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1.
Locusts (Locusta migratoria) were stimulated with pulses of pure tones of frequencies between 5 kHz and 25 kHz. Interneurons responding to these stimuli (auditory interneurons) were recorded intracellularly and identified by dye injection. Their output functions were investigated by injection of depolarizing current during simultaneous registration of components of flight steering behavior of the animals, i.e. movements of the head and the abdomen and flight activity. Three different types of effects were found, corresponding to 3 functional classes of interneurons:
(1)  Auditory interneurons in the metathoracic ganglion can activate (Fig. 1) or inhibit (Fig. 2) the flight oscillator when depolarized.
(2)  Resting tethered locusts can perform lateral bending of the abdomen and, less prominent, head turns towards the sound source at frequencies between 5 and 15 kHz and at high intensities (70 dB and up, Fig. 3). Auditory interneurons were found which are sensitive to sound pulses with frequencies of 5 kHz to 15 kHz and some of them are directional (Fig. 4). Injection of depolarizing current into these cells causes movements of head and abdomen to the same side (Figs. 6, 7).
(3)  A third population of metathoracic and abdominal interneurons is also excited by pure tone pulses (Figs. 9, 11, 12). Current injected into these cells, and into a descending auditory interneuron (Fig. 8) results in spike activity, driving the head and the abdomen in opposite directions. These movements are components of the characteristic steering behavior seen in the negatively phonotactic response to pulsed ultrasound of intact tethered animals, which is thought to be involved in bat avoidance (Robert 1989).
The frequency responses of the interneurons and their output effects are discussed in the context of two basically different behaviors: a positive phonotaxis, which might be used during intraspecific communication, and an avoidance steering behavior to escape hunting bats.  相似文献   

2.
1.  The activity of tympanal high- and low-frequency receptors in the migratory locustLocusta migratoria was recorded with glass capillary microelectrodes, and Lucifer Yellow was then injected through the microelectrode to reveal the cells' metathoracic projections.
2.  A photodetector device was used to monitor the abdominal respiratory movements, which caused clearly visible deflections of the tympanal membrane.
3.  The auditory receptors respond not only to sound stimuli but also to the respiratory movements; these phasic (Figs. 1–3) or tonic (Fig. 4) responses are especially pronounced during the inspiration and expiration movements, and less so during the constriction phases.
4.  The magnitude of the response to sound depends on the phase of the stimulus with respect to the respiratory movements. At certain phases sound elicits no response at all (Fig. 5).
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3.
Summary The activity of flight interneurons was recorded intracellularly in intact, tethered flying locusts (Locusta migratoria) and after removal of sensory input from the wing receptors. Depolarization patterns and spike discharges were characterized and compared for the two situations.In general, depressor interneurons (n=6) showed only minor changes in their activity as a result of deafferentation (Fig. 1). Exceptions were interneurons 308 and 506 (Fig. 2). By contrast, all but one of the elevator interneurons (n=9) produced distinctly different depolarization patterns in intact locusts and following deafferentation. Three different groups of elevator interneurons were found (excluding the one exceptional neuron, Fig. 6). (i) One group of interneurons (n=4) produced different, superthreshold depolarizations in intact and deafferented animals (Fig. 3). Characteristic, biphasic depolarizations were recorded from these fibres at lower wingbeat frequencies in the intact situation but only single, delayed potentials were recorded after deafferentation. (ii) The second group of interneurons (n=3) exhibited distinct rhythmic activity only in intact animals. After deafferentation their depolarizations were small and often below the threshold for spike initiation (Fig. 4). (iii) One interneuron produced rhythmic flight motor oscillations only after deafferentation. In intact locusts the membrane potential of this neuron showed very small oscillations and remained subthreshold (Fig. 5).Four main conclusions emerge from these data. (i) The activity of elevator interneurons is under greater sensory control than that of the depressors. This confirms the results of our previous electromyographic and motoneuronal analyses, (ii) A considerable portion of elevator activity is generated as a result of phasic sensory feedback. An essential input is from the hindwing tegulae (Table 1; Pearson and Wolf 1988). (iii) The activity of depressor interneurons appears to be determined by central mechanisms to a major extent. (iv) Different sets of central neurons appear to be involved in flight pattern generation in intact and deafferented locusts —although the two sets share many common elements.Abbreviations EMG electromyogram - PSP postsynaptic potential (EPSP excitatory andIPSP inhibitory)  相似文献   

4.
