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Results for “Lateral Line System”

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PubMed2002

The sensory basis of olfactory search behavior in banded kokopu ( Galaxias fasciatus).

The sensory basis of olfactory search behavior was investigated in the banded kokopu, Galaxias fasciatus, using a flow tank. In the presence of a 2 cm s(-1) current flow, banded kokopu use both water current and chemical information to locate a food odor source. The superficial neuromasts of the lateral line system mediate the rheotactic component of the odor search. A physical block of one olfactory nostril did not affect the olfactory search strategy employed by banded kokopu in still water or in the presence of a current flow. Thus, there is no evidence that banded kokopu perform a bilateral comparison of the olfactory stimulus during their odor search. Previously, olfaction and gustation have been the only sensory systems shown to directly mediate orientation and movement towards odor sources in fish. The use of hydrodynamic cues by fish in location of an olfactory source has been previously proposed, but without direct experimental identification of the sensory systems employed. This study identifies the contributing roles of both olfactory and hydrodynamic sensory systems to the olfactory search repertoire of fish.

Animals↗
PubMed2000

Toxicity of Co2+: implications for lateral line studies.

It has been reported that superficial neuromasts, a type of lateral line organ, mediate rheotaxis in fish. These studies used Co2+ at 2 mmol l(-1) for 3 h to ablate the entire lateral line system. The recommended concentration is 0.1 mmol l(-1). The present study shows that at 2 mmol l(-1) Co2+ is highly toxic to blind Mexican cave fish. Fish exposed to this concentration died in less than 17 h, and produced copious mucus. No control fish died. No cobalt treated fish died after 3 h exposure, but cobalt-treated fish swam about their aquaria faster than control fish and tended to swim at the surface. Hence, both survival and behavior were changed by the excessive concentration of Co2+.

Animals↗
PubMed1997

Dipole source localization by mottled sculpin. I. Approach strategies.

Lake Michigan mottled sculpin respond to a chemically-inert vibrating sphere (a dipole source) with an initial orientation towards the source followed by a step-wise progression towards and final strike at the source. An analysis of videotape recordings of this behavior indicate that although pathways to the source varied, they tended to be influenced by the fish's position at signal onset. Fish heading toward the source at signal onset approached the source in an indirect fashion by either (a) keeping the source to one side in a smoothly arching path to the source or (b) alternating between keeping the source to the left and to the right. When the source was to the side of the fish at the time of stimulus onset, fish tended to approach the source in a more direct path. Most (79%) initial orienting responses placed the fish within 45 degrees of the source, but response angles were not strongly correlated with initial source angle. Most (83%) unsuccessful strikes (misses) occurred when the source was directly in front of the fish (+/- 20 degrees) and source angles associated with misses were significantly smaller than source angles associated with successful strikes. Approach strategies used by mottled sculpin in finding dipole sources appear to include (1) moving in a direction that increases the pressure difference along the head while keeping it consistently low (between 1 and 10 Pa) across the head, (2) narrowing the fish-to-source gap with each successive step in the pathway, (3) keeping the source lateralized (on average, 30 degrees to one or the other side of the head) and (4) avoiding approach positions that are perpendicular to the flow line or that place the fish in the pressure null area of the dipole field. These results are consistent with the hypothesis that spatial excitation patterns along the lateral line system play a major role in encoding both source direction and distance.

Animals↗
PubMed1982

Schooling behavior of tadpoles: a potential indicator of ototoxicity.

Fish and tadpoles in schools use hair cells of their lateral line system to assess their position in relation to neighbors. This suggests that pharmaceutical agents that damage hair cells in the mammalian inner ear may also alter geometry in fish and tadpole schools. We used a computer-based image analysis system to examine the effect of the ototoxic aminoglycoside antibiotic, streptomycin, on school geometry for tadpoles of the African clawed frog Xenopus laevis. Tadpoles exposed to streptomycin in the surrounding water show a general tendency toward clumping, and an increase in the distance over which they orient parallel to neighbors, compared to controls. These behavioral responses appear in 18 min or less, and are evident in some tadpoles exposed to concentrations as low as 5 micrograms/ml. Results suggest that analysis of spatial relations in tadpole schools could serve as a method for rapidly detecting ototoxic potential of agents suspected of damaging hair cells.

Animals↗
PubMed1993

Lamellated receptors in the skin of the hagfish, Myxine glutinosa.

The adult hagfish, Myxine glutinosa, does not exhibit a lateral line system. The hypodermal layer of the dorsal head and body skin contains a prominent receptor system--lamellated corpuscles--arranged in a segmental pattern close to the body fascia. The topography and the structural organization of the lamellated receptors are described at the light- and electronmicroscopical levels. Spinal nerves supply the lamellated receptor organs. A mechanoreceptive function and evolutionary aspects are discussed.

