摘要:

AbstractThe electrical properties of the muscles of locust oviduct have been examined using intracellular recordings. The muscle cells are both dye and electrically coupled. They possess a wide array of spontaneous electrical activity ranging from slow oscillations of membrane potential to action potentials. In addition to possessing spontaneous electrical activity, certain regions of the oviduct are under motor control. The amplitude of evoked excitatory junction potentials (EJPs) increased step wise revealing innervation from a maximum of three motor units. These EJPs underwent summation and facilitation, and reached a critical threshold at which point the membrane revealed an active response. Bath applied glutamate, aspartate, proctolin, and octopamine were tested for their ability to alter resting potential and EJPs.L‐glutamate (1.6 × 10−5Mand above) produced a dose‐dependent depolarization of membrane potential accompanied by a reduction in amplitude of EJPs. AlthoughL‐aspartate resulted in similar effects, the concentrations required were higher than those for glutamate. Proctolin (6.3 ×−11M− 6.0 × 10−9M) resulted in a dose‐dependent depolarization but had little or no effect on amplitude of EJPs. Application ofD, L‐octopamine (3.2 × 10−5M− 1.7 × 10−4M) induced a small hyperpolarisation and a reduction in amplitude of EJP. It is suggested that contractions of locust oviduct appear to be regulated by a combination of a classical neurotransmitter such as glutamate, along with the neuromodulat

ISSN:0022-3034    

DOI:10.1002/neu.480170502

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe time course of the reaction to axotomy in the leech AP cell was determined by measuring the duration of the spontaneous spikes at different times after the operation. The axotomy performed by section of the segmental roots containing the AP axon induced an increase of the spike duration, which persisted over 30 days. A different time course was found when the axotomy was performed by nerve crush: the changes in duration of the spontaneous spikes, which occurred during the early 2 weeks, were significantly reduced afterwards. Dye staining of some cells axotomized by crushing revealed that the reversion of the changes, which had been set up by axotomy, was in some cases concomitant with the reconnection between proximal and distal axon stumps. The section of a single axonal branch was never sufficient to affect the membrane properties of the AP cells.It is concluded that the changes observed in axotomized AP cells are not produced by simple axonal injury and that the maintainance of normal properties in the somatic membrane requires the presence of at least part of the distal axon arborization.

ISSN:0022-3034    

DOI:10.1002/neu.480170503

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

年代:1986

数据来源: WILEY

摘要:

AbstractMicrotubule (MT) number, axonal area, and MT density were examined in unmyelinated axons of rat cervical vagus nerve. Study of nerve regions proximal (1–5 mm) and distal (35–40 mm) to the nodosum ganglion in controls (incubation at 37°C for 1 h) showed that the number of MT per axon is significantly less in distal than in proximal nerve regions. Cooling (incubation at 0°C for 1 h) caused a significant reduction in the number of MT per axon in both nerve regions. The unmyelinated axons from both nerve regions showed a comparable reduction in MT number by cooling, indicating that axonal MT stability to cold was not significantly different between these two nerve regions. In these nerves no detectable changes were found in cross‐axonal area of unmyelinated axons between distal and proximal nerve regions. In another experimental series, in distal nerve regions (35–40 mm from the nodosum ganglion) the number of MT was not further reduced in nerves incubated at 0°C by increasing the incubation time. Similar results were obtained from colchicine treated nerves (incubation at 37°C, with 10 mMcolchicine for 1 and 2 h). Distal nerve regions (35–40 mm from the nodosum ganglion) showed a similar reduction in the number of MT per axon when nerves were incubated at 0°C or with colchicine, suggesting that this drug, as well as cold, may be affecting a similar population of axonal MT, i.e., MT susceptible to anti‐MT agents. These results indicate that approximately one‐half of the axonal MT are stable to cold as well as to colchicine in rat

ISSN:0022-3034    

DOI:10.1002/neu.480170504

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

年代:1986

数据来源: WILEY

摘要:

AbstractA comparison of wind‐mediated escape behavior of two species of cockroaches revealed striking differences. In contrast toPeriplaneta americana, Blaberus craniiferwas unable to escape from a live predator or move away from a synthetically generated puff of wind. Other behavioral differences included degree of preference for areas of low light intensity and propensity to dig and thus bury oneself when disturbed. Anatomical differences, although present, did not seem sufficient to account for the behavioral differences. Also,B. craniiferwas able to escape from generated wind puffs but not a live predator when its temperature was raised. These points suggest that the behavioral differences in escape behavior can be attributed to differences in the physiological state of the two nervous system

