Electrophysiological Measurements Research Articles

Increasing Ambient GABA Levels in the Hippocampus to Improve Cognition in a Mouse Model of Schizophrenia: A Research Protocol

Introduction: Schizophrenia is a complex psychiatric disorder characterized by cognitive, positive, and negative symptoms, with cognitive impairments significantly affecting learning, memory, and executive functions. The hippocampus, particularly the CA1 region, is a critical area of interest due to its role in learning and memory and its dysfunction in schizophrenia. This protocol explores the effects of increasing ambient Gamma-Aminobutyric Acid (GABA) levels in the CA1 region on cognitive functions in a Methylazoxymethanol Acetate (MAM) model of schizophrenia. Methods: Utilizing a two-by-two factorial design, male Sprague-Dawley rats undergo either a sham or MAM treatment, followed by a control or GABA modulation intervention. The study will employ GABA transporter inhibitor Tiagabine to increase ambient GABA levels and assess its impact on neuronal excitability and cognitive function. Behavioural assessments will include the Morris water maze and the Attentional set-shifting test to evaluate spatial memory and cognitive flexibility. Histological examinations and electrophysiological measurements will provide insights into structural and functional changes in the hippocampus. Results: The results are expected to demonstrate neurodevelopmental disruptions in MAM-treated offspring and improvements in cognitive performance following GABA modulation. Enhanced spatial memory and cognitive flexibility are anticipated in MAM-treated rats with GABA modulation, as evidenced by performance in the Morris water maze and Attentional set-shifting test. Electrophysiological recordings are likely to show increased tonic inhibition in the CA1 region. Discussion: This study aims to extend the understanding of tonic inhibition in schizophrenia treatment. By focusing on ambient GABA modulation, the research could offer novel insights into therapeutic strategies for schizophrenia, especially in enhancing cognitive functions. However, the translational applicability of intracerebral administration of uptake inhibitors like Tiagabine poses a significant challenge, highlighting the need for future research in more clinically viable methods of GABA modulation. Conclusion: This study was designed to contribute to schizophrenia research, particularly in understanding cognitive impairments and developing potential therapeutic strategies targeting the GABAergic system. The proposed findings could pave the way for novel treatments, improving the quality of life for individuals with schizophrenia.

Odor Biosensors Based on Cell Expressing Olfactory Receptor: Recent Advances

AbstractInspired by the powerful biological olfaction, scientists extracted numerous materials such as olfactory sensory neuron, olfactory receptor (OR) protein, and odorant binding protein from animal olfactory systems, then combined them with transducers to form multiple odor biosensors. These biosensors, despite well inheriting the sensing ability of creatures, have several drawbacks, such as complex preparation process, unstable sensing material characteristics, and high cost. Unlike the biological materials listed above, cell expressing heterologous OR maintains a stable sensing performance after passaging for multiple generations, also its experimental operation is simple, and cost is low. Therefore, odor biosensors based on cell expressing OR have been well developed in recent years. In this review, we first listed several odor biosensors based on cell expressing OR, mainly focusing on fluorescent and electrophysiological measurement methods. Furthermore, we illustrated the techniques to improve the biosensor performance, e. g., wider detection range, longer lifetime, more OR types, and higher quantification efficiency. In addition, we explained the possible prospects such as big sensor array and predicting odor response.

Association Between Intracochlear Electrode Design and Electrically-Evoked Compound Action Potential Measures in Cochlear Implant Users.

