurons with no cooling sensitivity down to 19°C [cold-insensitive (CI) + DS neurons]. LT-CS + DS neurons showed highly irregular discharge patterns during the dry cornea characterized by numerous spiking bursts, reflecting small temperature changes in the cornea. Their receptive fields (RFs) were mainly located in the cornea's center, the first place for tears to ebb from the surface and be susceptible to external temperature fluctuations. HT-CS and CI + DS neurons showed a gradual rise in firing rate to a stable level over ∼60 s after the dry stimulus onset. Their RFs were located mostly in the cornea's periphery, the last place for tears to evaporate. The exquisite sensitivity to cooling in LT-CS + DS neurons was highly correlated with heat sensitivity (∼45°C). There was a perfect correlation between noxious heat sensitivity and capsaicin responsiveness in each neuron type. The high sensitivity to noxious osmotic stress was a defining property of the HT-CS and CI + DS neurons, while high sensitivity to menthol was a major characteristic of the LT-CS + DS neurons. These observations suggest that three types of DS neurons serve different innocuous and nociceptive functions related to corneal dryness.

Responses of primate spinothalamic neurons to graded and to repeated noxious heat stimuli

1979 ◽  
Vol 42 (5) ◽  
pp. 1370-1389 ◽  
Author(s):  
D. R. Kenshalo ◽  
R. B. Leonard ◽  
J. M. Chung ◽  
W. D. Willis
Keyword(s):  
Skin Temperature ◽  
Power Function ◽  
Dynamic Range ◽  
Background Activity ◽  
Receptive Fields ◽  
Peak Frequency ◽  
High Threshold ◽  
Wide Dynamic Range ◽  
Noxious Heat ◽  
Thermal Stimuli

1. The responses of primate spinothalamic tract cells innervating the glabrous skin of the foot to noxious thermal stimuli have been examined. 2. Of the 41 cells studied, 98% responded to noxious thermal stimuli. Heating the cutaneous receptive field with a series of stimuli from 35 to 43, 47, and 50 degrees C produced a graded increase in discharge rate. The responses were characterized by an onset, which occurred after the temperature change had either slowed or stopped, an acceleration in the discharge up to a peak, and then an adaptation to a new base-line level. The time constants of adaptation were faster than those reported for C polymodal nociceptors. 3. No systematic differences were found in the responses to noxious thermal stimuli of cells with wide dynamic range receptive fields and of cells with narrow dynamic range, high-threshold receptive fields. There were also no differences in the responses of cells located in the marginal zone and of cells located in the neck of the dorsal horn. 4. The relationship between peak frequency and final skin temperature with a 30 s stimulus duration can best be described by a power function with an exponent of 2.1. An increase in the stimulus duration to 120 s resulted in an increase in the exponent of the power function to 3.2. 5. Repetition of the series of 30-s heat stimuli resulted in an increase in peak frequency, total impulse count, and background activity. Repetition of stimuli having a duration of 120 s produced an increase in the peak frequency at 43 and 45 degrees C, a smaller increase at 47 degrees C, and a decrease at 50 degrees C. Background activity was increased by the lower temperature stimuli, but was decreased following higher temperature stimuli. 6. In six additional cells, the skin was heated with three consecutive presentations at each temperature level (43, 45, 47, and 50 degrees C) for 30 s. No change was observed in the peak frequencies of the responses to successive stimuli of the same intensity. However, the exponent of the power function relating the average peak frequency for the six cells to changes in skin temperature was 3.9. This exponent was larger than that seen when two series of graded heat stimuli of 120 s duration were used, indicating more sensitization despite the fact the total time of exposure to noxious heat was less. 7. A role for both high-threshold and wide dynamic range spinothalamic cells in transmitting nociceptive information to the diencephalon is postulated.

Patterns of responses of neurons in cuneate nucleus to controlled mechanical stimulation of cutaneous velocity receptors in the cat

1980 ◽  
Vol 43 (6) ◽  
pp. 1673-1699 ◽  
Author(s):  
V. Golovchinsky
Keyword(s):  
Receptive Field ◽  
Mechanical Stimulation ◽  
Receptive Fields ◽  
Neuronal Firing ◽  
High Threshold ◽  
Pacinian Corpuscles ◽  
Sharp Separation ◽  
First Order ◽  
Discharge Patterns ◽  
Stimulation Of

