共查询到20条相似文献,搜索用时 31 毫秒
1.
Parallel processing of proprioceptive information in the terminal abdominal ganglion of the crayfish
P. L. Newland T. Nagayama 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,172(4):389-400
The processing of proprioceptive information from the exopodite-endopodite chordotonal organ in the tailfan of the crayfish Procambarus clarkii (Girard) is described. The chordotonal organ monitors relative movements of the exopodite about the endopodite. Displacement of the chordotonal strand elicits a burst of sensory spikes in root 3 of the terminal ganglion which are followed at a short and constant latency by excitatory postsynaptic potentials in interneurones. The afferents make excitatory monosynaptic connections with spiking and nonspiking local interneurones and intersegmental interneurones. No direct connections with motor neurones were found.Individual afferents make divergent patterns of connection onto different classes of interneurone. In turn, interneurones receive convergent inputs from some, but not all, chordotonal afferents. Ascending and spiking local interneurones receive inputs from afferents with velocity thresholds from 2–400°/s, while nonspiking interneurones receive inputs only from afferents with high velocity thresholds (200–400°/s).The reflex effects of chordotonal organ stimulation upon a number of uropod motor neurones are weak. Repetitive stimulation of the chordotonal organ at 850°/s produces a small reduction in the firing frequency of the reductor motor neurone. Injecting depolarizing current into ascending or non-spiking local interneurones that receive direct chordotonal input produces a similar inhibition. 相似文献
2.
T. Nagayama M. Sato 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,172(3):281-294
The organization of exteroceptive inputs to identified ascending interneurones of the crayfish, Procambarus clarkii (Girard), has been analyzed by stimulation of hairs on the uropod and simultaneous intracellular recordings from ascending interneurones. The spikes of single afferent neurones which innervated hairs on the distal ventral surface of the exopodite were consistently followed by a depolarizing synaptic potential in many identified ascending interneurones with a constant and short central delay of 0.7–1.5 ms. The amplitude of the potentials depended on the membrane potential of the ascending interneurones. Each afferent neurone made divergent outputs onto several ascending interneurones and each ascending interneurone received convergent inputs from several afferent neurones. Certain ascending interneurones made inhibitory or excitatory connections with other ascending interneurones. These central interactions were always one-way, and the spikes from one ascending interneurone consistently evoked excitatory or inhibitory post-synaptic potentials in other interneurones which followed with a constant and short latency of 0.7–1.0 ms. The inhibitory postsynaptic potential was reversed by injection of steady hyperpolarizing current.Abbreviations EPSP
excitatory post-synaptic potential
- IPSP
inhibitory post-synaptic potential 相似文献
3.
T. Ushizawa T. Nagayama M. Takahata 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,179(1):1-13
Electrical stimulation of mechanosensory afferents innervating hairs on the surface of the exopodite in crayfish Procambarus clarkii (Girard) elicited reciprocal activation of the antagonistic set of uropod motor neurones. The closer motor neurones were excited while the opener motor neurones were inhibited. This reciprocal pattern of activity in the uropod motor neurones was also produced by bath application of acetylcholine (ACh) and the cholinergic agonist, carbamylcholine (carbachol). The closing pattern of activity in the uropod motor neurones produced by sensory stimulation was completely eliminated by bath application of the ACh blocker, d-tubocurarine, though the spontaneous activity of the motor neurones was not affected significantly. Bath application of the acetylcholinesterase inhibitor, neostigmine, increased the amplitude and extended the time course of excitatory postsynaptic potentials (EPSPs) of ascending interneurones elicited by sensory stimulation. These results strongly suggest that synaptic transmission from mechanosensory afferents innervating hairs on the surface of the tailfan is cholinergic.Bath application of the cholinergic antagonists, dtubocurarine (vertebrate nicotinic antagonist) and atropine (muscarinic antagonist) reversibly reduced the amplitude of EPSPs in many identified ascending and spiking local interneurones during sensory stimulation. Bath application of the cholinergic agonists, nicotine (nicotinic agonist) and oxotremorine (muscarinic agonist) also reduced EPSP amplitude. Nicotine caused a rapid depolarization of membrane potential with, in some cases, spikes in the interneurones. In the presence of nicotine, interneurones showed almost no response to the sensory stimulation, probably owing to desensitization of postsynaptic receptors. On the other hand, no remarkable changes in membrane potential of interneurones were observed after oxotremorine application. These results suggest that ACh released from the mechanosensory afferents depolarizes interneurones by acting on receptors similar to vertebrate nicotinic receptors.Abbreviations
ACh
cetylcholine
-
mns
motor neurones
-
asc int
ascending interneurone 相似文献
4.
