Recording Sessions Research Articles

Development of an online tooth morphology course in response to COVID-19 restrictions.

Tooth morphology, a foundation of clinical and laboratory dentistry, is traditionally taught using lectures supported by study using extracted teeth, plastic replica, wax or chalk carving, or drawing.1 The need to review this model has been highlighted recently by pressures that include the difficulty to obtain and retain good quality teaching specimens, and reduction in teaching hours.1 During academic year 2020–2021, in response to the COVID-19 pandemic and in line with government restriction, our institution curtailed physical presence on campus for staff and students posing additional challenges to the delivery of our tooth morphology course. The delivery of lectures through recordings uploaded to a virtual learning environment (VLE) or remote lecturing using communication platforms cannot fully alleviate the problem. Learning with models (2D or 3D) is preferable to help integrate knowledge acquired in lectures with the 3D structure and appreciate differences in dental morphology. Flash cards offer a potential solution as they provide multiple views of the same tooth and highlight distinguishing features of the teeth. While some learners easily translate 2D information into 3D representations, others struggle with the process.2 In addition, assessment of knowledge in 2D is not aligned with its clinical application. dvantage of the Canvas VLE available at our institution to develop a self-directed tooth morphology learning environment proposing multiple entry points in 2D or 3D to students. We generated interactive FDI (Fédération Dentaire Internationale, FDI World Dental Federation) grids representing permanent or deciduous dentitions. Each button on the grid was linked to a Canvas VLE page containing either a 2D flashcard or a 3D interactive model for each tooth (Figure 1). The dental schools at the University of Dundee and the University of Michigan in Ann Arbor both created a series of 3D dental morphology models for permanent or deciduous dentitions available from the SketchFab website. These models were embedded into Canvas pages, allowing students to access the model in situ without access to external sites. Staff-led interactive sessions were held through Microsoft Teams using unlabeled 3D models loaded to Microsoft PowerPoint. These were screen shared to discuss dental features and quiz students. Each week, lecture notes and recordings were made available (see Supporting Information for full description). Assessment was performed through Canvas quizzes using embedded 3D models that students had not previously seen. Each question required learners to correctly identify a 3D tooth model and answer a question regarding the developmental milestones of the tooth. In response to the problems described above, the solution developed has allowed the continuation of delivery of material for which 3D spatial representation is important. The models were labeled to highlight individual features, providing students with an integrated 3D learning tool that could potentially rival extracted teeth as it offers immediate feedback on feature identification. Examination results for the 2021 cohort (68.7 ± 1.8%) are in line with the average results of the cohorts from 2016 to 2019 (71.5 ± 1.2%, p = 0.237 Student's t-test). The use of 2D and 3D approaches combined with lecture recording, notes, and live sessions for discussions with instant feedback allowed us to cater to different learning modes, and diverse schedules, and gave control to learners, in line with the principles of the Universal Design for Learning.3 While more research will be needed to investigate if students can translate virtual 3D learning to the identification of extracted teeth and if this can be implemented as a replacement for in-person teaching, we believe that this approach offers a strong alternative for students that prefer a self-paced learning environment to directed education. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Miles Davis, “Ko Ko,” and the Making of a Fallacy

ABSTRACT Recalling his first recording session with Charlie Parker on 26 November 1945, Miles Davis said he was so nervous that Dizzy Gillespie had to step in and play the trumpet solos on “Ko Ko,” the fast final tune of the session. Others present—producer Teddy Reig, pianist Sadik Hakim (aka Argonne Thornton), and Dizzy himself—all verified this story, that it was Gillespie and not Davis who played on “Ko Ko.” Yet despite this straighforward line of testimony, jazz writers and fans have questioned this account since the 1950s. More recently, the serious argument that it was in fact Miles who played the solos, not Dizzy, has appeared in various credible forums, including authoritative websites, Facebook groups involving professional jazz historians, and the magazine JazzTimes. This article examines this revisionist claim and finds it without foundation. In addition to the abundant and unanimous testimony of eyewitnesses, the musical evidence shows that in other solos recorded before and after the 1945 session, Gillespie reprised large portions of the complex “Ko Ko” solos. During a live performance of “Ko Ko” in 1947, he even played a sophisticated variation of the intro, a vanishingly unlikely occurrence had Miles Davis played the original.

