Thalamic projecting neurons in the feline nucleus cuneatus. A combined horseradish peroxidase and high voltage electron microscopic study

Ellis, Leland C.; DiOrio, James P.; Rustioni, Aldo

doi:10.1007/bf01258001

Cited by 3 publications

(2 citation statements)

References 52 publications

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“…PA terminals preferentially contact small dendrites and only rarely synapse on cell bodies, a finding that agrees with evidence reported elsewhere (Walberg, 1966;Wen et al, 1979;Fyffe et al, 1986) and also with data on cutaneous afferent fibers that end at spinal levels (Maxwell and Rethelyi, 1987). In cat, dendrites of cuneothalamic neurons are contacted by large terminals morphologically similar to PA terminals (Ellis et al, 1982). However, we cannot exclude the possibility that PA terminals also contact other projecting neurons or local circuit neurons.…”

Section: Discussionsupporting

confidence: 90%

Ultrastructural and immunocytochemical characterization of primary afferent terminals in the rat cuneate nucleus

Biasi

Vitellaro‐Zuccarello

Bernardi

et al. 1994

J of Comparative Neurology

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The cuneate nucleus is a relay center for somatosensory information by receiving tactile and proprioceptive inputs from primary afferent fibers that ascend in the dorsal funiculus. The morphology, synaptic contacts, and neurochemical content of primary afferent terminals in the cuneate nucleus of rats were investigated by combining anterograde transport of horseradish peroxidase conjugated to wheat-germ agglutinin or to cholera toxin (injected in cervical dorsal root ganglia) with postembedding immunogold labeling for glutamate and GABA. Both tracers gave similar results. Two types of terminals were labeled: type I terminals were irregularly shaped, had a mean area of 4.0 microns 2, synapsed on several dendrites, and were contacted by other terminals, some of which were GABA positive. Type II terminals were dome-shaped, had a mean area of 2.18 microns 2, and made synaptic contact on a single dendrite. All the anterogradely labeled terminals (interpreted as endings of primary afferents) were enriched in glutamate but not in GABA. The finding that identified primary afferent terminals are enriched in glutamate with respect to other tissue profiles strongly suggests a neurotransmitter role for glutamate in this afferent pathway to the rat cuneate nucleus.

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Section: Discussionsupporting

confidence: 90%

Ultrastructural and immunocytochemical characterization of primary afferent terminals in the rat cuneate nucleus

Biasi

Vitellaro‐Zuccarello

Bernardi

et al. 1994

J of Comparative Neurology

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“…Consequently, the single units in this study are believed to represent the cuneate sample with the most complete degree of unit activation from the spinal cord. The principal output of the cuneate nucleus is the medial lemniscus, which arises from the large round cells located mainly in the dorsal two-thirds of the nucleus caudal to the obex (Ellis and Rustioni, 1981;Ellis et al, 1982). There are additional projections to the cerebellum, pretectum, and tectum arising from cells in the rostra1 region (Cooke et al, 1971a;Cheek et al, 1975;Hand and Van Winkle, 1977;Bull and Berkley, 1984) and descending to the spinal cord (Burton and Loewy, 1977;Bromberg et al, 1981).…”

Section: Population Studymentioning

confidence: 96%

Peripheral and Spinal Inputs to Physiologically Identified Thalamic and Nonthalamic Relay Neurons in Cat Cuneate Nucleus

Bromberg

1987

Somatosensory Research

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A single-unit population study of the feline cuneate nucleus was carried out to identify principal neuron types, their distribution within the nucleus, pattern of peripheral activation, and receptive field characteristics. Units were also tested for response to isolated dorsal column or dorsolateral funicular electrical stimulation. The nucleus was explored in a uniform pattern, and sample size was optimized by applying the search stimulus shocks to the dorsal spinal cord. Single units were defined as spinal afferents, cuneothalamic-relay (CTR) neurons, and non-cuneothalamic-relay (non-CTR) neurons. The following features were observed: The distribution within the nucleus of specific cell types agreed with cytoarchitectural studies: Spinal afferent fibers were superficial and caudal; 22% of neurons were CTR neurons; CTR neurons were most dense in the middle of the nucleus and were largely separate from non-CTR neurons. Of the 58 neurons tested for response to isolated dorsal column and dorsolateral funicular stimulation, 24% were activated from both tracts. Convergent input from the off-focus periphery (defined as other than the ipsilateral forelimb) was detected in both CTR and non-CTR neurons, most commonly from the contralateral forepaw. Several neurons were activated from three limbs. Thirty-seven percent of units were unresponsive to hair movement, touch, muscle palpation, or movement of joints. Compared to spinal fibers and non-CTR neurons, CTR neurons were most likely to have an identifiable input.

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Transneuronal Transport of Wheatgerm Agglutinin Conjugated with Horseradish Peroxidase in the Somatosensory System of the Rat: A Light- and Electron-Microscopic Study

Spreafico

Biasi

Frassoni

et al. 1985

Somatosensory Research

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Experiments were performed in order to investigate, at the light- and electron-microscopic levels, the transneuronal transport of wheatgerm agglutinin conjugated with horseradish peroxidase (WGA:HRP) in the somatosensory system of rats. In five adult albino rats, various amounts of WGA:HRP at different concentrations were bilaterally injected in the dorsal column nuclei (DCN). In one additional animal, WGA:HRP was injected in one side, whereas free HRP was injected in the contralateral DCN. In another five rats, WGA:HRP was injected in the first somatosensory cortex (SI). The postinjection survival time of the animals ranged from 30 to 48 hr. The histochemical visualization of the enzyme was performed using either paraphenylenediamine-pyrocatechol (PPD-PC) or tetraethylbenzidine (TMB) as chromogens on adjacent horizontal serial sections. All the reacted samples were studied at the light-microscopic level, and sections from four animals were processed for the ultrastructural investigation. After DCN injections, a massive anterograde labeling was always observed in nucleus ventralis posterolateralis (VPL) of the thalamus, where also labeled neurons and glial cells were detected at both the light- and the electron-microscopic levels. Labeled neurons and terminals in the lateral border of nucleus reticularis (Re) of the thalamus were also observed after either DCN or SI injection of WGA:HRP. Our results show that WGA:HRP is effectively transported not only anterogradely and retrogradely through the somatosensory system of the rat, but also transneuronally. The transneuronal transfer of the tracer seems to be mainly related to the postlabeling survival time of the animal, and it does not occur when free HRP is injected. In controlled experimental conditions, WGA:HRP can therefore be useful for tracing secondary projections. Moreover, in the present report, the existence of a mediolateral arrangement of the projections of the somatosensory-related area of Re toward VPL is directly demonstrated. As for the histochemical procedure employed, differences in sensitivity are shown between PPD-PC and TMB, although the same general pattern of labeling is present with both chromogens.

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Thalamic projecting neurons in the feline nucleus cuneatus. A combined horseradish peroxidase and high voltage electron microscopic study

Cited by 3 publications

References 52 publications

Ultrastructural and immunocytochemical characterization of primary afferent terminals in the rat cuneate nucleus

Ultrastructural and immunocytochemical characterization of primary afferent terminals in the rat cuneate nucleus

Peripheral and Spinal Inputs to Physiologically Identified Thalamic and Nonthalamic Relay Neurons in Cat Cuneate Nucleus

Transneuronal Transport of Wheatgerm Agglutinin Conjugated with Horseradish Peroxidase in the Somatosensory System of the Rat: A Light- and Electron-Microscopic Study

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