Dorsal Horn Spatial Representation of Simple Cutaneous Stimuli

1998 ◽  
Vol 79 (2) ◽  
pp. 983-998 ◽  
Author(s):  
Paul B. Brown ◽  
Ronald Millecchia ◽  
Jeffrey J. Lawson ◽  
Stephanie Stephens ◽  
Paul Harton ◽  
...  
Keyword(s):  
Dorsal Horn ◽  
Spatial Representation ◽  
Single Point ◽  
Receptive Fields ◽  
Width Ratio ◽  
Contour Plots ◽  
Somatotopic Map ◽  
Length Width ◽  
Stimulus Features ◽  
Segmental Representations

Brown, Paul B., Ronald Millecchia, Jeffrey J. Lawson, Stephanie Stephens, Paul Harton, and James C. Culberson. Dorsal horn spatial representation of simple cutaneous stimuli. J. Neurophysiol. 79: 983–998, 1998. A model of lamina III–IV dorsal horn cell receptive fields (RFs) has been developed to visualize the spatial patterns of cells activated by light touch stimuli. Low-threshold mechanoreceptive fields (RFs) of 551 dorsal horn neurons recorded in anesthetized cats were characterized by location of RF center in cylindrical coordinates, area, length/width ratio, and orientation of long axis. Best-fitting ellipses overlapped actual RFs by 90%. Exponentially smoothed mean and variance surfaces were estimated for these five variables, on a grid of 40 points mediolaterally by 20/segment rostrocaudally in dorsal horn segments L4–S1. The variations of model RF location, area, and length/width ratio with map location were all similar to previous observations. When elliptical RFs were simulated at the locations of the original cells, the RFs of real and simulated cells overlapped by 64%. The densities of cell representations of skin points on the hindlimb were represented as pseudocolor contour plots on dorsal view maps, and segmental representations were plotted on the standard views of the leg. Overlap of modeled and real segmental representations was at the 84% level. Simulated and observed RFs had similar relations between area and length/width ratio and location on the hindlimb: r( A) = 0.52; r( L/ W) = 0.56. Although the representation of simple stimuli was orderly, and there was clearly only one somatotopic map of the skin, the representation of a single point often was not a single cluster of active neurons. When two-point stimuli were simulated, there usually was no fractionation of response zones or addition of new zones. Variation of stimulus size (area of skin contacted) produced less variation of representation size (number of cells responding) than movement of stimuli from one location to another. We conclude that stimulus features are preserved poorly in their dorsal horn spatial representation and that discrimination mechanisms that depend on detection of such features in the spatial representation would be unreliable.

Quantitative analysis of dorsal horn cell receptive fields following limited deafferentation

1995 ◽  
Vol 74 (5) ◽  
pp. 2065-2076 ◽  
Author(s):  
H. R. Koerber ◽  
P. B. Brown
Keyword(s):  
Dorsal Horn ◽  
Receptive Fields ◽  
Afferent Input ◽  
Width Ratio ◽  
Survival Times ◽  
Long Survival ◽  
Dorsal Horns ◽  
Length Width ◽  
Low Threshold ◽  
And Control

1. To test the hypothesis that subtotal deafferentation of dorsal horn cells can stimulate plastic changes in their receptive fields (RFs), diffuse deafferentation of the cat hindlimb dorsal horn was produced by transection of L7 or L6 and L7 dorsal roots. The following single-unit cutaneous low-threshold mechanoreceptor RF properties were compared between operated and control dorsal horns: 1) distance of RF center from tips of toes, 2) RF length-width ratio; and 3) RF area. 2. In both L7 and L6-L7 rhizotomized animals there was an increased incidence of silent electrode tracks in the most deafferented portion of the hindlimb map (the foot and toe representation). In the rhizotomized L6-L7 animals, there was also an increased incidence of symmetrically placed tracks in deafferented and control dorsal horns, in which cell RFs had no mirror-symmetrical components. In addition, cells in the lateral half of the L6 and L7 dorsal horns exhibited a proximal shift in the location of their RFs. In the rhizotomized L7 animals there was a distal shift of RFs in the L5 segment at long survival times. RFs had lower length-width ratios in L5 and L6 at short survival times and in L6 at long survival times. 3. In intact preparations, dorsal horn cells normally respond to inputs via single or small numbers of low-threshold cutaneous mechanoreceptors. Because these rhizotomies do not remove all inputs from any given area of skin, the deafferentations would produce only patchy loss of input from individual receptors. Therefore observed changes cannot be accounted for entirely by loss of afferent input, suggesting that some reorganization of dorsal horn cell RFs occurred. We conclude that the threshold stimulus for plastic change is less than total deafferentation of dorsal horn cells. At least some of the mechanisms underlying these changes may be active in normal animals in the maintenance of the somatotopic map or in conditioning.

