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1.
P. Distler 《Histochemistry and cell biology》1990,93(6):617-626
Summary Synaptic contacts between GABA-immunoreactive neurons, antennal receptor fibers and non-GABA-immunoreactive neurons in the glomerular neuropil of the antennal lobes have been identified by means of a combination of (i) immunohistochemical labeling and (ii) labeling of afferent fibers of the antenna by experimentally induced degeneration. Characteristic contacts of these neurons are: a) Serially arranged polysynaptic contacts between degenerated antennal fibers, GABA-immunoreactive neurons and non-GABA-immunoreactive neurons. b) Monosynaptic contacts between degenerated antennal fibers and non-GABA-immunoreactive neurons. c) Reciprocal synaptic contacts between immunostained and non-stained neurons and synaptic contacts between individual GABA-immunoreactive neurons. d) Synaptic output contacts of GABA-immunoreactive neurons with degenerated antennal fibers.GABA-immunoreactive neuron profiles in the glomeruli are assigned to multiglomerular local interneurons (Distler 1989a); non-immunolabeled profiles may be assigned to projection neurons and other not yet identified interneurons. 相似文献
2.
D. Malun 《Histochemistry and cell biology》1991,96(3):197-207
Summary Two types of central neurons in the antennal lobe of the American cockroach Periplaneta americana were labeled with a combination of two specific markers. Their synaptic contacts were characterized and their distribution on the neurons examined. A uniglomerular pheromone-sensitive projection neuron with dendritic arbor in the male-specific macroglomerulus (attractant neuron) was characterized physiologically by intracellular recording and then filled with biocytin, which was converted to a marker for this individual neuron by a preembedding procedure. In a postembedding procedure local, multiglomerular interneurons were marked by immunogold labeling of GABA. Two kinds of synaptic contacts were found on the attractant neuron. (i) Input synapses from GABA-immunoreactive profiles. There were many of these, which (together with results of previous studies) suggests that local interneurons mediate polysynaptic transmission from antennal receptor fibers to the projection neuron. (ii) Output synapses onto GABA-immunoreactive profiles and onto non-identified neurons. These contacts indicate that signals generated by the projection neurons in a given glomerulus are passed back to multiglomerular interneurons and hence are also transmitted to other glomeruli. 相似文献
3.
D Malun 《Histochemistry》1991,96(3):197-207
Two types of central neurons in the antennal lobe of the American cockroach Periplaneta americana were labeled with a combination of two specific markers. Their synaptic contacts were characterized and their distribution on the neurons examined. A uniglomerular pheromone-sensitive projection neuron with dendritic arbor in the male-specific macroglomerulus (attractant neuron) was characterized physiologically by intracellular recording and then filled with biocytin, which was converted to a marker for this individual neuron by a preembedding procedure. In a postembedding procedure local, multiglomerular interneurons were marked by immunogold labeling of GABA. Two kinds of synaptic contacts were found on the attractant neuron. (i) Input synapses from GABA-immunoreactive profiles. There were many of these, which (together with results of previous studies) suggests that local interneurons mediate polysynaptic transmission from antennal receptor fibers to the projection neuron. (ii) Output synapses onto GABA-immunoreactive profiles and onto non-identified neurons. These contacts indicate that signals generated by the projection neurons in a given glomerulus are passed back to multiglomerular interneurons and hence are also transmitted to other glomeruli. 相似文献
4.
P Distler 《Histochemistry》1990,93(4):401-408
Dopamine-like immunoreactivity was demonstrated histochemically in about ten local interneurons in the antennal lobe of Periplaneta americana. The somata of these neurons are within the ventrolateral group of cell bodies. Additional immunohistochemical tests revealed that the same neurons also have a GABA-like immunoreactivity. Immunohistochemical dopamine staining (preembedding) of preparations in which the antennal receptor fibers had been caused to degenerate showed that in the glomerular neuropil these antennal fibers form output synapses on dopamine-immunoreactive neurons. The latter form output synapses on unstained neuron profiles. 相似文献
5.
6.
