Reconstruction of brain neuronal pathways in brain from the diffusion tensor MRI data

MRI based fiber tracking is a diagnostic method based on the diffusion tensor MRI data, which allows to find pathways of neuronal bundles in brain in vivo. In this work we propose a method of neuronal pathways reconstruction using A-star algorithm, with the possibility to assess its the effectiveness. One of the criteria is the probabilistic search parameter G, defined by a set of diffusion coefficients in a given volume element. The parameter G obtained trajectory correlated to its length has the meaning of entropy and allows to assess reliability of the found path. The proposed method was tested on simulated data with the characteristic behavior of trajectories of the complex variations, different cases of intersection of the beams passing through the intersection without a common voxels, and obtained characteristics of the corresponding probability

Somatosensory-Evoked Early Sharp Waves in the Neonatal Rat Hippocampus

The developing entorhinal–hippocampal system is embedded within a large-scale bottom-up network, where spontaneous myoclonic movements, presumably via somatosensory feedback, trigger hippocampal early sharp waves (eSPWs). The hypothesis, that somatosensory feedback links myoclonic movements with eSPWs, implies that direct somatosensory stimulation should also be capable of evoking eSPWs. In this study, we examined hippocampal responses to electrical stimulation of the somatosensory periphery in urethane-anesthetized, immobilized neonatal rat pups using silicone probe recordings. We found that somatosensory stimulation in ~33% of the trials evoked local field potential (LFP) and multiple unit activity (MUA) responses identical to spontaneous eSPWs. The somatosensory-evoked eSPWs were delayed from the stimulus, on average, by 188 ms. Both spontaneous and somatosensory-evoked eSPWs (i) had similar amplitude of ~0.5 mV and half-duration of ~40 ms, (ii) had similar current-source density (CSD) profiles, with current sinks in CA1 strata radiatum, lacunosum-moleculare and DG molecular layer and (iii) were associated with MUA increase in CA1 and DG. Our results indicate that eSPWs can be triggered by direct somatosensory stimulations and support the hypothesis that sensory feedback from movements is involved in the association of eSPWs with myoclonic movements in neonatal rats

Sensory feedback synchronizes motor and sensory neuronal networks in the neonatal rat spinal cord

© The Author(s) 2016.Early stages of sensorimotor system development in mammals are characterized by the occurrence of spontaneous movements. Whether and how these movements support correlated activity in developing sensorimotor spinal cord circuits remains unknown. Here we show highly correlated activity in sensory and motor zones in the spinal cord of neonatal rats in vivo. Both during twitches and complex movements, movement-generating bursts in motor zones are followed by bursts in sensory zones. Deafferentation does not affect activity in motor zones and movements, but profoundly suppresses activity bursts in sensory laminae and results in sensorimotor uncoupling, implying a primary role of sensory feedback in sensorimotor synchronization. This is further supported by largely dissociated activity in sensory and motor zones observed in the isolated spinal cord in vitro. Thus, sensory feedback resulting from spontaneous movements is instrumental for coordination of activity in developing sensorimotor spinal cord circuits

Modified Recording Chamber for Sustained Kainate-Induced Gamma Oscillations in Submerged Rat Hippocampal Slices

© 2016, Springer Science+Business Media New York.Fast neuronal network oscillations in an in vitro model are a challenging task. Here, we report that sustained gamma (31–35 Hz) oscillations can be induced by kainate (50 nM) in submerged rat hippocampal slices using modified Hájos’s type recording chamber with a superfusion inlet positioned close to the CA3 pyramidal cell layer. The general features of these kainate-induced gamma oscillations were similar to those previously reported in the hippocampal slices using the interface-type chamber and superfused hippocampus in vivo. We suggest that close positioning of the superfusion inlet improves oxygen supply and temperature control of the oscillation-generating network and that this modification could be useful in studies of the gamma rhythmogenesis in the submerged slices

Follicular Nerve Evoked Responses in the Neonatal Rat Barrel Cortex

© 2016, Springer Science+Business Media New York.In the whisker-related somatosensory system, functional organization of the neuronal circuits is typically assessed through exploration of the responses evoked by whisker deflections. Here, we describe the responses evoked in the neonatal rat barrel cortex by direct electrical stimulation of the follicular nerve and its peripheral branches. Individual whisker follicles and follicular nerves were exposed through a cut on the skin. The electrical stimulation of the follicular nerve and the follicle at different locations using bipolar electrodes reliably evoked responses in the corresponding cortical barrel column. General features of the electrically evoked responses were similar to those evoked by the whisker deflection. However, the delays of the responses evoked by the electrical stimulation were 5-6 ms shorter than those evoked by mechanical whisker stimulation. Also, the magnitude of the follicular nerve evoked responses depended on the stimulation site along the follicle and follicular nerve. We propose that electrical stimulation of a follicular nerve and its branches can be a useful approach to assessing the functional follicle topography