1.  Locusts (Locusta migratoria) flying under open-loop conditions respond to simulated course deviations (movements of an artificial horizon around the roll axis) with compensatory head movements and with steering reactions of wing muscles (Figs. 3, 4). Steering was quantified as shifts of the relative latency between spikes in the left and right M97 (first basalar muscle). For practical reasons these shifts are a more useful measure than corrective torque itself, to which they are linearly proportional over much of the range (Fig. 2).
2.  Steering in M97 is elicited visually (horizon movement) and by proprioceptive input reporting head movements (neck reflexes). Compensatory head movements reduce the strength of steering because the reduction in visual information signalling deviations is only partially balanced by proprioceptive input from the neck (Fig. 4C).
3.  Under closed-loop conditions, flying locusts stabilize the position of an artificial horizon against a constant bias (Figs. 5–7), the horizon oscillating slightly along the normal orientation. Head movements do not follow the horizon movements as closely as under open-loop conditions, but on average head movements are compensatory, i.e. the mean mismatch between head and horizon is less than the mean mismatch between body and horizon.
4.  The horizon position is stabilized when the head is free to move, but also when the head is immobilized. In the latter case the oscillations along the straight flight path are more pronounced (Fig. 7), indicating that the reduction of steering by compensatory head movements (as seen under open-loop conditions, Fig. 4C) reduces overshoot.
5.  The control and the significance of (compensatory) head movements for course control are discussed.
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5.
1.  Some units in the lateral ocellar nerves of the locust,Locusta migratoria, are influenced transsynaptically by the activity of ascending fibres in the thoracic connectives and therefore may be efferent to the afferent ocellar system.
2.  A variety of sensory inputs excite the ocellar nerve units, including illumination of the compound eyes, active and passive movement of the wings, wind stimuli to the thorax and sound.
3.  Most ocellar interneurons are influenced transsynaptically by electrical stimulation of the cervical connectives. L-neurons are depolarized and the components of their response to a rectangular light pulse are changed in amplitude. Only a few S-neurons could be examined. All of them were excited directly or indirectly.
4.  The descending ocellar interneurons (DN's) are influenced by stimulation of the contralateral connective, perhaps via efference to the ocellus or to ocellar L-cells.
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6.
1.  We studied the response of plurisegmental interneurons in the suboesophageal ganglionic mass of female spiders (Cupiennius salei) to male vibratory courtship signals.
2.  The opisthosomal vibrations (low frequency component) and the pedipalpal percussions (high frequency component) are processed in parallel by interneuron type I and type II, respectively (Figs. 3, 7).
3.  Type III, IV and V interneurons represent the macrostructure of the male courtship signals (Figs. 8, 9, 10), i.e. the beginning and the end of a series (type III, V) or the end of the series only (type IV). The macrostructure is known to influence the response probability of the female. The spontaneous bursting activity of a type VI neuron undergoes slow and long lasting changes upon stimulation with natural courtship signals (Fig. 11).
4.  Many interneurons responded to natural signals but not to behaviourally effective computer models. This is presumably due to the lack of spectral complexity of the model compared to natural signals. Differences in the natural conspecific and heterospecific signals, however, are represented by the neuronal response (Fig. 3).
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7.
1.  The oscillations of the tympanal membrane of Locusta migratoria were analysed by combined laser vibrometry and interferometry. Simultaneously the activity in the tympanal nerve was recorded extracellularly. The animal was stimulated by sound pulses and one of the hindlegs was passively moved in a sinusoidal manner simulating stridulation. These stimuli were applied separately and in combination.
