Efferent tectal cells of crucian carp: Physiology and morphology

Niida, Akiyoshi; Ohono, Takashi; Iwata, Katsumi

doi:10.1016/0361-9230(89)90066-x

Cited by 15 publications

(11 citation statements)

References 32 publications

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“…The retinofugal projections terminate in the superficial layers (Vanegas, 1975a,b), but the monosynaptic latencies of the tectal evoked spikes found in the present study indicate that deeper layers, where the efferent cells lie (Vanegas, 1975a;Niida et al, 1989;Meek, 1990), were also activated directly by the stimulus. Responses that were evoked using low stimulus intensities were probably due to activation of superficial layers, since the spike was often observed to jump to a shorter latency when the stimulus intensity was increased.…”

Section: Origin and Nature Of Tectal Evoked Responsesmentioning

confidence: 59%

“…In fishes, the visual world is retinotopically relayed to the contralateral optic tectum (Schwassmann, 1975). Since a direct tectospinal connection is absent in teleost fishes (Vanegas, 1975a;Meek, 1990), their visuomotor behaviour must depend, to a large extent, on projections from the tectum to the reticulospinal system (Vanegas, 1975a;Niida et al, 1989;Meek, 1990), which provides most of the projections from the brain to the spinal cord (e.g. de Waegh et al, 1985;Oka et a/., 1986;Dean and Paul, 199 1).…”

Section: Introductionmentioning

confidence: 99%

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Differential Responses of Single Reticulospinal Cells to Spatially Localized Stimulation of the Optic Tectum in a Teleost Fish, Salmo trutta

Bosch

Paul

1993

Eur J of Neuroscience

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To determine whether the topographically organized retinal input to the optic tectum is subsequently mapped onto the reticular formation, the responses of antidromically identified reticulospinal cells to tectal surface stimulation were investigated in 45 decerebrated, paralysed trout. The tectum was stimulated through a silver ball surface electrode at 24 different locations, and extracellular recordings were made from the rhombencephalic brainstem with glass microelectrodes filled with a 10% solution of horseradish peroxidase (HRP) in Tris buffer (pH 7.4). After recording, the HRP was, in some cases, iontophoretically expelled from the pipette to identify its location and visualized in histological sections by a modified Hanker-Yates method. Individual reticulospinal neurons discharged 1-4 spikes at short latency in response to stimulation of each of the 24 tectal locations. From one tectal location per cell, this initial response was followed by a late, sustained burst. With a short stimulus train (6 pulses, 55 Hz) the burst could last for over a second with discharge rates of up to 500 Hz. Sometimes this burst could be evoked from neighbouring tectal locations, but only by greatly increasing the stimulus strength. We conclude that the reticular formation receives a highly divergent monosynaptic connection from all locations of the tectum and that the longer latency, sustained burst response is due to a mapped connection between the tectum and the reticular formation. Since the late burst could be preceded by a silent period lasting for approximately 32 ms, we cannot rule out a dependence on interneurons situated between the tectum and the reticulospinal cells.

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Section: Origin and Nature Of Tectal Evoked Responsesmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Differential Responses of Single Reticulospinal Cells to Spatially Localized Stimulation of the Optic Tectum in a Teleost Fish, Salmo trutta

Bosch

Paul

1993

Eur J of Neuroscience

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“…MeLr and MeLc extend elaborate dendrites into the deeper layers of the tectum. Here, the cell bodies of tectofugal projection neurons are situated (Meek and Schellart, 1978;Nguyen et al, 1999), which, in other teleosts, have been reported to send a predominantly ipsilateral and excitatory projection to the nMLF (Bosch and Paul, 1993;Herrero et al, 1998a;Niida et al, 1998;Zompa and Dubuc 1998a,b;Isa and Sasaki, 2002;Torres et al, 2002;Perez-Perez et al, 2003). MeLr and MeLc extend axons into the spinal cord, arborizing predominantly in its rostral segments, in which their axon terminals colocalize with motor neurons and interneurons .…”

Section: Discussionmentioning

confidence: 77%

Visual Prey Capture in Larval Zebrafish Is Controlled by Identified Reticulospinal Neurons Downstream of the Tectum