Cochlear implant (CI) electrode design has changed over time. Changes in intracochlear electrode design might influence the spread of neural activation along the auditory nerve and the number of independent channels. This study aimed to investigate the impact of intracochlear electrode design on the electrode-neuron interface using electrophysiological measures. Prospective cohort study. A single tertiary hospital. Fifty-two ears who were implanted with CI divided into 3 groups based on the design of intracochlear electrode arrays. Twenty-three ears were implanted with lateral wall straight electrodes. Eighteen ears were implanted with the slim perimodiolar electrode, and 11 ears were implanted with the old perimodiolar electrode. Various electrically-evoked compound action potential (ECAP) metrics were measured to quantify spread of excitation and channel interaction. ECAP threshold and slope were not significantly different among groups. ECAP spread of excitation (SOE) half-width and channel interaction index (CII) were significantly larger in subjects implanted with the lateral wall straight electrodes, indicating a wider spread of excitation compared to those with perimodiolar electrodes. Electrode impedance was significantly lower in subjects implanted with perimodiolar electrodes than those with lateral wall electrodes. Perimodiolar electrode groups yielded significantly narrower SOE half-widths and smaller CII than the lateral wall straight electrode group. This may indicate that the electrode array that hugged the modiolus had less overlap in neural excitation between adjacent electrodes, resulting in reduced channel interaction and potentially better spectral resolution than the electrode array positioned more laterally.

Prolonged activity-deprivation causes pre- and postsynaptic compensatory plasticity at neocortical excitatory synapses.

Homeostatic plasticity stabilizes firing rates of neurons, but the pressure to restore low activity rates can significantly alter synaptic and cellular properties. Most previous studies of homeostatic readjustment to complete activity silencing in rodent forebrain have examined changes after two days of deprivation, but it is known that longer periods of deprivation can produce adverse effects. To better understand the mechanisms underlying these effects and to address how presynaptic as well as postsynaptic compartments change during homeostatic plasticity, we subjected mouse cortical slice cultures to a more severe five-day deprivation paradigm. We developed and validated a computational framework to measure the number and morphology of presynaptic and postsynaptic compartments from super resolution light microscopy images of dense cortical tissue. Using these tools, combined with electrophysiological miniature excitatory postsynaptic current measurements, and synaptic imaging at the electron microscopy level, we assessed the functional and morphological results of prolonged deprivation. Excitatory synapses were strengthened both presynaptically and postsynaptically. Surprisingly, we also observed a decrement in the density of excitatory synapses, both as measured from colocalized staining of pre- and postsynaptic proteins in tissue, and from the number of dendritic spines. Overall, our results suggest that cortical networks deprived of activity progressively move towards a smaller population of stronger synapses.Significance statement Blocking activity in neocortical slice cultures produced coordinated pre and postsynaptic changes at excitatory synapses. Functional and structural assays suggest that deprivation results in fewer excitatory synapses, but each is strengthened both pre- and postsynaptically. This may contribute to the emergence of epileptiform activity.

Electromechanical Coupling and Anatomy of the In-Vivo Gastroduodenal Junction.

Few biomarkers support diagnosis and treatment of disorders of gut-brain interaction (DGBI), although gastroduodenal junction (GDJ) electromechanical coupling is a target for novel interventions. Rhythmic 'slow waves', generated by interstitial cells of Cajal (ICC), and myogenic 'spikes' are bioelectrical mechanisms underpinning motility. In this study, simultaneous in-vivo high-resolution electrophysiological and impedance planimetry measurements were paired with immunohistochemistry to elucidate GDJ electromechanical coupling. Following ethical approval, the GDJ of anaesthetized pigs (N=12) was exposed. Anatomically-specific, high-resolution electrode arrays (256 electrodes) were applied to the serosa. EndoFLIP catheters (16 electrodes; Medtronic, MN, USA) were positioned luminally to estimate diameter. Post-mortem tissue samples were stained with Masson's trichrome and Ano1 to quantify musculature and ICC. Electrical mapping captured slow-waves (N=512) and spikes (N=1071). Contractions paralleled electrical patterns. Localized slow waves and spikes preceded rhythmic contractions of the antrum, and non-rhythmic contractions of the duodenum. Slow-wave and spike amplitudes were correlated in the antrum (r=0.74, p<0.001) and duodenum (r=0.42, p<0.001). Slow-wave and contractile amplitudes were correlated in the antrum (r=0.48, p<0.001) and duodenum (r=0.35, p<0.001). Distinct longitudinal and circular muscle layers of the antrum and duodenum had a total thickness of (2.8 ± 0.9) mm and (0.4 ± 0.1) mm, respectively. At the pylorus, muscle layers merged and thickened to (3.5 ± 1.6) mm. Pyloric myenteric ICC covered less area (1.5 ± 1.1 %) compared to the antrum (4.2 ± 3.0 %) and duodenum (5.3 ± 2.8 %). Further characterization of electromechanical coupling and ICC biopsies may generate DGBI biomarkers.