M. Burrows H. J. Pflüger 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,171(4):437-446
Summary The output connections of a bilaterally symmetrical pair of wind-sensitive interneurones (called A4I1) were determined in a non-flying locust (Schistocerca gregaria). Direct inputs from sensory neurones of specific prosternai and head hairs initiate spikes in these interneurones in the prothoracic ganglion.The interneurone with its axon in the right connective makes direct, excitatory connections with the two mesothoracic motor neurones innervating the pleuroaxillary (pleuroalar, M85) muscle of the right forewing, but not with the comparable motor neurones of the left forewing. The connections can evoke motor spikes.The interneurones also exert a powerful, but indirect effect on the homologous metathoracic pleuroaxillary motor neurones (muscle 114), and a weaker, indirect effect on subalar motor neurones of the hindwings. No connections or effects were found with other flight motor neurones, or motor neurones innervating hindleg muscles, including common inhibitor 1 which also innervates the pleuroaxillary muscle.One thoracic interneurone with its cell body in the right half of the mesothoracic ganglion and with its axon projecting ipsilaterally to the metathoracic ganglion receives a direct input from the right A4I1 interneurone.These restricted output connections suggest a role for the A4I1 interneurones in flight steering.Abbreviations
DCMD
descending contralateral movement detector
-
EPSP
excitatory postsynaptic potential
-
TCG
tritocerebral commissure giant (interneurone) 相似文献
5.
T. Nagayama M. Araki P. Newland 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2002,188(8):621-630
The uropods of decapod crustaceans play a major role in the production of thrust during escape swimming. Here we analyse the output connections of a pair of giant interneurones, that mediate and co-ordinate swimming tail flips, on motor neurones that control the exopodite muscles of the uropods. The lateral giants make short latency output connections with phasic uropod motor neurones, including the productor, the lateral abductor and adductor exopodite motor neurones that we have identified both physiologically and anatomically. On the other hand, tonic motor neurones, including the ventral abductor and reductor exopodite motor neurones, receive no input from the lateral giants. We show that there is no simple reciprocal activation of the phasic opener (lateral abductor) and closer (adductor) motor neurones of the exopodite, but instead both phasic motor neurones are activated in parallel with the productor motor neurone during a tail flip. Our results show that the neuronal pathways activating the tonic and phasic motor neurones of the exopodite are apparently independent, with phasic motor neurones being activated during escape movements and tonic motor neurones being activated during slow postural movements. 相似文献
6.
H. Adelsberger J. Dudel 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,180(1):53-61
Whereas the inhibitory innervation of the deep extensor abdominal muscle in crayfish is mediated by a weakly acting common
inhibitor, the opener muscle exhibits a stronger inhibition. In the present study the most abundant γ-aminobutyric acid-activated
chloride channel on distal fibers of crayfish opener muscle was characterized by measuring the current responses after applying
pulses of γ-aminobutyric acid to outside-out patches. The results were compared to those obtained earlier with the chloride
channel on the deep extensor abdominal muscle of the same species. The double logarithmic plot of the dose-response relationship
had a slope of n
H = 2.2 in contrast to n
H = 5.3 for the channel on the deep extensor abdominal muscle. The rise time of the current response declined to 1 ms at a
γ-aminobutyric acid concentration of 50 mmol · l−1. With lower concentrations the rise time increased to a maximal value of 280 ms. No peak of the rise time at low γ-aminobutyric
acid concentrations, as observed for the channel on the deep extensor abdominal muscle, was obvious. The open and closed times
were similar to those of the channel of the deep extensor abdominal muscle. Different reaction schemes were discussed to describe
the kinetics of the chloride channel of the opener muscle.
Accepted: 12 August 1996 相似文献
7.
T. Friedel F. G. Barth 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):223-233
Spiders can use air particle movements to localize moving prey. We studied the responses of 32 wind-sensitive interneurones
in the hunting spider Cupiennius salei to prey stimuli.
Stimulation with a tethered flying fly or with artificial air pulses activated plurisegmental interneurones that responded
to changes in air movement velocity and were thus well suited to represent the highly fluctuating air stream typical of prey
stimuli. In most interneurones (n = 18) the responses to the stimulation of different legs were not significantly different from each other.