2.  Sound stimulation elicited high-frequency membrane oscillations, whereas leg movements induced slow rhythmic membrane displacements. During combined sound and movement stimulation these two types of oscillations superimposed without mutual interference.
3.  The tympanal nerve responded to sound with well synchronized receptor activity. The leg movement elicited less synchronized, phase-coupled activity. During combined sound and movement stimulation the responses to the two types of stimuli interfered strongly.
4.  The activity patterns of single receptor fibres and auditory interneurons were reanalysed from this point of view. The extent of synchronization of the receptors is found to be the major difference between the sound-induced and the movement-induced activation of the auditory system. A filter mechanism is postulated, consisting in the activation of some higher order auditory interneurons only by well-synchronized presynaptic activity, such as is induced by steeply rising sound pulses.
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8.
Locusts (Locusta migratoria) were flown in a flight simulator which converts yaw torque into angular motion of the visual environment (Fig. 1). The modalities and the time-course of steering behavior under these closed-loop conditions have been investigated.
1.  Locusts flying under visual closed-loop conditions stabilize their visual environment by performing correctional steering manoeuvres. Besides torque production, due to differential wing movements and ruddering, correctional steering also involves head movements (Fig. 6).
2.  During open-loop steering, ruddering and yaw torque begin some 60 ms after the onset of the visually simulated deviation from course. Head movements occur some 90 ms after stimulus onset, i.e. some 30 ms later than yaw torque (Figs. 3, 5) and therefore do not initiate thoracic steering outputs.
3.  Open- and closed-loop correctional steering do not differ in their behavioral components or temporal organization (Figs. 2, 6, Table 1).
4.  In the absence of major disturbances, correctional steering under closed-loop conditions is performed with minimal ruddering (only a few degrees in amplitude), that probably produces little or no aerodynamic drag (Fig. 6).
5.  Locusts prevented from moving their heads still stabilize their visual environment in the closed-loop situation. However, the precision of steering is affected by this constraint (Figs. 8, 9, 10, 12). Head immobilization also alters the temporal coordination of correctional steering (Figs. 7, 11).
6.  These results show that head movements, in addition to their generally accepted role in vision improvement, also contribute to the precision and temporal coordination of correctional flight manoeuvres. The mechanism is partly via proprioceptive feedback.
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9.
1.  Coordinated movements of the wings during flight in the locust result from coordinated activity of flight neurons in the thoracic ganglia. Many flight interneurons and motoneurons fire synchronous bursts of action potentials during the expression of the flight motor pattern. The mechanisms which underlie this synchronous firing were investigated in a deafferented preparation of Locusta migratoria.
2.  Simultaneous intracellular recordings were taken from flight neurons in the mesothoracic ganglion using glass microelectrodes filled with fluorescent dye.
3.  Three levels of synchronous activity between synergistic motoneurons and between the right and left partners of bilaterally symmetrical pairs of interneurons were observed: bursting which was loosely in phase but which showed little correlation between the temporal parameters of individual bursts in the two neurons; bursting which showed synchrony of the beginning and end of bursts; and bursts which showed highly synchronous spike-for-spike activity.
4.  Direct interactions between the neurons had little or no part to play in maintaining any of the levels of synchrony, even in instances of very close synchrony (spikes in different neurons occurring within 1 ms of each other). Highly synchronous firing was a consequence of common synaptic input impinging on neurons with similar morphological and physiological properties.
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10.
1.  In order to understand the functional organization of the crustacean olfactory system, we are using intracellular recording and staining techniques to correlate the structure and function of single, odorant-sensitive interneurons in the brain of the crayfishProcambarus clarkii. We describe here the anatomy and physiology of interneurons that connect the brain with the medullae terminales or other eyestalk ganglia.
2.  All of the interneurons in our study (Table 1, Figs. 3–15) are at least third-order olfactory neurons (second-order olfactory interneurons) because they respond to chemostimulation of the olfactory organ (the antennules) but do not branch in the olfactory lobe (the neuropil to which primary olfactory receptor cells of the antennules project).
