Papers in Neurosciences by Enrique Soto
Vestibular prosthesis: from basic research to clinics, 2023
Galvanic vestibular stimulation activates the parietal and temporal cortex in humans: A functional near-infrared spectroscopy (fNIRS) study., 2023
Galvanic vestibular stimulation (GVS) helps stabilize subjects when balance and posture are compr... more Galvanic vestibular stimulation (GVS) helps stabilize subjects when balance and posture are compromised. This work aimed to define the cortical regions that GVS activates in normal subjects. We used functional near-infrared spectroscopy (fNIRS) to test the hypothesis that GVS activates similar cortical areas as a passive movement. We used transcranial current stimulation (cathode in the right mastoid process and anode in the FPz frontopolar point) of bipolar direct current (2 mA), false GVS (sham), vibration (neutral stimulus), and back and forth motion (positive control of vestibular movement) in 18 clinically healthy volunteers. Seventy-two brain scans were performed, applying a
The article shows a theoretical (part 1) improvement in the stabilization of the gaze in galvanic... more The article shows a theoretical (part 1) improvement in the stabilization of the gaze in galvanic vestibular stimulation.
A mathematical model of the formation of output information in a biosensor of angular acceleratio... more A mathematical model of the formation of output information in a biosensor of angular acceleration is presented. The functional and numerical parameters of the model have been determined by results of experiments made in 2001-2008. A comparison with the mathematical model of J. M. Goldberg and C. Fernandez (1971) describing the change in spike frequency of the primary afferent neuron spikes in response to an angular acceleration of the head as it turns around a vertical axis is carried out.
The study of cardiovascular function with galvanic vestibular stimulation has provided evidence o... more The study of cardiovascular function with galvanic vestibular stimulation has provided evidence on the neural structures that are involved in the vestibulo-autonomic reflex. This study determined if the effect on heart rate using galvanic vestibular stimulation persists after provoking a sympathetic response and if this response differs when using unilateral or transmastoid (bilateral) stimulation. We analysed heart rate and heart rate variability using unilateral and transmastoid galvanic vestibular stimulation combined with cardiovascular reflex evoked by postural change in 24 healthy human subjects. Three electrode configurations were selected for unilateral stimulation considering the anatomical location of each semicircular canal. We compared recordings performed in seated and standing positions, and with unilateral and transmastoid stimulation. With subjects seated, a significant transient decrease in heart rate was observed with unilateral stimulation. With transmastoid stimulation, heart rate decreased in both seated and standing positions. Average intervals between normal heartbeats recorded with stimulation resemble parasympathetic cardiac function induced by auricular vagal nerve stimulation. Our results indicate that unilateral stimulation does not eliminate the natural heart rate increase caused by orthostatic hypotension. In contrast, transmastoid stimulation provoked a transient reduction in heart rate, even when subjects were standing. These responses should be considered while performing experiments with galvanic vestibular stimulation and subsequent effects in cardiac regulation mechanisms.
Galvanic Vestibular Stimulation(GVS) induce the sensation of movement in subjects in flight simul... more Galvanic Vestibular Stimulation(GVS) induce the sensation of movement in subjects in flight simulators and in cosmonauts, creating a cognitive simulation of movement. The system consists of a control unit, a function generator, and a power amplifier. GVS is capable of activating the neurons of the vestibular system and inducing the sensation of movement. When applied in coordination with a flight simulation program GVS modifies the eye movement control responses, electrically activating the vestibular-ocular, vestibule-colic, and vestibule-spinal reflexes. The ultimate goal of this type of stimulation is to generate augmented reality in the pilots during training or potentially also during a flight in microgravity.