Parametric studies of dorsal horn neurons responding to tactile stimulation

1975 ◽  
Vol 38 (1) ◽  
pp. 19-25 ◽  
Author(s):  
P. B. Brown ◽  
J. L. Fuchs ◽  
D. N. Tapper
Keyword(s):  
Dorsal Horn ◽  
Discharge Rate ◽  
Spontaneous Discharge ◽  
Width Ratio ◽  
Size And Shape ◽  
Dorsal Horn Neurons ◽  
Tactile Input ◽  
Somatotopic Map ◽  
Length Width ◽  
Central Delay

Dorsal horn neurons responding to tactile input were recorded in segments L3-S2 of unanesthetized, low-spinal cats. Single units were characterized with regard to receptive field (RF) location, RF size and shape, spontaneous discharge rate, central delay, and convergence of four tactile afferent types. 1. RF size increased from the toes to the calf region. 2. Length-width ratio increased from the toes to the calf and declined from the calf to the hip. 3. The relation between RF size and position on the limb was independent of segmental and laminar location of the neurons. 4. RF size was positively correlated with spontaneous discharge rate. 5. The relation between RF size and shape and RF position can be interpreted in terms of regional variations in the magnitude of the gradient of representation in the dorsal horn somatotopic map. 6. Central delay was negatively correlated with both RF size and rate of ongoing discharge. 7. There were no statistically significant differences among the laminae with respect to central delay, RF size or shape, ongoing discharge, or convergence combinations of the four tactile afferent systems. 8. Data presented were at variance with Wall's laminar cascading model for laminae IV-VI. Our results suggest that the model should be modified, at least to emphasize monosynaptic tactile input to all three of these laminae.

Influence of map scale on primary afferent terminal field geometry in cat dorsal horn

1991 ◽  
Vol 66 (3) ◽  
pp. 696-704 ◽  
Author(s):  
R. J. Millecchia ◽  
L. M. Pubols ◽  
R. V. Sonty ◽  
J. L. Culberson ◽  
W. E. Gladfelter ◽  
...  
Keyword(s):  
Dorsal Horn ◽  
Receptive Fields ◽  
Primary Afferent ◽  
Afferent Terminal ◽  
Absolute Requirement ◽  
Primary Afferent Fibers ◽  
Somatotopic Map ◽  
Field Geometry ◽  
Map Scale ◽  
Primary Afferent Terminal

1. Thirty-one physiologically identified primary afferent fibers were labeled intracellularly with horseradish peroxidase (HRP). 2. A computer analysis was used to determine whether the distribution of cutaneous mechanoreceptive afferent terminals varies as a function of location within the dorsal horn somatotopic map. 3. An analysis of the geometry of the projections of these afferents has shown that 1) terminal arbors have a greater mediolateral width within the region of the foot representation than lateral to it, 2) terminal arbors have larger length-to-width ratios outside the foot representation than within it, and 3) the orientation of terminal arbors near the boundary of the foot representation reflects the angle of the boundary. Previous attribution of mediolateral width variations to primary afferent type are probably in error, although there appear to be genuine variations of longitudinal extent as a function of primary afferent type. 4. Nonuniform terminal distributions represent the first of a three-component process underlying assembly of the monosynaptic portions of cell receptive fields (RFs) and the somatotopic map. The other two components consist of the elaboration of cell dendritic trees and the establishment of selective connections. 5. The variation of primary afferent terminal distributions with map location is not an absolute requirement for development of the map; for example, the RFs of postsynaptic cells could be assembled with the use of a uniform terminal distribution for all afferents, everywhere in the map, as long as cell dendrites penetrate the appropriate portions of the presynaptic neuropil and receive connections only from afferent axons contributing to their RFs.(ABSTRACT TRUNCATED AT 250 WORDS)

Organization and receptive fields of primate spinothalamic tract neurons

1975 ◽  
Vol 38 (3) ◽  
pp. 572-586 ◽  
Author(s):  
A. E. Applebaum ◽  
J. E. Beall ◽  
R. D. Foreman ◽  
W. D. Willis
Keyword(s):  
Receptive Field ◽  
Receptive Fields ◽  
Ventral Surface ◽  
Field Size ◽  
Width Ratio ◽  
High Threshold ◽  
Spinothalamic Tract ◽  
Dorsal Funiculus ◽  
Length Width ◽  
Low Threshold