P. Distler 《Histochemistry and cell biology》1990,93(4):401-408
Summary Dopamine-like immunoreactivity was demonstrated histochemically in about ten local interneurons in the antennal lobe of Periplaneta americana. The somata of these neurons are within the ventrolateral group of cell bodies. Additional immunohistochemical tests revealed that the same neurons also have a GABA-like immunoreactivity.Immunohistochemical dopamine staining (preembedding) of preparations in which the antennal receptor fibers had been caused to degenerate showed that in the glomerular neuropil these antennal fibers form output synapses on dopamine-immunoreactive neurons. The latter form output synapses on unstained neuron profiles. 相似文献
7.
Synapses formed by normal and abnormal hippocampal mossy fibers 总被引:3,自引:0,他引:3
8.
《International Journal of Insect Morphology and Embryology》1988,17(3):243-294
The structure and postembryonic development of antennae and deutocerebrum in various insect orders are reviewed. First, the number and/or size of system components, i.e. antennal sensilla, neuroreceptors, deutocerebral neurons and synaptic complexes (glomeruli), are compared in adult insects. Second, the neuronal organization of the system is examined. Evidence of projection of the neuroreceptors from the 2 basal antennal segments (scape and pedicel) in the antennal mechanosensory and motor center and from the distal segments (flagellum) in the antennal lobe is discussed. Third, the types of cerebral neurons found in the antennal lobe are described. Fourth, all synaptic contacts between neurons in the antennal lobe take place in discrete glomeruli whose ultrastructure and neurotransmitters are examined. Evidence of individual identifiability of glomeruli is given. Fifth, various sexual dimorphisms present in the antenna and antennal lobe, related or not to sex pheromone perception, are described at sensillar, neuronal, and glomerular levels. Sixth, the postembryonic development of neurons and glomeruli is analyzed in holo- and hemimetabolous insects. In conclusion, the columnar organization of the system is emphasized, alternative models of antennal-neuron projection into glomeruli are considered, and the functional significance of identified glomeruli is discussed. 相似文献
9.
A large deutocerebral serotonin-immunoreactive neuron arborizes profusely in the glomeruli of the antennal lobes, and also sends neurites into the lateral lobe and the calyces of the mushroom bodies in the ipsilateral protocerebrum. Electron micrographs of the glomerular neuropil show that the main synapses of the serotonin-immunoreactive arborizations are output contacts with unidentified neuron profiles. Only a few synaptic input contacts with serotonin-labeled fibers were observed. 相似文献
10.
Summary Receptor cell axons from the antennal flagellum terminate in the glomeruli of the ipsilateral deutocerebrum in Periplaneta americana and Locusta migratoria. Processes from several groups of deutocerebral neurons also enter the glomeruli and terminate in characteristic branching patterns. There, they contact the antennal axons. Connections are both convergent and divergent. Not only do single central neurons collect the inputs from many receptor cells, but receptor axons were often observed to branch and terminate at more than one deutocerebral neuron. The axons from a portion of the neurons go to form the deutocerebral bundle of the tractus olfactorioglobularis. These axons of the bundle terminate in the ipsilateral calyx of the corpus pedunculatum and in the lateral lobus protocerebri. The processes of the majority of the deutocerebral neurons stay within the deutocerebrum itself and may serve as local interneurons. Part of some antennal fibers terminate in the lobus dorsalis. The lobus glomeratus receives inputs from the maxillary palps and also from processes of deutocerebral neurons.Electron microscopy of synaptic connections and anatomical experiments reveal a complicated pattern of connections between receptor axons and higher order neurons as well as between higher order neurons themselves within the glomeruli.The ratio of the number of antennal fibers to that of relay fibers could easily lead to the interpretation, that the deutocerebrum merely serves as a device for reducing the number of transmission channels. However, coupled with physiological data, anatomical details such as conand divergence of input and interconnections between input channels suggest rather a filtering system and a highly complicated integrative network. 相似文献
11.