The primary neurotransmitter released by the efferent terminals of the olivocochlear pathway is a... more The primary neurotransmitter released by the efferent terminals of the olivocochlear pathway is acetylcholine (ACh), which binds to nicotinic ACh α9-α10 located at the base of the outer hair cell (OHC) (Taranda et al., 2009), and M2 and M4 muscarinic receptors, in the synaptic complex of both the lateral olivocochlear pathway (LOC) and the medial olivocochlear pathway (MOC) (Maison et al., 2010). ACh and the calcitonin gene-related peptide co-localize in the efferent neurons of the OC bundle. Immunoreactivity to γ-aminobutyric acid was also detected in the OC cochlear efferents, although it seems to be limited to the apex of the cochlea (Maison,
In this work we synthetized seven samples of titania doped with nanoparticles of gadolinium oxide... more In this work we synthetized seven samples of titania doped with nanoparticles of gadolinium oxide which, previously, were doped with europium at 2 mol%. The doped samples of titania were synthetized using the sol gel method and the nanoparticles of gadolinium oxide were synthetized by the precipitation reaction of precursors of gadolinium nitrate hexahydrate and europium nitrate pentahydrate. All the titania samples were submitted to a thermal treatment at 750°C. Optical properties, such as the absorption, emission, and emission decay times, besides the X-ray diffraction patterns and the Raman spectra were recorded and analysed. The band gap was calculated from the extrapolation of the linear fit in the absorption edge range in the Tauc plot, the electronic transitions of the europium were identified. Finally, due to the high luminescent intensity of the nanoparticles of gadolinium oxide doped with europium, the possible incorporation of these into the matrix of titania, the possibility for exciting these using lower energy (375 nm) and consequently the shift in the band gap; made it possible to propose the material be used for photocatalytic and photonic applications.
Galvanic Vestibular Stimulation(GVS) induce the sensation of movement in subjects in flight simul... more Galvanic Vestibular Stimulation(GVS) induce the sensation of movement in subjects in flight simulators and in cosmonauts, creating a cognitive simulation of movement. The system consists of a control unit, a function generator, and a power amplifier. GVS is capable of activating the neurons of the vestibular system and inducing the sensation of movement. When applied in coordination with a flight simulation program GVS modifies the eye movement control responses, electrically activating the vestibular-ocular, vestibule-colic, and vestibule-spinal reflexes. The ultimate goal of this type of stimulation is to generate augmented reality in the pilots during training or potentially also during a flight in microgravity.
Dudakova O. S. Construction of an infinite set of classes of partial monotone functions of multi-... more Dudakova O. S. Construction of an infinite set of classes of partial monotone functions of multi-valued logic Gashkov S. B., Gashkov I. B., and Frolov A. B. Complexity of solving small degree equations in a ring of
Using the sol-gel technique a SiO 2-PMMA hybrid matrix was synthesized by the simultaneous hydrol... more Using the sol-gel technique a SiO 2-PMMA hybrid matrix was synthesized by the simultaneous hydrolysis of tetraethyl orthosilicate (TEOS) and the polymerization of methyl methacrylate (MMA). The hybrid material was doped with terbium ions for it's luminescent properties for applications in thin film devices, sensors and as an active laser media. The optical properties of the material were characterized by UV-vis and photoluminescence spectroscopy. Surface morphology of the material properties were observed using atomic force microscopy and the material's composition was studied using Raman spectroscopy. Distribution of the dopant inside matrix was analyzed by confocal microscopy. Measurements indicate that a homogeneous, non-porous composite was obtained with the terbium ions retaining their luminescent properties with good optical transmission across all the visible spectra.
The application of galvanic vestibular stimulation is considered for the galvanic correction of p... more The application of galvanic vestibular stimulation is considered for the galvanic correction of pilot's vestibular activity during visual flight control on a flight-dynamic stand and in extreme flight situations.
We studied the surface morphology and biocompatibility of hydrogenated amorphous silicon-germaniu... more We studied the surface morphology and biocompatibility of hydrogenated amorphous silicon-germanium (a-Si 1-x Ge x :H) thin films prepared by Low Frequency Plasma Enhanced Chemical Vapor Deposition (LF-PECVD). These films were deposited on a Corning 2947 glass substrate having a thickness of 3 µm, the electrical performance showed a decreased electrical resistance for low regime voltage. The root mean square (RMS) surface roughness of the films was measured by atomic force microscopy (AFM) in a non-contact mode. A biocompatibility tests was carried out using primary cultures of dorsal root ganglion (DRG) of Wistar rats. The DRG neurons were incubated for 18 hours on a-Si 1-x Ge x :H thin films, and subsequent electrophysiological recording was performed. These neurons displayed typical ionic currents, including a fast-inward current at the beginning of voltage clamp pulse (Na + current) and ensuing outward currents (K + current). In current clamp experiments, depolarizing current pulse injection caused typical action potential discharge of the neurons. These results confirmed the feasibility of using a-Si 1-x Ge x :H thin films as a biocompatible material.
