The dendritic varicosity: a mechanism for electrically isolating the dendrites of cat retinal amacrine cells?

Ellias, Samuel; Stevens, J. R.

doi:10.1016/0006-8993(80)90401-1

Cited by 93 publications

(54 citation statements)

References 11 publications

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“…Equal voltage injections were applied at branch B, and the attenuation factors were calculated by using Eqs. 7 Fig. 4 by computing the voltage that would result from an equal current injection (in contrast to the equal voltage injection of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…A question often posed concerning amacrine cells is whether single dendrites or subdendritic regions may operate independently and serve to parcel the amacrine into functional subunits. Rall (6) has pointed out that a narrowing of processes may augment the synaptic operations upstream from the stricture, and one study (7), emphasizing this concept, has suggested that single varicosities of some amacrine dendrites may form functional subunits.…”

mentioning

confidence: 99%

“…3 without the Bo factor. Beginning with the primary dendrite, one then proceeds to more distal [7] where V = voltage at a point x and Vo = voltage at point of application. Voltage decay towards the soma is determined by V =VO [8] cosh(l/A) + B1 sinh(l/A)' [8 where B1 is as in Eq.…”

mentioning

confidence: 99%

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Electroanatomy of a unique amacrine cell in the rabbit retina.

Miller¹,

Bloomfield²

1983

Proc. Natl. Acad. Sci. U.S.A.

100

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Intracellular electrophysiological recordings were obtained from a specialized class of "starburst" amacrine cells by using an isolated superperfused retina-eyecup preparation of the rabbit. These cells were injected intracellularly with horseradish peroxidase and identified with light microscopy. A computer-controlled image-processing system was used to map and display the three-dimensional dendritic organization and provide information on length and sublaminar distribution of dendritic processes. Starburst amacrines show an unusual dendritic architecture that includes thin intermediate dendritic segments. Analysis with steadystate cable equations suggests that these thin segments may provide electrical isolation of distal processes, raising the possibility that a single dendrite, which lies beyond the thin segment, may constitute a functional subunit of the cell.For nearly a century, silver-staining techniques applied to the vertebrate retina have revealed a rich variety of neuronal cell types that vary in size, density, and form of dendritic branching patterns (1). Variations in morphology such as the overall dendritic spread may relate to differences in receptive field size (2); the sublaminar distribution of dendritic branching among thirdorder neurons also may determine physiological polarity of the cell (ON, OFF, ON-OFF) (3). What about variations in the number of dendrites and the pattern of dendritic architecture? What functional significance can be attributed to the microscopic design of dendrites and dendritic branching? This problem has received comparatively little attention, although a recent analysis of Golgi-stained ganglion cells has appeared (4). The question of dendritic architecture is especially relevant for considerations of amacrine cells because the dendrites of these neurons have both post-and presynaptic anatomy (5). A question often posed concerning amacrine cells is whether single dendrites or subdendritic regions may operate independently and serve to parcel the amacrine into functional subunits. Rall (6) has pointed out that a narrowing of processes may augment the synaptic operations upstream from the stricture, and one study (7), emphasizing this concept, has suggested that single varicosities of some amacrine dendrites may form functional subunits.We have obtained intracellular recordings from a specialized class of amacrine cells that have cell bodies localized on opposing sides of the inner plexiform layer. Both ON and OFF types have been observed. When these cells are stained with intracellularly injected horseradish peroxidase (HRP), they clearly conform to the "starburst" amacrines described previously (8, 9) on the basis of Golgi-stained material. These cells possess an unusual dendritic organization that consists of thin intermediate segments and varicosities confined to the more distal branches. The application of steady-state cable equations suggests that these thin segments serve (i) to promote electrical isolation of dendritic segments distal to the thin segme...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Electroanatomy of a unique amacrine cell in the rabbit retina.

Miller¹,

Bloomfield²

1983

Proc. Natl. Acad. Sci. U.S.A.

100

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“…This interesting cytoarchitecture of pneumotaxic neurons revealed in vivo is in agreement with the reported dendritic morphology of some lPB neurons observed in vitro (Herbert and Bellintani-Guardia, 1995). If such dendritic varicosities could be taken as the sites of synaptic contact as commonly assumed (Ellias and Stevens, 1980;Allen and Hopkins, 1988;Surkis et al, 1996), those pneumotaxic neurons would likely pick up information from nociceptive afferents that travel in parallel with vsc, perhaps by local terminal axonal bifurcation or branches arising from stem axons.…”

Section: Pneumotaxic Neurons Integrate Pain And/or Musculoskeletal Inmentioning

confidence: 99%

Cytoarchitecture of Pneumotaxic Integration of Respiratory and Nonrespiratory Information in the Rat

Song¹,

Yu²,

Poon³

2006

J. Neurosci.

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The "pneumotaxic center" in the Kölliker-Fuse and medial parabrachial nuclei of dorsolateral pons (dl-pons) plays an important role in respiratory phase switching, modulation of respiratory reflex, and rhythmogenesis. Recent electrophysiological and neural tracing data implicate additional pneumotaxic nuclei in (and a broader role for) the dl-pons in integrating respiratory and nonrespiratory information. Here, we examined the cytoarchitecture of the greater pneumotaxic center and its integrating function by using combined extracellular recording and juxtacellular labeling of unit respiratory rhythmic neurons in dl-pons in urethane-anesthetized, vagotomized, paralyzed, and servo-ventilated adult Sprague Dawley rats. Perievent histogram analysis identified four major types of neuronal discharge patterns: inspiratory, expiratory (with three subdivisions), inspiratory-expiratory, and expiratory-inspiratory phase spanning, sometimes with mild tonic background activity. Most recorded neurons were localized in the Kölliker-Fuse and medial parabrachial nuclei, but some were also found in lateral parabrachial nucleus, intertrigeminal nucleus, principal trigeminal sensory nucleus, and supratrigeminal nucleus. The majority of labeled neurons had large and spatially extended dendritic trees that spanned several of these dl-pons subnuclei, often with terminal dendrites ending in the ventral spinocerebellar tract. The distal sections of the primary and higher-order dendrites exhibited rich varicosities, sometimes with dendritic spines. Axons of some labeled neurons were traced all the way to the ventrolateral pons (vl-pons). These findings extend and generalize the classical definition of the pneumotaxic center to include extensive somaticaxonal-dendritic integration of complex descending and ascending respiratory information as well as nociceptive and possibly musculoskeletal and trigeminal information in multiple dl-pons and vl-pons structures in the rat.

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“…It will be of interest to measure axon diameters from preparations immersed in sucrose-supplemented fixatives and compare these with spike conduction velocity (cf., Bishop et al, 1953;Stone and Holländer, 1971;Boycott and Wässle, 1974;Freeman, 1978). Likewise, the space constant of beaded and smoothly contoured neurites are expected to differ (e.g., Ellias and Stevens, 1980). Labeling entire individual cells within populations of specific cell types (see references cited in the Introduction) should facilitate systematic measurements of the diameter and taper of smooth dendrites, and the size and distribution of phenotypically normal beads, across entire retinae.…”

Section: Applicabilitymentioning

confidence: 99%

Moniliform deformation of retinal ganglion cells by formaldehyde‐based fixatives

Stradleigh

Greenberg

Partida

et al. 2015

J of Comparative Neurology

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Protocols for characterizing cellular phenotypes commonly use chemical fixatives to preserve anatomical features, mechanically stabilize tissue, and stop physiological responses. Formaldehyde, diluted in either phosphate-buffered saline or phosphate buffer, has been widely used in studies of neurons, especially in conjunction with dyes and antibodies. However, previous studies have reported that these fixatives induce the formation of bead-like varicosities in the dendrites and axons of brain and spinal cord neurons. We report here that these formaldehyde formulations can induce bead formation in the dendrites and axons of adult rat and rabbit retinal ganglion cells, and that retinal ganglion cells differ from hippocampal, cortical, cerebellar, and spinal cord neurons in that bead formation is not blocked by glutamate receptor antagonists, a voltage-gated Na + channel toxin, extracellular Ca 2+ ion exclusion, or temperature shifts. Moreover, we describe a modification of formaldehyde-based fixatives that prevents bead formation in retinal ganglion cells visualized by green fluorescent protein expression and by immunohistochemistry.

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The dendritic varicosity: a mechanism for electrically isolating the dendrites of cat retinal amacrine cells?

Cited by 93 publications

References 11 publications

Electroanatomy of a unique amacrine cell in the rabbit retina.

Electroanatomy of a unique amacrine cell in the rabbit retina.

Cytoarchitecture of Pneumotaxic Integration of Respiratory and Nonrespiratory Information in the Rat

Moniliform deformation of retinal ganglion cells by formaldehyde‐based fixatives

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