Summary We have used specific antisera against protein-conjugated-aminobutyric acid (GABA) in immunocytochemical preparations to investigate the distribution of putatively GABAergic neurons in the brain and suboesophageal ganglion of the sphinx mothManduca sexta. About 20000 neurons per brain hemisphere exhibit GABA-immunoreactivity. Most of these are optic-lobe interneurons, especially morphologically centrifugal neurons of the lamina and tangential neurons that innervate the medulla or the lobula complex. Many GABA-immunoreactive neurons, among them giant fibers of the lobula plate, project into the median protocerebrum. Among prominent GABA-immunoreactive neurons of the median protocerebrum are about 150 putatively negative-feedback fibers of the mushroom body, innervating both the calyces and lobes, and a group of large, fan-shaped neurons of the lower division of the central body. Several commissures in the supra- and suboesophageal ganglion exhibit GABA-immunoreactivity. In the suboesophageal ganglion, a group of contralaterally descending neurons shows GABA-like immunoreactivity. The frontal ganglion is innervated by immunoreactive processes from the tritocerebrum but does not contain GABA-immunoreactive somata. With few exceptions the brain nerves do not contain GABA-immunoreactive fibers. 相似文献
12.
Summary A large deutocerebral serotonin-immunoreactive neuron arborizes profusely in the glomeruli of the antennal lobes, and also sends neurites into the lateral lobe and the calyces of the mushroom bodies in the ipsilateral protocerebrum. Electron micrographs of the glomerular neuropil show that the main synapses of the serotonin-immunoreactive arborizations are output contacts with unidentified neuron profiles. Only a few synaptic input contacts with serotonin-labeled fibers were observed. 相似文献
13.
Summary Synaptic junctions are found in all parts of the nucleus, being almost as densely distributed between cell laminae as within these laminae.In addition to the six classical cell laminae, two thin intercalated laminae have been found which lie on each side of lamina 1. These laminae contain small neurons embedded in a zone of small neural processes and many axo-axonal synapses occur there.Three types of axon form synapses in all cell laminae and have been called RLP, RSD and F axons. RLP axons have large terminals which contain loosely packed round synaptic vesicles, RSD axons have small terminals which contain closely packed round vesicles and F axons have terminals intermediate in size containing many flattened vesicles.RLP axons are identified as retinogeniculate fibers. Their terminals are confined to the cell laminae, where they form filamentous contacts upon large dendrites and asymmetrical regular synaptic contacts (with a thin postsynaptic opacity) upon large dendrites and F axons. RSD axons terminate within the cellular laminae and also between them. They form asymmetrical regular synaptic contacts on small dendrites and on F axons. F axons, which also occur throughout the nucleus, form symmetrical regular contacts upon all portions of the geniculate neurons and with other F axons. At axo-axonal junctions the F axon is always postsynaptic.Supported by Grant R 01 NB 06662 from the USPHS and by funds of the Neurological Sciences Group of the Medical Research Council of Canada. Most of the observations were made while R. W. Guillery was a visiting professor in the Department of Physiology at the University of Montreal. We thank the Department of Physiology for their support and Mr. K. Watkins, Mrs. E. Langer and Mrs. B. Yelk for their skillful technical assistance. 相似文献
14.
T. A. Christensen B. R. Waldrop I. D. Harrow J. G. Hildebrand 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,173(4):385-399
Intracellular recordings were made from the major neurites of local interneurons in the moth antennal lobe. Antennal nerve stimulation evoked 3 patterns of postsynaptic activity: (i) a short-latency compound excitatory postsynaptic potential that, based on electrical stimulation of the antennal nerve and stimulation of the antenna with odors, represents a monosynaptic input from olfactory afferent axons (71 out of 86 neurons), (ii) a delayed activation of firing in response to both electrical- and odor-driven input (11 neurons), and (iii) a delayed membrane hyperpolarization in response to antennal nerve input (4 neurons).Simultaneous intracellular recordings from a local interneuron with short-latency responses and a projection (output) neuron revealed unidirectional synaptic interactions between these two cell types. In 20% of the 30 pairs studied, spontaneous and current-induced spiking activity in a local interneuron correlated with hyperpolarization and suppression of firing in a projection neuron. No evidence for recurrent or feedback inhibition of projection neurons was found. Furthermore, suppression of firing in an inhibitory local interneuron led to an increase in firing in the normally quiescent projection neuron, suggesting that a disinhibitory pathway may mediate excitation in projection neurons. This is the first direct evidence of an inhibitory role for local interneurons in olfactory information processing in insects. Through different types of multisynaptic interactions with projection neurons, local interneurons help to generate and shape the output from olfactory glomeruli in the antennal lobe.Abbreviations AL
antennal lobe
- EPSP
excitatory postsynaptic potential
- GABA
-aminobutyric acid
- IPSP
inhibitory postsynaptic potential
- LN
local interneuron
- MGC
macroglomerular complex
- OB
olfactory bulb
- PN
projection neuron
- TES
N-tris[hydroxymethyl]methyl-2-aminoethane-sulfonic acid 相似文献
15.