Pre- and postsynaptic signatures in the prelimbic cortex associated with "alcohol use disorder" in the rat.

The transition to alcohol use disorder (AUD) involves persistent neuroadaptations in executive control functions primarily regulated by the medial prefrontal cortex. However, the neurophysiological correlates to behavioral manifestations of AUD are not fully defined. The association between cortical neuroadaptations and behavioral manifestations of addiction was studied using a multi-symptomatic operant model based on the DSM-5 diagnostic criteria for AUD. This model aimed to characterize an AUD-vulnerable and AUD-resistant subpopulation of outbred male Wistar rats and was combined with electrophysiological measurements in the prelimbic cortex (PL). Mirroring clinical observations, rats exhibited individual variability in their vulnerability to develop AUD-like behavior, including motivation to seek for alcohol (crit 1), increased effort to obtain the substance (crit 2), and continued drinking despite negative consequences (crit 3). Only a small subset of rats met all the aforementioned AUD criteria (3 crit, AUD-vulnerable), while a larger fraction was considered AUD-resilient (0 crit). The development of AUD-like behavior was characterized by disruptions in glutamatergic synaptic activity, involving decreased frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and heightened intrinsic excitability in layers 2/3 PL pyramidal neurons. These alterations were concomitant with a significant impairment in the ability of mGlu2/3 receptors to negatively regulate glutamate release in the PL but not in downstream regions like the basolateral amygdala or nucleus accumbens core. In conclusion alterations in PL synaptic activity were strongly associated with individual addiction scores, indicating their role as potential markers of the behavioral manifestations linked to AUD psychopathology.

Unveiling the Hidden Impact: Hematoma Volumes Unravel Circuit Disruptions in Intracerebral Hemorrhage.

Intracerebral hemorrhage (ICH) imposes a significant burden on patients, and the volume of hematoma plays a crucial role in determining the severity and prognosis of ICH. Although significant recent progress has been made in understanding the cellular and molecular mechanisms of surrounding brain tissue in ICH, our current knowledge regarding the precise impact of hematoma volumes on neural circuit damage remains limited. Here, using a viral tracing technique in a mouse model of striatum ICH, two distinct patterns of injury response were observed in upstream connectivity, characterized by both linear and nonlinear trends in specific brain areas. Notably, even low-volume hematomas had a substantial impact on downstream connectivity. Neurons in the striatum-ICH region exhibited heightened excitability, evidenced by electrophysiological measurements and changes in metabolic markers. Furthermore, a strong linear relationship (R2 = 0.91) was observed between hematoma volumes and NFL damage, suggesting a novel biochemical index for evaluating changes in neural injury. RNA sequencing analysis revealed the activation of the MAPK signaling pathway following hematoma, and the addition of MAPK inhibitor revealed a decrease in neuronal circuit damage, leading to alleviation of motor dysfunction in mice. Taken together, our study highlights the crucial role of hematoma size as a determinant of circuit injury in ICH. These findings have important implications for clinical evaluations and treatment strategies, offering opportunities for precise therapeutic approaches to mitigate the detrimental effects of ICH and improve patient outcomes.

