摘要:

AbstractA general paradigm is described that permits testing the ability of an arthropod to learn (by operant conditioning) to alter the position of a single leg segment in order to relate to behaviorally appropriate reinforcement. The paradigm was designed so that intracellular recording from identified neurons involved would be possible during the training of a locust or grasshopper, for which extensive neuron maps are available. As a prelude to such studies, electromyograms were made from the antagonistic muscles that move the conditioned limb, which in the present experiments was the tibia of the metathoracic leg. Negative (aversive) reinforcement was provided by a loud sound/vibration and positive (reward) reinforcement by food in the form of sugar‐water or fresh‐growing grass. In the aversive reinforcement experiments the sound, which reflexly caused flexion, was on continually except when the tibia of one hind leg was voluntarily placed in an electronically set position “window” displaced, in extension, away from the preferred position. In feeding experiments, food was brought automatically to the mouth by a motor‐driven arm when the tibia was held within a position window set away from the preferred position in either extension or flexion. Whole or headless insects learned to turn off the sound permanently, except for sporadic brief interruptions, by tonic shifting of tibial position. Insects learned to bring food to the mouth by modifying the plateau phase of a position displacement lasting for a few minutes, that was found to occur from time to time also in controls. In aversive learning, minimum times to turn off the sound were 22 sec for the easiest position and 4 min for the most difficult. The longest time in the easiest position was 1 min 40 sec and in the most difficult 39 min; excluding measurement for individuals that did not learn. In reward learning, the minimum time in the easiest position was just under 1 min, and 12 min in the most difficult position. The longest times were about 8 hr regardless of d

ISSN:0022-3034    

DOI:10.1002/neu.480110402

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

年代:1980

数据来源: WILEY

摘要:

AbstractMice ranging in age from 16 to 44 days were injected intracerebrally with3H‐leucine, and incorporation into total brain proteolipids and the myelin proteolipid protein was measured. All proteolipids were isolated from whole brain by ether precipitation and separated into their individual components by SDS polyacrylamide gel electrophoresis. Two major proteolipids with apparent molecular weights of 20,700 and 25,400 were observed in these preparations, and their proportion increased over the developmental period examined. A Ferguson plot analysis comparing these proteins with those of isolated myelin showed that the 25,400‐dalton proteolipid component from whole brain was the myelin proteolipid protein. Rates of incorporation of3H‐leucine into total brain proteolipids peaked at 22 days of age. Synthesis of the myelin proteolipid protein increased rapidly to a maximum value at 22 days and decreased rather slowly until at 44 days it was about 83% of its maximum rate of synthesis. The data indicate that the developmental pattern of synthesis of the myelin proteolipid protein is unlike that of the myelin basic proteins. Synthesis of the major myelin proteins is developmentally asynchronous in that peak synthesis of the myelin proteolipid appears to occur several days later than the basic proteins. In addition, it maintains its maximum rate of synthesis over a longer period of time than do the basic pro

ISSN:0022-3034    

DOI:10.1002/neu.480110403

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe salivary neuroeffector system ofHelisomaconsists of the paired salivary glands and buccal ganglia. Previous work demonstrated that neuronal control was required for coordination of activity in the two salivary glands. This neuronal control is provided by a pair of identified buccal ganglion neurons, 4R and 4L. This study examines the organization of this neuronal control and addresses the questions of monosynaptic vs. polysynaptic pathways as well as the bilateral effects of each neuron 4. Action potentials in neuron 4 elicit one‐for‐one EPSPs in a subpopulation of the salivary cells. These EPSPs can, in some cases, be increased by TEA injection into a neuron 4 and are unaffected by the addition of six‐times normal calcium. These data coupled with the constancy of synaptic transmission, as well as morphological evidence, further indicate the monosynaptic nature of the connection between neurons 4 and salivary secretory cells. Three different mechanisms exist to insure that activity in 4R and 4L result in coordinated activation of the salivary glands: (1) Lucifer Yellow injection and direct intracellular recording and stimulation demonstrate that both 4R and 4L can send axons to and innervatebothsalivary glands; (2) both 4R and 4L receive virtually identical synaptic input from higher‐order buccal ganglion neurons; and (3) 4R and 4L are electrically coupled. Thus, the system is organized with a high degree of redundancy, and bilateral synchrony of glandular activity is assured by mechanisms at various levels of neuronal organ