Different interneurones had different response characteristics and their latencies largely overlapped suggesting that there
is parallel processing of the signals by populations of interneurones with different response characteristics.
In two interneurones the number of spikes and the spiking pattern elicited by stimulation of each of the eight legs markedly
differed depending on the leg stimulated. These neurones may play an important role in directional information processing.
Stimulation of the adjacent legs from front to back or from back to front revealed two interneurones sensitive to the direction
of successive stimulation of the legs. These neurones may be able to detect the motion of an air movement source in a preferred
direction and thus act as nearfield motion detectors to localize a moving prey item.
Accepted: 28 September 1996 相似文献
8.
G. J. Laurent M. Burrows 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,162(5):563-572
Summary Tactile stimulation of a leg of the locustSchistocerca gregaria can lead to specific reflex movements of that leg. At the same time nonspiking interneurones that are presynaptic to the participating motor neurones are excited or inhibited, suggesting that they are directly involved in these reflexes. The afferent pathways mediating these effects have been examined by recording from individual afferents and nonspiking interneurones.Afferent spikes fromtrichoid orcampaniform sensilla on specific regions of a leg evoke chemically-mediated EPSPs with a constant central latency of about 1.5 ms in certain nonspiking interneurones. The branches of an interneurone and the afferents from which it receives inputs overlap in the neuropil of the ganglion.No afferents have been found to evoke IPSPs directly in the nonspiking interneurones. Instead the inhibition is caused by a population of spiking local interneurones that are themselves excited directly by the afferents, and whose spikes evoke IPSPs in certain nonspiking interneurones.The tactile reflexes can involve movements about one or more joints of the leg, and these coordinated responses are explained by the participation of specific nonspiking interneurones that distribute the sensory inputs to the appropriate sets of motor neurones. For example, when hairs on the dorsal surface of a tarsus are touched, the tarsus is levated. This reflex involves nonspiking local interneurones which are excited directly by these hair afferents and which make direct excitatory connections with the single levator tarsi motor neurone. 相似文献
9.
E. Kalogianni M. Burrows 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,178(6):735-748
The neural pathways underlying the processing of signals from locust (Schistocerca gregaria) ovipositor hairs by different classes of interneurones are investigated.Spikes in the sensory neurones from these hairs evoke chemically-mediated, unitary EPSPs with a short and constant latency in six identified non-giant projection interneurones with cell bodies in the terminal abdominal ganglion. Five of these interneurones receive direct inputs from the valves ipsilateral to their neuropilar branches, whereas the other receives direct inputs from valves on both sides. The sensory neurone from a single hair makes divergent connections with several interneurones and those from different hairs make convergent connections with a given interneurone. The amplitude of the EPSPs evoked depends on the position of a hair along the proximal-distal axis of the valve, with sensory neurones from more distal hairs generating larger amplitude EPSPs.Deflection of hairs also excites three of the four giant projection interneurones through polysynaptic pathways and some local interneurones in the terminal abdominal ganglion through monosynaptic connections. Branches of non-giant projection interneurones, local interneurones, but not those of the giant interneurones, overlap the axon terminals of the ovipositor hair afferents in the terminal abdominal ganglion. 相似文献
10.
A. K. Tryba H. B. Hartman 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):215-221
Receptors monitoring muscle force innervate the opener muscle apodeme in the walking legs of the blue crab, Callinectes sapidus. Biocytin backfills reveal 9–15 bipolar neurons with somata as large as 60 μm positioned at the distal end of the apodeme.
Sensory endings insert into the apodeme and are in series with the opener muscle. The axons of these neurons form the opener
apodeme sensory nerve that merges with the most distal branch of the opener motor nerve. Recordings reveal that the receptors
are not spontaneously active nor do they respond to passive muscle stretch. Isometric muscle contraction evoked by stimulating
the opener excitor motor neuron is the adequate stimulus for receptor firing. Most significant is the finding that during
contraction, over a wide range of forces, the firing rate of individual receptors closely parallels the rate of change of
isometric force. The peak instantaneous frequency typically occurs at the force derivative maximum, but not at maximum force
development. Thus, receptors of the opener apodeme sensory nerve more closely monitor changes in isometric force rather than
the total force achieved.
Accepted: 20 September 1996 相似文献
11.
