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1. Rhombencephalic and mesencephalic structures involved in electroreception were investigated by electrophysiological methods in the weakly electric fish Gnathonemus petersii. 2. The existence of a synchronous response to electric field stimulation of the fish in the mesencephalic exterolateral nucleus (n.ext.-lat.mes) with 2.5-3 ms latency was confirmed.(More)
The motoneurons which innervate the mormyrid electric organ are driven by a descending volley from the medullary relay nucleus. This nucleus does not initiate the electric organ discharge (EOD) but is driven in an obligatory manner by another center, a command nucleus. One goal of the present study was to identify this command nucleus anatomically. A second(More)
The rhombencephalic posterior lateral line lobe nucleus (nLLL) and its connections were investigated in the mormyrid fish Gnathonemus petersii, at light and electron microscopical levels using HRP tracing. The nLLL, constituted on each side of about 1500 large, round shaped, adendritic cells, is located in the intermediate cell and fibre layer exclusively,(More)
The peripheral and central aspects of the extraocular system were studied in the weakly electric fish Gnathonemus petersii. All six extraocular muscles show a similar composition of large and small fibers grouped characteristically in the proximal and distal regions respectively. The exit of the three extraocular nerves from the brain is similar to that in(More)
By horseradish peroxidase (HRP) labelling the course and origin of the II-X cranial nerves are identified in the teleost fish Gnathonemus petersii. Roots as well as motor and sensory nuclei in the viscero- and somatomotor and somatosensory areas are localised. Earlier data of comparative and experimental anatomical observations are completed, partly(More)
Long ascending fiber systems were investigated in the spinal cord of a teleost fish, Gnathonemus petersii. Concomitant results of Fink-Heimer degeneration tracing as well as CaBP28K immunohistochemical labelling demonstrate the existence of a well defined direct pathway from the very lowest spinal level to the caudal lobe of the cerebellum. HRP retrograde(More)
Previous electrophysiological data indicate that the afferent electrosensory impulses conveyed towards the mesencephalon are blocked in the rhombencephalic electrosensory lateral line nucleus (nELL) by the concomitantly occurring EOD (electric organ discharge) command-associated (corollary) discharge. Electron-microscopic observations and anterograde(More)