3.  Much of the central nervous system, including the three main divisions of the brain (protocerebrum, deuterocerebrum, tritocerebrum) (Fig. 1) and the medullae terminales (Fig. 2), are involved in integrating olfactory or multimodal (including olfactory) information, since these areas contain neurites of olfactory interneurons. Previous studies have indicated that regions involved in such processing include the olfactory lobes and accessory lobes of the deuterocerebrum, and regions I, II, IV, and VII (in some species) of the medullae terminales. Our results show that also prominent among regions involved in olfactory or multimodal (including olfactory) integration are the anterior and posterior optic neuropils of the protocerebrum (Figs. 3–11, 14, 15), the lateral and medial antennular neuropils of the deuterocerebrum (Figs. 3, 4, 7), the tegumentary neuropils (Figs. 3, 4, 8, 11) and the antennal neuropils (Figs. 3–5) of the tritocerebrum, and neuropils III, VI, XII of the medullae terminales (Figs. 12, 13).
4.  These olfactory interneurons were sensitive to chemostimulation (unimodal), chemo- and mechanostimulation (bimodal), or chemo-, mechano-, and photostimulation (trimodal) (Table 1). Responses could be excitatory or inhibitory, even for a given neuron (Table 1). Morphologically complex interneurons (those having bilateral branching) were more likely to have complex response characteristics (trimodal sensitivity) (Figs. 8–12) than were morphologically simpler interneurons (those having unilateral branching) (Figs. 3–7, 14, 15). Olfactory interneurons with a soma in the medulla terminalis showed the most complex response profiles: they were trimodal, and were excited by odorants but were inhibited by touch and/or light (Figs. 12, 13). This finding suggests that these are complex, high order interneurons.
5.  Our studies reveal that olfactory and other sensory information is transmitted between the brain and the medullae terminales (and possibly other eyestalk ganglia) by a coactivated, parallel array of structurally and functionally diverse neurons.
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11.
1.  The terminal ganglion ofLocusta migratoria contains a number of non-giant, wind-sensitive, ascending and local interneurones. Six ascending (Figs. 1, 2) and 6 local (Figs. 6, 7) interneurones have been identified morphologically on the basis of intracellular stains with Lucifer Yellow.
2.  The physiological responses of the various cell types were recorded as the cerci were exposed to sound, wind, or electrical stimulation (Figs. 3, 8). Some cells summate the input from both cerci (Fig. 3), while others are excited by input from one side and inhibited by input from the other (Fig. 8). Conduction velocities for several non-giant ascending interneurones range from 1.5 m/s (cell 1) –2.1 m/s (cell 25).
3.  The morphologies and physiological responses of giant (GIN 1) and non-giant ascending interneurones (cells la, b) with somata in cluster 1 of neuromere 9 were compared using simultaneous intracellular recordings (Figs. 2A, 4). These neurones have very similar dendritic arborizations (Fig. 4A, B), and respond almost identically to cercal stimulation (Fig. 4Ci), but there do not appear to be any connections with GIN 1 (Fig. 4Cii, iii).
4.  The morphology (Fig. 5A, C), and response to cercal stimulation by wind (Fig. 5B) of a nongiant interneurone (cell 7) with its soma in cluster 1 of segment 8 (Fig. 5), are very similar to those of cluster 1 cells such as GIN 1 in segment 9.
5.  Of the 6 local interneurones (Figs. 6, 7) all except one (cell 9) have bilateral arborizations which may extend over several neuromeres within the ganglion (cells 10, 22). Several of the interneurones (cells 5, 9, 24) do not produce action potentials in response to cercal stimulation (Figs. 8, 10) or injection of depolarizing current (Fig. 11).
6.  Simultaneous recordings from pairs of interneurones demonstrate that giants and locals (GIN 2/cell 5; GIN 1/cell 9), as well as different local interneurones (cell 24/cell 5), receive input from the same wind-sensitive filiform afferent (Fig. 9).