A technique is described for recording from axons belonging to the spinothalamic tract of the monkey. The axons arose from cell bodies located within the spinal cord since the latency of orthodromic activation by afferents within the dorsal funiculus was short. The axons were antidromically activated from the ipsilateral diencephalon. The spectrum of conduction velocities indicates that the recordings favored large-diamter axons. However, all of the classes of spinothalamic tract units described from soma-dendritic recordings were represented in the sample. When the locations of the axons in the ventrolateral white matter were mapped, there was virtually complete overlap in the distributions of hair-activated, low-, and high-threshold spinothalamic tract axons, suggesting that the "lateral spinothalamic tract" conveys tactile, as well as pain and temperature, information. The only segregated population of axons were those belonging to units activated by receptors in deep tissues, including muscle. These were in a band along the ventral surface of the cord. The stimulus points for antidromically activating spinothalamic cells of axons were in the known diencephalic course of the spinothalamic tract, including the ventral posterior lateral nucleus. Stimulus point locations were similar for high-threshold and other categories of units. Receptive-field sizes were smaller for high-threshold spinothalamic cells or axons than for hair-activated or low-threshold units. Receptive-field size was correlated with position on the hindlimb. The smallest fields belonged to cells in lamina I, with progressively larger sizes for cells in laminae IV and V. Receptive-field shape was evaluated by the length/width ratio, which was smallest for high-threshold units and progressively larger for low-threshold and hair-activated units. The receptive-field positions of spinothalamic tract axons were related to the locations of the axons. There was a rough somatotopic representation in the tract, with the most caudal dermatomes represented dorsolaterally, and the most rostral ventromedially.

The detailed somatotopic organization of the dorsal horn in the lumbosacral enlargement of the cat spinal cord

1986 ◽  
Vol 55 (3) ◽  
pp. 604-617 ◽  
Author(s):  
P. Wilson ◽  
D. E. Meyers ◽  
P. J. Snow
Keyword(s):  
Dorsal Horn ◽  
Receptive Fields ◽  
Glabrous Skin ◽  
Lateral Part ◽  
Depth Range ◽  
Dorsal Horn Neurons ◽  
Somatotopic Organization ◽  
Line Of Discontinuity ◽  
Somatotopic Map ◽  
Alpha Chloralose

The somatotopic organization of spinocervical tract cells and unidentified dorsal horn neurons that lie in the same depth range as the spinocervical tract cells has been examined in detail in the lumbosacral enlargement of cats anesthetized with alpha-chloralose. Only gentle hair movement or light touch of glabrous skin were used as stimuli. Within the region of the dorsal horn containing these neurons there is a precise somatotopic organization. However, there is considerable variation between animals in the relationship between the somatotopic map and the lumbosacral segmental boundaries. The somatotopic map described here is considered to be restricted to a 300- to 500-micron thick lamina. In the medial half to two-thirds of this lamina in the L6 and L7 segments the toes are represented in a rostrocaudal sequence from toe 2 to toe 5. Over the most medial 200-500 micron of this part of the dorsal horn are found cells that respond to stimulation of the glabrous skin of the toe pads and the central pad. The toe representation is surrounded by a strip of foot representation, which is in turn surrounded by a strip of leg representation. The most lateral part of the lamina curves ventrally in the L6 and L7 segments and contains a continuous rostrocaudal representation of the skin of the thigh. In this region are found both spinocervical tract cells and unidentified dorsal horn neurons with receptive fields on the thigh. The skin of the hindlimb is represented such that a line of discontinuity runs down the posteromedial thigh, leg, and foot. Skin lateral to this line is represented caudally, while skin medial to it is represented rostrally.

Cross-correlation analysis of connectivities among cat lumbosacral dorsal horn cells

1979 ◽  
Vol 42 (5) ◽  
pp. 1199-1211 ◽  
Author(s):  
P. B. Brown ◽  
H. R. Koerber ◽  
R. P. Yezierski
Keyword(s):  
Correlation Analysis ◽  
Dorsal Horn ◽  
Cross Correlation ◽  
Receptive Fields ◽  
Base Line ◽  
Causal Relations ◽  
Cell Pair ◽  
Dorsal Horns ◽  
Cross Correlation Analysis ◽  
Somatotopic Map

1. Eighty-three cell pairs were recorded in dorsal horns of 19 cats. Cross-correlograms were flat in 65 cell pairs; of the remaining 18 pairs, cross-correlograms had broad peaks or troughs suggestive of nonmonosynaptic causal relations in their discharges; one cell pair had a biphasic deviation from base line. 2. No cross-correlograms indicative of monosynaptic interactions were observed. 3. All cell pairs with nonflat cross-correlograms had overlapping receptive fields. 4. It is concluded that monosynaptically connected cell pairs are rare at the interelectrode distances used in this experiment because such cell pairs must lie close together on the somatotopic map or because our recording methods bias against monosynaptically linked cell pairs.

