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B Pomeranz

Publications and source records attributed to B Pomeranz.

50 records · Page 3Linked to original sources
PubMed1977

Dendritic bottlenecks of crustacean motoneurons.

Cobalt-labelled fast flexor motoneurons of the crayfish (Procambarus) were studied by electron microscopy after treatment with diaminobenzidine. The neurons were traced into the abdominal ganglion to locations at which they made contacts with the lateral giant fibres of the nerve cord. Fine secondary dendritic branches extended from the primary dendrites of the fast flexor motoneurons to the lateral giant fibre. These fine branches had bottlenecks at various places along their lenghts and also at their junctions with primary dendrites. Chemical synapses occurred at the bottlenecks and at other locations on the fine branches. It is postulated that chemical synapses at dendritic bottlenecks could act to modify the effectiveness of the excitatory drive provided by the lateral giant fibres to the fast flexor motoneurons, most likely by 'gating' electrical signals conveyed by the fine dendrites.

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PubMed1975

Ultrastructural correlates of interneuronal function in the abdominal ganglion of Aplysia californica.

The synaptic inputs and outputs of the major interneuron L10 of the abdominal ganglion of Aplysia were studied using an intracellular staining technique for the electron microscope. The sites of both the chemical synaptic input and output of L10 are localized to the dendritic arborizations that arise from the axon in the ganglion neuropil. Thus, the interneuronal functions are mediated at the dendritic processes and could occur in the absence of spiking in the axon and cell body. The sites of L10 synaptic output are presumed to be at aggregations of vesicles and mitochondria in the dendrites. The synaptic vesicle content of L10, a cholinergic neuron, with many large dense vesicles resembles that described for serotonergic cells in Aplysia, making distinction of synaptic pharmacology by ultrastructure difficult. Focal membrane specializations with a clear synaptic cleft were not observed between L10 and its large population of postsynaptic cells. In contrast, clear focal input sites were frequently found on L10. Gap junctions, sites of probable electrical coupling between L10 and other neurons, were also found. These observations are discussed as evidence that many synapses do not have focal specializations.

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PubMed1970

Dendritic-tree anatomy codes form-vision physiology in tadpole retina.

In tadpole frog retina, the development of four classes of visual form detectors matched the growth of four types of ganglion cell dendritic trees. From this correlation of electrophysiology and anatomy we concluded that the structure of retinal ganglion cell dendritic trees provides the code for detection of visual shapes.

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PubMed1968

Cord cells responding to fine myelinated afferents from viscera, muscle and skin.

1. Micro-electrode recordings were made in the thoracic cord of acute spinal cats. Cells, which were located in the histologically defined lamina 5, responded both to the fine myelinated afferents from the splanchnic nerve and to afferents from the skin. Splanchnic afferents inhibit the effect of converging cutaneous inputs for periods up to 150 msec. Skin stimuli may also inhibit the effect of afferent nerve impulses from viscera. Some cells respond monosynaptically to the splanchnic afferents, others indirectly.2. Fine myelinated afferents from gastrocnemius (group 3) stimulate lamina 5 cells which also have cutaneous receptive fields. Cutaneous and group 3 muscle afferents interact by mutual inhibition in their effect on the cells.3. Fine myelinated afferents from skin excite lamina 5 cells. The cutaneous responses of lamina 5 cells contrast with those of lamina 4 cells in the following respects: (a) the receptive fields are larger, (b) they respond with an increased latency to Abeta afferents, (c) there is a low pressure threshold at the edge, (d) they respond to a wide range of pressure stimuli from light brush to heavy pinch applied to the centre of the receptive fields and (e) they respond to ADelta afferents.4. Lamina 5 cells receive fine myelinated afferents either from viscera or from muscle or from skin. Lamina 4 receives large myelinated afferents from skin and lamina 6 receives large myelinated afferents from muscle. The results suggest the hypothesis that some fine myelinated afferents form a class of afferents which signal the state of tissue, and end on lamina 5 cells.

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PubMedDate not supplied

Sympathetic denervation impairs epidermal healing in cutaneous wounds.

The involvement of peripheral nerves in dermal wound healing, particularly in the inflammatory response has not been extensively studied. Therefore, this study was performed to examine the role of peripheral nerves in the healing of rat skin linear incisions. We report that chemical sympathectomy with 6-hydroxydopamine significantly impaired wound healing as measured on days 7, 11, and 14 postsurgery (by day 14, 48% of the sympathectomized rats were healed in contrast with 84% of the controls; p = 0.0104). In contrast, neonatal capsaicin treatment, which predominantly destroys sensory afferents, had no effect on wound healing (p > 0.05 on all days). These results support the hypothesis that sympathetic efferents are important for wound healing. Unlike previous research, which showed that peripheral nerves influence ischemic skin flaps, we are the first to demonstrate a role for peripheral nerves in the healing of skin incisions. Because inflammation is an important step in cutaneous wound healing, we propose that a reduction of neurogenic inflammation caused by sympathectomy may explain the impaired wound healing that we observed in our study.

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