A magnetoencephalography dataset for motor and cognitive imagery-based brain-computer interface

Recent advancements in magnetoencephalography (MEG)-based brain-computer interfaces (BCIs) have shown great potential. However, the performance of current MEG-BCI systems is still inadequate and one of the main reasons for this is the unavailability of open-source MEG-BCI datasets. MEG systems are expensive and hence MEG datasets are not readily available for researchers to develop effective and efficient BCI-related signal processing algorithms. In this work, we release a 306-channel MEG-BCI data recorded at 1KHz sampling frequency during four mental imagery tasks (i.e. hand imagery, feet imagery, subtraction imagery, and word generation imagery). The dataset contains two sessions of MEG recordings performed on separate days from 17 healthy participants using a typical BCI imagery paradigm. The current dataset will be the only publicly available MEG imagery BCI dataset as per our knowledge. The dataset can be used by the scientific community towards the development of novel pattern recognition machine learning methods to detect brain activities related to motor imagery and cognitive imagery tasks using MEG signals.

Large-Scale and Multiscale Networks in the Rodent Brain during Novelty Exploration.

Neural activity is coordinated across multiple spatial and temporal scales, and these patterns of coordination are implicated in both healthy and impaired cognitive operations. However, empirical cross-scale investigations are relatively infrequent, because of limited data availability and to the difficulty of analyzing rich multivariate datasets. Here, we applied frequency-resolved multivariate source-separation analyses to characterize a large-scale dataset comprising spiking and local field potential (LFP) activity recorded simultaneously in three brain regions (prefrontal cortex, parietal cortex, hippocampus) in freely-moving mice. We identified a constellation of multidimensional, inter-regional networks across a range of frequencies (2–200 Hz). These networks were reproducible within animals across different recording sessions, but varied across different animals, suggesting individual variability in network architecture. The theta band (∼4–10 Hz) networks had several prominent features, including roughly equal contribution from all regions and strong inter-network synchronization. Overall, these findings demonstrate a multidimensional landscape of large-scale functional activations of cortical networks operating across multiple spatial, spectral, and temporal scales during open-field exploration.

The traceback method in child language acquisition research: identifying patterns in early speech

abstractThis paper discusses the traceback method, which has been the basis of some influential papers on first language acquisition. The method sets out to demonstrate that many or even all utterances in a test corpus (usually the last two sessions of recording) can be accounted for with the help of recurrent fixed strings (likeWhat’s that?) or frame-and-slot patterns (like [What’sX?]) that can also be identified in the remaining dataset (i.e., the previous sessions of recording). This is taken as evidence that language learning is much more item-based than previously assumed. In the present paper we sketch the development of the method over the last two decades, and discuss its relation to usage-based theory, as well as the cognitive plausibility of its components, and we highlight both its potential and its limitations.

The contractiongram: A method for the visualization of uterine contraction evolution using the electrohysterogram

Uterine contractions’ monitoring has been pointed out as an important tool that may be useful in the preterm risk assessment, term birth estimation and uterine physiology investigation. The multichannel EHG provides a mapping of the myometrium electrical activity projection on the selected channels, providing a wealth of information, including pacemaker regions, signal propagation and contraction amplitude and spectral characteristics. The EHG multichannel data representation, regarding contractile activity, presents an interpretation challenge, given the presence of the multiple contractions of, possibly, different types, in the respective acquisition channels, for different recording sessions and gestational ages of one or multiple pregnant subjects. Typically, an EHG dataset contains data from various subjects, for which multiple recording sessions could be performed, possibly leading to hundreds of recordings. The post-processing step of this data for contraction retrieval may result in multidimensional datasets, requiring interpretation in multiple research scenarios. In this work, a novel representation method is introduced, the Contractiongram, an intuitive graphical tool to facilitate the interpretation of the EHG contractile data for a subject or a whole dataset, throughout the pregnancy, including multisession acquisition scenarios. An application example is presented for a widely used open access EHG database. A contraction detection and classification were a result of a previous research work and used as a data pool for this study. The graphical representation obtained in the current study is a suitable tool for the identification of uterine contraction patterns in selected channels corresponding to different myometrial regions, in designated gestational ages.