Animals↗
PubMed1992

Neuropeptides in the torus semicircularis of the carp (Cyprinus carpio).

The distribution of fibers and cell bodies containing neurotensin, neurokinin A, galanin, or somatostatin-28(1-12) immunoreactivity in the torus semicircularis of the carp was studied using an indirect immunoperoxidase technique. In this mesencephalic region, a high-density of galanin-immunoreactive fibers was found, whereas neurokinin A or somatostatin-28(1-12)-immunoreactive processes were observed at a moderate density and neurotensin-immunoreactive fibers at a low density. Cell bodies containing somatostatin-28(1-12) immunoreactivity were observed in both central and lateral nuclei. The torus semicircularis was not immunoreactive for dynorphin A. The presence of these neuropeptides in the carp torus semicircularis suggests that such neuroactive substances may be involved in auditory and visual mechanisms, as well as in the control of inputs arising from the lateral line system.

Animals↗
PubMed2004

Parapineal specific expression of gfi1 in the zebrafish epithalamus.

We describe the isolation of zebrafish growth factor independent 1 (gfi1) and present an analysis of its pattern of expression during early development. As with its murine homologue, gfi1 expression is detected in the ganglion cells of the neural retina and in developing hair cells of the ear. In keeping with a role in the development of sensory hair cells, gfi1 is also expressed in neuromasts of the anterior and posterior lateral line system. Finally, gfi1 is expressed in the developing epithalamus in the dorsal diencephalon where its transcription is restricted to the parapineal.

Amino Acid Sequence↗
PubMedDate not supplied

Origin of the vertebrate inner ear: evolution and induction of the otic placode.

The vertebrate inner ear forms a highly complex sensory structure responsible for the detection of sound and balance. Some new aspects on the evolutionary and developmental origin of the inner ear are summarised here. Recent molecular data have challenged the longstanding view that special sense organs such as the inner ear have evolved with the appearance of vertebrates. In addition, it has remained unclear whether the ear originally arose through a modification of the amphibian mechanosensory lateral line system or whether both evolved independently. A comparison of the developmental mechanisms giving rise to both sensory systems in different species should help to clarify some of these controversies. During embryonic development, the inner ear arises from a simple epithelium adjacent to the hindbrain, the otic placode, that is specified through inductive interactions with surrounding tissues. This review summarises the embryological evidence showing that the induction of the otic placode is a multistep process which requires sequential interaction of different tissues with the future otic ectoderm and the recent progress that has been made to identify some of the molecular players involved. Finally, the hypothesis is discussed that induction of all sensory placodes initially shares a common molecular pathway, which may have been responsible to generate an 'ancestral placode' during evolution.

Animals↗
PubMed1985

Functional morphology of the piper Hyporhamphus ihi with reference to the role of the lateral line in feeding.

As a basis for understanding the function of the halfbeak of the piper Hyporhamphus ihi (Phillips), details of the structure and dimensions of the anterior lateral line on the head and lower jaw of the piper are described. The anterior lateral line is composed of a series of cranial canals; the supraorbital-postorbital canal; the suborbital canal; and the preopercular-mandibular canal which extends along the lower jaw. Each canal opens to the surface by a series of pores, and individual neuromasts exist in specialized regions of the canals between each of the pores. Piper are nocturnal plankivores and they possess the feeding structures and digestive tract suited to this diet. The hypothesis is proposed that they use the anterior lateral line system in prey detection, and this paper shows that the piper's elongate body form, swimming behaviour, and lack of a specialized visual system are all consistent with this hypothesis.

Animals↗
PubMed1976

Uptake of bovine serum albumin by rainbow trout from hypersmotic solutions: a model for vaccinating fish.

Immersion of juvenile rainbow trout (Salmo gairdneri) in a solution containing either urea or sodium chloride at 1650 milliosmoles and 2 percent of bovine serum albumin (BSA) resulted in an uptake of BSA into the blood of the fish after a 3-minute exposure. Similar blood levels of BSA were also obtained by placing the fish in 1650 millosmoles of sodium chloride for about 2 minutes, and then immersing them in 2 percent BSA solution for 3 minutes. Uptake of BSA into the fish appeared to be primarily through the lateral line system and secondarily through the gills.

Animals↗
PubMed1984

The spiracular organ of sharks and skates: anatomical evidence indicating a mechanoreceptive role.

The elasmobranch spiracular organ is a specialized receptor associated with the first visceral pouch. The structure of the sensory epithelium of the spiracular organ and the pattern of central termination of the afferent neurons that innervate it show that the spiracular organ is a mechanoreceptor closely related to the lateral line system of sense organs. Its position and orientation within the spiracular cleft suggest that it plays a role in proprioception or equilibrium-audition.