7.  Local interneurones 5 and 22 are in different neuromeres of the terminal ganglion but have a similar gross morphology (Figs. 6, 7, 10). Cell 5, however, has arborizations projecting into both posterior cercal glomeruli (Fig. 7 A, inset), whereas only the ipsilateral branches of cell 22 extend posteriorly to the cercal glomerulus (Fig. 10C). Physiologically, cell 5 is depolarized by wind directed at both cerci (Fig. 10 A), cell 22 mainly by wind directed at the ipsilateral cercus (Fig. 10C). Cell 5 does not produce action potentials in response to wind whereas cell 22 does.
8.  Cell 5 occurs as a bilateral pair in the terminal ganglion (Figs. 7B, inset; 11). Simultaneous recordings of the bilateral homologues show that they share the input of at least one wind-sensitive filiform afferent (Fig. 11D), and that there are no connections between them (Fig. 11E). Simultaneous penetrations of local interneurone 5 and giant interneurones demonstrate a short-latency excitatory connection from GIN 3 to cell 5 (Fig. 12 A), and a long-latency excitatory connection from GIN 2 to cell 5.
9.  The roles of giant and non-giant interneurones in transmitting information to thoracic motor centres are discussed.
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12.
1.  Intracellular recordings of suboesophageal neurons were performed in the cricketGryllus bimaculatus during applied changes of head temperature in the range 8 to 32.5 °C. The temperature was controlled by perfusing the head with Ringer solution of appropriate temperature. Subsequent staining with Lucifer Yellow revealed descending, ascending or T-shaped cells with ventrally located somata (Fig. 1).
2.  In 6 out of 7 neurons recorded (Fig. 1, neurons A, B, C, D, E, G) the firing rate was correlated with abdominal ventilatory pumping (Fig. 2a, b). These neurons also received input from cereal sensory hairs (Fig. 2c). Furthermore, one of them (Fig. 1, neuron A) showed responses to auditory (Fig. 2d) and another (Fig. 1, neuron E) to visual input (Fig. 2e).
3.  Activity of every tested neuron was correlated with the temperature of the perfusing Ringer solution: the amplitude and duration of spikes and excitatory postsynaptic potentials increased with cooling (Fig. 3). Two types of temperature-dependent changes in firing rate were identified. In type I the spiking rate was higher at higher temperature (Figs. 4a, b; 5). In type II spiking rate was related to the direction of temperature change (Fig. 4c, d).
4.  The possible involvement of one of the recorded cells (Fig. 1, neuron F) in thermoreception processes is discussed. Activity of this neuron was not related to the rhythm of abdominal ventilatory pumping, nor did the cell receive cereal, visual or auditory input. Its activity was related mainly to the direction of temperature changes i.e. with an increase in firing rate during cooling, independent of the temperature at which the cooling started and with a transient decrease in firing rate during warming from starting point of 10 °C.
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13.
1.  An extracellular recording and staining technique has been used to study the structure of individual ventral-cord elements in the auditory pathway ofLocusta migratoria.
2.  Three groups of auditory ventral-cord neurons can be distinguished: (a) neurons ascending to the supraesophageal ganglion, (b) T-shaped neurons, and (c) neurons limited to the thoracic ventral cord.
3.  The ventral-cord neurons ascending to the supraesophageal ganglion link the auditory centers of the thorax to those of the supraesophageal ganglion. These are, at least in part, richly arborized neurons of large diameter.
4.  The ventral-cord neurons with T structure send equivalent signals along both arms of the T; they resemble the neurons of the first group in that they make synaptic connections in the supraesophageal ganglion, but they also conduct auditory information to caudal regions of the thorax via the descending trunk of the axon.
5.  In the supraesophageal ganglion there are several extensive projection areas of the auditory ventral-cord neurons. No direct connections to the mushroom bodies, the central body or the protocerebral bridge could be demonstrated.
6.  The thoracic ventral-cord neurons act as short segmental interneurons, providing a connection between the tympanal receptor fibers and the ascending and T-shaped ventral-cord neurons. They play a crucial role in auditory information processing.
