Variations of glycogen: I. Following stimulation of Knollenorgan sensory cells, a lateral line electroreceptor of mormyrid fish

1995 ◽  
Vol 165 (5) ◽  
pp. 329-335 ◽  
Author(s):  
B. A. Djebar ◽  
J. -P. Denizot
Keyword(s):  
Lateral Line ◽  
Sensory Cells ◽  
Mormyrid Fish ◽  
Stimulation Of

Responses of cells of posterior lateral line lobe to activation of electroreceptors in a mormyrid fish

1976 ◽  
Vol 39 (4) ◽  
pp. 693-712 ◽  
Author(s):  
B. Zipser ◽  
M. V. Bennett
Keyword(s):  
Lateral Line ◽  
Granule Cells ◽  
Afferent Fiber ◽  
Skin Surface ◽  
Specific Receptor ◽  
High Frequencies ◽  
Posterior Lateral Line ◽  
Mormyrid Fish ◽  
Low Threshold ◽  
Stimulation Of

Activity of neurons in the lateral line lobe was studied by intracellular recording of responses to stimulation of the lateral line nerves and of electroreceptors on the skin surface. Two modes of activation occur for cells responding to inputs from medium receptors. There is a direct monosynaptic input mediated by a single fiber. Short latency of response and antidromic spread from cell to afferent fiber indicate that the mediating synapse is electrotonic. The second input is from a number of additional fibers and is relayed, presumably by the granule cells. At shortest latency this input is disynaptic, probably involving at least one electrotonic synapse. A relay is indicated by heterosynaptic facilitation of the PSP and by pronounced depression with repetitive stimulation. The monosynaptic input may be on the axon. Disynaptic inputs are distributed over the dendrites, and impulses can arise in the dendrites. What appear to be spikes restricted to dendritic regions are often recorded as small brief potentials in the cell body. There is a somatotopic projection of the electroreceptors to the lateral line lobe. The monosynaptic input comes from a specific receptor in the periphery. Strong disynaptic inputs come from a group of receptors generally found anterior, but less commonly posterior or lateral, to the receptor giving rise to the monosynaptic input. Additional inputs that are inhibitory come from surrounding receptors. The inhibition only affects responses to the disynaptic input. The different inputs and multiple sites of impulse initiation must modify the cell's response as compared with the input-output relations that would be obtained with inputs acting on a single summation point. Cells responding to activation of large receptors are infrequent. They are characterized by low threshold, little latency change near threshold, and ability to follow high frequencies of stimulation.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Mormyromast electroreceptor organs and their afferent fibers in mormyrid fish. II. Intra-axonal recordings show initial stages of central processing

1990 ◽  
Vol 63 (2) ◽  
pp. 303-318 ◽  
Author(s):  
C. C. Bell
Keyword(s):  
Lateral Line ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Direct Stimulation ◽  
Postsynaptic Potentials ◽  
Central Processing ◽  
Refractory Periods ◽  
Synaptic Potentials ◽  
Afferent Fibers ◽  
Stimulation Of

1. Physiologically and morphologically identified primary afferent fibers from mormyromast electroreceptor organs were recorded intracellularly. The fiber recordings were made from the nerve root of the posterior lateral line nerve, where the fibers enter the brain, and from the electrosensory lateral line lobe (ELL), near the central terminals of the fibers. 2. The intracellular recordings reveal a variety of potentials, synaptic and nonsynaptic, in addition to the large orthodromic action potentials from the periphery. The goal of the present study was to describe and interpret these various potentials in mormyromast afferent fibers as a first step in understanding the processing of electrosensory information in ELL. 3. Three types of synaptic potentials were recorded inside mormyromast afferent fibers: 1) electric organ corollary discharge (EOCD) excitatory postsynaptic potentials (EPSPs), driven by the motor command that elicits the electric organ discharge (EOD); 2) EPSPs evoked by electrosensory stimulation of electroreceptors in the skin near the electroreceptor from which the recorded fiber originates or by direct stimulation of an electrosensory nerve; and 3) inhibitory postsynaptic potentials (IPSPs) evoked by electrosensory stimulation of more distant electroreceptors. These synaptic potentials can be attributed to synaptic input to postsynaptic cells in ELL that is observed inside the afferent fibers because of electrical synapses between the fibers and the postsynaptic cells. 4. The peripherally evoked EPSPs could frequently be shown to be unitary. The unitary EPSPs were identical to the orthodromic spikes in originating from a single electroreceptor, in threshold, and in latency shift with increasing stimulus intensity. These similarities suggest that the unitary EPSPs are electrotonic EPSPs caused by impulses in other mormyromast afferent fibers that terminate on some of the same postsynaptic cells as the recorded fiber. The peripherally evoked IPSPs had a longer latency than the EPSPs or orthodromic spikes, requiring the presence of an inhibitory interneuron. 5. The peripherally evoked EPSPs, both unitary and nonunitary, show absolute refractory periods of 3-8 ms, followed by relative refractory periods of approximately 8 ms, when tested with two identical stimuli to a nerve. These refractory periods are interpreted as because of refractoriness in the fine preterminal branches of the axonal arbor. 6. A depolarizing afterpotential is commonly associated with the orthodromic spike and probably results from the successful propagation of the spike into the entire terminal arbor. The depolarizing afterpotential has a refractory period that is similar to that of the peripherally evoked EPSPs and that is also interpreted as refractoriness in the fine preterminal branches.(ABSTRACT TRUNCATED AT 400 WORDS)