Spontaneous persistent activity and inactivity in vivo reveals differential cortico-entorhinal functional connectivity

Understanding the functional connectivity between brain regions and its emergent dynamics is a central challenge. Here we present a theory-experiment hybrid approach involving iteration between a minimal computational model and in vivo electrophysiological measurements. Our model not only predicted spontaneous persistent activity (SPA) during Up-Down-State oscillations, but also inactivity (SPI), which has never been reported. These were confirmed in vivo in the membrane potential of neurons, especially from layer 3 of the medial and lateral entorhinal cortices. The data was then used to constrain two free parameters, yielding a unique, experimentally determined model for each neuron. Analytic and computational analysis of the model generated a dozen quantitative predictions about network dynamics, which were all confirmed in vivo to high accuracy. Our technique predicted functional connectivity; e. g. the recurrent excitation is stronger in the medial than lateral entorhinal cortex. This too was confirmed with connectomics data. This technique uncovers how differential cortico-entorhinal dialogue generates SPA and SPI, which could form an energetically efficient working-memory substrate and influence the consolidation of memories during sleep. More broadly, our procedure can reveal the functional connectivity of large networks and a theory of their emergent dynamics.

Porcine Model of Cerebral Ischemic Stroke Utilizing Intracortical Recordings for the Continuous Monitoring of the Ischemic Area.

Our aim was to use intracortical recording to enable the tracking of ischemic infarct development over the first few critical hours of ischemia with a high time resolution in pigs. We employed electrophysiological measurements to obtain quick feedback on neural function, which might be useful for screening, e.g., for the optimal dosage and timing of agents prior to further pre-clinical evaluation. Micro-electrode arrays containing 16 (animal 1) or 32 electrodes (animal 2-7) were implanted in the primary somatosensory cortex of seven female pigs, and continuous electrical stimulation was applied at 0.2 Hz to a cuff electrode implanted on the ulnar nerve. Ischemic stroke was induced after 30 min of baseline recording by injection of endothelin-1 onto the cortex adjacent to the micro-electrode array. Evoked responses were extracted over a moving window of 180 s and averaged across channels as a measure of cortical excitability. Across the animals, the cortical excitability was significantly reduced in all seven 30 min segments following endothelin-1 injection, as compared to the 30 min preceding this intervention. This difference was not explained by changes in the anesthesia, ventilation, end-tidal CO2, mean blood pressure, heart rate, blood oxygenation, or core temperature, which all remained stable throughout the experiment. The animal model may assist in maturing neuroprotective approaches by testing them in an accessible model of resemblance to human neural and cardiovascular physiology and body size. This would constitute an intermediate step for translating positive results from rodent studies into human application, by more efficiently enabling effective optimization prior to chronic pre-clinical studies in large animals.

Investigating the Effect of Contextual Cueing with Face Stimuli on Electrophysiological Measures in Younger and Older Adults.

Extracting repeated patterns from our surroundings plays a crucial role in contextualizing information, making predictions and guiding our behavior implicitly. Previous research showed that contextual cueing enhances visual search performance in younger adults. In this study, we investigated whether contextual cueing could also improve older adults' performance and whether age-related differences in the neural processes underlying implicit contextual learning could be detected. Twenty-four younger and 25 older participants performed a visual search task with contextual cueing. Contextual information was generated using repeated face configurations alongside random new configurations. We measured RT difference between new and repeated configurations; ERPs to uncover the neural processes underlying contextual cueing for early (N2pc), intermediate (P3b), and late (r-LRP) processes; and multiscale entropy and spectral power density analyses to examine neural dynamics. Both younger and older adults showed similar contextual cueing benefits in their visual search efficiency at the behavioral level. In addition, they showed similar patterns regarding contextual information processing: Repeated face configurations evoked decreased finer timescale entropy (1-20 msec) and higher frequency band power (13-30 Hz) compared with new configurations. However, we detected age-related differences in ERPs: Younger, but not older adults, had larger N2pc and P3b components for repeated compared with new configurations. These results suggest that contextual cueing remains intact with aging. Although attention- and target-evaluation-related ERPs differed between the age groups, the neural dynamics of contextual learning were preserved with aging, as both age groups increasingly utilized more globally grouped representations for repeated face configurations during the learning process.