7.  The possible functional properties of the various morphological sections of the auditory ventral-cord neurons are discussed, with reference to their connections with motor and other neuronal systems.
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14.
Details are given of techniques for preparing surface spreads of locust spermatocytes for light and electron microscopy. The pachytene synaptonemal complex (SC) karyotypes of Locusta migratoria and Schistocerca gregaria are analysed and compared. Up to six different SCs can be identified in Locusta migratoria based on lengths, centromere positions, and possession of nucleolar organiser regions, but only two SCs are identifiable in Schistocerca gregaria. The total SC length is significantly greater in Schistocerca gregaria than in Locusta migratoria, and this difference is almost exactly proportional to the difference in the genomic DNA contents of the two species.  相似文献   

15.
This paper describes the morphology and response characteristics of two types of paired descending neurons (DNs) (classified as DNVII1 and DNIV1) and two lobula neurons (HR1 and HP1) in the honeybee, Apis mellifera.
1.  The terminal arborizations of the lobula neurons are in juxtaposition with the dendritic branches of the DNs (Figs. 2, 3b, 5). Both of the DNs descend into the ipsilateral side of the thoracic ganglia via the dorsal intermediate tract (Fig. 6) and send out many blebbed terminal branches into the surrounding motor neuropil (Figs. 3c, 7).
2.  Both the lobula and descending neurons respond in a directionally selective manner to the motion of widefield, periodic square-wave gratings.
3.  The neurons have broad directional tuning curves (Figs. 10, 11). HR1 is maximally sensitive to regressive (back-to-front) motion and HP1 is maximally sensitive to progressive (front-to-back) motion over the ipsilateral eye (Fig. 11). DNVII1 is maximally sensitive when there is simultaneous regressive motion over the ipsilateral eye and progressive motion over the contralateral eye (Fig. 12a). Conversely, DNIV1 is optimally stimulated when there is simultaneous progressive motion over the ipsilateral eye and regressive motion over the contralateral eye (Fig. 12b).
4.  The response of DNIV1 is shown to depend on the contrast frequency (CF) rather than the angular velocity of the periodic gratings used as stimuli. The peak responses of both regressive and progressive sensitive DNs are shown to occur at CFs of 8–10 Hz (Figs. 13, 14).
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16.
1.  The effects of chronic deafferentation, 3–180 days, are tested on the function and morphology of the crab (Carcinus maenas) ventilatory central pattern generator (CPGv). Almost all afferent axons are carried in the mixed sensory/motor levator nerve. The ability to speed the CPGv cycle rate by stimulating this nerve (Wilkens and DiCaprio 1994) decreases as the afferent neurons degenerate. Stimulation of the levator nerve eliminates motor units from the output even after 60 days of deafferentation, similar to the effects seen in acute preparations.
2.  The 3 oval organ afferent axons of the levator nerve have central somata and survive scaphognathectomy. Impulses carried by these axons are known to inhibit the CPGv in acutely deafferented preparations and they are believed to be responsible for the persistent inhibition following small afferent degeneration seen here.
3.  After 6 months of deafferentation the motor neuron collateral arborization densities within the thoracic ganglia are reduced, but all motor neurons appear to survive. These long-term deafferented CPGvs generate accurate motor patterns at similar rates to the control CPGv, but at reduced intraburst spike frequency. The crab CPGv is quite stable following chronic deafferentation.
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17.
Intracellular recordings and Lucifer-yellow fillings were used in a wandering spider,Cupiennius salei Keys., to identify central neuronal correlates of local reflex activity in muscle c2, which inserts on the leg coxa. Here we describe related neuronal elements in the hindleg neuromere of the fused, subesophageal-ganglion complex:
1.  Projectionsof primary sensory axons excited by hair deflection are confined to ventral parts of the ipsilateral leg-neuromere (Fig. 1); their central terminals end near longitudinal, interganglionic tracts.
2.  Two identified excitatorymotor neurons for muscle c2 (which is a promotor/adductor of the coxa) are also confined to the ipsilateral (hindleg) ganglion. The dendritic branches and the efferent axonal segment extend in regions well dorsal to the sensory projections (Fig. 2); we found neither morphological nor electrophysiological evidence for direct synaptic contacts between hair afferents and motor neurons (Fig. 3).
