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Direct electrical stimulation can modulate the activity of brain networks for the treatment of several neurological and neuropsychiatric disorders and for restoring lost function. However, precise neuromodulation in an individual requires the accurate modelling and prediction of the effects of stimulation on the activity of their large-scale brain networks. Here, we report the development of dynamic input-output models that predict multiregional dynamics of brain networks in response to temporally varying patterns of ongoing microstimulation. In experiments with two awake rhesus macaques, we show that the activities of brain networks are modulated by changes in both stimulation amplitude and frequency, that they exhibit damping and oscillatory response dynamics, and that variabilities in prediction accuracy and in estimated response strength across brain regions can be explained by an at-rest functional connectivity measure computed without stimulation. Input-output models of brain dynamics may enable precise neuromodulation for the treatment of disease and facilitate the investigation of the functional organization of large-scale brain networks.

Studies of neuronal oscillations have contributed substantial insight into the mechanisms of visual, auditory, and somatosensory perception. However, progress in such research in the human olfactory system has lagged behind. As a result, the electrophysiological properties of the human olfactory system are poorly understood, and, in particular, whether stimulus-driven high-frequency oscillations play a role in odor processing is unknown. Here, we used direct intracranial recordings from human piriform cortex during an odor identification task to show that 3 key oscillatory rhythms are an integral part of the human olfactory cortical response to smell: Odor induces theta, beta, and gamma rhythms in human piriform cortex. We further show that these rhythms have distinct relationships with perceptual behavior. Odor-elicited gamma oscillations occur only during trials in which the odor is accurately perceived, and features of gamma oscillations predict odor identification accuracy, suggesting that they are critical for odor identity perception in humans. We also found that the amplitude of high-frequency oscillations is organized by the phase of low-frequency signals shortly following sniff onset, only when odor is present. Our findings reinforce previous work on theta oscillations, suggest that gamma oscillations in human piriform cortex are important for perception of odor identity, and constitute a robust identification of the characteristic electrophysiological response to smell in the human brain. Future work will determine whether the distinct oscillations we identified reflect distinct perceptual features of odor stimuli., Intracranial recordings from human olfactory cortex reveal a characteristic spectrotemporal response to odors, including theta, beta and gamma oscillations, and show that high-frequency responses are critical for accurate perception of odors.

We estimate the elasticity of single polymer chains using atomic force microscope (AFM)-based oscillatory experiments. An accurate estimate of elasticity using AFM is limited by assumptions in describing the dynamics of an oscillating cantilever. Here, we use a home-built fiber-interferometry-based detection system that allows a simple and universal point-mass description of cantilever oscillations. By oscillating the cantilever base and detecting changes in cantilever oscillations with an interferometer, we extracted stiffness versus extension profiles for polymers. For polyethylene glycol (PEG) in a good solvent, stiffness–extension data showed significant deviation from conventional force–extension curves (FECs) measured in constant velocity pulling experiments. Furthermore, modeling stiffness data with an entropic worm-like chain (WLC) model yielded a persistence length of (0.5 ± 0.2 nm) compared to anomaly low value (0.12 nm ± 0.01) in conventional pulling experiments. This value also matched well with equilibrium measurements performed using magnetic tweezers. In contrast, polystyrene (PS) in a poor solvent, like water, showed no deviation between the two experiments. However, the stiffness profile for PS in good solvent (8M Urea) showed significant deviation from conventional force–extension curves. We obtained a persistence length of (0.8 ± 0.2 nm) compared to (0.22 nm ± 0.01) in pulling experiments. Our unambiguous measurements using interferometer yield physically acceptable values of persistence length. It validates the WLC model in good solvents but suggests caution for its use in poor solvents.

The development of coronavirus disease (COVID-19) deaths in selected nations and states is compared to the result of calculations using a conventional SEIR model of pandemic development. The model is based on the infection multiplier, R0, defined as the number of people infected by each infectious person. The infection rate increases exponentially when R0 >1.0; it remains constant at R0 = 1.0 and decreases for R0 < 1.0. R0 is determined by population behavior (frequency and proximity of interactions) and the ease by which a victim is infected by an infectious person (virulence of the virus). It is reduced by herd immunity when a large fraction of the population acquires immunity by vaccination or by recovering from infection.The daily death rates in the U.S. and northern Europe exhibited peaks in April/May 2020 and Dec. 2020/Jan. 2021 with more a modest rate during the summer of 2020 and a gradually decreasing rate since Jan. 2021. The model produces this type of oscillatory response if it assumes that the population’s R0 responds to information reported about the pandemic, but with a delay between infections and resulting behavioral adjustments. Oscillatory behavior is typical of a control loop with delay in its feedback.The analysis concludes thatGiven the history of R0 the model predicts the development of pandemic deaths. However, since R0 is determined by the population’s behavior, control of the pandemic in democracies depends primarily on preparation and the persuasive power of political and scientific authorities. Data for S. Korea and New Zealand demonstrate the effectiveness of such methods.For each death in the U.S. about 169 persons were infected, but fewer than half of them were identified as cases.The pandemic was prolonged in the U.S. because the population chose to keep R0 near 1.0 by relaxing restrictions once the death rate subsided.Initial values of R0 as high as 5.0 were observed, leading to infections doubling about every 2 days. If unabated, the resulting exponential growth increases the infected population by a factor of about 5000 before the death from the first infections is recorded.Arrival from Italy probably initiated the pandemic in the eastern U.S., but, by the time the first death was recorded the number of domestic infections exceeded by far those that were imported. Import restrictions beyond this point are ineffective except in delaying the arrival of more virulent mutations.If no social restrictions had been adopted, approximately 1.6 million deaths would have resulted in the U.S. The vaccine, although developed and deployed at record speed, was too late to ameliorate this result.A third peak in death rate in Sept. 2021 may be prevented if more than 80% of the population is vaccinated.

Brain decoding can predict visual perception from non-invasive electrophysiological data by combining information across multiple channels. However, decoding methods typically confound together the multi-faceted and distributed neural processes underlying perception, so it is unclear what specific aspects of the neural computations involved in perception are reflected in this type of macroscale data. Using MEG data recorded while participants viewed a large number of naturalistic images, we analytically separated the brain signal into a slow 1/f drift (

Oscillatory behavior in tissue biology is ubiquitous and may be observed in the form of either chemical or mechanical signals. We present here and solve a mechanical cell model that exhibits oscillations emerging from delayed viscoelastic rheological laws. These include a time delay between the mechanical response and the rest-length changes, which evolve proportionally to the delayed cell deformation and use a remodeling rate parameter. We show that different regimes (no oscillatory response, sustained oscillations, and unstable oscillations) are obtained for different values of the delay or the remodeling rate. The results are analytically demonstrated in a one-dimensional problem with one and two cells that are represented by simple line elements. Oscillations of the cell deformations are obtained whenever different delays coexist, or when the delay is size-dependent. We also extend our results to a multicellular two-dimensional vertex model that includes the same rheological law, and which inherits the presence of critical values of the delay or remodeling rate. We numerically show that indeed the size-dependent rest-length changes induce oscillations in the cell shapes and areas.

Microtubules (MTs) are important cytoskeletal structures engaged in a number of specific cellular activities, including vesicular traffic and motility, cell division, and information transfer within neuronal processes. MTs also are highly charged polyelectrolytes. Recent in vitro electrophysiological studies indicate that different brain MT structures, including two-dimensional (2D) sheets (MT sheets) and bundles, generate highly synchronous electrical oscillations. However, no information has been heretofore available as to whether isolated MTs also engage in electrical oscillations, despite the fact that taxol-stabilized isolated MTs are capable of amplifying electrical signals. Herein we tested the effect of voltage clamping on the electrical properties of isolated non-taxol stabilized brain MTs. Electrical oscillations were observed on application of holding potentials between ±200 mV that responded accordingly with changes in amplitude and polarity. Frequency domain spectral analysis of time records from isolated MTs disclosed a richer oscillatory response as compared to that observed in voltage clamped MT sheets from the same preparation. The data indicate that isolated brain MTs are electrical oscillators that behave as “ionic-based” transistors whose activity may be synchronized in higher MT structures. The ability of MTs to generate, propagate, and amplify electrical signals may have important implications in neuronal computational capabilities.Significance StatementMicrotubules (MTs) are important cytoskeletal structures engaged in a number of specific cellular activities. Recent in vitro electrophysiological studies indicate that different brain MT structures generate highly synchronous electrical oscillations. However, no information is available as to whether isolated MTs also engage in electrical oscillations. In the present study, we provide evidence that non-taxol stabilized isolated MTs generated electrical oscillations with richer frequency spectrum as compared to MT sheets. Thus, structured MT complexes may render more coherent responses at given oscillatory frequencies, suggesting entrainment in combined MT structures. The present study provides to our knowledge the first experimental evidence for electrical oscillations of single brain MTs.

Complex systems such as ecosystems, the climate and stock markets produce emergent behaviour which is capable of undergoing dramatic change when pushed beyond a tipping point. Such complex systems display Early Warning Signals in their behaviour when they are close to a tipping point. Here we show that a complex chemical reaction network can also display early warning signals when it is in close proximity to the boundary between oscillatory and steady state concentration behaviours. We identify early warning signals using both an active sensing method, based on the recovery time of an oscillatory response after a perturbation in temperature, and a passive sensing method, based upon a change in the shape of the oscillations. The presence of the early warning signals indicates that complex, dissipative chemical networks can intrinsically sense their proximity to a boundary between behaviours.

This chapter starts with several exemplary systems that illustrate a vast variety and richness of oscillatory systems, oscillatory responses and the related phenomena. Although they appear to be of complicated and diverse nature, some of them can be mechanically modelled in a simplified way that reflects their essential characteristics. The ones considered are assured by the restoring force, so the focus in the second part of Chap. 1 is on their typical mechanical models and the derivation of the corresponding equations of motion that contains such restoring force.

Optogenetic tools provide a new and efficient way to dynamically program gene expression with unmatched spatiotemporal precision. To date, their vast potential remains untapped in the field of cell-free synthetic biology, largely due to the lack of simple and efficient light-switchable systems. Here, to bridge the gap between cell-free systems and optogenetics, we studied our previously engineered one component-based blue light-inducible Escherichia coli promoter in a cell-free environment through experimental characterization and mathematical modeling. We achieved10-fold dynamic expression and demonstrated rapid and reversible activation of the target gene to generate oscillatory response. The deterministic model developed was able to recapitulate the system behavior and helped to provide quantitative insights to optimize dynamic response. This in vitro optogenetic approach could be a powerful new high-throughput screening technology for rapid prototyping of complex biological networks in both space and time without the need for chemical induction.

Motor functions improve during childhood and adolescence, but little is still known about the development of cortical motor circuits during early life. To elucidate the neurophysiological hallmarks of motor cortex development, we investigated the differences in motor cortical excitability and connectivity between healthy children, adolescents, and adults by means of navigated suprathreshold motor cortex transcranial magnetic stimulation (TMS) combined with high-density electroencephalography (EEG). We demonstrated that with development, the excitability of the motor system increases, the TMS-evoked EEG waveform increases in complexity, the magnitude of induced activation decreases, and signal spreading increases. Furthermore, the phase of the oscillatory response to TMS becomes less consistent with age. These changes parallel an improvement in manual dexterity and may reflect developmental changes in functional connectivity. Hum Brain Mapp 38:2599-2615, 2017. © 2017 Wiley Periodicals, Inc.

The paper deals with the proportional-derivative (PD) compensator tuning to attenuate oscillatory response evoked by an impulse disturbance at the input of the controlled plant. Selected tuning methods are surveyed, applied to a benchmark example and compared in terms of time- and frequency domain performance measures.

2019 IEEE International Ultrasonics Symposium (IUS), ISBN:978-1-7281-4596-9, ISBN:978-1-7281-4595-2, ISBN:978-1-7281-4597-6

A nonprehensile manipulation system consisting of a dexterous plate (e.g., a peel) which is intended to induce a rotating movement on a disk (e.g., a pizza) is studied. A dynamic model based on the Euler-Lagrange equations is first derived. Then, a controllability analysis of this model is carried out, which shows some intrinsic limitations of the proposed system. Later, a closed-loop control strategy is proposed to induce the desired rotating speed in the disk, while maintaining the position of both the disk and the plate as close to zero as possible. A stability analysis is performed to show the boundedness of all the states, the oscillatory response of all of them, and the maximum amplitude of these oscillations. A numerical simulation is employed to verify the proposed controller and the predicted behavior found in the stability analysis.