ISSN:0022-3034    

DOI:10.1002/neu.480110404

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

年代:1980

数据来源: WILEY

摘要:

AbstractCrustacean neuromuscular synapses arising from a single excitor axon are known to be well differentiated among different muscle fibers but little is known about their condition along single fibers. Focal recording techniques were used to examine the quantal transmitter release and facilitation properties of synapses in the single excitatory innervated distal accessory flexor muscle of the lobster,Homarus americanus. Synapses were reliably differentiated with respect to quantal output so that those located near the tendon end were 1.15–4.12 times greater than those at the opposite, exoskeletal end (p<0.01, pairedt‐test). Regional differences were also seen in the amount of facilitation determined from twin pulse experiments. The fine structural basis for these differences was determined by serial section electron microscopy of 10‐μm segments at each end to ensure that the area of focal recording was sampled. No quantitative differences were found in the terminals or synapses in the two regions. Instead, the physiological diversity was correlated with number and size of presynaptic dense bars. Thus, the tendon end had a greater number and larger mean surface area of dense bars compared to the exoskeletal end. This heterogeneity of excitatory multiterminal innervation is correlated with the axonal branching pattern. Thus, the main axon and the larger primary axon branches lie in close proximity to the tendon end of the muscle fibers, whereas the exoskeletal end is innervated by smaller secondary and tertiary axonal branches. This proximity to the large axonal branches of the higher quantal output synapses at the tendon end may be regulated by some neural influence including a timing of innervation and/or access to greater amounts of metabolites in the larger branches which may be conducive to forming high‐output

ISSN:0022-3034    

DOI:10.1002/neu.480110405

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe electrotonically coupled network of about 100 neuroendocrine caudodorsal cells (CDC) of the freshwater snailLymnaea stagnalisexhibits three states of excitability with distinct electrophysiological characteristics. Transitions between these states occur spontaneously or can be induced experimentally. The CDC produce an ovulation hormone, and the excitability states are clearly related to the egg‐laying cycle of the snail. Two hours before egg laying, the cells enter an active state, which lasts one hour. This phase is characterized by a spontaneous firing pattern, which in preparations can be evoked as an afterdischarge, and during which the hormone is thought to be released. After this, the cells enter an inhibited state in which no other activity than directly stimulus‐dependent ortho‐ and antidromic action potentials can be evoked. This phase lasts till about four hours after egg laying. The subsequent resting state is characterized by facilitation of the responses upon repetitive stimulation of the cells, leading to depolarization of the network and additional action potentials. In this phase, an afterdischarge can be evoked, which brings the cells into the active stage

ISSN:0022-3034    

DOI:10.1002/neu.480110406

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

年代:1980

数据来源: WILEY

摘要:

AbstractMutations that eliminate circadian rhythmicity in two species ofDrosophilaaffect the location of cells in a neurosecretory cell group. This is the first example of mutations which affect the morphology of an identifiable cell group in theDrosophilabrain.

ISSN:0022-3034    

DOI:10.1002/neu.480110407

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

年代:1980

数据来源: WILEY

摘要:

AbstractCultures prepared from dispersed fetal hypothalamic tissue have cells which can be identified as neurons by their morphology and electrical activity. The elongation of neuritic processes in these cultures is increased by treatment with 1‐β‐D‐arabinofuranosylcytosine (ara‐C). Hypothalamic cultures have measurable quantities of immunoreactive substance P and neurotensin, and the neurons can accumulate

ISSN:0022-3034    

DOI:10.1002/neu.480110408

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

年代:1980

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480110401

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

年代:1980

数据来源: WILEY