摘要:

AbstractRecently evidence was presented that, following transection, spinal cords of larval lampreys could regenerate functional connections. The demonstration in isolated spinal cord–notochord preparations consisted of fictive swimming coordinated across the lesion site. In the study reported here curare was added to the bath to eliminate the possible contribution from reflexes mediated by contractions from any remaining muscle fibers attached to the notochord. Coordination remained in the presence of curare, adding further evidence that indeed the regenerated fibers formed functionally appropriate connection

ISSN:0022-3034    

DOI:10.1002/neu.480190302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPrevious work on canaries and zebra finches has shown that large differences between the sexes exist in the structure of dendrites in n. robustus archistriatalis (RA), one of the principal nuclei involved in the control of song. This sex difference is associated with a general or complete absence of song in females. If dendritic morphology in RA is causally related to capacity for song, large sex differences in structure should not occur in avian species in which both sexes sing. We now report this prediction confirmed for buff‐breasted wrens (Thryothorus leucotis), a species in which the members of a breeding pair sing duets with each other. Total dendritic length and number of dendritic branches in RA do not differ in this species. Dendrites from males project about 8 μm further from the cell body than dendrites from females, apparently because of longer dendritic segments near the cell body. We argue that this suggests that differential influences on the structure of RA occurred early in the lives of the wre

ISSN:0022-3034    

DOI:10.1002/neu.480190303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMicroelectrode mapping experiments indicate an ipsilateral representation of the oropharynx and a well‐defined, bilateral input from the proximal portion of the maxillary barbels and snout region within the vagal lobe of channel catfish. The map of the oropharyngeal epithelium is distorted so that the gill arches are rotated through an angle of 90° along the transverse plane, and the dorsally mapped region of the gill rakers is tilted posteriorly in the sagittal plane of the vagal lobe. Multiunit recording studies fail to provide definitive boundaries of adjacently mapped domains of oropharyngeal structures. Gustatory receptive fields of neurons in the vagal lobe correspond to their location on the topological map obtained by tactile stimulation of the oropharyngeal epithelium. A few single unit recordings indicate restricted receptive fields and different response patterns of taste, tactile, and proprioceptive neurons in the vagal lobe of catfi

ISSN:0022-3034    

DOI:10.1002/neu.480190304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn a multiganglionic preparation of the lobster abdominal nerve cord, composed of the first through fifth ganglia (A1–A5) and attached second swimmeret, tactile stimulation of the cuticular surface of the swimmeret initiates a postural motor program in A2 for abdominal extension, whereas deflection of feathered hair sensilla that fringe the swimmeret rami does not affect postural motor activity recorded from A2 (Kotak and Page, 1986a). This report demonstrates that partial isolation of A2 from adjacent abdominal ganglia by sectioning the A1–A2 or the A2–A3 connectives both increases the strength of the extension response evoked by cuticular stimulation and disinhibits a postural flexion inhibition response initiated by feathered hair stimulation. Complete isolation of A2, by cutting the A1–A2 and the A2–A3 connectives, further increases the strength of these postural responses. Intersegmental inhibition of these responses originates in the ganglia adjacent to A2, since mechanoresponsiveness of A2 is not affected by resection of a more distant connective (A3–A4). These results provide evidence for the presence in adjacent abdominal ganglia of intersegmental interneurons that regulate the access of swimmeret sensory activity to the postural motor ne