Lipid levels correlate with neuronal and dopaminergic markers during the differentiation of SH-SY5Y cells

Parkinson's Disease (PD) is characterised by the loss of dopaminergic neurons and the deposition of protein inclusions called Lewy Bodies (LBs). LBs are heterogeneous structures composed of protein and lipid molecules and their main constituent is the presynaptic protein α-synuclein. SH-SY5Y cells are neuroblastoma cells commonly used to model PD because they express dopaminergic markers and α-synuclein and they can be differentiated into neuronal cells using established protocols. Despite increasing evidence pointing towards a role of lipids in PD, limited knowledge is available on the lipidome of undifferentiated and differentiated SH-SY5Y cells. Using a combination of lipidomics, proteomics, morphological and electrophysiological measurements, we identified specific lipids, including sphingolipids, whose levels are affected by the differentiation of SH-SY5Y neuroblastoma cells and found that the levels of these lipids correlate with those of neuronal and dopaminergic markers. These results provide a quantitative characterisation of the changes in lipidome associated with the differentiation of SH-SY5Y cells into more neuronal and dopaminergic-like phenotype and serve as a basis for further characterisation of lipid disruptions in association with PD and its risk factors in this dopaminergic-like neuronal cell model.

Cognitive resilience/reserve: Myth or reality? A review of definitions and measurement methods.

This review examines the concept of cognitive reserve (CR) in relation to brain aging, particularly in the context of dementia and its early stages. CR refers to an individual's ability to maintain or regain cognitive function despite brain aging, damage, or disease. Various factors, including education, occupation complexity, leisure activities, and genetics are believed to influence CR. We revised the literature in the context of CR. A total of 842 articles were identified, then we rigorously assessed the relevance of articles based on titles and abstracts, employing a systematic approach to eliminate studies that did not align with our research objectives. We evaluate-also in a critical way-the methods commonly used to define and measure CR, including sociobehavioral proxies, neuroimaging, and electrophysiological and genetic measures.The challenges and limitations of these measures are discussed, emphasizing the need for more targeted research to improve the understanding, definition, and measurement of CR. The review underscores the significance of comprehending CR in the context of both normal and pathological brain aging and emphasizes the importance of further research to identify and enhance this protective factor for cognitive preservation in both healthy and neurologically impaired older individuals. This review examines the concept of cognitive reserve in brain aging, in the context of dementia and its early stages. We have evaluated the methods commonly used to define and measure cognitive reserve. Sociobehavioral proxies, neuroimaging, and electrophysiological and genetic measures are discussed. The review emphasizes the importance of further research to identify and enhance this protective factor for cognitive preservation.

Longitudinal Assessment of Outcome Measures of Diaphragm Motor Unit Connectivity As Biomarkers of Phrenic Motor Unit Degeneration and Compensation

Phrenic motor neurons (MNs) form the final link from the central nervous system (CNS) to the diaphragm muscle. Ventilatory function is modulated by the CNS via groups of muscle fibers each controlled by a single MN (motor units). Processes such as injury, aging, and neurodegeneration can result in losses of MNs, and their motor unit (MU) counterparts, but MNs and MUs have some capacity for compensation through mechanisms such as axonal sprouting and collateral sprouting to regain connectivity with denervated muscle. Motor unit number (motor unit number estimation, MUNE), MU size (single motor unit potential amplitude, SMUP), and summated muscle excitation (compound muscle action potential amplitude, CMAP) have been used clinically and preclinically for decades to track MU connectivity but efforts have largely focused on limb muscles. We aimed to apply these measures to a model of phrenic MN degeneration (intrapleural injection of cholera toxin B fragment conjugated to saporin, CTB-SAP).We hypothesized that CTB-SAP-induced phrenic motor neuron death would result in loss of diaphragm MU number and compensatory increases in MU size. Under isoflurane anesthesia, rats were bilaterally, intrapleurally injected with CTB-SAP (25 μg) to target phrenic MNs and extra CTB (25 μg) to label surviving phrenic MNs, and control rats received unconjugated CTB (25 μg) and SAP (25 μg). Diaphragm CMAP, SMUP, and MUNE were acquired bilaterally and averaged at baseline/pre-injection (n=14), as well as 7 (n=14), 14 (n=14), 21 (n=6), and 28 (n=14) days post-injection. No baseline differences between groups were found. MUNE showed a significant change for time (p&lt;0.05), treatment (p&lt;0.001), and interaction time x treatment (p&lt;0.01) with ~40% reduction of MUNE in CTB-SAP rats. Average SMUP of CTB-SAP rats demonstrated a significant change with time (p&lt;0.05) and treatment (p&lt;0.01), but no significant interaction with ~50-60% increase in SMUP amplitude. CMAP showed no significant change. Our results show a significant ~40% loss of MUs in CTB-SAP rats, similar to previous studies on morphological MN counts. In parallel with MU loss, MUs enlarged (increased SMUP), consistent with compensatory increases of MU size likely through MU collateral sprouting. In conclusion, our findings suggest that the use of diaphragm MU electrophysiological measures can provide insights into the onset and progression of CTB-SAP-induced pathology concerning the loss of phrenic MU integrity. Hence, these biomarkers can be used to investigate mechanisms of phrenic motor neuron degeneration and compensation, and to expedite the translation of experimental findings to clinical testing. Supported by a Spinal Cord Injury and Disease Research grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Functional Characterization of an Ammonia Transporter RhBG Mutation Identified in Diabetic Kidney Disease Patients