Spectral signatures of L-DOPA-induced dyskinesia depend on L-DOPA dose and are suppressed by ketamine

L-DOPA-induced dyskinesias (LID) are debilitating motor symptoms of dopamine-replacement therapy for Parkinson's disease (PD) that emerge after years of L-DOPA treatment. While there is an abundance of research into the cellular and synaptic origins of LID, less is known about how LID impacts systems-level circuits and neural synchrony, how synchrony is affected by the dose and duration of L-DOPA exposure, or how potential novel treatments for LID, such as sub-anesthetic ketamine, alter this activity. Sub-anesthetic ketamine treatments have recently been shown to reduce LID, and ketamine is known to affect neural synchrony. To investigate these questions, we measured movement and local-field potential (LFP) activity from the motor cortex (M1) and the striatum of preclinical rodent models of PD and LID. In the first experiment, we investigated the effect of the LID priming procedures and L-DOPA dose on neural signatures of LID. Two common priming procedures were compared: a high-dose procedure that exposed unilateral 6-hydroxydopamine-lesioned rats to 12 mg/kg L-DOPA for 7 days, and a low-dose procedure that exposed rats to 7 mg/kg L-DOPA for 21 days. Consistent with reports from other groups, 12 mg/kg L-DOPA triggered LID and 80-Hz oscillations; however, these 80-Hz oscillations were not observed after 7 mg/kg administration despite clear evidence of LID, indicating that 80-Hz oscillations are not an exclusive signature of LID. We also found that weeks-long low-dose priming resulted in the emergence of non-oscillatory broadband gamma activity (> 30 Hz) in the striatum and theta-to-high-gamma cross-frequency coupling (CFC) in M1. In a second set of experiments, we investigated how ketamine exposure affects spectral signatures of low-dose L-DOPA priming. During each neural recording session, ketamine was delivered through 5 injections (20 mg/kg, i.p.) administered every 2 h. We found that ketamine exposure suppressed striatal broadband gamma associated with LID but enhanced M1 broadband activity. We also found that M1 theta-to-high-gamma CFC associated with the LID on-state was suppressed by ketamine. These results suggest that ketamine's therapeutic effects are region specific. Our findings also have clinical implications, as we are the first to report novel oscillatory signatures of the common low-dose LID priming procedure that more closely models dopamine replacement therapy in individuals with PD. We also identify neural correlates of the anti-dyskinetic activity of sub-anesthetic ketamine treatment.

Robust and accurate decoding of hand kinematics from entire spiking activity using deep learning

Objective. Brain–machine interfaces (BMIs) seek to restore lost motor functions in individuals with neurological disorders by enabling them to control external devices directly with their thoughts. This work aims to improve robustness and decoding accuracy that currently become major challenges in the clinical translation of intracortical BMIs. Approach. We propose entire spiking activity (ESA)—an envelope of spiking activity that can be extracted by a simple, threshold-less, and automated technique—as the input signal. We couple ESA with deep learning-based decoding algorithm that uses quasi-recurrent neural network (QRNN) architecture. We evaluate comprehensively the performance of ESA-driven QRNN decoder for decoding hand kinematics from neural signals chronically recorded from the primary motor cortex area of three non-human primates performing different tasks. Main results. Our proposed method yields consistently higher decoding performance than any other combinations of the input signal and decoding algorithm previously reported across long-term recording sessions. It can sustain high decoding performance even when removing spikes from the raw signals, when using the different number of channels, and when using a smaller amount of training data. Significance. Overall results demonstrate exceptionally high decoding accuracy and chronic robustness, which is highly desirable given it is an unresolved challenge in BMIs.

