摘要:

AbstractThe innervation of the distal and proximal heads of the accessory flexor muscle in three portunid crabs and two non‐portunid decapods was studied electrophysiologically. In all species studied, the proximal head received only the two previously reported accessory flexor axons, an excitor and an inhibitor. The same two axons also innervated the distal head in all species, but in the portunids the distal head also received excitation from at least three, and probably sometimes four, of the main flexor excitor efferents. The accessory inhibitor exertend very strong effects in the tonic muscle fibers found in the proximal head and in the most proximal bundle of the distal head. The newly described inhibitory and excitatory distributions may have important implications for locomotory behavio

ISSN:0022-3034    

DOI:10.1002/neu.480160502

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe physiological and morphological properties of the giant interneurons in the hermit crabPagurus pollicarisare described. The cell bodies are located anteriorly in the supraesophageal ganglion, close to the mid‐line. Each cell sends a neurite posteriorly and then laterally, so that they cross over in the center of the ganglion. Each axon then branches: one branch runs laterally while the other travels posteriorly and leaves the ganglion in the circumesophageal connective on the side contralateral to the cell body. The giant axons travel in the circumesophageal connectives and through the thoracic and abdominal ganglia without branching. Each giant axon makes synaptic contact with its ipsilateral giant abdominal flexor motor neuron and with a second flexor motor neuron that has its axon in the contralateral third root.In the supraesophageal ganglion there is a bidirectional synapse between the two giant interneurons. Intracellular recordings from the giant axons show that there is a delay of 0.5 to 0.75 ms that cannot be accounted for by spike propagation along the axons, and may be accounted for by a chemical synapse between the giant interneuron

ISSN:0022-3034    

DOI:10.1002/neu.480160503

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

年代:1985

数据来源: WILEY

摘要:

AbstractThese experiments in the slowly adapting stretch receptor of crayfish test the effects of brief length perturbations (i.e., pulses) when presented in isolation at different constant elongations or superimposed on trapezoidal stretches of different amplitudes. Within“in vivo”lengths, during static responses, perturbations reduced firing rates to below control values and, in extreme cases, could silence the receptor. This effect, or “down‐step,” was sustained, occurred above a threshold pulse amplitude and background stretch, and increased with both stimulus characteristics, but was not present during dynamic responses. Beyond“in vivo”lengths, and in a few cases within those limits but close to the extremes, the receptor was silent but perturbations could restore activity. Lengthening pulses were more effective than shortening ones in generating after‐effects. Perturbations change, during indefinitively long periods, the receptor's length or static sensitivity acting as a negative feedback which tends to maintain the discharge rate within fixed values. Perturbations disclose marked nonlinerities, which suggest that the classical view of a proportional control in the reflex loop in which the receptor participates may not operate in nat

ISSN:0022-3034    

DOI:10.1002/neu.480160504

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe influence of early protein–calorie malnutrition on synaptic transmission in the rat prefrontal cortex was studied by evoking direct cortical responses with different trains of threshold electrical pulses. Malnutrition resulted in a requirement for increased pulse train stimulating current, reflecting a diminished release of neurotransmitter from the preterminal endings. In addition there was an increase in the time constant of pyramidal cells, indicating that axodendritic synapses have a disability for integrating high frequency inputs at the post synaptic level. It is concluded that early malnutrition alters dynamic properties of axodentritic synapses at both the pre‐ and the postsynaptic lev

ISSN:0022-3034    

DOI:10.1002/neu.480160505

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe ability of two electrical synapses (neuron L4‐R4 and neuron L19‐R19) to regenerate in the adultHelisomanervous system was examined. The L4‐R4 electrical connection exhibited rapid restoration to 50% of normal strength, whereas L19‐R19 reconnection was weak or absent. This disparity is attributable to the inability of neuron 19 to sprout effectively across a crush site in the buccal commissure, although peripheral sprouting was pronounced. The factors which underlie the inability of neuron 19 (but not neuron 4) to sprout into a central environment are unknown, but dictate differential synapse restoration in this adult nervous

ISSN:0022-3034    

DOI:10.1002/neu.480160506

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

年代:1985

数据来源: WILEY

摘要:

AbstractProctolin enhances nerve‐evoked, phasic contractions of a selected respiratory muscle of the shore crab,Carcinus maenas, but has no effect on muscle tonus. Proctolin also increases the work and power output of this muscle. These effects are functionally appropriate in view of previous reports that proctolin stimulates the ventilatory rhythm. They also suggest that proctolin exerts coordinated modulatory control at the central and peripheral levels of the gill ventilatory system. In contrast, serotonin, dopamine and octopamine have no effect on this muscl

ISSN:0022-3034    

DOI:10.1002/neu.480160507

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

年代:1985

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480160501

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

年代:1985

数据来源: WILEY