In this work, we evaluate the effect of two peptides Sa12b (EDVDHVFLRF) and Sh5b (DVDHVFLRF-NH 2)... more In this work, we evaluate the effect of two peptides Sa12b (EDVDHVFLRF) and Sh5b (DVDHVFLRF-NH 2) on Acid-Sensing Ion Channels (ASIC). These peptides were purified from the venom of solitary wasps Sphex argentatus argentatus and Isodontia harmandi, respectively. Voltage clamp recordings of ASIC currents were performed in whole cell configuration in primary culture of dorsal root ganglion (DRG) neurons from (P7-P10) CII Long-Evans rats. The peptides were applied by preincubation for 25 s (20 s in pH 7.4 solution and 5 s in pH 6.1 solution) or by co-application (5 s in pH 6.1 solution). Sa12b inhibits ASIC current with an IC 50 of 81 nM, in a concentration-dependent manner when preincubation application was used. While Sh5b did not show consistent results having both excitatory and inhibitory effects on the maximum ASIC currents, its complex effect suggests that it presents a selective action on some ASIC subunits. Despite the similarity in their sequences, the action of these peptides differs significantly. Sa12b is the first discovered wasp peptide with a significant ASIC inhibitory effect.
Previous works showed that opioid peptides are produced by olivocochlear efferent neurons, while ... more Previous works showed that opioid peptides are produced by olivocochlear efferent neurons, while cochlear hair cells express opioid receptors. It has been proposed that opioids protect the auditory system from damage by intense stimulation, although their use for therapeutic or illicit purposes links to hearing impairment. Therefore, it is relevant to study the effect of opioids in the auditory system to define their functional expression and mechanism of action. This study investigated the modulation of the Ca 2+ currents by opioid peptides in the rat outer hair cells (OHC) using the whole-cell patch-clamp technique. The influence of agonists of the three opioid receptor subtypes (μ, δ, and κ) was studied. The κ opioid receptor agonist U-50488 inhibits the Ca 2+ currents in a partially reversible form. Coincidently, norbinaltorphimine (a κ receptor antagonist) blocked the U-50488 inhibitory effect on the Ca 2+ current. The δ and the μ opioid receptor agonists did not significantly affect the Ca 2+ currents. These results indicate that the κ opioid receptor activation inhibits the Ca 2+ current in OHC, modulating the intracellular Ca 2+ concentration when OHCs depolarize. The modulation of the auditory function by opioids constitutes a relevant mechanism with a potential role in the physiopathology of auditory disturbances.
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Papers in Neurosciences by Enrique Soto
áreas de la corteza visual en nuestro cerebro. El
El procesamiento de la información visual se realiza
a través de un paso inicial de segregación sensorial
de las propiedades de un estímulo visual, algo como
una deconstrucción de la imagen visual, que separa el
color, la forma y el movimiento......
nados de toxinas con implicaciones biomédicas y métodos
para su estudioresultan de una primera aproximación para
mostrar de manera panorámica el trabajo de investigación que
desarrollan los miembros de la Red Iberoamericana Temática
CYTED 212RT0467 (Biotox) en el campo de las toxinas con implicaciones
para la Biomedicina.
El texto no pretende ser exhaustivo, más bien se trata de
un material introductorio, de carácter general, cuyo propósito
comunicativo es servir como presentación delas líneas de investigación
de los principales grupos de Argentina, Brasil, Chile,
Costa Rica, Cuba, España, México y Venezuela pertenecientes a
la Red Biotox que se ocupan de toxinas o cuentan con un arsenal
metodológico para su caracterización físico-química,
biológica o su acción farmacológica.
Los autores son reconocidos especialistas en sus respectivas
áreas de trabajo a los cuales agradezco el esfuerzo en la elaboración
de este material que puede ser útil a profesionales y
estudiantes interesados en conocer aspectos del estado del arte
en investigaciones sobre toxinas o métodos para su estudio,
en el ámbito iberoamericano. En principio, estos textos fueron
concebidos para apoyar las exposiciones que se realizaron en
el I Taller-Científico Técnico de Biotox celebrado en el Instituto
Clodomiro Picado, Costa Rica (6-10 agosto, 2012), que dio inicio a
las actividades de la Red. Invito a los interesados a acompañar
la lectura de los artículos con las correspondientes presentaciones
de sus autores. Las presentaciones pueden encontrarse
en la Multimedia: Memorias de las actividades de la Red CYTED
212RT0467, Biotox: Toxinas de Interés para la Biomedicina, 2012
(Costa Rica) y posteriormente serán depositadas en la página
Web de la Red que se encuentra en desarrollo