Afferent Pathways↗
PubMed1994

A dual embryonic origin for vertebrate mechanoreceptors.

Neuromasts, the mechanoreceptors of the lateral line system of fishes and aquatic amphibians, have previously been thought to develop exclusively from embryonic epidermal placodes. Use of fate mapping techniques shows that neuromasts of the head and body of zebrafish, Siamese fighting fish, and Xenopus are also derived from neural crest. Neural crest migrates away from the neural tube in developing vertebrates to form much of the peripheral nervous system, pigment cells, and skeletal elements of the head. The data presented here demonstrate that neuromasts are derived from both neural crest and epidermal placodes.

Animals↗
PubMed1976

Mechanoreceptors for near-field water displacements in crayfish.

1. Mechanosensory hairs on the surface of the crayfish telson are dually innervated, one sensory cell responding to headward, the other to tailward deflection of the hair. The average conduction velocity of headward elements was 0.8 m/s (variance 0.08) and of tailward elements 1.2 m/s (variance 0.19). In a frequency range from 0.05 to 200 Hz, thresholds were lowest near 20 Hz: 0.08 mum (pp) for headward-sensitive and 0.1 mum (pp) for tailward-sensitive cells. 2. The receptors are displacement sensitive since thresholds are of the same order of magnitude over the frequency range 1-70 Hz when the hair is moved by a vibrating wire loop. With natural stimuli (surface waves), the velocity component of the particle movement (and consequently force) becomes influential. The coding of a broad range of stimulus intensities is aided by variations in mechanical properties of the hair. 3. Marked directionality (better than 4:1), in addition to the dual innervation, enhances vector detection. At least part of this characteristic stems from the hingelike articulation of the hair on the body surface: the hair can be moved easily 40 degrees tailward and 20 degrees headward, but must be forced in the orthogonal direction. Morphological studies indicate the presence of a double pivoted hinge, with rigid guides for movement of the hair shaft. Preliminary results of electron microscope examination show a clearly polarized arrangement of densely packed microtubules in the two dendrites; they appear interconnected in groups of two and three along a line parallel to the sensitivity plane of the receptor. 4. The 50-fold threshold difference between the results of behavioral experiments in lobsters (24) and the data for the individual receptors reported here may be due to improvement in signal-to-noise ratio by central nervous averaging of the input from an estimated 2 X 10(3) receptors (Procambarus), and/or to the kind of threshold criteria applied to individual receptor thresholds. As would be expected (35), the sensory cells of each directional class synapse with separate interneurons: in this way, the organism might employ differential microphones to reduce background noise. 5. The receptors are analogous to those of the lateral-line system in lower vertebrates in having receptors with sensitivities polarized by 180 degrees. These similarities suggest that in both cases monitoring of near field water displacements has proved in essential way of orienting in opaque waters.

Animals↗
PubMed2001

Evidence for an active process and a cochlear amplifier in nonmammals.

The last two decades have produced a great deal of evidence that in the mammalian organ of Corti outer hair cells undergo active shape changes that are part of a "cochlear amplifier" mechanism that increases sensitivity and frequency selectivity of the hearing epithelium. However, many signs of active processes have also been found in nonmammals, raising the question as to the ancestry and commonality of these mechanisms. Active movements would be advantageous in all kinds of sensory hair cells because they help signal detection at levels near those of thermal noise and also help to overcome fluid viscosity. Such active mechanisms therefore presumably arose in the earliest kinds of hair cells that were part of the lateral line system of fish. These cells were embedded in a firm epithelium and responded to relative motion between the hair bundle and the hair cell, making it highly likely that the first active motor mechanism was localized in the hair-cell bundle. In terrestrial nonmammals, there are many auditory phenomena that are best explained by the presence of a cochlear amplifier, indicating that in this respect the mammalian ear is not unique. The latest evidence supports siting the active process in nonmammals in the hair-cell bundle and in intimate association with the transduction process.

Amphibians↗
PubMed2003

Effects of running water on lateral line responses to moving objects.