3.  Various types of identifiedinterneurons give responses correlated with the reflex. We classified them, by anatomical criteria, aslocal interneurons confined to the ipsilateral hindleg neuromere (Figs. 4, 5) and asplurisegmental interneurons arborizing in more than one neuromere (Figs. 6, 7, 8).
Although detailed electrophysiological tests of functional connections are not available for all these elements, we discuss how the various interneurons identified here may be involved in the local reflex response and in the coordinated, intersegmental reflex behavior that is observed when the unrestrained spider uses all 8 legs to raise its body (see the companion paper by Eckweiler and Seyfarth 1988).  相似文献   

18.
In response female pheromone the male gypsy moth flies a zigzagging path upwind to locate the source of odor. He determines wind direction visually. To learn more about the mechanism underlying this behavior, we studied descending interneurons with dye-filled micro-electrodes. We studied the interneuronal responses to combinations of pheromone and visual stimuli.
1.  We recorded 5 neurons whose directionally selective visual responses to wide field pattern movement were amplified by pheromone (Figs. 2–6).
2.  The activity of the above neurons was more closely correlated with the position of the moving pattern than with its velocity (Fig. 4).
3.  One neuron showed no clearly directional visual response and no response to pheromone. Yet in the presence of pheromone it showed directionally selective visual responses (Fig. 6).
4.  We recorded 4 neurons whose directionally selective visual responses were not modulated by pheromone (Fig. 7), ruling out the possibility that the effect of the pheromone was simply to raise the activity of all visual neurons.
5.  Our results suggest that female pheromone amplifies some neural pathways mediating male optomotor responses, especially the directionally selective responses to the transverse movement of the image, both below and above the animal.
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19.
The response characteristic of visual interneurons of the brain was studied in Locusta migratoria and Schistocerca gregaria. Alternating light and dark, moving dots, bars and striped patterns were used for stimulation (Fig. 3). These stimuli were recorded with a video system and replayed on TV-screens during the experiment to allow fast testing of the sensitivity of a neuron to different stimuli during the limited time of intracellular recording. Data were stored and analysed by computer. The neurons were anatomically identified by intracellular injection of Lucifer yellow. Neutral (non-visual) and several classes of spiking interneurons of the medulla and lobula sensitive to visual stimuli could be distinguished by anatomical and physiological characteristics (Figs. 1, 2). The visual cells respond either to light-on, or to light-off, flicker, moving small dots, bars or striped patterns (Figs. 2–6). One class is directionally sensitive to pattern movement either from back to front or into the reverse direction (horizontal cells; Figs. 7, 8) and may therefore be involved in optomotor flight control.Dedicated to Prof. Dr. Dietrich Burkhardt on the occasion of his 60th birthday  相似文献   

20.
1.  In an arena, female Acheta domesticus, which walked directly to a standard model calling song (CS) in a pretest, displayed angular deviations and complete 360° circling following unilateral occlusion of the posterior and anterior tympana. Following removal of the occlusion, the crickets once again oriented directly to the sound source (Fig. 1). Following unilateral removal of the tibia of a prothoracic leg just distal to the ear, crickets oriented directly to a standard CS. Unilateral leg amputation just proximal to the ear caused angular deviations and circling which was similar to that following occlusion of an ear (Fig. 2).
2.  Thresholds of auditory interneurons increased dramatically (to greater than 85 dB) following occlusion of the ear which provides excitatory input to these neurons. Removal of the occlusion restored responsiveness (Fig. 3).
3.  The mean number of complete turns by a cricket with one ear occluded is greatest in response to syllable periods that are most attractive and thus can be used as a measurement of the relative attractiveness of the CS presented (Figs. 4, 5). Females that did not significantly discriminate between different syllable periods before unilateral occlusion of an ear, discriminated between CS syllable periods by their degree of circling following occlusion.
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