Nigrothalamic neurons were identified into thesubstantia nigra by their retrograde labelling with horseradish peroxidase. Axon terminals that contain glutamate (the excitatory transmitter) were revealed immunocytochemically with an immunogold electron microscopic technique. Ultrastructural parameters (the large and small diameters of axon terminals, area of their profiles, coefficient of form of profiles, large and small diameters of synaptic vesicles) were analyzed in all 240 synapses under study. Synaptic contacts localized on both nigrothalamic and unidentified neurons belonged to three morphologically specific groups. Synapses of the groups I and III, according to classification by Rinvik and Grofova, were characterized by a symmetric type of synaptic contact and contained polymorphic synaptic vesicles. Contacts in group-II synapses were asymmetric, and respective terminals contained round vesicles. Among the studied synapses, 65.8% were classified as group-I contacts, 25.0% belonged to group II, and 9.2% belonged to group III. Glutamate-positive axon terminals formed predominantly group-II synapses; such connections constituted 70% of this group's synapses. Sixty percent of glutamate-positive synapses were localized on the distal dendrites and 23% on the proximal dendrites, while 17% of such synapses were distributed on the somata of nigral neurons. Such a pattern of distribution of glutamate-positive synapses was observed on both nigrothalamic and unidentified nigral neurons. About 7% of glutamate-positive synapses were formed by very large axon terminals containing round synaptic vesicles; yet, the contacts of these terminals were of a symmetric type. Twenty percent of group-I synapses, i.e., synapses considered inhibitory connections, were found to manifest a weak immune reaction to glutamate.Neirofiziologiya/Neurophysiology, Vol. 28, No. 6, pp. 285–295, November–December, 1996. 相似文献
16.
Excitatory local circuits and their implications for olfactory processing in the fly antennal lobe 总被引:8,自引:0,他引:8
Conflicting views exist of how circuits of the antennal lobe, the insect equivalent of the olfactory bulb, translate input from olfactory receptor neurons (ORNs) into projection-neuron (PN) output. Synaptic connections between ORNs and PNs are one-to-one, yet PNs are more broadly tuned to odors than ORNs. The basis for this difference in receptive range remains unknown. Analyzing a Drosophila mutant lacking ORN input to one glomerulus, we show that some of the apparent complexity in the antennal lobe's output arises from lateral, interglomerular excitation of PNs. We describe a previously unidentified population of cholinergic local neurons (LNs) with multiglomerular processes. These excitatory LNs respond broadly to odors but exhibit little glomerular specificity in their synaptic output, suggesting that PNs are driven by a combination of glomerulus-specific ORN afferents and diffuse LN excitation. Lateral excitation may boost PN signals and enhance their transmission to third-order neurons in a mechanism akin to stochastic resonance. 相似文献
17.
Jean Y. Jew M.D. 《Cell and tissue research》1985,241(3):529-538
Summary Amine-containing small intensely fluorescent (SIF) cells are ubiquitous in vertebrate sympathetic ganglia and, in some species, SIF cells have been identified as interneurons. The hypothesis proposed in this study is that SIF cells in superior sympathetic ganglia of the guinea pig function as interneurons, with efferent connections characteristic for the species. Fluorescence (catecholamine) microscopy and 5-hydroxydopamine marker for electron microscopy were used to study SIF cells, their processes and connections in this ganglion.Brightly fluorescent fibers were seen attached to virtually all SIF cells, and were of two types. The first type, single or arranged in cords, interconnected elements of the SIF-cell system; these apparent linkages joined individual SIF cells as well as adjacent clusters. The electron-microscopic evidence for synaptic contacts between SIF cells warrants the claim that integrated action is a presumed function of these elements. The second type of SIF-cell process was generally of greater length. These individual, branching fibers made presumed connections with dendrites of most principal ganglionic neurons. This arrangement suggested by histofluorescence preparations was confirmed by electron microscopy to involve synaptic connections, and the postsynaptic element was shown to be continuous with the perikaryon of the principal ganglionic neuron. Ultrastructural evidence that collections of dense-cored vesicles occur within processes of both principal ganglionic neurons and SIF cells, in proximity to unsheathed portions of plasma membrane, leads to the conclusion that interstitial diffusion of catecholamine from both may occur; the finding of SIF cell processes adjacent to fenestrated blood vessels suggests that catecholamine may also be transported through capillaries. 相似文献
18.