ISSN:0022-3034    

DOI:10.1002/neu.480170505

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe sensilla on the male and female second swimmerets are sexually dimorphic. Female swimmerets contain many long “smooth hairs” (long simple setae) on the coxa and rami. The endopodite of the male swimmeret has an accessory lobe covered with short “bristly spines” (serrate setae). In both sexes the swimmeret rami are lined by “feathered hairs” (plumose setae). The influence of mechanosensory stimulation of these sensilla upon abdominal tonic motor activity was analyzed in an in vitro swimmeret‐nerve cord preparation. Movement of several clusters of smooth hairs produced an abdominal extension program by exciting the flexor inhibitor f5, inhibiting the flexor excitors, and activating several extensors. Stimulation of the male bristly spines excited the medium‐sized flexor excitors f3 and f4. In both sexes the feathered hairs did not generate any response to mechanical stimulation. We infer that in nongravid females the smooth hairs are involved in receiving mechanosensitive cues to support abdominal extension. Bristly spines may contribute to postural adjustments that assist mating. The long latencies of these responses and their propagation to adjacent ganglia suggest that they are mediated by postural interneurons rather than by direct afferent terminations on postu

ISSN:0022-3034    

DOI:10.1002/neu.480170506

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe present study shows that the drug 5,7‐dihydroxytryptamine (5,7‐diHT) can be used reliably to deplete the neurotransmitter serotonin (5‐HT) from the nervous system of the snailHelisoma. The depletion is more effective in axonal and synaptic regions (85–90%) than in the somata (55%), is reasonably specific for serotonin (dopamine is affected to a much lesser extent), and is transient, with normal levels of neurotransmitter being restored by 2 months. A physiological correlate of 5‐HT depletion has been shown in that an EPSP elicited by a cerebral serotonergic neuron (C1) onto a buccal motoneuron (B19) is much smaller during depletion and also recovers with time as 5‐HT regains normal concentration. Despite the severe 5‐HT depletion and physiological impairment, the gross morphology of neuron C1 remains indistinguishable from controls. Serotonergic depletion is not accompanied by development of receptor supersensitivity nor by the production of serotonin in extraneu

ISSN:0022-3034    

DOI:10.1002/neu.480170507

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe used the oxalate‐pyroantimonate method to demonstrate the ultrastructural distribution of calcium within rat sciatic nerve 4 h after a crush injury. In normal nerve there are discrete gradients of axoplasmic calcium precipitate with the amount of precipitate decreasing in the axoplasm beneath the Schmidt Lantermann clefts and in the paranodal regions at the node of Ranvier. Near the crush site a marked increase in endoneurial and intra‐axonal calcium precipitate correlated with morphologic evidence of axonal degeneration. More distant from the crush site, both in the distal segment destined to degenerate and in the proximal segment destined to regenerate, the most prominent finding was a loss of the normal gradient of precipitate beneath the Schmidt Lantermann clefts. The calcium influx at the crush site corresponds to the known role of calcium in triggering degeneration. The alterations in the distal axon may be an early stage leading to degeneration. Alteration in calcium distribution in the proximal nerve stump may play a role in the regulation of the response to inj

ISSN:0022-3034    

DOI:10.1002/neu.480170508

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe buccal motor system in the sea slugPleurobranchaea californicais multifunctional; similar sets of neurons and muscles generate different behaviors through similar electrophysiological motor patterns. Such multifunctional systems compromise the traditional practice of identifying a motor pattern and then using that pattern to indicate the behavior in reduced preparations. We address this issue in a series of experiments leading to the comparison of differential Pavlovian conditioning in whole animals with the conditioned behavior of the same animals during electrophysiological recording. Because differential conditioning requires two conditioned stimuli (CSs), we show here that each of two CSs activated the conditioned response from animals after they received the stimulus (CS+) paired with an unconditioned stimulus (UCS). Conditioning sessions consisted of 5 training trials with a 2‐h intertrial interval. In one study, experimental animals received a 60‐s CS+, derived from beer (Sbr), paired with a 50‐s electrical shock UCS whose onset occurred 10 s after the CS+onset; control animals received the Sbrand UCS explicitly unpaired. In a second study, animals received similar procedures as in the first but with a CS+consisting of squid homogenate (Ssq). Tests with both CSs showed that animals did not discriminate between Sbrand Ssqbefore beginning conditioning, but did so afterward. Experimental animals exhibited robust food aversion (withdrawal and suppressed feeding) to the CS+, but retained strong appetitive responses to the CS they did not receive in training; response thresholds to the CS+changed as much as 1000‐fold by comparison to the preconditioning values. Control animals exhibited similar though significantly smaller behavioral changes as the experimental animals. Both stimuli evoked associatively learned responses, but Sbrproduced greater experimental‐control differences than Ssqdid. Two accompanying papers show the results of using both CSs in differential conditioning, and describe the behavioral/electrophysiological co