Impact of referencing scheme on decoding performance of LFP-based brain-machine interface

Objective. There has recently been an increasing interest in local field potential (LFP) for brain-machine interface (BMI) applications due to its desirable properties (signal stability and low bandwidth). LFP is typically recorded with respect to a single unipolar reference which is susceptible to common noise. Several referencing schemes have been proposed to eliminate the common noise, such as bipolar reference, current source density (CSD), and common average reference (CAR). However, to date, there have not been any studies to investigate the impact of these referencing schemes on decoding performance of LFP-based BMIs. Approach. To address this issue, we comprehensively examined the impact of different referencing schemes and LFP features on the performance of hand kinematic decoding using a deep learning method. We used LFPs chronically recorded from the motor cortex area of a monkey while performing reaching tasks. Main results. Experimental results revealed that local motor potential (LMP) emerged as the most informative feature regardless of the referencing schemes. Using LMP as the feature, CAR was found to yield consistently better decoding performance than other referencing schemes over long-term recording sessions. Significance. Overall, our results suggest the potential use of LMP coupled with CAR for enhancing the decoding performance of LFP-based BMIs.

Changes on soundscapes reveal impacts of wildfires in the fauna of a Brazilian savanna

Wildfire is a natural process in Brazilian savannas, but human activities alter fire regimes and threaten biodiversity. In this study, we used an ecoacoustics approach to assess fauna responses and recovery after wildfire in a Brazilian savanna. Six passive acoustic monitoring devices were used to record soundscapes before and after a wildfire a at burned and non-burned sites for one year and one month (September 2012 to September 2013). Power Spectral Density and the Acoustic Complexity Index were used to track biophony. Before the fire, the two sites had similar biophonic patterns (PSD: T = 1136, Z = 1.52, P = 0.12; ACI: T = 1117, Z = 1.10, P = 0.26) and soniferous species richness (Site 1 = 52 and Site 2 = 49). However, in the first two sessions of recordings after the fire, biophony became higher at the burned site during the day (PSD: T = 211 and 233; Z = 4.13 and 6.41; ACI: T = 120 and 469, Z = 5.14 and 7.07; all P < 0.00). During the night, biophony was usually higher at the non-burned site until May 2013 (PSD: T = 0 to 453; Z = 3.30 to 5.90; ACI: T = 333 to 491, Z = 3.80 to 4.93; all P < 0.00). Biophony became similar (P = 0.17 to 0.38) at the two sites or higher (P = 0.00 to 0.01) at the burned site from July to September 2013 (PSD: T = 55 to 1167; Z = 1.35 to 6.89; ACI: T = 719 to 1365, Z = 0.87 to 3.04). After the fire, a reduction of soniferous species at the burned site was observed for insects and bats. Both biophonic activity and soniferous species showed a tendency to recover one year after the fire, but there were still less species in September 2013 (non-burned = 43 and burned = 37) when compared to September 2012 at both sites (Site 1 = 52 and Site 2 = 49). Our results showed that changes in the natural regimes of fire can negatively impact the biodiversity and reinforce the need for monitoring protocols and inspection of wildfires.

