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21.
Octopaminergic dorsal unpaired median (DUM) neurons of locust thoracic ganglia are important components of motor networks and are divided into various sub-populations. We have examined individually stained metathoracic DUM neurons, their dendritic projection patterns, and their relationship to specific architectural features of the metathoracic ganglion, such as longitudinal tracts, transverse commissures, and well-defined sensory neuropils. The detailed branching patterns of individually characterized DUM neurons of various types were analyzed in vibratome sections in which architectural features were revealed by using antibodies against tubulin and synapsin. Whereas DUM3,4,5 and DUM5 neurons (the group innervating leg and "non-wing-power" muscles) had many ventral and dorsal branches, DUM1 and DUM3,4 neurons (innervating "wing-power" muscles) branched extensively only in dorsal areas. The structure of DUM3 neurons differed markedly from that of the other DUM neurons examined in that they sent branches into dorsal areas and had differently structured side branches that mostly extended laterally. The differences between the branching patterns of these neurons were quantified by using currently available new reconstruction algorithms. These structural differences between the various classes of DUM neurons corresponded to differences in their function and biophysical properties. 相似文献
22.
Summary. L- and D-aspartic acids (L-Asp and D-Asp) are present in the majority of nervous systems. In phylogeny, significant levels
have been reported in mollusc brains, particularly cephalopods. To examine the role of L- and D-Asp on a cephalopod receptor,
we studied ligand gating of a squid glutamate receptor (SqGluR) expressed in HEK 239 (human embryonic kidney) cells. Under
voltage clamp, application of L-glutamate (L-Glu; 1–30 mM), but not D-glutamate (D-Glu), or L- or D-Asp, evoked an inward
current of 0.1 nA. L- or D-Asp (200 μM) applied with 20 mM L-Glu, slowed the time course of activation and inactivation of
the L-Glu gated current (time constant increased from 1 s (L-Glu alone) to 3 s (D-Asp and L-Glu) and to 19 s (L-Asp and L-Glu)).
Our results suggest that in molluscan systems, aspartic acid could act as a neuromodulator during glutamatergic transmission
and could significantly alter synaptic integration by slowing glutamate receptor gating. 相似文献
23.
P. Kloppenburg J. Erber 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,176(1):111-118
1. | The effects of the biogenic amines serotonin and octopamine on motion-sensitive neurons in the lobula of the honey bee were analysed electrophysiologically. Single cell activity was recorded intracellularly during application of amines. Field potentials in the lobula were recorded to measure the effects on populations of motion-sensitive neurons. |
2. | Serotonin and octopamine modulate the response properties of motion-sensitive neurons in the lobula in a functionally antagonistic way. |
3. | The application of serotonin, in most cases, reduces background activity as well as responses to moving stripe patterns by motion-sensitive lobula neurons. The direction specificity can also decrease after serotonin application. In accordance with the single cell recordings, the amplitudes of lobula field potentials evoked by moving stripe patterns are also reduced by application of serotonin. |
4. | Octopamine leads to an increase in the amplitude and the initial slope of field potentials evoked by moving stripe patterns. However, there were no uniform effects at the single cell level after octopamine application. |
5. | The modulatory effects of serotonin and octopamine on motion-sensitive neurons correlate well with some behavioral modifications elicited by these substances (Erber et al. 1991; Erber and Kloppenburg, companion paper). |
24.
ágnes?VehovszkyEmail author Henriette?Szabó Christopher?J.?H.?Elliott 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2004,190(10):837-846
In the pond snail Lymnaea stagnalis octopamine-containing (OC) interneurons trigger and reconfigure the feeding pattern in isolated CNS by excitation of the central pattern generator. In semi-intact (lip–mouth—CNS) preparations, this central pattern generator is activated by chemosensory inputs. We now test if sucrose application to the lips activates the OC neurons independently of the rest of the feeding central pattern generator, or if the OC interneuron is activated by inputs from the feeding network. In 66% of experiments, sucrose stimulated feeding rhythms and OC interneurons received regular synaptic inputs. Only rarely (14%) did the OC interneuron fire action potentials, proving that firing of OC interneurons is not necessary for the sucrose-induced feeding. Prestimulation of OC neurons increased the intensity and duration of the feeding rhythm evoked by subsequent sucrose presentations. One micromolar octopamine in the CNS bath mimicked the effect of OC interneuron stimulation, enhancing the feeding response when sucrose is applied to the lips. We conclude that the modulatory OC neurons are not independently excited by chemosensory inputs to the lips, but rather from the buccal central pattern generator network. However, when OC neurons fire, they release modulatory octopamine, which provides a positive feedback to the network to enhance the sucrose-activated central pattern generator rhythm. 相似文献
25.