Metabolic acidosis is a major complication of CKD (chronic kidney disease) and DKD (diabetic kidney disease). The kidney responds to metabolic acidosis by eliminating acid, primarily by producing and excreting NH4+ in the urine. Two Rh glycoproteins, RhBG and RhCG, expressed in the collecting duct are directly involved in NH3/NH4+transport. We previously determined that RhBG transports both NH4+ and NH3 across the basolateral membrane of intercalated cells. Impaired NH3/NH4+ production and/or transport may be a factor in increasing acid load and worsening kidney disease. In type 2 diabetes, net endogenous acid production is significantly elevated, and the proportion of acid excreted as NH4+ is decreased even after accounting for diet and renal function. This is significant given that the association between acidosis and faster decline in GFR is now well established. In DKD, impaired NH4+ excretion as a potential risk factor for progression of kidney disease remains poorly understood. Specifically, the genetic risk factors contributing to DKD are unclear. Hypothesis: Defined RhBG variant(s) linked to DKD cause impaired NH3/NH4+ transport that may contribute to DKD development and progression. Methods: We conducted whole-exome sequencing (WES) analysis using data from A therosclerosis R isk i n C ommunities (ARIC) study and the C hronic R enal I nsuffciency C ohort (CRIC) study. We selected DKD patients with the most rapid GFR decline and compared them with: 1) subjects without kidney disease (healthy control); 2) diabetic patients without CKD (DM control); 3) CKD patients without diabetes (CKD control). This approach will identify single nucleotide variants (SNVs) of RhBG associated with DKD. This will also determine if the detected variants contribute to the development of kidney disease per se and whether they contribute to the development of diabetes and/or fast GFR decline. To study function, we expressed RhBG variants (and wild-type RhBG) in Xenopus oocytes by microinjecting oocytes with the respective mRNA. The effect of defined SNV of RhBG on NH3/NH4+ transport was assessed from measurements of changes in intracellular pH (pHi), membrane potential (Vm), whole cell currents (I) or surface pH (pHs) induced by exposing the oocytes to bath solutions containing NH4Cl or methyl ammonium chloride (MA/MA+). Results: We identified an SNV, rs3748569 (minor allele frequency MAF &gt; 0.05), that was significantly associated with DKD. Significance was determined compared to DM control (OR=1.38, p=0.0026) and healthy control (OR=1.26, p=0.01). This variant has also been predicted to be deleterious by 4 bioinformatic tools. Our electrophysiological measurements showed that the resultant amino acid switch, G315R, completely inhibited transport of NH3 and NH4+ (p&lt;0.001) and the transport of MA and MA+ (p&lt;0.0001), compared with RhBG-WT. Conclusions: WES results suggest that this naturally occurring RhBG mutation, G315R, contributes to DKD occurrence. This effect is through the development of kidney disease and less likely due to development of diabetes. It is therefore likely a general CKD risk factor. Inhibition of NH3/NH4+ transport by this mutation is a contributing factor to its deleterious effect. This work provides experimental validation of computational predictions concerning CKD and diabetes. NIH-U54 GM104940, Paul Teschan Research, NIH-R01, Carol Lavin Bernick, Tulane institutional. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A systematic review of animal and human data comparing the nasal potential difference test between cystic fibrosis and control

