Morphological parameters of mauthner neurons of goldfishes with modified asymmetry of motor behavior

Михайлова, Г. З.; Tiras, N. R.; Pavlík, V.; Santalova, I. M.; Grigorieva, E. E.; Мошков, Д. А.

doi:10.1007/s11062-006-0021-2

Cited by 11 publications

(10 citation statements)

References 24 publications

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“…Adaptation using bilateral stimulation was induced using the protocol described earlier [14]. To test the level of adaptational changes in one of the MNs, we used both bilateral and contralateral (with respect to a dominant MN) vestibular stimulation using the technique developed earlier [9,11].…”

Section: Methodsmentioning

confidence: 99%

“…They are, to a considerable extent, determined, on the one hand, by the morphofunctional asymmetry of MNs that is manifested in behavior as the motor asymmetry of the fish [7,8] and, on the other hand, by variations of this asymmetry depending on the preceding loading on one afferent input or another. It was found that experimental adequate stimulation or unilateral elimination of one input selectively influences the structure and function of the individual MN; this leads to a change in the inborn motor asymmetry of the fish [9,10]. Regulation of all the above modifications at the level of the individual MN has not at present been studied.…”

Section: Introductionmentioning

confidence: 99%

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Stabilization of motor asymmetry in the goldfish under the influence of optokinetic stimulation

et al. 2008

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Adaptation as a memory model appears, at the cellular level, as an increase in the resistivity of neurons to fatigue under the influence of repetitive natural training stimulation. Selective induction of adaptational changes in separate compartments of one and the same neuron can also serve as an important instrument for identification of the roles of these compartments in the integrative function of the individual neuron. Mauthner neurons (MNs) of fishes (the goldfish in particular) possess a clearly differentiated soma and two dendrites, lateral and ventral ones. The soma and lateral dendrite of each MN receive afferentation from the ipsilateral vestibular apparatus; at present, the functional and morphological aspects of selective adaptational modifications induced in these compartments by adequate vestibular stimulation have been examined in detail. As to the ventral MN dendrite receiving visual afferentation from the contralateral eye via the ipsilateral tectum, it remained impossible until now to realize the respective approach. We found that training sessions of visual optokinetic stimulation performed in certain modes provide selective activation of one MN through its ventral dendrite and increase the resistivity of this cell to fatiguing stimulation. Therefore, we first demonstrated the possibility of adaptational changes in an individual ventral dendrite of the MN. If fishes were preliminarily adapted with respect to vestibular stimulation, and the resistivity of the soma and lateral dendrite was selectively increased, the resistivity to fatiguing visual test stimulation also increased. On the other hand, if fishes were preliminarily adapted with respect to visual stimulation, the resistivity to fatiguing vestibular stimulation also increased. The observed increase in the resistivity of MNs of fishes adapted due to sensory stimulation of one afferent input with respect to sensory stimulation of other sensory input, as well as an increase in the resistivity to sensory stimulation of one modality, probably show that the mechanism of increase in the resistivity is the same in both cases.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stabilization of motor asymmetry in the goldfish under the influence of optokinetic stimulation

et al. 2008

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“…To obtain 3-D reconstructions (images) of MNs and to estimate the dimensions of the right and left neurons, we used the technique described earlier [19]. Serial 3-µm-thick sections of the medulla were studied using a light microscope provided with a digital camera.…”

Section: Methodsmentioning

confidence: 99%

“…The true volume of the MNs was estimated as the sum of the volumes of these three main (greatest) components (taking into account a preliminary calculated coefficient of compression of the tissue). Alignment of images of the medulla sections with respect to each other and 3-D reconstruction of the MNs were performed using the corresponding computer software [19,20]. For electron microscopic studies, we prepared serial slices of the medulla (10 µm thick).…”