Heart Full of Rhythm: The Big Band Years of Louis Armstrong by Ricky Riccardi

Reviewed by: Heart Full of Rhythm: The Big Band Years of Louis Armstrong by Ricky Riccardi Vincent Pelote Heart Full of Rhythm: The Big Band Years of Louis Armstrong. By Ricky Riccardi. New York: Oxford University Press, 2020. [432 p. ISBN 9780190914110 (hardcover) $34.95; ISBN9780190914127 (e-book), $47.25.] Illustrations, bibliography, index. Heart Full of Rhythm: The Big Band Years of Louis Armstrong is author Ricky Riccardi's second book on the trumpet player and vocalist affectionately known to millions as "Satchmo." It follows his award-winning and critically acclaimed earlier book, What a Wonderful World: The Magic of Louis Armstrong's Later Years (New York: Pantheon Books, 2011). That earlier book covered the last twenty-five years (1946–71) of Armstrong's life and art, while his current work covers the years 1929–47. Riccardi, director of research collections for the Louis Armstrong House Museum, relies on access to the hundreds of reel-to-reel tapes that Armstrong made during his lifetime. These tapes contain stories, reminiscences, jokes, and conversations with others and is a treasure trove of research source material for anyone writing a book on the great man. There are also scrapbooks full of newspaper clippings and other materials that Riccardi makes copious use of, along with material from other sources. In Riccardi's first book, he defended Armstrong from wrong-headed critics who consistently disparaged Armstrong's recordings and performances, mostly with his All-Stars. Once again, Riccardi takes on the critics in the jazz press as well as those in the Black and White mainstream press against criticism of Armstrong's recordings and performances from his big-band years. He was attacked by the jazz press for abandoning jazz and becoming "commercial" by leading a big band and performing pop tunes and other nonjazz material. The Black press criticized him for what they considered his racially offensive performance practices (e.g, jokes with Black stereotypes, references to "darkies" in certain songs, etc.), and the White press also took issue with Armstrong's performances, sometimes using racist language in doing so. All the while, he was generally very popular with audiences—both Black and White—who wanted to be entertained, and Armstrong knew how to do that quite well. It is Riccardi's assertion that Armstrong was more than just a jazz musician. He was a pop icon and entertainer who not only led a big dance band that showcased his playing and singing of popular songs but also was renowned as a radio and movie personality. In fact, Armstrong [End Page 231] can be credited with a number of firsts for Blacks in radio and movies. In 1937, as host of the Fleischmann's Yeast Hour, Armstrong became the first African American to host a commercial radio broadcast. The film Pennies from Heaven (1936) gave Armstrong the honor of being the first Black actor to get top billing, alongside Bing Crosby and the movie's other White stars. His popularity was such that he was the first African American jazz musician to publish his own autobiography (Swing That Music [New York: Longmans, Green, 1936]). The popular fairy tale that many jazz critics like to push is that after Armstrong's groundbreaking jazz recordings in the 1920s—starting with his early output with King Oliver, continuing with records made with Clarence Williams, and concluding with his own Hot Five and Hot Seven sessions—he had pretty much stopped creating meaningful contributions to jazz and went commercial. Nothing could be further from the truth. Riccardi chronicles Armstrong's career starting in March 1929, when he and Black musicians Happy Caldwell and Kaiser Marshall took part in the first integrated jazz recording session—with White musicians Jack Teagarden, Joe Sullivan, and Eddie Lang—that produced the jazz classic "Knockin' a Jug." The following recording session with Armstrong, accompanied by members of the Luis Russell Orchestra and White banjoist Eddie Condon, produced "I Can't Give You Anything but Love," which OKeh Records decided to issue in both the "race" records catalog (aimed at the Black buying market) as well as its popular series. Discographers should be aware that Riccardi, in his notes section (p. 344), clears up...

A Prototype System for Sound Recording in Motion

In this paper a method to record soundscapes using a mobile recording system is proposed. The purpose of this method is the verisimilar reproduction of soundscapes as spatiotemporal continua without any sonic traces of the recording process, i.e. transparently. Thus, the recorded audio signal retains the finest details of the soundscape’s evolution due to both spatial and temporal variability, which would be impossible to capture with other methods. This method is proposed as an approach to audio reproduction that could simulate an actual experience of a soundwalk. For this purpose an apparatus for recording in motion was designed, named Moving Sound-Receptor [MSR]. It can be used to record along either accessible or inaccessible horizontal tracks (eg. over the surface of a lake) as well as along vertical trajectories. This method has been applied to a variety of outdoor recording sessions, the most characteristic of which are presented in this paper. In addition, the MSR is introduced from the point of view of its conception and its design and how these reflect in the choice of its components and their assembly.

