Responses to dipole stimuli of anterior lateral line nerve fibres in goldfish, Carassius auratus, under still and running water conditions

The nucleus medialis is the main first-order target of the mechanosensory lateral line (LL) system. This report definitively demonstrates that mechanosensory LL inputs also terminate in the ipsilateral dorsal portion of the descending octaval nucleus (dDO) in the goldfish. The dDO, which is the main first-order auditory nucleus in bony fishes, includes neurons that receive direct input from the otolithic end organs of the inner ear and project to the auditory midbrain. There are two groups of such auditory projection neurons: medial and lateral. The medial and the lateral groups in turn contain several neuronal populations, each of which includes one or more morphological cell types. In goldfish, the exclusively mechanosensory anterior and posterior LL nerves terminate only on specific cell types of auditory projection neurons in the lateral dDO group. Single neurons in the lateral dDO group may receive input from both anterior and posterior LL nerves. It is possible that some of the lateral dDO neurons that receive LL input also receive input from one or more of the otolithic end organs. These results are consistent with functional studies demonstrating low frequency acoustic sensitivity of the mechanosensory LL in teleosts, and they reveal that the anatomical substrate for sensory integration of otolithic and LL inputs is present at the origin of the central ascending auditory pathway in an otophysine fish.

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Responses of Medullary Lateral Line Units of the Goldfish,Carassius auratus, to Amplitude-Modulated Sinusoidal Wave Stimuli

International Journal of Zoology ◽

10.1155/2010/762621 ◽

2010 ◽

Vol 2010 ◽

pp. 1-14 ◽

Cited By ~ 5

Author(s):

Ramadan Ali ◽

Joachim Mogdans ◽

Horst Bleckmann

Keyword(s):

Lateral Line ◽

Amplitude Modulation ◽

Carrier Frequency ◽

Carassius Auratus ◽

Phase Locking ◽

Modulation Frequency ◽

Constant Amplitude ◽

Sinusoidal Wave ◽

Strong Phase ◽

Goldfish Carassius Auratus

This paper describes the responses of brainstem lateral line units in goldfish,Carassius auratus, to constant-amplitude and to amplitude-modulated sinusoidal water motions. If stimulated with constant-amplitude sinusoidal water motions, units responded with phasic (50%) or with sustained (50%) increases in dicharge rate. Based on isodisplacement curves, units preferred low (33 Hz, 12.5%), mid (50 Hz, 10% and 100 Hz, 30%) or high (200 Hz, 47.5%) frequencies. In most units, responses were weakly phase locked to the carrier frequency. However, at a carrier frequency of 50 Hz or 100 Hz, a substantial proportion of the units exhibited strong phase locking. If stimulated with amplitude-modulated water motions, units responded with a burst of discharge to each modulation cycle, that is, units phase locked to the amplitude modulation frequency. Response properties of brainstem units were in many respects comparable to those of midbrain units, suggesting that they emerge first in the lateral line brainstem.

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Brainstem lateral line responses to sinusoidal wave stimuli in still and running water

Journal of Experimental Biology ◽

10.1242/jeb.205.10.1471 ◽

2002 ◽

Vol 205 (10) ◽

pp. 1471-1484 ◽

Cited By ~ 4

Author(s):

Sophia Kröther ◽

Joachim Mogdans ◽

Horst Bleckmann

Keyword(s):

Lateral Line ◽

Large Degree ◽

Type I ◽

Water Type ◽

Running Water ◽

Central Processing ◽

Goldfish Carassius Auratus ◽

Canal Neuromast ◽

Discharge Rates ◽

Afferent Fibers

SUMMARYThe fish lateral line consists of superficial and canal neuromasts. In still water, afferent fibers from both types of neuromast respond equally well to a sinusoidally vibrating sphere. In running water, responses to a vibrating sphere of fibers innervating superficial neuromasts are masked. In contrast,responses of fibers innervating canal neuromasts are barely altered. It is not known whether this functional subdivision of the peripheral lateral line is maintained in the brain. We studied the effect of running water on the responses to a 50 Hz vibrating sphere of single units in the medial octavolateralis nucleus (MON) in goldfish Carassius auratus. The MON is the first site of central processing of lateral line information. Three types of units were distinguished. Type I units (N=27) were flow-sensitive; their ongoing discharge rates either increased or decreased in running water, and as a consequence, responses of these units to the vibrating sphere were masked in running water. Type II units (N=7) were not flow-sensitive; their ongoing discharge rates were comparable in still and running water, so their responses to the vibrating sphere were not masked in running water. Type III units (N=7) were also not flow-sensitive, but their responses to the vibrating sphere were nevertheless masked in running water. Although interactions between the superficial and canal neuromast system cannot be ruled out, our data indicate that the functional subdivision of the lateral line periphery is maintained to a large degree at the level of the medial octavolateralis nucleus.

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