Somatotopic organization of hindlimb cutaneous dorsal root projections to cat dorsal horn.

Brown, Paul B.; Culberson, James L.

doi:10.1152/jn.1981.45.1.137

Cited by 37 publications

(17 citation statements)

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“…They also tabulated degeneration data available at the time and showed that presence of overlap between a dorsal root dermatome and a segmental representation was a good predictor of projection of the dorsal root to the dorsal horn segment. This was con® rmed and extended by the work of Brown and Culberson (1981), who showed not only that rostrocaudal extents of dorsal root projections were consistent with the notion that preand postsynaptic somatotopy are in register, but also that the relative mediolateral positions of the rostral extension of the S 1 projection and the caudal extension of the L 5 projection were best explained in terms of presynaptic somatotopy. Brown (1980, 1982) extended these observations to the level of single cutaneous nerves, showing that pairs of nerves had relative mediolateral and rostrocaudal positions predictable on the basis of presynaptic somatotopy, and degrees of separation or overlap which matched their innervation ® elds' separation or overlap.…”

Section: Lines Of Evidencesupporting

confidence: 58%

“…The sizes and shapes of dorsal horn cell RFs vary as a function of RF location, and therefore as a function of cell location in the map (Brown et al, 1975). RFs are smallest on the toes, increasing rapidly in area up to the distal calf, and remaining constant or declining slightly at more proximal locations.…”

Section: Somatotopic Gradients and Geometries Of Dorsal Horn Cell Rfsmentioning

confidence: 99%

“…The limited evidence available (e.g., P.B. Brown et al, 1975;A.G. Brown et al, 1987a± c) indicates that within the low threshold excitatory RFs of dorsal horn cells there are no major portions of the RF which are devoid of monosynaptic connections.…”

Section: As a Consequence Of These Developmental Processes The Shapementioning

confidence: 99%

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Assembly of the dorsal horn somatotopic map

Koerber

Millecchia

1997

Somatosensory & Motor Research

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We hypothesize: (a) peripheral innervation densities determine map scales in dorsal horn, (b) dorsal horn cell (DHC) receptive field (RF) geometries are determined by map scales, and (c) morphologies of primary afferents (PAs) and DHCs reflect their developmental history. We suggest the following sequence: (A) PAs project in a somatotopic mediolateral sequence. (B) DHCs assemble prototype RFs by sampling presynaptic neuropil with their dendrites. (C) PAs then project to all levels where their RFs are contained within prototype RFs of DHCs. (D) A competitive mechanism produces the adult form of DHC RFs. (E) Adult distributions of PA terminals and DHC dendrites reflect this developmental history. (F) Mediolateral somatotopic gradients are determined by RF densities of axons entering at the same levels. (G) Map scales at different rostrocaudal levels are determined by somatotopic gradients. (H) Geometries of DHC RFs are determined by constant convergence and divergence of monosynaptic connections. (I) Secondary processes further modify geometries of DHC RFs. (J) Residual self-organizing capacity supports maintenance and plastic mechanisms. We adduce the following evidence: (1) agreement between monosynaptically coupled inputs and cells' excitatory low threshold mechanoreceptive fields; (2) the temporal sequence of events during penetration of the gray matter by PAs; (3)variation of PA terminal and DHC dendritic domains as a function of map scale; (4) somatotopic gradients and geometries of DHC RFs in adult dorsal horn; (5) calculations of peripheral innervation densities and dorsal horn map scales; and (6) constant divergence and convergence between PAs and DHCs.