Gahtan¹,

Tanger²,

Baier³

2005

J. Neurosci.

303

335

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Many vertebrates are efficient hunters and recognize their prey by innate neural mechanisms. During prey capture, the internal representation of the prey's location must be constantly updated and made available to premotor neurons that convey the information to spinal motor circuits. We studied the neural substrate of this specialized visuomotor system using high-speed video recordings of larval zebrafish and laser ablations of candidate brain structures. Seven-day-old zebrafish oriented toward, chased, and consumed paramecia with high accuracy. Lesions of the retinotectal neuropil primarily abolished orienting movements toward the prey. Wild-type fish tested in darkness, as well as blind mutants, were impaired similarly to tectum-ablated animals, suggesting that prey capture is mainly visually mediated. To trace the pathway further, we examined the role of two pairs of identified reticulospinal neurons, MeLc and MeLr, located in the nucleus of the medial longitudinal fasciculus of the tegmentum. These two neurons extend dendrites into the ipsilateral tectum and project axons into the spinal cord. Ablating MeLc and MeLr bilaterally impaired prey capture but spared several other behaviors. Ablating different sets of reticulospinal neurons did not impair prey capture, suggesting a selective function of MeLr and MeLc in this behavior. Ablating MeLc and MeLr neurons unilaterally in conjunction with the contralateral tectum also mostly abolished prey capture, but ablating them together with the ipsilateral tectum had a much smaller effect. These results suggest that MeLc and MeLr function in series with the tectum, as part of a circuit that coordinates prey capture movements.

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“…Such an indirect route would demand that tectobulbar stimulation excite tectal neurons, either by stimulation of tectal afferents in the bulb (Guthrie & Banks, 1974), or by antidromic activity in the tectobulbar axons. Although intratectal collaterals of these axons, which could mediate this antidromic tectal excitation, have not been seen in Golgi preparations (Meek & Schellart, 1978) or HRP backfills of tectobulbar neurons (Grover & Sharma, 1981), they have been clearly shown by intracellular lucifer dye injection (Niida et al, 1989). These axon collaterals of the types XII and XIII tectobulbar neurons were found to ramify in the SAC, a tectal layer where the type XIV but not type VI tectoisthmic neurons have dendrites (Meek & Schellart, 1978).…”

Section: Activity Elicited By Tectobulbar Stimulationmentioning

confidence: 97%

Nucleus isthmi in goldfish:In vitrorecordings and fiber connections revealed by HRP injections

Schmidt

1993

Vis Neurosci

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Recordings of field potentials in nucleus isthmi (NI) were obtained in an in vitro preparation of goldfish brain using a lateral approach. Horseradish peroxidase (HRP) was injected from recording electrodes to verify recordings within the nucleus and to label axonal pathways and cell bodies. Activity in NI was repetitive and could be elicited by stimulation of the optic nerve, tectum, pretectum, or tectobulbar tract. Spontaneous activity was present in some preparations and consisted of bursts with intervening silent periods. Anatomical and electrophysiological evidence indicated that the primary isthmotectal pathway is composed of fine fibers that exit NI rostrally and pass through pretectum to enter tectum rostrally. An afferent pathway consisting of both fine-and large-diameter fibers entered NI ventromedially; the large diameter axons have been previously reported in percomorph fishes, but were not thought to be present in cyprinids such as goldfish. The large diameter axons arise from labeled cell bodies in the region of the lateral thalamic nucleus. No labeled cell bodies were seen in ipsilateral nucleus pretectalis superficialis, pars magnocellularis, where they are seen in percomorphs. The fine axons, which have not been reported in percomorph fishes, were shown to arise from tectal bipolar (type VI) neurons. As in percomorphs, tectal type XIV neurons were also labeled. This and corroborating recordings from nucleus isthmi constitute the first demonstration of a tectoisthmic projection in a cyprinid fish.

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Efferent tectal cells of crucian carp: Physiology and morphology

Cited by 15 publications

References 32 publications

Differential Responses of Single Reticulospinal Cells to Spatially Localized Stimulation of the Optic Tectum in a Teleost Fish, Salmo trutta

Differential Responses of Single Reticulospinal Cells to Spatially Localized Stimulation of the Optic Tectum in a Teleost Fish, Salmo trutta

Visual Prey Capture in Larval Zebrafish Is Controlled by Identified Reticulospinal Neurons Downstream of the Tectum

Nucleus isthmi in goldfish:In vitrorecordings and fiber connections revealed by HRP injections

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