scholarly journals Information diversity in individual auditory cortical neurons is associated with functionally distinct coordinated neuronal ensembles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jermyn Z. See ◽  
Natsumi Y. Homma ◽  
Craig A. Atencio ◽  
Vikaas S. Sohal ◽  
Christoph E. Schreiner
Keyword(s):  
Cortical Neurons ◽  
Single Neuron ◽  
Receptive Fields ◽  
Acoustic Feature ◽  
Neuronal Ensembles ◽  
Neuron Spike ◽  
Information Diversity ◽  
Feature Selectivity ◽  
Stimulus Features ◽  
Time Specific

AbstractNeuronal activity in auditory cortex is often highly synchronous between neighboring neurons. Such coordinated activity is thought to be crucial for information processing. We determined the functional properties of coordinated neuronal ensembles (cNEs) within primary auditory cortical (AI) columns relative to the contributing neurons. Nearly half of AI cNEs showed robust spectro-temporal receptive fields whereas the remaining cNEs showed little or no acoustic feature selectivity. cNEs can therefore capture either specific, time-locked information of spectro-temporal stimulus features or reflect stimulus-unspecific, less-time specific processing aspects. By contrast, we show that individual neurons can represent both of those aspects through membership in multiple cNEs with either high or absent feature selectivity. These associations produce functionally heterogeneous spikes identifiable by instantaneous association with different cNEs. This demonstrates that single neuron spike trains can sequentially convey multiple aspects that contribute to cortical processing, including stimulus-specific and unspecific information.

scholarly journals Diversity of Pod Shape in Pisum

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 203
Author(s):  
Thomas Henry Noel Ellis ◽  
Julie M. I. Hofer ◽  
Eleni Vikeli ◽  
Michael J. Ambrose ◽  
Paola Higuera-Poveda ◽  
...  
Keyword(s):  
Allelic Variation ◽  
Size Variation ◽  
Width Ratio ◽  
Negative Regulators ◽  
Wide Range ◽  
Yield Determination ◽  
Organ Specific ◽  
Length Width ◽  
End Use ◽  
Pod Length

The seed-containing pod is the defining structure of plants in the legume family, yet pods exhibit a wide range of morphological variation. Within a species pod characters are likely to be correlated with reproductive strategy, and within cultivated forms will correspond to aspects of yield determination and/or end use. Here variation in pod size, described as pod length: pod width ratio, has been analyzed in pea germplasm represented by 597 accessions. This pod size variation is discussed with respect to population structure and to known classical pod morphology mutants. Variability of the pod length: width ratio can be explained by allelic variation at two genetic loci that may correspond to organ-specific negative regulators of growth.

Meshing Method of High Precision FEM in Large Complex Structural Simulations

2012 ◽  
Vol 195-196 ◽  
pp. 701-704
Author(s):  
Yan Hua Xue ◽  
Zhi Guang Wang ◽  
Xiao Hong Li ◽  
Xin Jiang
Keyword(s):  
Finite Element ◽  
Complex Structure ◽  
Width Ratio ◽  
Two Dimensional ◽  
Element Analysis ◽  
Large Complex ◽  
Mesh Density ◽  
Length Width ◽  
Complex Structural ◽  
Dimensional Element

Shing is playing an important role in the large complex structural FEM simulations; it has a direct effect on calculating precision of structural simulations. For increasing the calculation accuracy and analysis accuracy of complex structure, the finite element meshing problems is proposed on the finite element analysis of large complicated structures. The effects caused by element type, mesh density and intergradations on calculating precision are studied and discussed. A research argues that with length-width ratio of 1~2 and length-thickness ration of 1.5~4.5 of two-dimensional rectangular element, the quality of meshing method of two-dimensional element is above normal. As the height of one-dimensional element is equal to the sum of reinforcing rib height of outer panel and half the thickness of panel, more accurate results can be obtained.

Morphogenesis of the silkworm egg

Development ◽  
1976 ◽  
Vol 36 (1) ◽  
pp. 13-18
Author(s):  
J. M. Legay
Keyword(s):  
Ovarian Follicle ◽  
Temporal Organization ◽  
Width Ratio ◽  
Follicle Development ◽  
Ovarian Follicle Development ◽  
Length Width ◽  
Form Stability

Ovarian follicle development, which accompanies morphogenesis of the silkworm egg has three distinct phases: spheric, ellipsoidal and flattened-ellipsoid. Transitions between phases are rapid and form-stability (characterized by length/width ratio) is preserved from the beginning of the ellipsoidal phase. The geometric stability of the follicle-oocyte-ovariole system, the polarity of the egg and the determinism in form changes reveal strikingly coordinated spatial and temporal organization.

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