Spontaneous Potentials Research Articles

Geoelectric survey of the Granite Gravel aquifer, Llano Uplift, Central Texas, to determine locations for water wells

An electrical geophysical survey was completed within a small area of the Llano Uplift of central Texas to determine locations to install two water wells in the Granite Gravel aquifer (GGA). Electrical resistivity tomography (ERT) was performed along two 188-m long profiles that intersected at the approximate center of a 100-m by 100-m self-potential (SP) map. The ERT survey was completed to map two-dimensional (2D) electric resistivity distributions in the GGA and the underlying Precambrian Town Mountain Granite (TMG) bedrock, whereas SP mapping was performed to delineate apparent streaming potential anomalies at the land surface that appeared correlated to the subsurface resistivity distributions, which exhibited strong lateral heterogeneity in the upper 35 m of the weathered layer that comprises the GGA. The depth to TMG bedrock, as shown by the resistivity distributions, varied substantially over relatively small profile distances and surface areas; however, the general electrical structure showed resistivity increasing with depth, beginning with a thin electrically conductive layer at the surface characterized by resistivity in the range of about 30–100 Ω-m, followed by a resistivity increase to 300–500 Ω-m at a depth that coincided with the water-table depth observed in the installed water wells. Resistivity of the TMG bedrock was generally greater than 500 Ω-m and exceeded 1000 Ω-m in some locations of the tomograms. Electrical structure beneath the survey area, as shown by the 2D resistivity distributions beneath the ERT profiles, delineated a relatively thick weathered section of GGA that spatially aligned with a conspicuous negative anomaly observed in the SP map after electrode-drift and terrain corrections were made. The combination of ERT and SP mapping guided selection of locations for two productive water wells within the small survey area despite substantial heterogeneity in the weathering profile of the GGA beneath the survey area.

Utilizing Hydrogen Underpotential Deposition for Carbon Monoxide Reduction to Formaldehyde

Formaldehyde is an essential building block for hundreds of chemicals and a promising liquid organic hydrogen carrier (LOHC), yet its indirect energy-intensive synthesis process prohibits it from playing more significant role. Here we report a direct CO reduction to formaldehyde (CORTF) process that hybridizes thermal and electro-catalysis and utilizes hydrogen underpotential deposition property to overcome thermodynamic barrier and scaling relationship restriction. Using molybdenum phosphide as catalyst, formaldehyde can be produced with nearly 100% Faradaic efficiency in aqueous KOH solution, with its formation rate being one order of magnitude higher compared with state-of-the-art thermal catalysis approach. Simultaneous tuning of current density and reaction temperature leads to more selective and productive formaldehyde synthesis, confirming the effectiveness of “hybrid” approach. DFT calculations reveal that desorption of *H2CO intermediate likely serves as rate-limiting step, and the participation of H2O turns the reaction into thermodynamically favorable. Furthermore, a full-cell reaction set-up was demonstrated with CO hydrogenation to HCHO being achieved without any energy input, which shows the spontaneous potential of the reaction. Our study shows the advantage of hybridizing thermal and electro-catalysis in realizing thermodynamics and scaling relation confined reaction, which could serve as a new strategy in future reaction design.

ARCABOUÇO ESTRATIGRÁFICO NEÓGENO-QUATERNÁRIO DA PORÇÃO OESTE DA BACIA DO SOLIMÕES, AMAZÔNIA OCIDENTAL

O contexto estratigráfico da porção oeste da Bacia do Solimões, na zona limítrofe entre Brasil, Peru e Colômbia, foi elaborado com base em dados de 9 logs de sondagem (P1 a P9) do Projeto Carvão no Alto Solimões. Com os dados geológicos (testemunhos) e geofísicos (Raios Gama, Resistividade e Potencial Espontâneo) foi elaborada a seção geológica A-A’, de direção geral SW-NE, com cerca de 400 km de extensão, onde foram definidas as espessuras e limites das formações Solimões (Mioceno-Plioceno) e Içá (Plioceno-Pleistoceno) e Depósitos Quaternários. A Formação Solimões exibe continuidade lateral nas sondagens P1 a P9 e espessura em torno de 332 metros, sendo constituída por intercalações de pelitos e arenitos, com calcários, linhitos e conglomerados subordinados, que exibem padrões de adelgaçamento, espessamento e interdigitação. A Formação Içá ocorre principalmente na porção leste da seção, sendo predominantemente arenosa, com raras intercalações de pelitos e linhitos e espessura variando entre 30 a 55m, recoberta por delgados depósitos Quaternários, compostos de areia e lama (silte e argila), com espessura de até 16 metros. Perfis geofísicos proporcionaram padrões de eletrofácies e em conjunto com dados litológicos permitiram a individualização dos limites estratigráficos e das litofácies internas, que foram correlacionados nos perfis analisados.

Simultaneous transcranial and transcutaneous spinal direct current stimulation to enhance athletic performance outcome in experienced boxers

Transcranial direct current stimulation (tDCS) is among the rapidly growing experimental approaches to enhance athletic performance. Likewise, novel investigations have recently addressed the effects of transcutaneous spinal Direct Current Stimulation (tsDCS) on motor functions such as reduced reaction time. The impact of tDCS, and tsDCS might be attributed to altered spontaneous neural activity and membrane potentials of cortical and corticomotoneuronal cells, respectively. Given the paucity of empirical research in non-invasive brain stimulation in sports neuroscience, especially in boxing, the present investigation studied the effects of neuromodulation on motor and cognitive functions of professional boxers. The study sample comprised 14 experienced male boxers who received random sequential real or sham direct current stimulation over the primary motor cortex (M1) and paraspinal region (corresponding to the hand area) in two sessions with a 72-h interval. Unlike sham stimulation, real stimulation improved selective attention and reaction time of the experienced boxers [enhanced selective attention (p < 0.0003), diminished right hand (p < 0.0001) and left hand reaction time (p < 0.0006)]. Meanwhile, the intervention left no impact on the participants’ cognitive functions (p > 0.05). We demonstrated that simultaneous stimulation of the spinal cord and M1 can improve the performance of experienced boxers through neuromodulation. The present study design may be extended to examine the role of neurostimulation in other sport fields.

Study of Fluid Flow Movement by Using Self Potential Data

The Self-Potential (SP) method is passive method in geophysics which works based on the natural presence of an electric field on the surface due to anomalies below the surface. SP value on surface can be generated by fluid flow through rock pores or fractures. We study fluid flow movement in subsurface using the velocity value of fluid flow derived from SP values measured on surface. For that purpose, we carried out mathematical modelling, connecting the Helmholtz-Smoluchovsky’s electrokinetic potential gradient equation with Darcy’s law. The velocity of fluid flow depends on the intrinsic permeability of rocks, electrokinetic potential gradient and electrohydrolic conductivity constant. We tested derived velocity of fluid flow on the SP data from a pilot project test site. Study results show that fluid flow in vertical direction can be identified from SP data at locations where there are significant changes of positive and negative SP values. Fluid flows from a high SP value to a low SP value and this flow is opposite the positive SP gradient. The SP value at study site lie in the range -80mV to -160mV, whereas the value of the water flow velocity lie in the range 0.08 cm/s - 0.21 cm/s.

Pressing Intervention Promotes the Skeletal Muscle Repair of Traumatic Myofascial Trigger Points in Rats.

ObjectiveTo observe the effect of pressing intervention on the skeletal muscle repair of myofascial trigger points (MTrPs) in rats and explore the mechanism of pressing intervention on the deactivation of trigger points.MethodsThirty SPF rats were randomly divided into blank group, model group and press group, with 10 rats in each group. The MTrPs models were established by blunt striking plus eccentric exercise, and then evaluated. The press group was given a pressing intervention with a self-made device for 14 days, and the rats in the other two groups were fed normally. Soft tissue tension (STT) D0.2 and pressure pain threshold (PPT) were measured before and after intervention. The skeletal muscle tissue at MTrPs was extracted and assessed by hematoxylin–eosin (HE) and Masson staining. The expression of collagen I, collagen III, α- smooth muscle actin (α-SMA), myosin heavy chain (MHC) and fibronectin (FN) were detected by Western Blotting. Enzyme linked immunosorbent assay (ELISA) was used to evaluate the expression of substance P (SP), 5-hydroxytryptamine (5-HT), cyclooxygenase 2 (COX-2) and prostaglandin E2 (PGE2).Results(1) Compared with the blank group, the PPT and D0.2 reduced (P < 0.05) in the model group; while compared with the model group, the PPT and D0.2 increased (P < 0.05) in the press group. (2) Compared with the blank group, the model group showed obvious spontaneous potentials with higher amplitude and frequency, which were also much higher than those of the press group (P < 0.05). (3) The HE and Masson staining results showed evident fibrosis in the muscle tissue of the model group, with a larger area of collagen fibers relative to that of the press group (P < 0.05). (4) The amount of collagen I, collagen III, FN, α- SMA, SP, 5-HT, COX-2 and PGE2 increased and the content of MHC decreased (P < 0.05) in the model group, as compared to the blank group; while all the substances (P < 0.05), instead of MHC which increased (P < 0.05), in the press group were decreased as compared to the model group.ConclusionPressing intervention on the MTrPs in rats can alleviate chronic inflammation, inhibit fibrosis, promote skeletal muscle repair and relieve pain.

Cuckoo Search Algorithm for model parameter estimation from self-potential data

The use of the Cuckoo Search Algorithm (CSA) is introduced for estimating the model parameters from both synthetic and field self-potential (SP) anomalies in this study. The CSA offers a simple and efficient way to optimization studies as a popular nature-inspired metaheuristic algorithm because it requires only two algorithm-based parameters (the number of population and probability of recognition of the egg), and instead of isotropic random walks, it employs Lévy flights for search. This work presents the first application of the CSA for inversion of SP anomalies in geophysics. The test studies with the synthetic data included the cases of the noise-free and noisy data. Additionally, the Bavarian (Germany), Süleymanköy (Turkey) and Malachite (Colorado, USA) anomalies, which are the well-studied benchmark field data sets in the literature, were tested with the field data. An uncertainty appraisal analysis was performed for each model parameter via the Metropolis-Hastings algorithm. Also, the estimated parameters from the CSA were compared with the previous studies used a variety of metaheuristic methods to invert the same field data sets. According to the results, the CSA can be integrated into the inversion of SP anomalies as an efficient alternative method.

Sequence Stratigraphy and Depositional Environment of the Zubair Formation in Rumaila Oilfields, Southern Iraq: Microfacies and Geochemistry

In the Rumaila oilfields in southern Iraq, the Zubair Formation was deposited in a shallow environment as three main facies, delta plain, backshore, and delta front depositional conditions indicating a transition from delta front and delta plain to a highstand level due to the finning upward mode. The facies of the Zubair clasts show well-sorted quartz arenite sandstone, poorly sorted quartz arenite sandstone, clayey sandstone that has not been properly sorted, sandy shale, and shale lithofacies. The minor lithofacies were identified using well-logging methods (gamma ray, spontaneous potential and sonic logs) and petrography. The Zubair clasts are of transition environment that appears to be transported from freshwater and deposited in a marine environment forming many fourth-order cycles reflect sea level rise fluctuations and still-stand under tectonics developed the sequence stratigraphy. A misalignment between relative sea-level and sediment supply caused asymmetry sedimentary cycles. A shallower environment of shale-dominated rocks rich in organic matter and pyrite were exposed. The basinal shale of Ratawi at the Zubair bottom and the shallow carbonate of Shuaiba emplace on the Zubair represent the beginning of the delta build up (delta front and delta plain) to a highstand stage.

Coupled inversion of hydraulic and self‐potential data from transient outflow experiments to estimate soil petrophysical properties

AbstractHydraulicproperties of soils could play an important role in affecting the partitioning of precipitation in the critical zone. In addition to traditional approaches, in the last two decades, many geophysical methods have been used to aid the hydrologic characterization and measurement of geological materials. In particular, the self‐potential (SP) method shows great potential in these hydrogeophysical applications. The objective of this study is to evaluate whether the addition of SP data can improve the estimation of hydraulic properties of soils in an outflow experiment. A stochastic, coupled hydrogeophysical inversion was developed, in which the governing equations were solved using the finite volume method and the parameter estimation was conducted using a Bayesian approach associated with the Markov chain Monte Carlo technique. The results show that the addition of SP data in the inversion could reduce the uncertainty related to the estimated hydraulic parameters of soils and the length of the associated 95% confidence interval can be shortened by ∼1/3. It is also shown that the electrical properties of soils at saturated and unsaturated conditions may also be estimated from the outflow experiment when SP data are available. Compared with hydraulic parameters, the accuracy of the estimated electrical properties is slightly lower. Among them, the saturated streaming potential coupling coefficientCsathas the highest accuracy and lowest uncertainty sinceCsatdirectly influences the magnitude of SP signals. The accuracy of other electrical parameters is lower than that ofCsat(and hydraulic parameters), and the associated uncertainty can be one order of magnitude larger.

Zearalenone alters the excitability of rat neuronal networks after acute in vitro exposure

Zearalenone (ZEA) is a mycotoxin produced by Fusarium species, detectable in various cereals and processed food products worldwide. ZEA displays a significant estrogenic activity, thus its main health risk is the interference with sexual maturation and reproduction processes. However, in addition to being key hormonal regulators of reproductive function, estrogenic compounds have a widespread role in brain, as neurotrophic and neuroprotective factors, and they may influence the activity of several brain areas not directly linked to reproduction, as well. Therefore, in the present study, acute effects of ZEA were studied on certain neuronal functions in rats.Experiments were performed on rat brain slices or live rats. Slices were incubated in ZEA-containing (10–100 μM) solution for 30 min. Electrically evoked and spontaneous field potentials were studied in the neocortex and in the hippocampus. At higher concentrations, ZEA incubation of the slices altered excitability and the pattern of epileptiform activity in neocortex and inhibited the development of LTP in hippocampus.For the verification of these in vitro results, in vivo electrophysiological and immunohistochemical investigations were also performed. ZEA was administered systemically (5 mg/kg, i.p.) to male rats and somatosensory evoked potentials and neuronal activation studied by c-fos expression were analyzed. No neuronal activation could be demonstrated in the hippocampus within 2 h of the injection. In the somatosensory cortex, ZEA did not change in vivo evoked potential parameters, but the activation of a small neuronal population could be demonstrated with the c-fos technique in this brain area. This result could be associated with the ZEA-induced alteration of epileptiform activity observed in vitro.Altogether, the toxin altered the excitability and plasticity of neuronal networks after direct treatment in slices, but the effects were less prominent on the given brain areas after systemic treatment in vivo. A probable explanation for the partial lack of in vivo effects may be that after a single injection, ZEA did not cross the blood-brain barrier at sufficient rate to allow the build-up of comparable concentrations in the investigated brain areas. However, in case of compromised blood-brain barrier functions or long-term repeated exposure, alterations in cortical and hippocampal functions cannot be ruled out.

Codell continuous oil accumulation in the northern Denver and SP logs Basin as defined by resistivity, density, and SP logs

A continuous Codell Sandstone oil accumulation is present in the northern Denver Basin downdip from water-wet Codell. The Codell oil accumulation can be defined by resistivity, spontaneous potential (SP), and density logs. Updip from the oil accumulation, average deep resistivity of the Codell decreases to below 4 ohm-m, SP response increases, and density porosity increases. Codell sandstones are continuous across the transition from downdip oil to updip water, so the updip seal does not seem to be caused by a stratigraphic trap. The transition corresponds to a change in thermal history; the area of the oil accumulation was subject to much higher heat flow than the updip wet area. This thermal maturity may have had an impact on clay diagenesis resulting in reduced porosity in the more thermally mature part of the Codell. This paper presents a wireline log-based workflow that can be used to identify and map regional changes in thermal maturity that control hydrocarbon accumulations and sweet-spots in low-permeability rocks such as the argillaceous Codell Sandstone.

Lithology Identification, Shale Volume Estimation and Formation Wate Saturation of Fenchuganj Gas Field Using Wireline Log Data