We investigated in goldfish, Carassius auratus, and trout, Oncorhynchus mykiss, how running water affects the responses of afferent fibers in the posterior lateral line nerve and of lateral line units in the brainstem medial octavolateralis nucleus to an object that is moved from anterior to posterior or opposite along the side of the fish. In still water, nerve fibers in both species responded to the moving object with alternating periods of increased and decreased firing rate. Most fibers in goldfish but none in trout discharged bursts of spikes in response to the object's wake. Responses of brainstem units were more variable and less distinct than nerve fiber responses. Bursting activity in response to the object's wake was found in only one brainstem unit. In running water, responses of goldfish nerve fibers were weaker than in still water. This effect was independent of object motion direction. Responses of trout fibers were weaker when the object was moved with the flow but were slightly stronger when the object was moved against the flow. In general, running water affected the responses of goldfish nerve fibers more strongly than the responses of trout fibers. Compared to still water, brainstem units in both species responded more weakly when the object was moved with the flow. When the object was moved against the flow, brainstem responses were on average comparable to those in still water. Measurements of changes in pressure and water velocity caused by the moving object indicate that the observed effects can largely be explained by peripheral hydrodynamic effects. However, physiological differences between goldfish and trout units indicate that the lateral line systems in these two species are adapted to different hydrodynamic conditions.

Animals↗
PubMed1990

Development and innervation of the paratympanic organ (Vitali organ) in chick embryos.

The paratympanic organ (Vitali organ) is a small sensory organ in the middle ear of birds. It possesses a sensory epithelium with hair cells similar to those of the inner ear. Injections of fluorescent carbocyanine tracers into the paratympanic organ of 9- to 11-day-old chick embryos labeled ganglion cells in the facial ganglia. Paratympanic nerve fibers enter the brainstem with the facial nerve but proceed to vestibular brainstem nuclei. A dorsal branch terminates in ventral areas of the cerebellum, while a ventral component projects to the descending vestibular nucleus, with some fibers turning medially into lateral parts of the medial vestibular nucleus. No fibers were labeled in the motor or sensory facial nucleus or in auditory brainstem nuclei. This projection pattern suggests a function of the paratympanic organ in equilibrium rather than audition. Projections similar to those of the paratympanic nerve have been reported for the lagenar nerve. Immunocytochemical techniques using an antiserum to gamma-aminobutyric acid (GABA) demonstrate that hair cells in the paratympanic organ develop GABA immunoreactivity at 5 days of incubation (E5), 2-4 days earlier than GABA immunoreactivity can be detected in hair cells of the inner ear, i.e. in the saccule (E6.5-7.0), the utricle (E7), the cristae (E8-9) and the cochlea (E9-9.5). Afferent fibers that are transiently GABAergic are rare in the paratympanic organ (1-2 fibers), though present from E6 to E7.5. The early onset of GABA immunoreactivity in the paratympanic organ may indicate that this organ matures (and possibly functions) earlier in ontogenetic development than its counterparts located in the inner ear. The present findings are consistent with the hypothesis that the paratympanic organ is homologous with the spiracular sense organ of fishes. The paratympanic organ of birds may represent a sense organ that is derived phylogenetically and ontogenetically from the lateral-line system.

Animals↗
PubMed1990

Morphological differences in neuromasts of the blind cave fish Astyanax hubbsi and the sighted river fish Astyanax mexicanus.

Vital staining and scanning electron microscopy were used to study the morphology of superficial neuromasts in the blind cave fish, Astyanax hubbsi, and its sighted congener, Astyanax mexicanus. In blind Astyanax the neuromasts are 80 X 50 microns in size and possess cupulae with an oval basal shape. The length of the cupula is correlated to the location of its neuromast. Head neuromasts were found to have the longest cupulae (up to 300 microns), and caudal neuromasts have the smallest. Cupulae of all lengths have been observed to be easily bent by water movements. The neuromasts are directionally sensitive in that the bending of their cupulae perpendicular to the longer axis of the cupulae provides maximal excitation. A comparison of superficial neuromasts in the blind A. hubbsi to those in sighted A. mexicanus revealed several structural differences. The neuromasts in the blind fish are twice as large. Their cupulae, in particular, are much longer and seem to have supporting attachments at their edges. The greater length of the cupulae in blind cave fish may be of particular importance for the functioning of the lateral line organ, since longer cupulae protrude beyond the boundary layer in faster water currents and thus can increase the sensitivity of the neuromast. The specific morphology of the neuromasts in the blind cave fish appears to reflect an evolutionary adaptation which can serve to improve the functioning of the lateral line system and thereby compensate for the lack of eyes.

Animals↗
PubMed1994

Directional sensitivity of hair cell afferents in the Octopus statocyst.

Changes in threshold sensitivity of hair cell afferents of the macula and crista of the Octopus statocyst were analyzed when the hair cells were stimulated with sinusoidal water movements from different directions. The experiments indicate that cephalopod statocyst hair cells are directionally sensitive in a way that is similar to the responses of the hair cells of the vertebrate vestibular and lateral line systems, with the amplitude of the response changing according to the cosine of the angle by which the direction of the stimulus (the deflection of the ciliary bundle) deviates from the direction of the hair cell's morphological polarization.

Action Potentials↗