ISSN:0022-3034    

DOI:10.1002/neu.480170509

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe present differential Pavlovian conditioning experiments on the sea slugPleurobranchaea californicaextend conditioning described in a preceding paper and provide the conditioning foundation for studies reported in another accompanying paper comparing learned behavior in whole animals with the behavior and motor patterns of electrophysiological preparations. All animals received two appetitive‐conditioned stimuli (CSs), one derived from beer (Sbr) and the other derived from squid muscle (Ssq), in different temporal relationships to an electric shock unconditioned stimulus (UCS). Two groups of animals were run concurrently. One group (n= 19) received Sbras the CS+in close temporal pairing with the UCS, and Ssqas the CS−explicitly unpaired with the UCS (Sbr+/Ssq−). The second group (n= 20) received the opposite contingencies (Sbr−/Ssq+). All animals received only one day of conditioning involving 5 trials with an intertrial interval of 2 h. There were two replicate experiments, each involving about half of the totaln, and each yielding similar results as the sum we report here. Before conditioning, animals exhibited feeding behavior (extension of the proboscis and bite‐strike responses) to both stimuli at similar low thresholds. Conditioning produced long‐term behavioral changes in all animals throughout the 4.5‐day postconditioning observation period. However, only the Sbr+/Ssq−animals consistently exhibited the appropriate differentially conditioned food‐aversion behavior which consisted of strong withdrawal and high‐threshold feeding responses to Sbr, and low‐threshold feeding responses to Ssq. We discuss the possibility that such differences between Sbr+/Ssq−and Sbr−/Ssq+conditioning may arise either from inherent differences in the responses of the animals to Sbrand Ssq, or, as seems more likely to us, from training and testing effects produced by differences in the compos

ISSN:0022-3034    

DOI:10.1002/neu.480170510

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe present study compares differential Pavlovian conditioning in whole animals with the behavior of the same animals during electrophysiological recording. Untrained specimens of the sea slugPleurobranchaeadid not discriminate between two appetitive stimuli, one derived from an extract of beer (Sbr) and the other from a homogenate of squid muscle (Ssq). When animals received Sbras the CS+and Ssqas the CS−in a single day of five‐trial, differential Pavlovian conditioning they learned to avoid selectively the Sbrbut continued to exhibit appetitive responses to Ssq. Quantitative measures show that there was over a 1000‐fold increase in the thresholds of the proboscis extension and bite‐strike responses, many animals ceased all feeding behavior, and exhibited withdrawal responses to Sbr. We examined the behavior of the same trained animals immediately before preparing them for physiological recording and during the recording session. There was a close one‐to‐one relationship between these behavioral observations, showing that the qualitative and quantitative features of whole‐animal Pavlovian conditioning persist into the physiological preparations. Unexpectedly, motor patterns from untrained preparations showed considerable variability both within the same preparation at different times and between preparations; conditioning appeared to increase such variability. Thus, it was not possible to state unequivocally the behavior of the animal by examining the electromyogram recording alone. Many of the trained preparations not only exhibited suppressed feeding behavior and withdrawal responses to Sbr, but, as a consequence of the multifunctional nature of thePleurobranchaeabuccal‐oral system, also regurgitated previously ingested Ssqor squid meat when they were stimulated with Sbr. We discuss the findings with respect to self‐organizing mechanisms that may establish motor patterns in multifunctional systems, and suggest that such mechanisms may lead to the generation of behaviors that are not specifically encoded by the conditioned

ISSN:0022-3034    

DOI:10.1002/neu.480170511

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

年代:1986

数据来源: WILEY