Eva Rácz

Publications of Eva Rácz

• Effect of unilateral labyrinthectomy on the molecular composition of perineuronal nets in the lateral vestibular nucleus of the rat.

  Authors: Adám Deák, Tímea Bácskai, Botond Gaál, Eva Rácz, Klara Matesz

  Neuroscience letters. 02/2012; 513(1):1-5.

  Disturbances in vestibular functions caused by unilateral labyrinthectomy (UL) are spontaneously restored during the process of vestibular compensation due to the plasticity of CNS. The underlyingDisturbances in vestibular functions caused by unilateral labyrinthectomy (UL) are spontaneously restored during the process of vestibular compensation due to the plasticity of CNS. The underlying molecular background of vestibular compensation is not yet fully understood. Recent studies have shown that the extracellular matrix (ECM) molecules have either permissive or non-permissive effect on the neural plasticity. In our previous study we have demonstrated changes in the expression of hyaluronan (HA) in the vestibular nuclei (VN) of the frog following peripheral vestibular lesion. The present work was undertaken to examine the expression of the HA and chondroitin sulfate proteoglycans (CSPGs) in the lateral vestibular nucleus (LVN) of the rat following UL by using histochemical methods. On the first postoperative day, the condensation of the ECM around the neurons, the perineuronal net (PNN) was not distinguished from the surrounding neuropil on the side of UL indicating the desorganization of its molecular structure. At survival day 3, the PNN was recognizable with the HA probe, whereas its staining for the CSPGs was restored by the time of the seventh postoperative day. In the neuropil, the intensity of the HA increased on the operated side, while the CSPGs reaction almost completely disappeared. The present study have demonstrated for the first time that the UL is accompanied by the modification of the HA, and CSPG staining pattern in the PNN of the LVN in the rat. As the reorganization of the PNN corresponds to the restoration of spontaneous activity of vestibular neurons, our study implies the role of HA and CSPGs in the vestibular compensation.

• Comment on "Tests of scaling and universality of the distributions of trade size and share volume: Evidence from three distinct markets".

  Authors: Eva Rácz, Zoltán Eisler, János Kertész

  Physical review. E, Statistical, nonlinear, and soft matter physics. 07/2009; 79(6 Pt 2):068101.

  In a recent publication, Plerou and Stanley [Phys. Rev. E 76, 046109 (2007)] use the Meerschaert-Scheffler estimator to verify the "inverse half-cubic law" of trade size distributions. We show thatIn a recent publication, Plerou and Stanley [Phys. Rev. E 76, 046109 (2007)] use the Meerschaert-Scheffler estimator to verify the "inverse half-cubic law" of trade size distributions. We show that this procedure systematically underestimates these tail exponents.

• Vestibulotrigeminal pathways in the frog, Rana esculenta.

  Authors: Clara Matesz, Gabriella Kovalecz, Gábor Veress, Adám Deák, Eva Rácz, Tímea Bácskai

  Brain research bulletin. 04/2008; 75(2-4):371-4.

  The aim of this study was to investigate whether primary vestibular afferent fibers establish direct connections with the motor and sensory trigeminal system in the brainstem of the frog. TheThe aim of this study was to investigate whether primary vestibular afferent fibers establish direct connections with the motor and sensory trigeminal system in the brainstem of the frog. The experiments were carried out on Rana esculenta. In anaesthetized animals the trigeminal and vestibular nerves were prepared, and their proximal stumps were labeled either with fluorescein binding dextran amine (trigeminal nerve) or tetramethylrhodamine dextran amine (vestibulocochlear nerve). With a confocal laser scanning microscope we could detect close connections between the vestibular fibers and branches of the dorsal dendritic array of the jaw-closing motoneurons, suggestive of monosynaptic contacts. In the other parts of the brainstem, vestibular terminals were detected in the termination areas of the mesencephalic trigeminal nucleus and of the Gasserian (Vth) ganglion and they were probably involved in polysynaptic connections. In agreement with the results obtained in mammalian species, the present findings suggest that the vestibulotrigeminal relationship is quite complex and uses multiple pathways to connect the vestibular apparatus with the motor and sensory nuclei of the trigeminal nerve in the anurans as well.

• On sensitivity amplification in intracellular signaling cascades.

  Authors: Eva Rácz, Boris M Slepchenko

  Physical biology. 02/2008; 5(3):36004.