Peter J. Simmons F. Claire Rind 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):203-214
The LGMD2 belongs to a group of giant movement-detecting neurones which have fan-shaped arbors in the lobula of the locust
optic lobe and respond to movements of objects. One of these neurones, the LGMD1, has been shown to respond directionally
to movements of objects in depth, generating vigorous, maintained spike discharges during object approach. Here we compare
the responses of the LGMD2 neurone with those of the LGMD1 to simulated movements of objects in depth and examine different
image cues which could allow the LGMD2 to distinguish approaching from receding objects. In the absence of stimulation, the
LGMD2 has a resting discharge of 10–40 spikes s−1 compared with <1 spike s−1 for the LGMD1. The most powerful excitatory stimulus for the LGMD2 is a dark object approaching the eye. Responses to approaching
objects are suppressed by wide field movements of the background. Unlike the LGMD1, the LGMD2 is not excited by the approach
of light objects; it specifically responds to movement of edges in the light to dark direction. Both neurones rely on the
same monocular image cues to distinguish approaching from receding objects: an increase in the velocity with which edges of
images travel over the eye; and an increase in the extent of edges in the image during approach.
Accepted: 23 October 1996 相似文献
12.
Nonspiking local interneurones are the important premotor elements in arthropod motor control systems. We have analyzed the synaptic interactions between nonspiking interneurones in the crayfish terminal (6th) abdominal ganglion using simultaneous intracellular recordings. Only 15% of nonspiking interneurones formed bi-directional excitatory connections. In 77% of connections, however, the nonspiking interneurones showed a one-way inhibitory interaction. In these cases, the presynaptic nonspiking interneurones received excitatory synaptic inputs from the sensory afferents innervating hairs on the surface of the uropods and the postsynaptic nonspiking interneurones received inhibitory synaptic inputs that were partly mediated by the inputs to the presynaptic nonspiking interneurones. The membrane hyperpolarization of the postsynaptic nonspiking interneurones mediated by the presynaptic nonspiking interneurones was reduced in amplitude when the hyperpolarizing current was injected into the postsynaptic interneurones, or when the external bathing solution was replaced with one containing low calcium and high magnesium concentrations. The role of these interactions in the circuits controlling the movements of the terminal appendages is discussed.Abbreviations AL antero-lateral - epsp excitatory postsynaptic potential - ipsp inhibitory postsynaptic potential - PL postero-lateral 相似文献
13.
M. Burrows H. J. Pflüger 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,163(4):425-440
1. | Two campaniform sensilla (CS) on the proximal tibia of a hindleg monitor strains set up when a locust prepares to kick, or when a resistance is met during locomotion. The connections made by these afferents with interneurones and leg motor neurones have been investigated and correlated with their role in locomotion. |
2. | When flexor and extensor tibiae muscles cocontract before a kick afferents from both campaniform sensilla spike at frequencies up to 650 Hz. They do not spike when the tibia is extended actively or passively unless it encounters a resistance. The fast extensor tibiae motor neurone (FETi) then produces a sequence of spikes in a thrusting response with feedback from the CS afferents maintaining the excitation. Destroying the two campaniform sensilla abolishes the re-excitation of FETi. |
3. | Mechanical stimulation of a single sensillum excites extensor and flexor tibiae motor neurones. The single afferent from either CS evokes EPSPs in the fast extensor motor neurone and in certain fast flexor tibiae motor neurones which follow each sensory spike with a central latency of 1.6 ms that suggests direct connections. The input from one receptor is powerful enough to evoke spikes in FETi. The slow extensor motor neurone does not receive a direct input, although it is excited and slow flexor tibiae motor neurones are unaffected. |
4. | Some nonspiking interneurones receive direct connections from both afferents in parallel with the motor neurones. One of these interneurones excites the slow and fast extensor tibiae motor neurones probably by disinhibition. Hyperpolarization of this interneurone abolishes the excitatory effect of the CS on the slow extensor motor neurone and reduces the excitation of the fast. The disinhibitory pathway may involve a second nonspiking interneurone with direct inhibitory connections to both extensor motor neurones. Other nonspiking interneurones distribute the effects of the CS afferents to motor neurones of other joints. |
5. | The branches of the afferents from the campaniform sensilla and those of the motor neurones and interneurones in which they evoke EPSPs project to the same regions of neuropil in the metathoracic ganglion. |
6. | The pathways described will ensure that more force is generated by the extensor muscle when the tibia is extended against a resistance. The excitatory feedback to the extensor and flexor motor neurones will also contribute to their co-contraction when generating the force necessary for a kick. |
14.