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Section: Lines Of Evidencesupporting

confidence: 58%

Section: Somatotopic Gradients and Geometries Of Dorsal Horn Cell Rfsmentioning

confidence: 99%

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Assembly of the dorsal horn somatotopic map

Koerber

Millecchia

1997

Somatosensory & Motor Research

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“…There is ample anatomical evidence demonstrating that primary afferent fibres entering the spinal cord synapse in the dorsal horn at other spinal levels (Wall & Werman, 1976;Brown & Culberson, 1981). In cats, fibres entering the dorsal horn in the lower cervical regions can spread fourteen spinal segments (Imai & Kusama, 1969).…”

Section: Discussionmentioning

confidence: 99%

“…Mechanically sensitive afferent fibres from muscle can be excited by passive muscle stretch, eliciting a rise in blood pressure and heart rate with little or no stimulation of the metabolically sensitive afferents (Kaufman & Rybicki, 1987;Stebbins, Brown, Levin & Longhurst, 1988 (Wilson, Wall, Matsukawa & Mitchell, 1992 (Spague & Ha, 1964;Imai & Kusama, 1969;Wall & Werman, 1976;Brown & Culberson, 1981;McNeil, Westlund & Coggeshall, 1989). In addition, we have shown that NMDA receptors in levels of the spinal cord adjacent to the L7 region are involved in the pressor response to muscle contraction and stretch (Hand et al 1996).…”

Section: Introductionmentioning

confidence: 90%

Microdialysis of a non‐NMDA receptor antagonist into the L7 dorsal horn attenuates the pressor response to static muscle contraction but not passive stretch in cats

Hand

Ga²,

Wilson³

1996

Experimental Physiology

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SUMMARYMean arterial pressure (MAP) and heart rate (HR) were measured during static contraction or passive stretch of the triceps surae muscle of chloralose-anaesthetized cats. MAP and HR increased by 46 + 5 mmHg and 17 + 3 beats min-', respectively, during a 1 min contraction.Passive stretch of the same muscle for 1 min reflexly increased MAP and HR by 40 + 7 mmHg and 14 + 3 beats minm , respectively. Microdialysis of 2 mm 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA receptor antagonist, into the dorsal horn at the L7 spinal level attenuated the reflex pressor response to static contraction (2 h of dialysis: AMAP = 23 + 5 mmHg, AHR = 8 + 2 beats min-'). By contrast, there was no attenuation of the pressor response to passive stretch at 2 h of CNQX perfusion. However, the simultaneous microdialysis of 2 mM CNQX into the L6 and S 1 levels blunted the pressor and tachycardic responses to contraction and stretch. These data show that the reflex pressor response to static muscle contraction is partly mediated by activation of non-NMDA receptors at the level of afferent fibre entry into the dorsal horn and through collateral pathways. Further, it appears that the afferent pathways within the dorsal horn for the signal transduction arising from static muscle contraction and passive stretch of the hindlimb are dissimilar.

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Variation of dorsal horn cell dendritic spread with map scale

et al. 1996

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Cells in laminae III, IV, and V of cat dorsal horn were injected with horseradish peroxidase or neurobiotin. Dorsal views of the dendritic domains were constructed in order to measure their lengths, widths, areas, and length/width ratios in the horizontal plane (the plane of the somatotopic map). Dendritic domain width and area in the horizontal plane were negatively correlated with fractional distance between the medial and lateral edges of the dorsal horn. These results are consistent with the hypothesis that dendritic domain width varies with map scale, which is maximal in the medial dorsal horn. This is similar to the variation in widths of primary afferent bouton distributions. The parallel variation of dorsal horn cell dendritic domain width and primary afferent bouton distribution width with map scale suggests that there is a causal relation between morphology and map scale in the dorsal horn representation of the hindlimb. This variation of adult morphology with map scale must reflect mechanisms responsible for the assembly of receptive fields.

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Somatotopic organization of hindlimb cutaneous dorsal root projections to cat dorsal horn.

Cited by 37 publications

References 0 publications

Assembly of the dorsal horn somatotopic map

Assembly of the dorsal horn somatotopic map

Microdialysis of a non‐NMDA receptor antagonist into the L7 dorsal horn attenuates the pressor response to static muscle contraction but not passive stretch in cats

Variation of dorsal horn cell dendritic spread with map scale

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