  Sensitivity amplification has long been regarded as a virtually universal property of signal transduction cascades, yet a comprehensive parameter analysis remains a challenge even for relativelySensitivity amplification has long been regarded as a virtually universal property of signal transduction cascades, yet a comprehensive parameter analysis remains a challenge even for relatively simple networks. We use a fast and accurate method to compute properties of multilevel cascades of activation-inactivation cycles and show that the monocyclic cascades amplify sensitivity only under specific conditions. In particular, it is found that efficient sensitivity amplification in a cascade, relative to the sensitivities of individual cycles, requires asymmetry in saturation of converter enzymes, with inhibitors much more saturated than activators.

• Organization of last-order premotor interneurons related to the protraction of tongue in the frog, Rana esculenta.

  Authors: Eva Rácz, Tímea Bácskai, Gábor Szabo, György Székely, Clara Matesz

  Brain research. 02/2008; 1187:111-5.

  Moving visual stimuli elicit a sequence of coordinated activity of muscles including tongue protraction. Morphological and physiological studies fail to reveal any direct tectal projections toMoving visual stimuli elicit a sequence of coordinated activity of muscles including tongue protraction. Morphological and physiological studies fail to reveal any direct tectal projections to hypoglossal motoneurons suggesting that the last-order premotor interneurons (LOPI) are the direct recipients of neural activities generated in the optic tectum. The aim of this study is to analyze the topographical organization of the last-order premotor interneurons related to protractor muscles of the tongue. In Rana esculenta, biotinylated dextran amine (BDA) was injected by iontophoresis into the subnucleus of the hypoglossal nerve containing the motoneurons of protractor muscles of the tongue. For visualizing BDA, sections were treated with avidin-biotin complex and a nickel-enhanced DAB chromogen reaction. The position of labeled neurons was reconstructed with a Neurolucida equipment. Morphologically heterogeneous populations of neurons were detected bilaterally, the majority of them were distributed ipsilateral to the site of injection and extended 1200 microm in rostral and 500 microm in caudal directions. Labeled neurons were found in the rhombencephalic reticular formation, the vestibular nuclei, the nucleus prepositus hypoglossi, the nucleus of solitary tract, the spinal nucleus of trigeminal nerve and the dorsal column nuclei. Our results indicate that the majority of last-order premotor interneurons related to protractor muscles of the tongue are located in the reticular formation of the brainstem. Since this area also receives a significant input from the vestibular system and from proprioceptive fibers, the last-order premotor interneurons presented here may be the target of convergence of sensory modalities involved in prey-catching behavior.

• Organization of dye-coupled cerebellar granule cells labeled from afferent vestibular and dorsal root fibers in the frog Rana esculenta.

  Authors: Eva Rácz, Timea Bácskai, Gabor Halasi, Endre Kovács, Clara Matesz

  The Journal of comparative neurology. 06/2006; 496(3):382-94.

  Application of neurobiotin to the nerves of individual labyrinthine organs and dorsal root fibers of limb-innervating segments of the frog resulted in labeling of granule cells in the cerebellumApplication of neurobiotin to the nerves of individual labyrinthine organs and dorsal root fibers of limb-innervating segments of the frog resulted in labeling of granule cells in the cerebellum showing a significant overlap with a partial segregation in the related areas of termination. In different parts of the cerebellum, various combinations of different canal and otolith organ-related granule cells have been discerned. The difference in the extension of territories of vertical canals vs. horizontal canals may reflect their different involvement in the vestibuloocular and vestibulospinal reflex. Dye-coupled cells related to the lagenar and saccular neurons were localized in more rostral parts of the cerebellum, whereas cells of the utricle were represented only in its caudal half. This separation is supportive of the dual function of the lagena and the saccule. The territories of granule cells related to the cervical and lumbar segments of the spinal cord were almost completely separated along the rostrocaudal axis of cerebellum, whereas their territories were almost entirely overlapping in the mediolateral and ventrodorsal directions. The partial overlap of labyrinthine organ-related and dorsal root fiber-related granule cells are suggestive of a convergence of sensory modalities involved in the sense of balance. We propose that the afferent input of vestibular and proprioceptive fibers mediated by gap junctions to the cerebellar granule cells subserve one of the possible morphological correlates of a very rapid modification of the motor activity in the vestibulocerebellospinal neuronal circuit.