The nasal potential difference test (nPD) is an electrophysiological measurement which is altered in patients and animal models with cystic fibrosis (CF). Because protocols and outcomes vary substantially between laboratories, there are concerns over its validity and precision. We performed a systematic literature review (SR) of the nPD to answer the following review questions: A. Is the nasal potential difference similarly affected in CF patients and animal models?”, and B. “Is the nPD in human patients and animal models of CF similarly affected by various changes in the experimental set-up?”. The review protocol was preregistered on PROSPERO (CRD42021236047). We searched PubMed and Embase with comprehensive search strings. Two independent reviewers screened all references for inclusion and extracted all data. Included were studies about CF which described in vivo nPD measurements in separate CF and control groups. Risk of bias was assessed, and three meta-analyses were performed. We included 130 references describing nPD values for CF and control subjects, which confirmed substantial variation in the experimental design and nPD outcome between groups. The meta-analyses showed a clear difference in baseline nPD values between CF and control subjects, both in animals and in humans. However, baseline nPD values were, on average, lower in animal than in human studies. Reporting of experimental details was poor for both animal and human studies, and urgently needs to improve to ensure reproducibility of experiments within and between species.

Simple dynamic cell culture system reduces recording noise in microelectrode array recordings

AbstractMicroelectrode arrays (MEAs) have applications in drug discovery, toxicology, and basic research. They measure the electrophysiological response of tissue cultures to quantify changes upon exposure to biochemical stimuli. Unfortunately, manual addition of chemicals introduces significant noise in the recordings. Here, we report a simple-to-fabricate fluidic system that addresses this issue. We show that cell cultures can be successfully established in the fluidic compartment under continuous flow conditions and that the addition of chemicals introduces minimal noise in the recordings. This dynamic cell culture system represents an improvement over traditional tissue culture wells used in MEAs, facilitating electrophysiology measurements. Graphical abstract

Two sides of the same coin? How are neural mechanisms of cognitive control, attentional difficulties and creativity related?

Creativity has been associated with increased distractibility, but at the same time - and seemingly paradoxically- also with increased focused attention. Therefore, this study focused on the attentional processes involved in creativity and attentional difficulties. Healthy primary school children (N = 62) between 9 and 13 years old performed a selective attention paradigm while electrophysiological measures were recorded that measured the neural mechanisms of cognitive control (P300), conflict monitoring (N200), and subconscious attentional shifts (Mismatch Negativity). Attentional difficulties were measured with a parental questionnaire and creativity was measured with a divergent mathematical creativity task and a creative drawing task. We found that more creativity was related to decreased neural mechanisms of cognitive control and conflict monitoring (i.e. less negative N200 and smaller P300 amplitudes), however without affecting task performance. In addition, attentional difficulties were related to less negative N200 amplitudes on the attended and non-attended standard trials of the selective attention paradigm, as well as reduced task performance. Tentatively, the current findings suggest that original responses are associated with decreased cognitive control, possibly by promoting remote associations. Furthermore, our data shows that attentional difficulties are associated with a lack of selective attention and impaired information processing. Hence, although less cognitive control is often referred to in a negative way, it might facilitate certain aspects of creative thinking without affecting task performance.