ISSN:0022-3034    

DOI:10.1002/neu.480190305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWe examined the distribution of fibronectin‐like (FNL) immunoreactivity associated with intact buccal ganglia, cell‐cultured buccal ganglia neurons and nonneuronal cells, and brain‐conditioned medium from the snailHelisoma. In addition, the possible roles of fibronectin in the regulation of neurite outgrowth were studied. Immunofluorescent staining for FNL antigens revealed intense staining in patches and fibrous arrays over the connective tissue sheaths of buccal ganglia and nerve trunks. Within the ganglia, heavy staining was seen surrounding neurons and in track‐like arrangements. In cell cultures, specific staining was associated with nonneuronal cell surfaces and to a lesser degree with the surface of identified neurons. In addition, a noncellular, substrate‐bound component of brain‐conditioned medium displayed FNL immunoreactivity. Since culturedHelisomaneurons require a substrate‐associated, brain‐derived conditioning factor (CF) in order to elaborate neurites with motile growth cones, we tested whether the FNL immunoreactive substance might act as a neuritotropic agent. Fibronectin antiserum suppressed, in a dose‐dependent manner, the CF‐induced sprouting of identified neurons in isolated cell culture. When added at increasing concentrations to neurons already growing in response to CF, fibronectin antiserum exerted a biphasic effect on neurite elongation; outgrowth was accelerated at low, but inhibited at high, antiserum concentrations. In contrast, growth cone structures associated with motility (filopodia and lamellipodia) were progressively reduced by increasing levels of antiserum. A short peptide derived from fibronectin's cell‐binding domain (Arg‐Gly‐Asp‐Ser) also greatly reduced neurite outgrowth. The combined results of this study indicate an abundance of FNL immunoreactive molecules within the CNS ofHelisoma, their probable production by nonneuronal cells, and their function as a substrate‐associated component of CF which promotes growth cone filopodi

ISSN:0022-3034    

DOI:10.1002/neu.480190306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn the flight system ofLocusta migratoriacertain muscles move a wing and a leg (bifunctional muscles) and are active during the performance of walking and flight. A preparation that allowed intracellular recordings during these behaviors was developed to analyze the activity of motoneurons supplying these and other muscles.Motoneurons innervating bifunctional muscles were active during walking and flight, whereas motoneurons innervating unifunctional flight muscles were active only during flight.Both motor patterns, walking and flight, were sometimes generated simultaneously in our preparation. In bifunctional motoneurons the two patterns were superimposed, whereas in unifunctional motoneurons only the flight motor pattern was observed.All flight interneurons we examined were either inactive or tonically inhibited during walking. All interneurons that were strongly modulated during walking were either inactive, inhibited, or only weakly modulated during flight.Anatomical investigations showed that unifunctional flight motoneurons have their main processes in the extreme dorsal region of neuropil. With the exception of the second basalar motoneurons, all bifunctional motoneurons have their processes extending more ventrally in the neuropil. Flight interneurons have their processes restricted to the dorsal neuropil. Interneurons that were rhythmically active during walking had their processes distributed more ventrally.We conclude that motoneurons innervating bifunctional muscles are active during both motor patterns, walking and flight, and that these patterns are produced by two distinct interneuronal networks. The pattern‐generating network for flight appears to be located in the extreme dorsal regions of the thoracic ganglia, and the network for walking is located more ventrall

ISSN:0022-3034    

DOI:10.1002/neu.480190307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe rapid axonal transport of a pulse of [35S]methionine‐labelled material was used to study the release of transported material from amphibian nerve maintained in vitro. Following creation of a moving pulse of activity in a dorsal root ganglion‐sciatic nerve preparation, the ganglion was removed and the nerve placed in a three‐compartment tray, the section of nerve in the middle compartment containing no truncated branches (unbranched section). All three compartments were filled with a saline solution that in some studies contained nonradioactive methionine (1.0 mmol/L). Analysis of studies in which nonradioactive methionine was absent revealed that labelled material appeared in the bathing solution of the end compartments that contained truncated branches, but not in the solution of the middle (unbranched) compartment. The quantity of label released in the branched compartments was approximately 6% of that remaining in the corresponding section of nerve following an 18–20 h incubation period. However, when nonradioactive methionine was present, all compartments showed an additional activity in the bathing solution of approximately 10% of that remaining in the nerve. In another study in which a position‐sensitive detector of ionizing radiation was used to monitor progress of the pulse, it was found that activity did not enter the bathing solution of a compartment prior to the pulse of activity. It is concluded that in the absence of methionine from the bathing solution, axonally transported material is released only from regions of nerve that contain severed axons; however, the presence of methionine allows transported material to be released from nerve containing intact axons. Ultrafiltration studies and thin‐layer chromatography revealed the majority of material released to be of low‐molecular weight (≤ 30,000 daltons) and not free

ISSN:0022-3034    

DOI:10.1002/neu.480190308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480190301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY