VibroEEG: Improved EEG source reconstruction by combined acoustic-electric imaging

Neural activity related to productive vocabulary knowledge effects during second language comprehension

Studies were undertaken to determine whether any correlation exists between the level of acetylcholine (ACh) release from the cerebral cortex and medulla and the electrical activity within those same brain areas during hypercapnia, hypoxia, and hypoxia plus hypercapnia in combination. The cerebral cortex and medulla of anesthetized dogs released ACh spontaneously through push–pull cannulae after perfusion with an anticholinesterase, sarin. Hypercapnia (12% CO2) evoked an increased release of ACh above the basic spontaneous level from the cerebral cortex and medulla, with a parallel rise in the integrated electrical activity as monitored by EEG recordings. Hypoxia plus hypercapnia (8% O2 + 12% CO2) induced an ACh release comparable with hypercapnia alone, but with no change in the electrical activity. Hypoxia (8% O2) produced no increase in ACh release or electrical activity. Areas in the medullary reticular formation responsive to injections of CO2-buffered bicarbonate solutions ("respiratory responsive areas") produced during hypercapnia an augmented release of ACh, paralleled by a concomitant rise in the electrical activity, both of which were of greater magnitude than that manifested in either the "nonrespiratory responsive areas" of the medulla or in the cerebral cortex. The data suggest that a correlation exists between the ACh release and the electrical activity during hypercapnia. Thus, cholinergic neurons in the cerebral cortex and medulla may be activated during hypercapnia and are possibly involved in the medullary regulation of respiration. Furthermore, the evidence supports the concept that the pathways involved in EEG activation and ACh release are distinct.

Activity-Induced Long-Term Potentiation of Excitatory Synapses in Developing Zebrafish Retina In Vivo

We report on the modification of the local structures of (310) Σ5 grain boundary in bulk silicon as the growth of crystal and its influence on electrical activity. The grain boundary was formed via floating-zone growth method utilizing bicrystal seed. The misalignment of the seed resulted in formation of the grain boundary with small deviations of crystal orientation from the Σ5 singular coincidence orientation. The deviations consist of tilt and twist components and they were found to monotonically decrease with respect to the distance from the seed crystal accompanied by the decrease in density of dislocations on the grain boundary. The change in the grain boundary structure allows a systematic study on the correlation between the structure and the electrical activity at the GB. The density of dislocations was found to control the electrical activity and the (310) Σ5 coincidence grain boundary without any dislocations is expected to show a very low electrical activity.

The neural activity patterns of suprachiasmatic nucleus (SCN) neurons are dynamically regulated throughout the circadian cycle with highest levels of spontaneous action potentials during the day. These rhythms in electrical activity are critical for the function of the circadian timing system and yet the mechanisms by which the molecular clockwork drives changes in the membrane are not well understood. In this study, we sought to examine how the clock gene Period1 (Per1) regulates the electrical activity in the mouse SCN by transiently and selectively decreasing levels of PER1 through use of an antisense oligodeoxynucleotide. We found that this treatment effectively reduced SCN neural activity. Direct current injection to restore the normal membrane potential partially, but not completely, returned firing rate to normal levels. The antisense treatment also reduced baseline [Ca2+]i levels as measured by Fura2 imaging technique. Whole cell patch clamp recording techniques were used to examine which specific potassium currents were altered by the treatment. These recordings revealed that the large conductance [Ca2+]i-activated potassium currents were reduced in antisense-treated neurons and that blocking this current mimicked the effects of the anti-sense on SCN firing rate. These results indicate that the circadian clock gene Per1 alters firing rate in SCN neurons and raise the possibility that the large conductance [Ca2+]i-activated channel is one of the targets.

The regulation of pH is a vital homeostatic function shared by all tissues. Mechanisms that govern H+ in the intracellular and extracellular fluid are especially important in the brain, because electrical activity can elicit rapid pH changes in both compartments. These acid-base transients may in turn influence neural activity by affecting a variety of ion channels. The mechanisms responsible for the regulation of intracellular pH in brain are similar to those of other tissues and are comprised principally of forms of Na+/H+ exchange, Na+-driven Cl-/HCO3- exchange, Na+-HCO3- cotransport, and passive Cl-/HCO3- exchange. Differences in the expression or efficacy of these mechanisms have been noted among the functionally and morphologically diverse neurons and glial cells that have been studied. Molecular identification of transporter isoforms has revealed heterogeneity among brain regions and cell types. Neural activity gives rise to an assortment of extracellular and intracellular pH shifts that originate from a variety of mechanisms. Intracellular pH shifts in neurons and glia have been linked to Ca2+ transport, activation of acid extrusion systems, and the accumulation of metabolic products. Extracellular pH shifts can occur within milliseconds of neural activity, arise from an assortment of mechanisms, and are governed by the activity of extracellular carbonic anhydrase. The functional significance of these compartmental, activity-dependent pH shifts is discussed.

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Activity-dependent development of the neuromuscular synapse during drosophila embryogenesis

The main problem associated with the use of aluminum as a p-type dopant in silicon power devices is its low electrical activity in silicon after the anneal process. In order to obtain a deeper insight into the possible mechanisms responsible for the loss of electrical activity, it is necessary to study three different states of the p-n junction fabrication: (1) the unimplanted starting or reference material; (2) the aluminum-implanted material; and (3) the implanted and annealed material. In this paper we present a detailed analysis of reflectivity and transmission measurements of the three different states extending from the far-infrared to the UV region, as well as depth profiles of the reflectivity from as-implanted and bevelled samples. From these investigations we have obtained information about two important aspects, namely lattice damage and free-carrier properties. The refractive index across the implanted layer is essentially constant and considerably larger than that of the crystalline state; together with recent transmission electron microscopy studies it is suggested that this change in refractive index is due to the formation of broken or weakened bonds. In the annealed state those defects induced by implantation which produce a change of the optical properties are healed out to a high degree. From the free-carrier absorption observed in the far-infrared direct information is obtained about the electrical properties, i.e., the mean concentration and mobility of the holes associated with the electrically active aluminum atoms in the thin p-type layer produced by annealing. We obtain an electrical activity (percentage of electrically active Al atoms) of 17%. This result is discussed and compared with recent sheet resistance-, spreading resistance-, and secondary-ion mass spectrometry data obtained from the same sample.

Invasive electrophysiological recordings in subcortical structures of nonhuman primates typically involve implanting electrodes into the brain through a skull-mounted chamber. These electrodes may be attached to the chamber temporarily for hours of neural recording, or permanently for long-term studies. Current challenges involve maintaining asepsis and integrating dual-modality monitoring of both electrical and chemical neural activity. We developed an implantable neural interface that provides such dual-modality monitoring in monkeys, while maintaining aseptic conditions for year-long periods. We leveraged osseointegrating materials and hermetic sealing strategies to prevent the transmission of pathogenic species, while preserving the modular functionality of chamber systems, such as sensor depth adjustability. The system also features an aspirating port for culturing chamber fluid to ensure continued asepsis. Our chamber system was shown to provide successful recordings of dopamine and electrical neural activity in two monkeys while maintaining negative bacteria culture results for over a year post-implantation. Sealed chamber systems prevent contamination and reduce the risk of compromising animal health by minimizing the accumulation of pathogenic organisms. Such sealed chambers also eliminate the need for frequent cleaning. However, neurochemical measurements require specialized electrodes with fragile carbon fiber tips and are not compatible with recently developed, sealed chamber systems. This advanced chamber design builds upon traditional chamber protocols to enable chronic measurements of chemical and electrical neural activity. This approach facilitates novel ways to study the brain in behaving primates while prioritizing the long-term health and welfare of the animals.

Spiking Irregularity and Frequency Modulate the Behavioral Report of Single-Neuron Stimulation

Epigenetic modification of the oxytocin receptor gene is associated with child-parent neural synchrony during competition

The design of bioelectronics capable of stably tracking brain-wide, single-cell, and millisecond-resolved neural activities in the developing brain is critical to the study of neuroscience and neurodevelopmental disorders. During development, the three-dimensional (3D) structure of the vertebrate brain arises from a 2D neural plate 1,2 . These large morphological changes previously posed a challenge for implantable bioelectronics to track neural activity throughout brain development 3-9 . Here, we present a tissue-level-soft, sub-micrometer-thick, stretchable mesh microelectrode array capable of integrating into the embryonic neural plate of vertebrates by leveraging the 2D-to-3D reconfiguration process of the tissue itself. Driven by the expansion and folding processes of organogenesis, the stretchable mesh electrode array deforms, stretches, and distributes throughout the entire brain, fully integrating into the 3D tissue structure. Immunostaining, gene expression analysis, and behavioral testing show no discernible impact on brain development or function. The embedded electrode array enables long-term, stable, brain-wide, single-unit-single-spike-resolved electrical mapping throughout brain development, illustrating how neural electrical activities and population dynamics emerge and evolve during brain development.

This research seeks to examine the impact of workstation types on the coupling of neural and vascular activities of the prefrontal cortex (PFC). The design of the workstations was found to impair the performance, physical and mental health of employees. However, the mechanism underlying cognitive activity involved during workstation design-related stress effects in the PFC has not been fully understood. We used electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) to simultaneously measure electrical activity and hemoglobin concentration changes in the PFC. The multimodal signal was collected from 23 healthy adult volunteers who completed the Montreal imaging stress task in ergonomic and non-ergonomic workstations. A supervised machine learning method based on temporally embedded canonical correlation analysis (tCCA) was utilized to obtain the association between neural activity and local changes in hemoglobin concentrations to enhance localization and accuracy. The results showed deactivation in alpha power rhythms and oxygenated hemoglobin, as well as declined activation pattern of the fused data in the right PFC at the non-ergonomic workstation. Additionally, all participants at the non-ergonomic workstation experienced a substantial rise in salivary alpha-amylase activity in comparison with the ergonomic workstation, indicating the existence of high-stress levels. The proposed tCCA approach obtains excellent results in discriminating workstation types achieving accuracies of 98.8% and a significant improvement of 8.0% ( $p ) and 9.4% ( $p ) over EEG-only and fNIRS-only, respectively. Our study suggests the use of functional neuroimaging in designing the workplace as it provides critical information on the causes of workplace-related stress.

The question of how consciousness and behavior arise from neural activity is fundamental to understanding the brain, and to improving the diagnosis and treatment of neurological and psychiatric disorders. There is significant murine and primate literature on how behavior is related to the electrophysiological activity of the medial prefrontal cortex and its role in working memory processes such as planning and decision-making. Existing experimental designs, however, have insufficient statistical power to unravel the complex processes of the prefrontal cortex. We therefore examined the theoretical limitations of such experiments, providing concrete guidelines for robust and reproducible science. We piloted the use of dynamic time warping and associated statistical tests to data from neuron spike trains and local field potentials, to quantify neural network synchronicity and correlate neuroelectrophysiology with rat behavior. Our results indicate the statistical limitations of existing data, making meaningful comparison between dynamic time warping with traditional Fourier and wavelet analysis currently impossible until larger and cleaner datasets are available.Significance StatementThe prefrontal cortex is important in decision-making, yet no robust method currently exists to correlate neuron firing in the PFC to behavior. We argue that existing experimental designs are ill-suited to addressing these scientific questions, and we propose a potential method using dynamic time warping to analyze PFC neural electrical activity. We conclude that careful curation of experimental controls is needed to separate true neural signals from noise accurately.