The nature of the sensory input to the neonatal rat barrel cortex

© 2016 the authors.Sensory input plays critical roles in the development of the somatosensory cortex during the neonatal period. This early sensory input may involve: (1) stimulation arising from passive interactions with the mother and littermates and (2) sensory feedback arising from spontaneous infant movements. The relative contributions of these mechanisms under natural conditions remain largely unknown, however. Here, we show that, in the whisker-related barrel cortex of neonatal rats, spontaneous whisker movements and passive stimulation by the littermates cooperate, with comparable efficiency, in driving cortical activity. Both tactile signals arising from the littermate’s movements under conditions simulating the littermates’ position in the litter, and spontaneous whisker movements efficiently triggered bursts of activity in barrel cortex. Yet, whisker movements with touch were more efficient than free movements. Comparison of the various experimental conditions mimicking the natural environment showed that tactile signals arising from the whisker movements with touch and stimulation by the littermates, support: (1) a twofold higher level of cortical activity than in the isolated animal, and (2) a threefold higher level of activity than in the deafferented animal after the infraorbital nerve cut. Together, these results indicate that endogenous (self-generated movements) and exogenous (stimulation by the littermates) mechanisms cooperate in driving cortical activity in newborn rats and point to the importance of the environment in shaping cortical activity during the neonatal period

Preferential initiation and spread of anoxic depolarization in layer 4 of rat barrel cortex

© 2017 Juzekaeva, Nasretdinov, Gainutdinov, Sintsov, Mukhtarov and Khazipov. Anoxic depolarization (AD) is a hallmark of ischemic brain damage. AD is associated with a spreading wave of neuronal depolarization and an increase in light transmittance. However, initiation and spread of AD across the layers of the somatosensory cortex, which is one of the most frequently affected brain regions in ischemic stroke, remains largely unknown. Here, we explored the initiation and propagation of AD in slices of the rat barrel cortex using extracellular local field potential (LFP) recordings and optical intrinsic signal (OIS) recordings. We found that ischemia-like conditions induced by oxygen-glucose deprivation (OGD) evoked AD, which manifested as a large negative LFP shift and an increase in light transmittance. AD typically initiated in one or more barrels and further spread across the entire slice with a preferential propagation through L4. Elevated extracellular potassium concentration accelerated the AD onset without affecting proneness of L4 to AD. In live slices, barrels were most heavily labeled by the metabolic level marker 2,3,5-triphenyltetrazolium chloride, suggesting that the highest metabolic demand is in L4 when compared to the other layers. Thus, L4 is the layer of the barrel cortex most prone to AD, which may be due to the highest metabolic demand and cell density in this layer

Developmental changes in electrophysiological properties and a transition from electrical to chemical coupling between excitatory layer 4 neurons in the rat barrel cortex

© 2016 Valiullina, Akhmetshina, Nasretdinov, Mukhtarov, Valeeva, Khazipov and Rozov.During development, sensory systems switch from an immature to an adult mode of function along with the emergence of the active cortical states. Here, we used patch-clamp recordings from neocortical slices in vitro to characterize the developmental changes in the basic electrophysiological properties of excitatory L4 neurons and their connectivity before and after the developmental switch, which occurs in the rat barrel cortex in vivo at postnatal day P8. Prior to the switch, L4 neurons had higher resting membrane potentials, higher input resistance, lower membrane capacity, as well as action potentials (APs) with smaller amplitudes, longer durations and higher AP thresholds compared to the neurons after the switch. A sustained firing pattern also emerged around the switch. Dual patch-clamp recordings from L4 neurons revealed that recurrent connections between L4 excitatory cells do not exist before and develop rapidly across the switch. In contrast, electrical coupling between these neurons waned around the switch. We suggest that maturation of electrophysiological features, particularly acquisition of a sustained firing pattern, and a transition from the immature electrical to mature chemical synaptic coupling between excitatory L4 neurons, contributes to the developmental switch in the cortical mode of function

The serotonin reuptake inhibitor citalopram suppresses activity in the neonatal rat barrel cortex in vivo

© 2016 Elsevier Inc.Inhibition of serotonin uptake, which causes an increase in extracellular serotonin levels, disrupts the development of thalamocortical barrel maps in neonatal rodents. Previous in vitro studies have suggested that the disruptive effect of excessive serotonin on barrel map formation involves a depression at thalamocortical synapses. However, the effects of serotonin uptake inhibitors on the early thalamocortical activity patterns in the developing barrel cortex in vivo remain largely unknown. Here, using extracellular recordings of the local field potentials and multiple unit activity (MUA) we explored the effects of the selective serotonin reuptake inhibitor (SSRI) citalopram (10-20 mg/kg, intraperitoneally) on sensory evoked activity in the barrel cortex of neonatal (postnatal days P2-5) rats in vivo. We show that administration of citalopram suppresses the amplitude and prolongs the delay of the sensory evoked potentials, reduces the power and frequency of the early gamma oscillations, and suppresses sensory evoked and spontaneous neuronal firing. In the adolescent P21-29 animals, citalopram affected neither sensory evoked nor spontaneous activity in barrel cortex. We suggest that suppression of the early thalamocortical activity patterns contributes to the disruption of the barrel map development caused by SSRIs and other conditions elevating extracellular serotonin levels

Evolution of drug therapy of mesothelioma in republic of Bashkortostan

The article presents the changes in drug therapy in pleural mesothelioma in regional clinical oncology center of Bashkortostan for 10 years. The evaluation of the effectiveness of chemotherapy regimens used and the frequency of their use over time. Literature review of recent treatment of mesothelioma.В статье представлены изменения в лекарственной терапии мезотелиомы плевры в республике Башкортостан за 10 лет. Проведена оценка эффективности используемых схем химиотерапии, и частота их применения с течением времени. Обзор литературы по современному лечению мезотелиом