1. The responses of single cuneate neurons to controled mechanical stimulation of skin were recorded in cats lightly anesthetized with a nitrous oxide-halothane mixture. The discharge patterns and peripheral receptive-field characteristics were studied in neurons driven by sensitive cutaneous mechanoreceptors, including slowly adapting skin mechanoreceptors. Virtually all cuneate neurons display maximum discharge during the velocity component of displacement. 2. Among cuneate neurons encountered in this study, approximately 46% were driven by guard hair mechanoreceptors, 15% were driven by field receptors, and 13% were driven by slowly adapting skin receptors. Neurons responding to stimulation of deep tissues (including claws) were not studied with controlled mechanical stimulation and accounted for 19%. The rest of the neurons were driven by Pacinian corpuscles, received afferent inputs from several different first-order afferents, or were not definitely identified. There was no clear evidence of down hair or high-threshold mechanoreceptor representation. 3. The discharge pattern in response to a constant-velocity stimulus proved most valuable in describing submodality classes of neurons driven by hair and field receptors since sensitivity of these neurons to dynamic and to static phases of stimulation constitute respective continua and, thus, preclude sharp separation into distinct groups. 4. The majority of neurons displayed response properties and receptive fields similar to those of first-order afferents. A minority of cells had receptive fields that were larger than those of primary afferents, with nearly identical modality and velocity characteristics throughout the receptive field. 5. Approximately 2% of recorded neurons displayed convergent properties not encountered in first-order afferents, including neurons driven from receptors of different modalities or from discontinuous receptive fields. 6. Inhibition of neuronal firing generated from outside the receptive field was rarely seen, possibly due to anesthetic conditions. In a small number of neurons, irregularities in the discharge were observed that might indicate inhibitory influences originating from within the receptive field.

Thalamic VPM nucleus in the behaving monkey. II. Response to air-puff stimulation during discrimination and attention tasks

1993 ◽  
Vol 69 (3) ◽  
pp. 753-763 ◽  
Author(s):  
N. Tremblay ◽  
M. C. Bushnell ◽  
G. H. Duncan
Keyword(s):  
Neuronal Response ◽  
Receptive Fields ◽  
Afferent Input ◽  
Systematic Difference ◽  
Field Size ◽  
Noxious Heat ◽  
Discriminative Performance ◽  
The Mean ◽  
Highly Correlated ◽  
Puff Intensity

1. Single-unit activity was recorded in the ventral posterior medial (VPM) thalamic nucleus of awake monkeys while they performed detection and discrimination tasks involving tactile air-puff stimuli presented to the face. Neuronal responsiveness was compared directly with the monkey's discriminative performance. In addition, neuronal activity was compared when the monkey's attention was directed to the air-puff stimulus and when it was directed to a concurrent visual stimulus. 2. Neurons responding to the air-puff stimuli were classified as slowly adapting (SA), rapidly adapting (RA), inhibitory (IN), or multimodal (MM), according to their responses to manual and thermal stimulation, as well as their adaption rates to the air puff. Of 47 neurons responsive to air-puff stimulation and studied extensively in the behavioral task, 14 were classified as RA, 15 as SA, 6 as IN, and 12 as MM. The 12 MM neurons were so classified because, in addition to air puff, they responded to noxious heat, innocuous cooling, or noxious pinch. 3. Neurons from each class had restricted contralateral receptive fields localized within one division of the trigeminal nerve. There was no systematic difference in receptive-field size among groups. 4. A prominent difference in tactile responsiveness of MM neurons was response latency. Although the mean latency for RA, SA, and IN neurons was not significantly different (6.1, 9.1, and 12.2 ms, respectively), the mean latency for MM neurons was significantly longer than that for each of the other neuronal categories (28.8 ms; Ps < 0.001). These data suggest that the excitatory tactile afferent input to MM neurons is different from that to low-threshold neurons. 5. For RA, SA, and MM neurons the frequency of the neuronal discharge evoked by the air-puff stimulation was proportional to the intensity of the air puff. Thus responses of each neuronal class coded air-puff stimulus intensity. 6. The monkeys' ability to detect air-puff stimuli of various intensities was compared with the frequency of neuronal responses to those stimuli. Both the percent success in detecting differences in air-puff intensity and the detection latency were highly correlated with neuronal response frequency. The responses of all three excitatory neuronal categories corresponded well with the monkey's performance. Thus any or all of RA, SA, and MM neurons could play a role in the discrimination of air-puff intensities.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Optimal delineation of single C-tactile and C-nociceptive afferents in humans by latency slowing