Effect of Modulated Masking on Cortical Auditory Evoked Potential in Normal Hearing Individuals: A Systematic Review and Meta-Analysis

Abstract Introduction The study of electrophysiological auditory measures with different types of masking makes it possible to understand temporal processing skills and the processes involved in speech recognition in noise situations. The use of modulated masking in cortical measures of hearing enables the obtainment of analysis parameters of the masking release and its impact on neural auditory processing. Objective To investigate the behavior of cortical auditory evoked potentials (CAEPs) with modulated masking in the normal hearing population. Data synthesis A total of 2,159 articles were identified in the initial search; of these, 12 were selected for full reading. After excluding studies that did not meet the eligibility criteria, six articles were included in the present systematic review.The results show that the type of masking has an influence on cortical auditory behavior, indicating a different effect on neural posture rergarding CAEP responses. Modulated noise as masking in the CAEP record generated statistically higher and earlier responses compared with non-modulated/steady noise, evidenced by the results obtained in the meta-analysis with subgroup analysis. These responses may indicate an influence of the type of noise in the neural auditory coding. Conclusion Better responses were observed in modulated masking in terms of the behavior of CAEPs. Decreased latency and increased amplitude of cortical measurements with the use of modulated noise indicate a lower masking effect of this noise in cortical auditory processing, evidencing the masking release phenomenon.

Evaluating Bacterial Nanocellulose Interfaces for Recording Surface Biopotentials from Plants.

The study of plant electrophysiology offers promising techniques to track plant health and stress in vivo for both agricultural and environmental monitoring applications. Use of superficial electrodes on the plant body to record surface potentials may provide new phenotyping insights. Bacterial nanocellulose (BNC) is a flexible, optically translucent, and water-vapor-permeable material with low manufacturing costs, making it an ideal substrate for non-invasive and non-destructive plant electrodes. This work presents BNC electrodes with screen-printed carbon (graphite) ink-based conductive traces and pads. It investigates the potential of these electrodes for plant surface electrophysiology measurements in comparison to commercially available standard wet gel and needle electrodes. The electrochemically active surface area and impedance of the BNC electrodes varied based on the annealing temperature and time over the ranges of 50 °C to 90 °C and 5 to 60 min, respectively. The water vapor transfer rate and optical transmittance of the BNC substrate were measured to estimate the level of occlusion caused by these surface electrodes on the plant tissue. The total reduction in chlorophyll content under the electrodes was measured after the electrodes were placed on maize leaves for up to 300 h, showing that the BNC caused only a 16% reduction. Maize leaf transpiration was reduced by only 20% under the BNC electrodes after 72 h compared to a 60% reduction under wet gel electrodes in 48 h. On three different model plants, BNC-carbon ink surface electrodes and standard invasive needle electrodes were shown to have a comparable signal quality, with a correlation coefficient of >0.9, when measuring surface biopotentials induced by acute environmental stressors. These are strong indications of the superior performance of the BNC substrate with screen-printed graphite ink as an electrode material for plant surface biopotential recordings.

Investigation on the contribution of swim bladder to hearing in crucian carp (Carassius carassius).

The swim bladder in some teleost fish functions to transfer the sound energy of acoustic stimuli to the inner ears. This study uses the auditory evoked potential tests, micro-computed tomography scanning, reconstruction, and numerical modeling to assess the contribution of the swim bladder to hearing in crucian carp (Carassius carassius). The auditory evoked potential results show that, at the tested frequency range, the audiogram of fish with an intact swim bladder linearly increases, ranging from 100 to 600 Hz. Over this frequency, the sound pressure thresholds have a local lowest value at 800 Hz. The mean auditory threshold of fish with an intact swim bladder is lower than that of fish with a deflated swim bladder by 0.8-20.7 dB. Furthermore, numerical simulations show that the received pressure of the intact swim bladders occurs at a mean peak frequency of 826 ± 13.6 Hz, and no peak response is found in the deflated swim bladders. The increased sensitivity of reception in sound pressure and acceleration are 34.4 dB re 1 μPa and 40.3 dB re 1 m·s-2 at the natural frequency of swim bladder, respectively. Both electrophysiological measurement and numerical simulation results show that the swim bladder can potentially extend hearing bandwidth and further enhance auditory sensitivity in C. carassius.