This study has been undertaken with a view to interpreting and analyzing different types of logs, detecting hydrocarbon-bearing sand zone, identifying the lithology, estimating shale volume, and determining water saturation of the formation of the Fenchuganj gas field. Fenchuganj gas field is in the southern part of Bangladesh in the Sylhet division. It lies in the Surma basin and characterized as a water drive gas field. Gamma Ray (GR) log and Spontaneous Potential (SP) log analysis help to interpret the formation lithology. After interpreting lithology, the gamma-ray log and SP log were analyzed further, and the hydrocarbon-bearing zone was detected. From the analysis of different logs, for well 4, so many gas-bearing sand zones have been detected. The gas-bearing zones are found between (1585-1595) m, (1600-1610) m, (2409-2420) m, (2265-2270) m, (2295-2303) m, (2435-2450) m, (2465-2480) m, (3150-3155) m, (2955- 2960) m. These are the gas-bearing zones of fenchugonj well-4 determined from the composite log of this field. Water-bearing sand zones are between (1708-1714) m and the fully compacted shale zone is between (1920-1930) m. From the analysis of different logs, for well 5, so many gas-bearing sand zones have been detected. The gas-bearing zones are found between (2365-2385.5) m, (1820-1830) m, (1782-1803) m, (305-308) m, (336.5-338.5) m, (607.5-609.5) m. These are the gas-bearing zone of fenchugonj well-5 determined from the composite log of the field. Shale volume has been estimated from the gamma-ray log and from resistivity logs by the true resistivity method. In well 4, the calculated value of shale volume by Gamma Ray method and true Resistivity methods were respectively 15% and 6%, in well 5 these values were 7.25% and 7.64%. Formation water resistivity was determined from the formula and taken as 0. 1ohm-m and mud filtrate resistivity 0.76 ohm-m. for well-4 and for well-5 it was taken as 0.7 ohm-m (from the provided composite log of well 4 and 5). Formation true resistivity Rt was estimated directly from the ILD log and true resistivity log. The average value of Rt for well-5 was 33.75 ohm-m and for well-4 the value is 34.09 ohm-m. From the RFOC log, flushed zone resistivity Rxo was calculated directly. Water saturation has been determined by three different techniques named Archie, Indonesia, and Simandoux method. For well 5, the value of average water saturation found from Archie, Indonesia, and Simandoux model was 8.5%,22%, and 24.84%, and for well-4. The value of average water saturation was found as 7.3%,18%, 20.51%respectively.

Epileptiform activity in mouse hippocampal slices induced by moderate changes in extracellular Mg2+, Ca2+, and K+

BackgroundRodent brain slices—particularly hippocampal slices—are widely used in experimental investigations of epileptiform activity. Oxygenated artificial cerebrospinal fluid (ACSF) is used to maintain slices in vitro. Physiological or standard ACSF containing 3–3.5 mM K+, 1–2 mM Mg2+, and 1–3 mM Ca2+ generally does not induce population epileptiform activity, which can be induced by ACSF with high K+ (8–10 mM), low Mg2+, or low Ca2+ alone or in combination. While low-Mg2+ ACSF without intentionally added Mg salt but with contaminating Mg2+ (≤ 50–80 µM) from other salts can induce robust epileptiform activity in slices, it is unclear whether such epileptiform activity can be achieved using ACSF with moderately decreased Mg2+. To explore this issue, we examined the effects of moderately modified (m)ACSF with 0.8 mM Mg2+, 1.3 mM Ca2+, and 5.7 mM K+ on induction of epileptiform discharges in mouse hippocampal slices.ResultsHippocampal slices were prepared from young (21–28 days old), middle-aged (13–14 months old), and aged (24–26 months old) C57/BL6 mice. Conventional thin (0.4 mm) and thick (0.6 mm) slices were obtained using a vibratome and pretreated with mACSF at 35–36 °C for 1 h prior to recordings. During perfusion with mACSF at 35–36 °C, spontaneous or self-sustained epileptiform field potentials following high-frequency stimulation were frequently recorded in slices pretreated with mACSF but not in those without the pretreatment. Seizure-like ictal discharges were more common in thick slices than in thin slices.ConclusionsProlonged exposure to mACSF by pretreatment and subsequent perfusion can induce epileptiform field potentials in mouse hippocampal slices.