Carolina E. Reisenman Andrew M. Dacks John G. Hildebrand 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(6):653-665
Local interneurons (LNs) play important roles in shaping and modulating the activity of output neurons in primary olfactory
centers. Here, we studied the morphological characteristics, odor responses, and neurotransmitter content of LNs in the antennal
lobe (AL, the insect primary olfactory center) of the moth Manduca sexta. We found that most LNs are broadly tuned, with all LNs responding to at least one odorant. 70% of the odorants evoked a
response, and 22% of the neurons responded to all the odorants tested. Some LNs showed excitatory (35%) or inhibitory (33%)
responses only, while 33% of the neurons showed both excitatory and inhibitory responses, depending on the odorant. LNs that
only showed inhibitory responses were the most responsive, with 78% of the odorants evoking a response. Neurons were morphologically
diverse, with most LNs innervating almost all glomeruli and others innervating restricted portions of the AL. 61 and 39% of
LNs were identified as GABA-immunoreactive (GABA-ir) and non-GABA-ir, respectively. We found no correlations between odor
responses and GABA-ir, neither between morphology and GABA-ir. These results show that, as observed in other insects, LNs
are diverse, which likely determines the complexity of the inhibitory network that regulates AL output. 相似文献
19.
Light- and electron-microscopic studies were used to investigate connections between specific subgroups of neurons in the myenteric plexus of the guineapig small intestine. Inputs to two classes of calretinin-immunoreactive (IR) nerve cells, longitudinal muscle motor neurons and ascending interneurons, were examined. Inputs from calbindin-IR primary sensory neurons and from three classes of descending interneurons were studied. Electron-microscopic analysis showed that calbindin-IR axons formed two types of inputs, synapses and close contacts, on calretinin-IR neurons. About 40% of inputs to the longitudinal muscle motor neurons and 70% to ascending interneurons were calbindin-IR. Approximately 50% of longitudinal muscle motor neurons were surrounded by bombesin-IR dense pericellular baskets and 40% by closely apposed varicosities. At the electron-microscope level, the bombesin-IR varicosities were found to form synapses and close contacts with the motor neurons. Dense pericellular baskets with bombesin-IR surrounded 36% of all ascending interneurons, and a further 17% had closely apposed varicosities. Somatostatin-and 5-HT-IR descending interneurons provided no dense pericellular baskets to calretinin-IR nerve cells. Thus, calretinin-IR, longitudinal muscle motor neurons and ascending interneurons receive direct synaptic inputs from intrinsic primary sensory neurons and from non-cholinergic, bombesin-IR, descending interneurons. 相似文献
20.
V. I. Bogomolets 《Neurophysiology》1972,4(1):66-71
Single unit responses in the middle cervical sympathetic ganglion ofEmys orbicularis to stimulation of other nerves and changes in these responses during the action of sympathetic blocking agents on the ganglion were investigated. The results showed that some fibers of the cervical sympathetic trunk of the turtle are interrupted in this ganglion. Postganglionic fibers pass out of the ganglion and enter the lateral branch and the sympathetic trunk. Other fibers pass through the ganglion without interruption and, together with postganglionic fibers, leave the ganglion in the cervical sympathetic trunk in a cranial direction. The velocity of conduction of excitation along the preganglionic fibers is between 4–3 and 2–1.5 m/sec and along the postganglionic fibers between 4–2.6 and 0.7–0.5 m/sec (fibers of types B2 and C). Synaptic delay in the fast-conducting fibers averages 6.6 msec. Preganglionic fast-conducting fibers form synaptic contacts on neurons with type B2 axons, while preganglionic slow-conducting fibers form contacts on neurons with type C axons. Terminals of two preganglionic fibers differing very slightly in their threshold of excitability, and probably constituting the same group, converge on some neurons.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukranian SSR, Kiev. Translated from Neirofiziologiya, Vol. 4, No. 1, pp. 83–89, January–February, 1972. 相似文献