There’s a Starman Waiting in the Sky

There’s a Starman Waiting in the Sky Jeffrey R. Di Leo, Publisher Editor (bio) “The time,” said David Bowie to William Burroughs, “is five years to go before the end of the earth.” Bowie was explaining to Burroughs some of the ideas underlying his fifth studio album, The Rise and Fall of Ziggy Stardust and the Spiders from Mars, which had been released about a year and half earlier. The two were meeting for the first time at the behest of Craig Copetas, who was conducting a two-way interview of them for Rolling Stone Magazine. Burroughs was nearing 60 at the time and Bowie was a few months shy of 27 — the mythical age of death of Brian Jones, Jimi Hendrix, Janis Joplin, Jim Morrison, Kurt Cobain, Amy Winehouse, and many other prominent musicians. The last track on Ziggy Stardust, “Rock ‘n’ Roll Suicide,” grimly recalls the fate of the 27 Club: You’re too old to lose it, too young to choose it And the clock waits so patiently on your songYou walk past the café but you don’t eat when you’ve lived too long You’re a rock ‘n’ roll suicide Though Bowie would far outlive the 27 Club, Ziggy does not. He is taken by the rock ‘n’ roll death drive. Sigmund Freud, who coined the notion of the death drive, regarded it as a mediation of Friedrich Nietzsche’s affirmation of the will and Arthur Schopenhauer’s negation of it. But this is not the death drive that took Ziggy. It was one tempered more by Lacanian than Freudian thought. Slavoj Žižek, the great contemporary Lacanian philosopher, argues that the death drive should not be confused with the return to the inorganic absence of any life-tension or with the craving for self-annihilation. For him, “the death drive, on the contrary, is the very opposite of dying, it is a name for the ‘undead’ eternal life itself, for the horrible fate of being caught in the endless repetitive cycle of wandering around in guilt and pain.” After the Ziggy Stardust tour, the Ziggy character disappeared as quickly as he appeared — giving way to the titular character of Bowie’s follow-up album, Aladdin Sane (1973). I’d like to think though that fifty years after his disappearance from the Bowie tour stage, he lives on in a variation of the “undead” eternal life described by Žižek — rising and falling in the endless repetitive cycle of the spinning of the well-worn black vinyl of Ziggy Stardust. ________ The setting for their meeting was Bowie’s home in London, which we are told was decorated in a science-fiction mode. A huge painting by an artist who was a cross between Salvador Dalí and Norman Rockwell hung over a plastic sofa. Lunch, reports Copetas, was a Jamaican fish dish served with avocados stuffed with shrimp and a Beaujolais nouveau. It was prepared by a Jamaican in the Bowie entourage and served by, what he describes as “two interstellar Bowieties.” The Starman himself was wearing three-tone NASA jodhpurs — those full-length trousers, worn for horseback riding, that are close-fitting below the knee and have reinforced patches on the inside of the leg. Keep your ‘lectric eye on me babe Put your ray gun to my headPress your space face close to mine, loveFreak out in a moonage daydream oh! yea! (Bowie, “Moonage Daydream”) Burroughs, who lived at the time in a two-room flat in Piccadilly and shared a cab with Copetas to Bowie’s home, must have thought he landed on another planet — the glam psychedelic one where the Starman-in-the-sky-who-would-like-to-come-and-meet-us-but-thinks-he’d-blow-our-minds lives. Their meeting was on November 17, 1973 — two years and two days after the first recording sessions for Ziggy Stardust had ended. While their meeting was not as significant in literary history as say the dinner Horace Liveright had with Ezra Pound, T. S. Eliot, and James Joyce on January 4, 1922, where by the end of dinner that night, Liveright had retained the services of...

Nocturnal Variability of Intraocular Pressure Monitored With Contact Lens Sensor Is Associated With Visual Field Loss in Glaucoma.