The article presents magnetoencephalography (MEG) data from healthy participants while undergoing the Hold/Release paradigm. During the paradigm, participants visually perceived a sequence of two letter strings which either assembled into real words (Hold condition) or pseudowords (Release condition). If the first letter string was morphologically valid, they held their attention (and/or held the item in working-memory) to wait for the second string, whereas if it were invalid, they could release it, respectively. We present data on high-frequency neuronal oscillations of the Hold condition compared to the Release condition. Making this information publicly available could allow other researchers to perform analyses and contribute to understanding the cognitive processes such as language, mnemonic or attentional processes. Keywords: Hold/release paradigm, Magnetoencephalography, Gamma oscillations, Language, Working memory, Attention

The paper presents the study of the 500-kV Vietnamese power system. The oscillatory response of the system is analyzed both with a modal analysis and a time domain analysis. The 500-kV system of Vietnam is modeled in details, including all the power plants with the corresponding regulators. The model is developed in collaboration with the Institute of Energy Science IES-VAST of Vietnam and it is validated with the data provided by the National Load Dispatch Centre (NLDC) of Vietnam. The simulation results reveal a clear identification of potential inter-area oscillations between North and South of the Country. A worsening of the observed phenomenon should be considered as possible, especially in the perspective of the new installation of a significant amount of power from renewable sources into the Vietnamese system.

Relying on evidence for the functional, neurochemical, and spectral parallelism between the late event-related potentials, delta oscillatory brain responses, and the skin conductance response (SCR) system the hypotheses about the existence of the SCR-related brain oscillations and their connectivity with the SCR system have been here suggested. In contrast to classical approach to event-related oscillations which relies on either stimulus- or response-locked time reference, an approach assigned as “oscillatory process-related oscillations” has been introduced. The method enables us to overcome the variability of latency period of the SCR. The hypothesis about the existence of the SCR-related brain oscillations and their delta nature has been confirmed through the grand averaging method. An unexpected finding was the complex nature of the SCR-related oscillations: in addition to the two second EEG segment which was correlated with the SCR system signals they also comprised an initial 200 ms segment uncorrelated with the SCR. The hypothesis about the connectivity between the SCR system and the respective delta brain oscillatory response has been operationalized through a multiple time series regression model. The predictor set consists of the SCR, its first three derivatives, and their mutual interactions. The Monte Carlo test of the causal link between the SCR system signals and the related delta EEG signal demonstrated significance in more than half of the participants. The findings have been considered from the standpoints of the segmental structure of the EEG, monoaminergic signaling and recently emerged the “brain-body dynamic syncytium” hypothesis.

Objectives This study investigated whether the method for eliciting vibration-induced oVEMPs could be improved by applying vibration directly to the teeth, and how vibration-induced oVEMP responses depend on the duration of the applied vibration. Methods In 10 participants, a hand-held shaker was used to present 100-Hz vibration tone pips to the teeth via a customised bite-bar or to other parts of the head. oVEMP potentials were recorded in response to vibration in three orthogonal directions and five stimulus durations (10–180 ms). The oVEMP responses were analysed in terms of the peak latency onset, peak-to-peak amplitude, and the quality of the trace. Results Vibration applied to the teeth via the bite-bar produced oVEMPs that were more consistent, of higher quality and of greater amplitude than those evoked by vibration applied to the head. Longer duration stimuli produced longer duration oVEMP responses. One cycle duration stimuli produced responses that were smaller in amplitude and lower quality than the longer stimulus durations. Conclusions Application of vibration via the teeth using a bite-bar is an effective means of producing oVEMPs. A 1-cycle stimulus is not optimal to evoke an oVEMP because it produces less robust responses than those of longer stimulus duration. A positive relationship between the duration of the stimulus and the response is consistent with the notion that the vibration-induced oVEMP is an oscillatory response to the motion of the head, rather than being a simple reflex response that occurs when the stimulus exceeds a threshold level of stimulation. Significance Applying acceleration to the teeth through a bite-bar elicits clearer oVEMP responses than direct application to other parts of the head and has potential to improve clinical measurements. A 100-Hz 1-cycle stimulus produces less robust oVEMP responses than longer 100-Hz stimuli.

