Multimodal Torus in the Weakly Electric Fish Eigenmannia

ISBN-13: 9783540125174 / Angielski / Miękka / 1983 / 72 str.

Henning Scheich; Sven O. E. Ebbesson

Opis

Ever since the behavioral work of Lissrnann (1958), who showed that the weak electric discharges of some families of fish (hitherto considered useless for prey capture or for scaring away enemies) are part of a strange sensory system, these fish have attracted attention from biologists. The subsequent discovery of the electroreceptors in the skin of gymnotids and mormyrids (Bullock et al. 1961; Fessard and Szabo 1961) and the evidence that the ampullae of Lorenzini of nonelectric sharks and rays are also electro- receptors (Digkgraaf and Kalmijn 1962) was a start for a lively branch of physiological, anatomical, and behavioral research. Many fmdings of general importance for these fields have made the case to which extremes the performance of the central and peri- pheral nervous systems can be driven. Among those fmdings is the temporal accuracy of the pacemaker of some high-frequency fish which controls the electric organ, pro- bably the most accurate biological clock (coefficient of variation < 0. 0 1 %, Bullock 1982). The functional analysis of the pacemaker cells and their axons has established most of our knowledge on electrotonic synapses, the alternative to chemical synapses (Bennett et al. 1967), and of the implications of axonal delay lines for achieving extreme synchrony of parallel inputs to postsynaptic elements (Bennett 1972; Bruns 1971).

Spis treści

1 General Introduction.- 2 General Description of the Torus and Commissural Connections.- 2.1 Introduction.- 2.2 Material and Methods.- 2.3 Results.- 2.4 Discussion.- 2.4.1 Torus Superlamination and the T Unit System.- 2.5 Summary.- 3 Connections with the Posterior Lateral Line Lobe.- 3.1 Introduction.- 3.2 Material and Methods.- 3.3 Results.- 3.3.1 Injections in the Posterior Lateral Line Lobe.- 3.3.2 Injections in the Torus.- 3.3.3 Projections to the Nucleus Praeeminentialis Pars Lateralis and Pars Medialis.- 3.4 Discussion.- 3.4.1 The Posterior Lateral Line Lobe-Toms Loops.- 3.4.2 Possible Roles of Feedback of the Descending Electrosensory Pathway.- 3.4.3 Interconnection of Posterior Lateral Line Lobe and Toral Layers.- 3.4.4 A Temporal Comparator in the Torus.- 3.5 Summary.- 4 Connections with the Mesencephalic Tectum.- 4.1 Introduction.- 4.2 Material and Methods.- 4.3 Results.- 4.3.1 Injections of the Tectum.- 4.3.2 Injections in the Torus.- 4.4 Discussion.- 4.4.1 Vertical Overlap of Inputs with Other Modalities.- 4.5 Summary.- 5 Connections with the Cerebellum.- 5.1 Introduction.- 5.2 Material and Methods.- 5.3 Results.- 5.4 Discussion.- 5.5 Summary.- 6 Connections with the Medial Octavolateralis Complex and with the Reticular Formation.- 6.1 Introduction.- 6.2 Material and Methods.- 6.3 Results.- 6.4 Discussion.- 6.5 Summary.- 7 Concluding Remarks.- 7.1 Organizational Frame of the Torus.- 7.2 Ascending Outputs of the Torus.- References.