Tactile hairs and leg reflexes in wandering spiders: physiological and anatomical correlates of reflex activity in the leg ganglia
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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.
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).
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).
central nervous system
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- Babu KS, Barth FG (1984) Neuroanatomy of the central nervous system of the wandering spider,Cupiennius salei (Arachnida, Araneida). Zoomorphology 104:344–359Google Scholar
- Babu KS, Barth FG, Strausfeld NJ (1985) Intersegmental sensory tracts and contralateral motor neurons in the leg ganglia of the spiderCupiennius salei Keys. Cell Tissue Res 241:53–57Google Scholar
- Eckweiler W (1987) Tasthaare, Beinmuskelreflexe und Einstellung der Körperhöhe bei Jagdspinnen. Doctoral dissertation. Fachbereich Biologie, J.W. Goethe-Universität, Frankfurt am MainGoogle Scholar
- Eckweiler W, Seyfarth E-A (1988) Tactile hairs and the adjustment of body height in wandering spiders: behavior, leg reflexes, and afferent projections in the leg ganglia. J Comp Physiol A 162:611–621Google Scholar
- Gronenberg W (1987) Neuronal elements in the CNS of a spider (Cupiennius salei): anatomy and physiology. In: Elsner N, Creutzfeldt O (eds) New frontiers in brain research. Proceedings of the 15th Göttingen neurobiology conference. Thieme, Stuttgart, p 78Google Scholar
- Hustert R (1985) Multisegmental integration and divergence of afferent information from single tactile hairs in a cricket. J Exp Biol 118:209–227Google Scholar
- Levine RB, Pak C, Linn D (1985) The structure, function and metamorphic reorganization of somatotopically projecting sensory neurons inManduca sexta larvae. J Comp Physiol A 157:1–13Google Scholar
- Maier L, Root TM, Seyfarth E-A (1987) Heterogeneity of spider leg muscle: histochemistry and electrophysiology of identified fibers in the claw levator. J Comp Physiol B 157:285–294Google Scholar
- Pflüger H-J, Bräunig P, Hustert R (1981) Distribution and specific central projections of mechanoreceptors in the thorax and proximal leg joints of locusts. II. The external mechanoreceptors: hair plates and tactile hairs. Cell Tissue Res 216:79–96Google Scholar
- Seyfarth E-A, Eckweiler W, Hammer K (1985) Proprioceptors and sensory nerves in the legs of a spider,Cupiennius salei (Arachnida, Araneida). Zoomorphology 105:190–196Google Scholar
- Speck-Hergenröder J, Barth FG (1987) Tuning of vibration sensitive neurons in the central nervous system of a wandering spider,Cupiennius salei Keys. J Comp Physiol A 160:467–475Google Scholar
- Strausfeld NJ, Seyan HS, Wohlers D, Bacon JP (1983) Lucifer yellow histology. In: Strausfeld NJ (ed) Functional neuroanatomy. Springer, Berlin Heidelberg New York, pp. 132–155Google Scholar