Numerous studies of motor control have confirmed beta and gamma oscillations in the primary motor cortices during basic movements. These responses include a robust beta decrease that precedes and extends through movement onset, a transient gamma response that coincides with the movement, and a post-movement beta rebound (PMBR) response that occurs after movement offset. While the existence of these responses has been confirmed by many studies, very few studies have examined their developmental trajectory. In the current study, we utilized magnetoencephalography (MEG) to investigate age-related changes in sensorimotor cortical oscillations in a large cross-section of children and adolescents (n = 94; age range = 9 -15 years-old). All participants performed a stimulus detection task with their right finger and the resulting MEG data were examined using oscillatory analysis methods and imaged using a beamformer. Consistent with adult studies, these youth participants exhibited characteristic beta (16–24 Hz) decreases prior to and during movement, as well as PMBR responses following movement offset, and a transient gamma (74–84 Hz) response during movement execution. Our primary findings were that the strength of the PMBR increased with age, while the strength of the gamma synchronization decreased with chronological age. In addition, the strength of each motor-related oscillatory response was significantly correlated with the power of spontaneous activity in the same frequency range and same voxel. This was the case for all three oscillatory responses. In conclusion, we investigated motor-related oscillatory activity in the largest cohort of children and adolescents reported to date, and our results indicated that beta and gamma cortical oscillations continue to develop as children transition into adolescents, and that these responses may not be fully matured until young to middle adulthood.

Distinct neural processes are thought to support the retrieval of semantic information that is (i) coherent with strongly-encoded aspects of knowledge, and (ii) non-dominant yet relevant for the current task or context. While the brain regions that support readily coherent and more controlled patterns of semantic retrieval are relatively well-characterised, the temporal dynamics of these processes are not well-understood. This study used magnetoencephalography (MEG) and dual-pulse chronometric transcranial magnetic stimulation (cTMS) in two separate experiments to examine temporal dynamics during the retrieval of strong and weak associations. MEG results revealed a dissociation within left temporal cortex: anterior temporal lobe (ATL) showed greater oscillatory response for strong than weak associations, while posterior middle temporal gyrus (pMTG) showed the reverse pattern. Left inferior frontal gyrus (IFG), a site associated with semantic control and retrieval, showed both patterns at different time points. In the cTMS experiment, stimulation of ATL at ∼150 msec disrupted the efficient retrieval of strong associations, indicating a necessary role for ATL in coherent conceptual activations. Stimulation of pMTG at the onset of the second word disrupted the retrieval of weak associations, suggesting this site may maintain information about semantic context from the first word, allowing efficient engagement of semantic control. Together these studies provide converging evidence for a functional dissociation within the temporal lobe, across both tasks and time.

Multisensory integration of visuo-tactile information presented on the body or a dummy body has a strong impact on body image. Previous researches show that alteration of body image induced by visuo-tactile integration is closely related to the activation of the parietal cortex, a sensory association area. The expression of brain-derived neurotrophic factor (BDNF) in the parietal area of macaque monkeys is thought to modulate the activation of the parietal cortex and alter the extension of body image during tool-use learning. However, the relationship between parietal cortex activation related to body image alterations and BDNF levels in humans remains unclear. We investigated the relationship between human serum BDNF levels and electroencephalography responses during a visuo-tactile integration task involving a rubber hand. We found cortical oscillatory components in the high frequency (gamma) band in the left parietal cortex. Moreover, the power values of these oscillations were positively correlated (p < 0.05) with serum BDNF levels. Our results suggest that serum BDNF could play a role in modulating the cortical activity in response to visuo-tactile integration processes related to body image alteration in humans.

No abstract available.

The paper presents an experimental study of oscillatory response in the Francis turbine of hydraulic unit. The experiment was performed on large-scale hydrodynamic test-bench with impeller diameter of 0.3 m. The effect of air injection on the intensity of pressure pulsations was studied at the maximum pressure pulsations in the hydraulic unit. It was revealed that air delivery into the water-conveyance system of the turbine results in almost two-fold reduction of pressure pulsations.