Groundwater flow monitoring using time-lapse electrical resistivity and Self Potential data

Groundwater flow monitoring is crucial to groundwater management and pollution control. Traditional in-situ hydrological surveys monitor groundwater flow, pressure or temperature changes to infer the actual conditions of the underground, but there are characteristics of stratum destructiveness and difficult to obtain the regional variation characteristics of groundwater. Compared with geophysical methods, it has the advantages of non-destructive detection and regional quantitative interpretation, and indirect understanding of the physical properties of underground media and groundwater. In this paper, we combine the time-lapse electrical resistivity (ERT) and self-potential (SP) methods to monitor the groundwater flow. The ERT result establishes linkages between the resistivity and porewater content of the underground space, and captures the difference in resistivity through the change of underground water content. The SP method provides a direct way to predict groundwater flow according to its movement characteristics. Then, the joint resistivity and potential field are further used to estimate the soil's apparent-permeability. We carry out a real pumping experiment at a hydrological observation site to verify the proposed method. The time-lapse ERT and SP results reveal a significant increase in resistivity but a decrease in permeability during water pumping and groundwater recharge, representing the process of groundwater decline and recovery. The results also matched well with the groundwater level in-situ hydrological data. The study demonstrates that the joint ERT and SP data can provide a direct and reliable way to monitor groundwater flow or other time-lapse hydrogeological surveys in the vadose zone.

GROUNDWATER POTENTIALS ESTIMATION USING SELF-POTENTIAL METHOD AS AN EARLY PREDICTION OF LAND SUBSIDENCE IN GAMPONG LENGKONG LANGSA CITY

The Self-Potential (SP) method was used to identify changes in the potential groundwater in the area of Gampong Lengkong, Langsa City. The data acquisition technique was carried out with a fixed base technique with a measurement count of four acquisition line. Research is conducted for two months that July and August are the same in order to monitor the changes in the SP value associated with the change of SP anomaly. Interpretation is done qualitatively and quantitatively. Qualitative interpretation through analysis maps of the isopotential contours compared between the first month and the second month of measurements in the field. The interpretation is quantitatively by assuming the source of the subsurface anomaly fix geometry models of cylinders or sphere is done by the inversion modeling using the Levenberg-Marquardt method. The results showed that there was a reduction in SP value in the second month, indicating the potential shortage of groundwater in the region. The decrease in groundwater potential is also shown in the inversion results where the result of the calculation of SP anomaly source parameters in the first month is estimated to be at 7.77 meters to 11.05 meters below the ground in the monthly measurements second.

Membangun Kecerdasan Emosional Melalui Zikir Dalam Perspektif Al-Qur’an

This research is to find out how to build emotional intelligence through dhikr (remembrance of Allah) from the perspective of the Qur'an. The method used in this research is a qualitative research method with a literature study approach. Emotional intelligence is one of the most important intelligences that every individual has. Because various events experienced by humans cannot be separated from emotional involvement. This paper describes that dhikr is a spiritual behavior that is effective in building emotional intelligence in terms of various interpretations of the verses of the Al-Qur'an, Islamic spiritual studies (Sufism), and exploration of the potential for human self and psyche. Indicators of emotional intelligence through dhikr in various verses of the Qur'an: (1) the heart becomes calm in Surat ar Ra'du verse 28; (2) the heart is opened by the light of Allah in Surat Al-Zumar verse 22; (3) gratitude for the blessings given by Allah in Surah Al-Maidah verse 11; (4) introsection of one's own potentials and weaknesses in Surah Maryam verse 67; (5) building emotional intelligence in Surat Al-Hijr verses 97-98; and various other verses.

Measurement of unsaturated meltwater percolation flux in seasonal snowpack using self-potential

AbstractThis paper presents a feasibility study of in situ field measurements of unsaturated meltwater percolation flux within the vertical profile of a snowpack, using the self-potential (SP) method. On-site snowmelt column tests calibrated the SP measurements. The SP data measured electrical field strength with an electrode spacing of 20 cm, and coincident water saturation (Sw) measurements using time domain reflectometry allowed calculation of SP-modeled vertical percolation flux (qsp), expressed as Darcy velocity. The results reflected transient diurnal snowmelt dynamics, with peak flux lagging arrival of a saturation wetting front. Peak dailyqspwas 60 to &gt;300 mm d−1, whereas daily snowmelt was 20–50 mm w.e. Surface refreezing events appeared to cause upward flow, possibly representing water redistribution toward the freezing boundary. Calculated fluxes were comparable to actual fluxes, although average errors ranged from −15 to +46% compared to average of melt expected from surface energy-balance and ablation stake measurements. By advancing method development to measure unsaturated meltwater percolation flux in snowpacks this study creates opportunities to study fundamental snowmelt processes, may improve mathematical modeling and may supplement glacier mass-balance studies and studies of snowmelt interactions with avalanches, groundwater and surface water.