James?D.?AngstadtEmail author Jeffrey?L.?Grassmann Kraig?M.?Theriault Sarah?M.?Levasseur 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2005,191(8):715-732
Postinhibitory rebound (PIR) is defined as membrane depolarization occurring at the offset of a hyperpolarizing stimulus and is one of several intrinsic properties that may promote rhythmic electrical activity. PIR can be produced by several mechanisms including hyperpolarization-activated cation current (Ih) or deinactivation of depolarization-activated inward currents. Excitatory swim motor neurons in the leech exhibit PIR in response to injected current pulses or inhibitory synaptic input. Serotonin, a potent modulator of leech swimming behavior, increases the peak amplitude of PIR and decreases its duration, effects consistent with supporting rhythmic activity. In this study, we performed current clamp experiments on dorsal excitatory cell 3 (DE-3) and ventral excitatory cell 4 (VE-4). We found a significant difference in the shape of PIR responses expressed by these two cell types in normal saline, with DE-3 exhibiting a larger prolonged component. Exposing motor neurons to serotonin eliminated this difference. Cs+ had no effect on PIR, suggesting that Ih plays no role. PIR was suppressed completely when low Na+ solution was combined with Ca2+ -channel blockers. Our data support the hypothesis that PIR in swim motor neurons is produced by a combination of low-threshold Na+ and Ca2+ currents that begin to activate near –60 mV. 相似文献
26.
A. Weisel-Eichler F. Libersat 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,179(1):103-112
We have tested the effect of a known insect neuromodulator, octopamine, on flight initiation in the cockroach. Using minimally dissected animals, we found that octopamine lowered the threshold for windevoked initiation of flight when applied to either of two major synaptic sites in the flight circuitry: 1) the last abdominal ganglion, where wind-sensitive neurons from the cerci excite dorsal giant interneurons, or 2) the metathoracic ganglion, where the dorsal giant interneurons activate interneurons and motoneurons which are involved in producing the rhythmic flight motor pattern in the flight muscles (Fig. 2).Correlated with this change in flight initiation threshold, we found that octopamine applied to the last abdominal ganglion increased the number of action potentials produced by individual dorsal giant interneurons when recruiting the cereal wind-sensitive neurons with wind puffs (Figs. 3, 4, 5) or with extracellular stimulation of their axons (Fig. 6). Octopamine increases the excitability of the giant interneurons (Figs. 7, 8). Also, when we stimulated individual dorsal giant interneurons intracellularly, the number of action potentials needed to initiate flight was reduced when octopamine was applied to the metathoracic ganglion (Fig. 9).Abbreviations
EMG
electromyogram
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dGIs
dorsal giant interneurons
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GI
giant interneuron
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A6
sixth abdominal ganglion
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T3
third thoracic ganglion
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EPSP
excitatory postsynaptic potential 相似文献
27.
