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  • Articles: DFG German National Licenses  (2)
  • 1985-1989  (2)
  • 1985  (2)
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  • Articles: DFG German National Licenses  (2)
Material
Years
  • 1985-1989  (2)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 157 (1985), S. 73-82 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The coxo-trochanteral joint of the locust hindleg is supplied with five mechanoreceptive sense organs: A hairplate (HP) and a row of hairs (RH), two strand receptors (SR1, SR2) and a muscle receptor organ (MRO) (BrÄunig 1982). We report here an investigation of these mechanoreceptors with regard to their afferent responses to static and dynamic mechanical stimulation. 2. The only receptor suited for continuous measurement of joint position is the HP: its units are active over the entire range of possible joint positions and their number increases in proportion to the degree of joint levation (Fig. 3). The RH complements the HP as an additional sensor for extreme levation (Fig. 4). 3. Both SR are sensitive to the dynamic phase of joint depressions. Units of the multicellular SR1 respond over the entire range of joint movements, the single unit of SR2 is tuned to the lower half of that range (Fig. 5). 4. The sensory cell of the MRO is activated when the organ is stretched during depression of the joint (Fig. 6). Increasing slack of the organ during levation is compensated by activation of its receptor muscle. The MRO motor neuron is progressively excited with increasing joint levation, mainly by HP and RH (Figs. 6, 7, 8). 5. During stimulation of internal mechanoreceptors (SR1, SR2, and the sensory cell of the MRO) and during spontaneous motor activity the MRO motor neuron is co-activated with levator motor neurons (Figs. 9, 10). This mechanism may help to compensate for slack before the reflexes from HP and RH set in (see 4.). 6. The motor neuron of the MRO receptor muscle is not only activated by sense organs of the coxo-trochanteral joint, but also by proprioceptors of neighboring joints (Fig. 11). 7. Since all coxo-trochanteral joint receptors exert reflexes on motor neurons of power muscles and the efferent unit of the MRO, manipulation and extirpation of any one receptor must result in direct effects on the motor output of the metathoracic ganglion, but also additional indirect effects due to altered operation of the MRO.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 157 (1985), S. 83-89 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Reflexes involving hind leg muscles during movement of the coxo-trochanteral joint were recorded after total ipsilateral deafferentation except for one of two groups of mechanoreceptors. These were (i) HP and RH, and (ii) SR1, SR2 and MRO. 2. Both groups of receptors influence coxotrochanteral and subcoxal, but not femoro-tibial muscles (Figs. 2, 3; Table 1). 3. Many subcoxal muscles are activated by both antagonistic groups of receptors. Their co-contraction may lock the subcoxal joint in a rigid position, thereby making it a firm support for resistance reflexes in more distal joints. 4. Reflexes onto coxo-trochanteral muscles were studied in more detail by direct selective mechanical stimulation of single receptors. All receptors elicit typical resistance reflexes: Sense organs sensitive to joint depression (SR1, SR2, MRO) activate levator motor units and inhibit depressor activity (Fig. 4). Sense organs sensitive to levation (HP, RH) cause analogous reactions of opposite sign (Fig. 5). 5. Tonic excitation by proprioceptors is necessary to maintain a certain level of spontaneous activity in certain motor neurons. For example after HP and RH extirpation, spontaneous activity of depressor motor units ceases, MRO ablation has comparable effects on levator units (Table 1).
    Type of Medium: Electronic Resource
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