Section: Methodsmentioning

confidence: 99%

Effects induced by an actin-polymerizing peptide in goldfish mauthner neurons

2006

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In goldfishes, we studied (i) manifestations of functional activity of Mauthner neurons (MNs) reflected in motor behavior and (ii) changes in 3-D morphometry (ratio of volumes) and ultrastructure of MNs after applications of an actin-polymerizing peptide obtained from scorpion venom and after vestibular rotational stimulations (trainings) inducing natural modification of functions of the MNs (adaptation). In MNs subjected to application of the peptide, the increase in the functional resistance and morphological stability caused by long-lasting stimulation directly depended on the dose of the applied peptide or on the effectiveness of trainings, whereas in intact and control MNs such stimulation resulted in significant decreases in the activity and volumes of these cells. At the ultrastructure level, both applications of the peptide and trainings caused the formation of extensive bundles of actin filaments ("stress-fibers") in the cytoplasm of MNs and led to an increase in the dimension of desmosome-like contacts (DLCs) in afferent synapses. At chemical synapses, the effect looked like a reciprocal decrease in the length of the active zones (a structural sign of long-term depression, LTD), while at mixed synapses this was manifested in an increase in the number of fibrillar bridges in the gaps of DLCs (a structural sign of long-term potentiation, LTP). The data obtained allow us to hypothesize that LTD of the efficacy of transmission through chemical synapses is involved in the formation of the adaptation state of the MNs and that polymerization of actin in the cytoplasm and DLCs underlies the mechanism of LTD and adaptation. The development of ultrastructural manifestations of LTP at mixed synapses after polymerization of actin by the peptide, which is related to a reciprocal increase in the efficacy of "mixed" afferent inputs, explains the maintenance of a high integral level of activity of the MNs, despite a drop in the functional activity of "chemical" afferent inputs. Therefore, the actin cytoskeleton plays a clearly significant role in the maintenance of the balance of excitation at the neuronal level.

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“…This is why many aspects of the functional role of the ventral dendrite of MNs remain unknown or have been studied to a much lesser extent than roles of the somatic part and of the lateral dendrite of the above cells. The existing data were obtained mostly in acute experiments with the use of a denervation technique [10,11].…”

Section: Introductionmentioning

confidence: 99%

Effects of optokinetic stimulation on motor asymmetry in the goldfish

et al. 2007

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In goldfish fries, we examined the effect of the optomotor reaction (drive to swim toward moving images of vertical dark bars) on the behavioral motor asymmetry. Contralateral optokinetic stimulation of fishes (rotation of the bars against the direction preferred by fishes in their turnings) gradually smoothed and, later on, inverted the motor asymmetry, while the asymmetry underwent no modifications in the case of ipsilateral optokinetic stimulation (rotation of the bars in the direction similar to that preferred for turnings). Contralateral optokinetic stimulation also induced long-lasting inversion of the motor asymmetry of immobilized fishes deprived of the possibility to follow the movement of bar images. Ipsilateral optokinetic stimulation of fishes with the enucleation of the ipsilateral eye enhanced their motor asymmetry, while contralateral stimulation either did not modify the motor asymmetry of such individuals or inverted this feature. These data agree with the concept that, in fishes, one eye dominates and more actively provides tracking of the movement of bars, while another eye is a subdominant one. In general, we first found that the use of specific visual stimulation allows one to modify for a long time the behavioral motor asymmetry of the fishes, which, as is known, correlates with the morphofunctional asymmetry of Mauthner neurons (MNs). Visual information that activates MNs influences mostly the ventral dendrites of these neurons; thus, our findings allow us to believe that stimulations, which initiate the optomotor reaction, can serve as an adequate physiological model of natural visual stimulation of MNs (with projection of the respective influences on the ventral dendrites of the above cells). The use of such an experimental paradigm opens up new possibilities for studies of the role of these dendrites in the functions of MNs and of the plasticity of morphofunctional organization of these cells.Keywords: free motor behavior of fishes, asymmetry of motor behavior, immobilization, optokinetic stimulation, optomotor reaction, unilateral enucleation of the eye.

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Morphological parameters of mauthner neurons of goldfishes with modified asymmetry of motor behavior

Cited by 11 publications

References 24 publications

Stabilization of motor asymmetry in the goldfish under the influence of optokinetic stimulation

Stabilization of motor asymmetry in the goldfish under the influence of optokinetic stimulation

Effects induced by an actin-polymerizing peptide in goldfish mauthner neurons

Effects of optokinetic stimulation on motor asymmetry in the goldfish

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