Visual Recognition Is Heralded by Shifts in Local Field Potential Oscillations and Inhibitory Networks in Primary Visual Cortex.

Learning to recognize and filter familiar, irrelevant sensory stimuli eases the computational burden on the cerebral cortex. Inhibition is a candidate mechanism in this filtration process, and oscillations in the cortical local field potential (LFP) serve as markers of the engagement of different inhibitory neurons. We show here that LFP oscillatory activity in visual cortex is profoundly altered as male and female mice learn to recognize an oriented grating stimulus—low-frequency (∼15 Hz peak) power sharply increases, whereas high-frequency (∼65 Hz peak) power decreases. These changes report recognition of the familiar pattern as they disappear when the stimulus is rotated to a novel orientation. Two-photon imaging of neuronal activity reveals that parvalbumin-expressing inhibitory neurons disengage with familiar stimuli and reactivate to novelty, whereas somatostatin-expressing inhibitory neurons show opposing activity patterns. We propose a model in which the balance of two interacting interneuron circuits shifts as novel stimuli become familiar.SIGNIFICANCE STATEMENT Habituation, familiarity, and novelty detection are fundamental cognitive processes that enable organisms to adaptively filter meaningless stimuli and focus attention on potentially important elements of their environment. We have shown that this process can be studied fruitfully in the mouse primary visual cortex by using simple grating stimuli for which novelty and familiarity are defined by orientation and by measuring stimulus-evoked and continuous local field potentials. Altered event-related and spontaneous potentials, and deficient habituation, are well-documented features of several neurodevelopmental psychiatric disorders. The paradigm described here will be valuable to interrogate the origins of these signals and the meaning of their disruption more deeply.

Determining model parameter from self-potential data using quantum-behaved particle swarm optimization

A new approach for quantitative analysis of self-potential (SP) data is introduced. In this paper, anomaly of SP is associated with simple geometric models such as a vertical cylinder, a horizontal cylinder and a sphere object. Then, in order to estimate the depth, the electric dipole moment, the anomaly body’s centre, the geometrical form factor and polarization of the anomaly, the method was developed and implemented. The development and implementation of the method is based on the global optimization concept. This method uses Quantum-behaved Particle Swarm Optimization (QPSO) algorithm to overcome the inversion problem on SP anomaly modelling. The QPSO algorithm was randomly tested on synthetic data which consist of different random noise levels. The result shows a close agreement between the assumed and the measured parameters. At last, the validity of the method was tested on real SP anomaly data and compared to the results given by other advanced inversion approaches.

Investigation of Scale-Dependent Groundwater/Surface-water Exchange in Rivers by Gradient Self-Potential Logging: Numerical Modeling and Field Experiments

Exchanges of groundwater and surface-water are fundamental to a wide range of water-supply and water-quality management issues but challenging to map beyond the reach scale. Waterborne gradient self-potential (SP) measurements are directly sensitive to water flow through riverbed sediments and can be used to infer exchange locations, direction (gain versus loss), scale, and relative changes, but to date applications to river corridor hydrology are limited. Numerical modeling and field experiments were therefore performed herein, each emphasizing waterborne gradient SP logging for identifying and locating focused vertical groundwater discharge (surface-water gain) and recharge (surface-water loss) in a river. Two and three-dimensional numerical models were constructed to simulate the polarities, appearances, and peak amplitudes of streaming-potential and electric-field anomalies on a riverbed and in the surface-water that were attributable to steady-state vertical fluxes of groundwater through high-permeability conduits in the riverbed. Effects of varied hydraulic length-scale of exchange and surface-water depth were tested through numerical modeling. Modeling results aided in data acquisition and interpretation for three repeated field experiments performed along a 1.5–2.0 km reach of the Quashnet River in Cape Cod, Massachusetts, where focused, meter-scale groundwater discharges occur at discrete locations within otherwise ubiquitous and more diffuse groundwater upwelling conditions. Strong gradient SP anomalies were repeatedly measured in the Quashnet River at previously confirmed locations of focused groundwater discharge, showing the efficacy of waterborne gradient SP logging in identifying and characterizing groundwater/surface water exchange dynamics at multiple river network scales.