P. S. Mangan A. K. Cometa W. O. Friesen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,175(6):709-722
Expression of swimming in the medicinal leech (Hirudo medicinalis) is modulated by serotonin, a naturally occurring neurohormone. Exogenous application of serotonin engenders spontaneous swimming activity in nerve-cord preparations. We examined whether this activity is due to enhanced participation of swim motor neurons (MNs) in generating the swimming rhythm. We found that depolarizing current injections into MNs during fictive swimming are more effective in shifting cycle phase in nerve cords following serotonin exposure. In such preparations, the dynamics of membrane potential excursions following current injection into neuronal somata are substantially altered. We observed: 1) a delayed outward rectification (relaxation) during depolarizing current injection, most marked in inhibitory MNs; and 2) in excitor MNs, an enhancement of postinhibitory rebound (PIR) and afterhyperpolarizing potentials (AHPs) following hyperpolarizing and depolarizing current pulses, respectively. In contrast, we found little alteration in MN properties in leech nerve cords depleted of amines. We propose that enhanced expression of swimming activity in leeches exposed to elevated serotonin is due, partly, to enhancement of relaxation, PIR and AHP in MNs. We believe that as a consequence of alterations in cellular properties and synaptic interactions (subsequent paper) by serotonin, MNs are reconfigured to more effectively participate in generating and expressing the leech swimming rhythm.Abbreviations
AHP
Afterhyperpolarizing potential
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DCC
Discontinuous current clamp
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DE
Dorsal excitor motor neuron
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DI
Dorsal inhibitor motor neuron
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IPSP
Inhibitory postsynaptic potential
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MN
Motor neuron
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PIR
Postinhibitory rebound
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VE
Ventral excitor motor neuron
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VI
Ventral inhibitor motor neuron 相似文献
28.
Edmund A. Arbas Ronald L. Calabrese 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(5):665-671
1. Leydig neurons fire spontaneously at low rates (less than 4 Hz), but their activity increases with mechanical stimulation or electrical stimulation of mechanosensory neurons. These conditions also cause acceleration of bursting in heart motor neurons. 2. The firing rate of Leydig cells was found to regulate heart rate in chains of isolated ganglia. When Leydig neurons were made to fire action potentials at relatively high frequencies (ca. 5-10 Hz), however, heart motor neurons ceased bursting and were either silenced or fired erratically. 3. Firing of Leydig neurons at high rates caused bilateral heart interneurons of ganglia 3 or 4 to fire tonically rather than in their normal alternating bursts Tonic firing of these heart interneurons accounts for the prolonged barrages of ipsps recorded in heart motor neurons and the disruption of their normal cyclic activity. 4. Preventing spontaneous activity of Leydig neurons with injected currents in isolated ganglia caused deceleration of the heartbeat rhythm but did not halt oscillation. 5. Electrical stimulation of peripheral nerve roots with Leydig neuron activity suppressed in isolated ganglia caused acceleration of heart rate. 相似文献
29.
《IRBM》2019,40(4):193-200
BackgroundDeep brain stimulation (DBS) is emerging as a viable treatment option for selected patients with dystonia. Intraoperative extracellular microelectrode recordings (MER) are considered as the standard electrophysiological method for the precise positioning of the DBS electrode into the target brain structure. Accurate targeting of the permanent stimulation electrode into the Globus Pallidus internus (GPi) is key to positive long-term effects. The suitability of the location is peroperatively assessed by microelectrodes that register single-unit neuronal activity. The aim of this article is to analyse electrophysiological recordings of patient's neuronal activity with a focus on the identification of markers relevant to the patient's clinical state.MethodsIn this study, 13 patients chronically treated with double-sided DBS GPi were examined with a microrecording. The signal (24 kHz) processing, included bandpass filtering (0.5–5 kHz), automated detection of artefacts and feature extraction. Pre-processed signals were analysed by means of statistical learning.ResultsThe results show that the GPi was distinguished from its vicinity with p < 0.001 and 3 machine learning models AUCs had an accuracy of higher than 0.87. The observed biomarker, Hjort mobility, additionally correlated with the long-term neuromodulation effect (rho = −0.4; p < 0.05). Furthermore, we revealed a change of neural activity associated with the active distal DBS contact localization along the medio-lateral direction.ConclusionThis paper demonstrates the quantitative relationship between electrophysiological findings and the clinical effects of pallidal stimulation in dystonia and suggested objectification predictors of the effectiveness of this therapy. 相似文献
30.
The role of short-term synaptic dynamics in motor control 总被引:5,自引:0,他引:5
During the past few years, much attention has been given to the role of short-term synaptic plasticity, in particular depression and facilitation, in sculpting network activity. A recent study shows that synaptic depression in rhythmic motor networks could switch the control of network frequency from intrinsic neuronal properties to the synaptic dynamics. Short-term synaptic plasticity is also involved in the stabilization and reconfiguration of motor circuits and in the initiation, maintenance and modulation of motor programs. 相似文献