H. Gras D. Kohstall 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(3):351-361
Ascending interneurones of the terminal ganglion of orthopterous insects are known to carry information on wind stimuli perceived
by cercal receptors to thoracic and cephalic ganglia. Neurones of these anterior ganglia control evasive walking behaviour.
We demonstrate that current injection into individual wind-sensitive local non-spiking interneurones and ascending giant interneurones
of the terminal ganglion can influence the orientation behaviour of walking crickets. To induce a change of turning during
“wind puff stimulation” by current injection into the lateral giant interneurone, its spike activity has to be modified by
at least 100%. In 5 of 12 different types of non-spiking interneurones a moderate shift of the membrane potential results
in a change of the mean speed of rotation and/or the frequency of turns. All preparations tested with different amounts of
current injection showed a proportional change of turning frequency. Normally, the turning behaviour is evasive with respect
to the wind source. During current injection this dependence is preserved, but the general orientation is readjusted. Taking
into account known connections between some of these interneurones and ascending neurones the tested wind-sensitive local
non-spiking interneurones of the terminal ganglion are likely to impose an offset on the mean direction of orientation controlled
by cephalic and thoracic neuronal networks.
Accepted: 3 September 1997 相似文献
15.
J. Rohrbacher 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,175(5):619-628
Simultaneous intracellular recordings were made from interneurons and from closer or opener mandibular motor neurons in the isolated suboesophageal ganglion of the larva of Manduca sexta. This article describes various morphologically and physiologically distinguishable premotor spiking interneurons which make direct excitatory connections with the motor neurons. In addition, two presumptive non-spiking interneurons make excitatory and inhibitory connections respectively with opener motor neurons. Both classes of interneurons receive excitatory and inhibitory sensory inputs from the mouthparts. Their circuitry and functions are discussed.Abbreviations
A
anterior
-
AP
action potential
-
CEC
circumoesophageal connective
-
Cl-MN
closer motor neuron
-
EPSP
excitatory postsynaptic potential
-
IN
interneuron
-
IPSP
inhibitory postsynaptic potential
-
MdN
mandibular nerve
-
MN
motor neuron
-
MxN
maxillary nerve
-
O-MN
opener motor neuron
-
PSP
postsynaptic potential 相似文献
16.
Parallel effects of joint receptors on motor neurones and intersegmental interneurones in the locust
Gilles Laurent 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1987,160(3):341-353
Summary At the distal end of a mesothoracic tibia of the locust,Schistocerca gregaria, is a chordotonal organ which monitors the position and movement of the tarsus relative to the tibia. It contains approximately 35 receptors that variously encode different spatial and temporal parameters (position, velocity and direction of movement). Some excite intersegmental interneurones that respond phasically or tonically, with directional sensitivity to active or imposed movements of the tarsus. Some of these interneurones are also excited by intrinsic movements of the tarsal segments. Others, besides being excited by tarsal proprioceptive inputs, are also excited by exteroreceptors on the tarsus.When stimulated mechanically or electrically, chordotonal afferents evoke excitatory postsynaptic potentials with a central latency of between 0.9 and 1.4 ms simultaneously in the intersegmental interneurones and in tarsal motor neurones. The central arborizations of the afferents, the intersegmental interneurones and the tarsal motor neurones overlap in certain neuropilar regions of the mesothoracic ganglion. Other afferents cause an inhibition of the motor neurones, with a longer and non-consistent latency suggesting the involvement of other intercalated interneurones.These results indicate that proprioceptive inputs from the tarsal joint receptors are transmitted in parallel and monosynaptically to tarsal motor neurones and to the intersegmental interneurones. 相似文献
17.