The Activity of Lateral-Line Efferent Neurones in Stationary and Swimming Dogfish

1972 ◽  
Vol 57 (2) ◽  
pp. 435-448 ◽  
Author(s):  
B. L. ROBERTS ◽  
I. J. RUSSELL
Keyword(s):  
Lateral Line ◽  
Body Movement ◽  
Cranial Nerves ◽  
Regulatory System ◽  
The Body ◽  
Muscle Fibres ◽  
Sense Organs ◽  
Efferent System ◽  
Natural Stimulation ◽  
Stimulation Of

1. The activity of efferent neurones innervating lateral-line organs on the body of dogfish was followed by recording from filaments of cranial nerve X in 41 decerebrate preparations. 2. The efferent nerves were not spontaneously active. 3. Tactile stimulation to the head and body, vestibular stimulation and noxious chemical stimulation were followed by activity of the efferent nerves. 4. In contrast, natural stimulation of lateral-line organs (water jets) did not reflexly evoke discharges from the efferent fibres. 5. Reflex efferent responses were still obtained to mechanical stimulation even after the lateral-line organs had been denervated. 6. Electrical stimulation of cranial nerves innervating lateral-lines organs was followed by reflex activity of the efferent fibres. But similar stimuli applied to other cranial nerves were equally effective in exciting the efferent system. 7. Vigorous movements of the fish, involving the white musculature, were preceded and accompanied by activity of the efferent fibres which persisted as long as the white muscle fibres were contracting. 8. Rhythmical swimming movements were accompanied by a few impulses in the efferent fibres grouped in bursts at the same frequency as the swimming movements. 9. It is concluded that the efferent neurones cannot contribute to a feedback regulatory system because they are not excited by natural stimulation of the lateral-line sense organs. The close correlation found between efferent activity and body movement suggests that the efferent system might operate in a protective manner to prevent the sense organs from being over-stimulated when the fish makes vigorous movements.

Electroreceptors and Direction Specific Arrangement in the Lateral Line System of Salamanders?

1981 ◽  
Vol 36 (5-6) ◽  
pp. 493-496 ◽  
Author(s):  
Bernd Fritzsch
Keyword(s):  
Lateral Line ◽  
Fiber Bundles ◽  
Sensory Cells ◽  
Lateral Line System ◽  
Line System ◽  
Lateral Line Organ ◽  
Posterior Lateral Line ◽  
Afferent Fibers ◽  
Lateral Line Afferents ◽  
Line Organ

Abstract The arrangement of the lateral line afferents of salamanders as revealed by transganglionic staining with horse­ radish peroxidase is described. Each lateral line organ is supplied by two fibers only. In the medulla these two afferent fibers run in separate fiber bundles. It is suggested, that only those fibers contacting lateral line sensory cells with the same polarity form together one bundle. Bundles formed by anterior or posterior lateral line afferents are also clearly separated. Beside the lateral line organs smaller pit organs are described. These organs are supplied by one afferent only which reveals an arrangement in the medulla different from that of the lateral line afferents. Based on anatomical facts, these small pit organs are considered to be electroreceptors. Centrifugally projecting neurons, most probably efferents, are described in the medulla.

The fine structure of ampullary electric receptors in Amiurus

1964 ◽  
Vol 160 (980) ◽  
pp. 345-359 ◽  
Keyword(s):  
Fine Structure ◽  
Lateral Line ◽  
Cell Group ◽  
Sensory Cells ◽  
Receptor Cells ◽  
Pit Organ ◽  
Accessory Cells ◽  
Myelinated Nerves ◽  
Square Array ◽  
Small Nerve

The small pit-organs of Amiurus have been included in the group of ampullary lateral-line organs. On morphological and physiological grounds these ampullary organs are thought to be electric receptors and not mechano-receptors; thus they can be distinguished from all other types of acoustico-lateralis organs of vertebrates. Each small pit-organ consists of a duct leading from the surface of the skin to an ampulla, beneath which there is a group of cells lying at the base of the epidermis. There are two main types of cells in this group: the receptor and the accessory cells. The apical surfaces of the receptor cells bear microvillae but no cilia: these microvillae project into the lumen of the ampulla. Myelinated nerves supply the organs at the base ; they lose their myelin sheaths before entering the cell group where they branch and innervate the receptor cells. Small nerve terminals are closely applied to the surface of the receptor cells and in some places are thought to be in synaptic contact. Near these regions characteristic dense bodies are found in the base of the receptor cells. The bodies are surrounded by an accumulation of small vesicles of about 300 to 500 Å in diameter; they resemble structures found in corresponding situations in other types of sensory cells. Dense inclusions are found in some receptor cells: these inclusions have a highly ordered fine structure which in some sections appears as a square array of dense dots having a centre-to-centre spacing of about 75 Å. These observations are discussed in relation to the supposed activity of small pit-organs as electric receptors and to their position in the group of ampullary lateral-line organs.

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