Localization of ventral giant interneuron connections to the ventral median branch of thoracic interneurons in the cockroach

1991 ◽  
Vol 22 (6) ◽  
pp. 643-658 ◽  
Author(s):  
Janet L. Casagrand ◽  
Roy E. Ritzmann
Keyword(s):  
Giant Interneuron

Projections from sensory neurons developing at ectopic sites in insects

Development ◽  
1981 ◽  
Vol 65 (Supplement) ◽  
pp. 209-224
Author(s):  
Hilary Anderson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Sensory Neurons ◽  
Sensory Systems ◽  
Genetic Mutation ◽  
Detailed Understanding ◽  
Giant Interneuron ◽  
The Central Nervous System ◽  
Ectopic Neurons

This paper reviews recent experiments which attempt to gain more understanding about the recognition processes involved in the formation of neuronal connexions by studying the degree of specificity with which sensory neurons form their central connexions. This is done by generating ectopic neurons (either by transplantation or by genetic mutation) whose axons grow into novel regions of the central nervous system, and then examining their projections and synapses. The sensory systems reviewed are: the Antennapedia, spineless-aristapedia, proboscipedia, and bithorax homeotic mutants of Drosphila melanogaster; the cercus-to-giant interneuron system of crickets, and the wind-sensitive hair system of locusts. The results show that ectopic neurons form projections that are discrete and characteristic, not random and chaotic. In those cases where single classes of sensilla have been studied, they follow either their normal CNS pathways or those pathways normally used by their segmental homologues. Ectopic sensory neurons can also form appropriate functional connexions in some cases but not in others. Possible reasons are discussed, but detailed understanding of the underlying events requires further experimentation.

Escape responses following elimination of the giant interneuron pathway in the cockroach, Periplaneta americana

1988 ◽  
Vol 445 (2) ◽  
pp. 370-375 ◽  
Author(s):  
Christopher M. Comer ◽  
J.P. Dowd ◽  
G.Thomas Stubblefield
Keyword(s):  
Periplaneta Americana ◽  
Giant Interneuron ◽  
Escape Responses

Distribution of electrotonic synapses on identified lamprey neurons: a comparison of a model prediction with an electron microscopic analysis

1983 ◽  
Vol 49 (3) ◽  
pp. 705-716 ◽  
Author(s):  
B. N. Christensen
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Light And Electron Microscopy ◽  
Dendritic Tree ◽  
Microscopic Analysis ◽  
Giant Axon ◽  
Chemical Components ◽  
Excitatory Postsynaptic Potential ◽  
Electron Microscopic ◽  
Giant Interneuron

1. Intracellular recordings of the monosynaptic excitatory postsynaptic potential (EPSP) were made from an identified giant interneuron in the lamprey spinal cord following stimulation of a single identified presynaptic giant axon. The EPSP had both electrotonic and chemical components. 2. The giant interneuron and sometimes the giant axon were labeled with horseradish peroxidase (HRP). Using combined light and electron microscopy (EM), gap junctions formed by the axon on the HRP-labeled dendritic trees of seven interneurons were identified and their position marked on dendritic diagrams made from tracings of the cells. 3. The total number of gap junctions on a giant interneuron varied from a minimum of 9 to a maximum of 23. The number of gap junctions on a branch of a dendritic tree varied from 1 to 9. For all seven neurons the closest gap junction was located approximately 65 microns from the soma and the furthest 280 microns from the soma. 4. When gap junction position was plotted as a function of electrotonic distance from the soma, the variability in their distribution decreased significantly. Synaptic location was found to be on the average about 0.5 space constants from the soma, and this value compared favorably with that determined from an analysis of half-width and rise time of the electrotonic synaptic potential for these neurons. 5. These results suggest that the presynaptic axon tends to make, on the average, synaptic contact at the same electrical distance from the soma.

Segmental origins of the cricket giant interneuron system

1987 ◽  
Vol 265 (1) ◽  
pp. 145-157 ◽  
Author(s):  
Gwen A. Jacobs ◽  
R. K. Murphey
Keyword(s):  
Giant Interneuron
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