A. Chrachri D. Neil B. Mulloney 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,175(3):371-380
The expression of both swimmeret and postural motor patterns in crayfish (Pacifastacus leniusculus) were affected by stimulation of a second root of a thoracic ganglion. The response of the swimmeret system depended on the state of the postural system. In most cases, the response of the swimmeret system outlasted the stimulus.Stimulation of a thoracic second root also elicited coordinated responses from the postural system, that outlasted the stimulus. In different preparations, either the flexor excitor motor neurones or the extensor excitor motor neurones were excited by this stimulation. In every case, excitation of one set of motor neurones was accompanied by inhibition of that group's functional antagonists.This stimulation seemed to coordinate the activity of both systems; when stimulation inhibited the flexor motor neurones, then the extensor motor neurones and the swimmeret system were excited. When stimulation excited the flexor motor neurones, then the extensor motor neurones and the swimmeret system were inhibited.Two classes of interneurones that responded to stimulation of a thoracic second root were encountered in the first abdominal ganglion. These interneurones could be the pathway that coordinates the response of the postural and swimmeret systems to stimulation of a thoracic second root.Abbreviations TSR
thoracic second root
- epsp
excitatory post-synaptic potential
- ipsp
inhibitory post-synaptic potential
- EJP
excitatory jonctional potential
- PS
power-stroke
- RS
return-stroke
- INT
interneurone
- N1
first segmental nerve
- N2
second segmental nerve
- N3
third segmental nerve
- A1
abdominal ganglion 1 相似文献
18.
William C. Lemon Richard B. Levine 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(6):597-610
During the metamorphosis of Manduca sexta the larval nervous system is reorganized to allow the generation of behaviors that are specific to the pupal and adult stages.
In some instances, metamorphic changes in neurons that persist from the larval stage are segment-specific and lead to expression
of segment-specific behavior in later stages. At the larval-pupal transition, the larval abdominal bending behavior, which
is distributed throughout the abdomen, changes to the pupal gin trap behavior which is restricted to three abdominal segments.
This study suggests that the neural circuit that underlies larval bending undergoes segment specific modifications to produce
the segmentally restricted gin trap behavior. We show, however, that non-gin trap segments go through a developmental change
similar to that seen in gin trap segments. Pupal-specific motor patterns are produced by stimulation of sensory neurons in
abdominal segments that do not have gin traps and cannot produce the gin trap behavior. In particular, sensory stimulation
in non-gin trap pupal segments evokes a motor response that is faster than the larval response and that displays the triphasic
contralateral-ipsilateral-contralateral activity pattern that is typical of the pupal gin trap behavior. Despite the alteration
of reflex activity in all segments, developmental changes in sensory neuron morphology are restricted to those segments that
form gin traps. In non-gin trap segments, persistent sensory neurons do not expand their terminal arbors, as do sensory neurons
in gin trap segments, yet are capable of eliciting gin trap-like motor responses.
Accepted: 10 January 1997 相似文献
19.
S. R. Soffe 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(6):711-715
Young Xenopus tadpoles were used to test whether the pattern of discharge in specific sensory neurons can determine the motor response
of a whole animal. Young Xenopus tadpoles show two main rhythmic behaviours: swimming and struggling. Touch-sensitive skin sensory neurons in the spinal cord
of immobilised tadpoles were penetrated singly or in pairs using microelectrodes to allow precise control of their firing
patterns. A single impulse in one Rohon-Beard neuron (= light touch) could sometimes trigger “fictive” swimming. Two to six
impulses at 30–50 Hz (= a light stroke) reliably triggered fictive swimming. Neither stimulus evoked fictive struggling. Twenty-five
or more impulses at 30–50 Hz (= pressure) could evoke a pattern of rhythmic bursts, distinct from swimming and suitable to
drive slower, stronger movements. This pattern showed some or all the characteristics of “fictive” struggling. These results
demonstrate clearly that sensory neurons can determine the pattern of motor output simply by their pattern of discharge. This
provides a simple form of behavioural selection according to stimulus.
Accepted: 28 November 1996 相似文献
20.
Dorsal unpaired median (DUM) neurones in the abdominal ganglia of the locust were impaled with microelectrodes and some were injected intracellularly with horseradish peroxidase so that their synapses could be identified in the electron microscope. Simultaneous recordings from DUM neurones in different abdominal ganglia revealed that they received common postsynaptic potentials from descending interneurones. Post-embedding immunocytochemistry using antibodies against GABA and glutamate was carried out on ganglia containing HRP-stained neurones. GABA-like immunoreactivity was found in 39% (n=82) of processes presynaptic to abdominal DUM neurones and glutamate-like immunoreactivity in 21% (n=42) of presynaptic processes. Output synapses from the DUM neurites were rarely observed within the neuropile. Structures resembling presynaptic dense bars but not associated with synaptic vesicles, were seen in some large diameter neurites. 相似文献