2017 ◽  
Vol 117 (4) ◽  
pp. 1608-1614 ◽  
Author(s):  
Roger H. Watkins ◽  
Johan Wessberg ◽  
Helena Backlund Wasling ◽  
James P. Dunham ◽  
Håkan Olausson ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Receptive Field ◽  
Mechanical Stimulation ◽  
Receptive Fields ◽  
High Threshold ◽  
Field Stimulation ◽  
Affective Touch ◽  
Wide Range ◽  
Low Threshold ◽  
Repetitive Electrical Stimulation

C-mechanoreceptors in humans comprise a population of unmyelinated afferents exhibiting a wide range of mechanical sensitivities. C-mechanoreceptors are putatively divided into those signaling gentle touch (C-tactile afferents, CTs) and nociception (C-mechanosensitive nociceptors, CMs), giving rise to positive and negative affect, respectively. We sought to distinguish, compare, and contrast the properties of a population of human C-mechanoreceptors to see how fundamental the divisions between these putative subpopulations are. We used microneurography to record from individual afferents in humans and applied electrical and mechanical stimulation to their receptive fields. We show that C-mechanoreceptors can be distinguished unequivocally into two putative populations, comprising CTs and CMs, by electrically evoked spike latency changes (slowing). After both natural mechanical stimulation and repetitive electrical stimulation there was markedly less latency slowing in CTs compared with CMs. Electrical receptive field stimulation, which bypasses the receptor end organ, was most effective in classifying C-mechanoreceptors, as responses to mechanical receptive field stimulation overlapped somewhat, which may lead to misclassification. Furthermore, we report a subclass of low-threshold CM responding to gentle mechanical stimulation and a potential subclass of CT afferent displaying burst firing. We show that substantial differences exist in the mechanisms governing axonal conduction between CTs and CMs. We provide clear electrophysiological “signatures” (extent of latency slowing) that can be used in unequivocally identifying populations of C-mechanoreceptors in single-unit and multiunit microneurography studies and in translational animal research into affective touch. Additionally, these differential mechanisms may be pharmacologically targetable for separate modulation of positive and negative affective touch information. NEW & NOTEWORTHY Human skin encodes a plethora of touch interactions, and affective tactile information is primarily signaled by slowly conducting C-mechanoreceptive afferents. We show that electrical stimulation of low-threshold C-tactile afferents produces markedly different patterns of activity compared with high-threshold C-mechanoreceptive nociceptors, although the populations overlap in their responses to mechanical stimulation. This fundamental distinction demonstrates a divergence in affective touch signaling from the first stage of sensory processing, having implications for the processing of interpersonal touch.

scholarly journals Hypersonic Aerodynamic Force Balance Using Micromachined All-Fiber Fabry–Pérot Interferometric Strain Gauges

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 316 ◽  
Author(s):  
Huacheng Qiu ◽  
Fu Min ◽  
Yanguang Yang ◽  
Zengling Ran ◽  
Jinxin Duan
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Force ◽  
High Sensitivity ◽  
Force Balance ◽  
Strain Gauges ◽  
External Temperature ◽  
Thermal Output ◽  
Hypersonic Wind Tunnel ◽  
Wide Range ◽  
Fabry Perot

This paper presents high-sensitivity, micromachined all-fiber Fabry–Pérot interferometric (FFPI) strain gauges and their integration in a force balance for hypersonic aerodynamic measurements. The FFPI strain gauge has a short Fabry–Pérot cavity fabricated using an excimer laser etching process, and the deformation of the cavity is detected by a white-light optical phase demodulator. A three-component force balance, using the proposed FFPI gauges as sensing elements, was fabricated, calibrated, and experimentally evaluated. To reduce thermal output of the balance, a simple and effective self-temperature compensation solution, without external temperature sensors, is proposed and examined through both oven heating and wind tunnel runs. As a result of this approach, researchers are able to use the balance continuously throughout a wide range of temperatures. During preliminary testing in a hypersonic wind tunnel with a free stream Mach number of 12, the measurement accuracies of the balance were clearly improved after applying the temperature self-compensation.

Stimulus-Related Gamma Oscillations in Primate Auditory Cortex

2002 ◽  
Vol 87 (6) ◽  
pp. 2715-2725 ◽  
Author(s):  
Michael Brosch ◽  
Eike Budinger ◽  
Henning Scheich
Keyword(s):  
Auditory Cortex ◽  
Receptive Fields ◽  
Stimulus Frequency ◽  
Gamma Oscillations ◽  
Stimulus Onset ◽  
Spatial Distance ◽  
Field Potentials ◽  
Wide Range ◽  
Auditory Field ◽  
Multielectrode System

With a multielectrode system, we explored neuronal activity in the γ range (>40 Hz) in the primary and caudomedial auditory cortex of six anesthetized macaque monkeys. Stimuli were tone bursts of 100- to 500-ms duration that were presented at sound pressure levels of 40–60 dB and were varied over a wide range of frequencies. These stimuli induced γ oscillations, not phase-locked to the onset of stimulation, in 465 of 616 multiunit clusters and at 321 of 422 sites at which field potentials were recorded. Occurrence of γ activity was stimulus dependent. It was mostly seen when the stimulus was at the units' preferred frequency. The incidence of γ activity decreased with increasing difference between stimulus frequency and preferred frequency. γ activity emerged 100–900 ms after stimulus onset with highest incidence ∼120 ms. Amplitudes of stimulus-induced γ oscillations in field potentials were, on average, almost twice the amplitude of spontaneously occurring γ oscillations. γ activity at different sites within the primary and the caudomedial auditory field could be synchronized at near-zero phase. Synchrony depended on the spatial distance and on the receptive fields similarity of pairs of units. It decreased with increasing distance between recording sites and increased with similarity of preferred frequencies of the pairs of units. The results indicate that stimulus-induced γ oscillations originate from sources in the auditory cortex. They further suggest that γ oscillations may provide a mechanism utilized in many parts of the sensory cortex, including the auditory cortex, to integrate neurons according to the similarity of their receptive fields.

scholarly journals Gold–Carbon Nanocomposites for Environmental Contaminant Sensing

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 719
Author(s):  
Shahrooz Rahmati ◽  
William Doherty ◽  
Arman Amani Babadi ◽  
Muhamad Syamim Akmal Che Mansor ◽  
Nurhidayatullaili Muhd Julkapli ◽  
...  
Keyword(s):  
Environmental Pollutants ◽  
High Sensitivity ◽  
Environmental Crisis ◽  
World Population ◽  
Chemical Contaminants ◽  
Carbon Nanocomposites ◽  
Minimal Sample ◽  
Wide Range ◽  
And Control ◽  
Analytical Tools

The environmental crisis, due to the rapid growth of the world population and globalisation, is a serious concern of this century. Nanoscience and nanotechnology play an important role in addressing a wide range of environmental issues with innovative and successful solutions. Identification and control of emerging chemical contaminants have received substantial interest in recent years. As a result, there is a need for reliable and rapid analytical tools capable of performing sample analysis with high sensitivity, broad selectivity, desired stability, and minimal sample handling for the detection, degradation, and removal of hazardous contaminants. In this review, various gold–carbon nanocomposites-based sensors/biosensors that have been developed thus far are explored. The electrochemical platforms, synthesis, diverse applications, and effective monitoring of environmental pollutants are investigated comparatively.

scholarly journals Pulsed Electromagnetic Cross-Well Exploration for Monitoring Permafrost and Examining the Processes of Its Geocryological Changes

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 60
Author(s):  
Viacheslav Glinskikh ◽  
Oleg Nechaev ◽  
Igor Mikhaylov ◽  
Kirill Danilovskiy ◽  
Vladimir Olenchenko
Keyword(s):  
High Performance ◽  
Geophysical Methods ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Data Interpretation ◽  
Industrial Facilities ◽  
Wide Range ◽  
Vector Finite Element ◽  
A New Technique ◽  
Pulsed Electromagnetic

This paper is dedicated to the topical problem of examining permafrost’s state and the processes of its geocryological changes by means of geophysical methods. To monitor the cryolithozone, we proposed and scientifically substantiated a new technique of pulsed electromagnetic cross-well sounding. Based on the vector finite-element method, we created a mathematical model of the cross-well sounding process with a pulsed source in a three-dimensional spatially heterogeneous medium. A high-performance parallel computing algorithm was developed and verified. Through realistic geoelectric models of permafrost with a talik under a highway, constructed following the results of electrotomography field data interpretation, we numerically simulated the pulsed sounding on the computing resources of the Siberian Supercomputer Center of SB RAS. The simulation results suggest the proposed system of pulsed electromagnetic cross-well monitoring to be characterized by a high sensitivity to the presence and dimensions of the talik. The devised approach can be oriented to addressing a wide range of issues related to monitoring permafrost rocks under civil and industrial facilities, buildings, and constructions.

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