The aim was to determine whether 24-hour recording of intraocular pressure (IOP)-related ocular dimensional changes with a contact lens sensor (CLS, Triggerfish) is associated with the rate of visual field (VF) progression in primary open-angle glaucoma (POAG) patients. This was a retrospective, observational cohort study. Patients with POAG were included from the Glaucoma Clinic and Diagnostic Innovations in Glaucoma Study at the Hamilton Glaucoma Center at University of California, San Diego. A session of 24-hour CLS recording was acquired for 1 eye from each patient. The mean follow-up time was 9.9±4.0 years. The association between CLS variables and rate of change of mean deviation was determined by univariate and multivariate mixed linear regression models. Thirty-two patients, aged 69.8±13.6 years were included, 50% were female. An average of 11.6±5.6 standard automated perimetry examinations was available with a mean rate of mean deviation progression of -0.2±0.4 dB/year. Mean IOP was 17.8±4.2 mm Hg. The mean number of IOP-lowering medications were 1.2±1.0. Each 10-unit larger nocturnal variability of IOP-related ocular dimensional changes measured by CLS recording was significantly associated with -0.25±0.11 dB faster VF loss in POAG patients (P=0.035). Twenty-four-hour CLS recording of IOP-related ocular dimensional change was associated with faster VF progression. Such CLS recordings are useful to assess the risk of in progression in POAG patients.

Approximate Entropy of Brain Network in the Study of Hemispheric Differences.

Human brain, a dynamic complex system, can be studied with different approaches, including linear and nonlinear ones. One of the nonlinear approaches widely used in electroencephalographic (EEG) analyses is the entropy, the measurement of disorder in a system. The present study investigates brain networks applying approximate entropy (ApEn) measure for assessing the hemispheric EEG differences; reproducibility and stability of ApEn data across separate recording sessions were evaluated. Twenty healthy adult volunteers were submitted to eyes-closed resting EEG recordings, for 80 recordings. Significant differences in the occipital region, with higher values of entropy in the left hemisphere than in the right one, show that the hemispheres become active with different intensities according to the performed function. Besides, the present methodology proved to be reproducible and stable, when carried out on relatively brief EEG epochs but also at a 1-week distance in a group of 36 subjects. Nonlinear approaches represent an interesting probe to study the dynamics of brain networks. ApEn technique might provide more insight into the pathophysiological processes underlying age-related brain disconnection as well as for monitoring the impact of pharmacological and rehabilitation treatments.

EEG Resting Asymmetries and Frequency Oscillations in Approach/Avoidance Personality Traits: A Systematic Review

Background: Brain cortical activity in resting electroencephalogram (EEG) recordings can be considered as measures of latent individual disposition to approach/avoidance behavior. This systematic review aims to provide an updated overview of the relationship between resting EEG cortical activity and approach/avoidance motivation personality traits. Methods: The review process was conducted according to the PRISMA-Statement, using PsycArticles, MEDLINE, Scopus, Science Citation Index, and Research Gate database. Restrictions were made by selecting EEG studies conducted in resting idling conditions, which included approach/avoidance personality traits or parallel measures, and an index of EEG brain activity. In the review 50 studies were selected, wherein 7120 healthy adult individuals participated. Results: The study of the relationship between resting EEG cortical activity and approach/avoidance personality traits provides controversial and unclear results. Therefore, the validity of resting asymmetry or frequency oscillations as a potential marker for approach/avoidance personality traits is not supported. Conclusions: There are important contextual and interactional factors not taken into account by researchers that could mediate or moderate this relationship or prove it scarcely replicable. Further, it would be necessary to conduct more sessions of EEG recordings in different seasons of the year to test the validity and the reliability of the neurobiological measures.

Precise quantification of the time course of voluntary activation capacity following Botulinum toxin injections in the biceps brachii muscles of chronic stroke survivors

BackgroundSpasticity is a key motor impairment that affects many hemispheric stroke survivors. Intramuscular botulinum toxin (BT) injections are used widely to clinically manage spasticity-related symptoms in stroke survivors by chemically denervating muscle fibers from their associated motor neurons. In this study, we sought to understand how BT affects muscle activation, motor unit composition and voluntary force generating capacity over a time period of 3 months. Our purpose was to characterize the time course of functional changes in voluntary muscle activity in stroke survivors who are undergoing BT therapy as part of their physician-prescribed clinical plan.MethodOur assessment of the effects of BT was based on the quantification of surface electromyogram (sEMG) recordings in the biceps brachii (BB), an upper arm muscle and of voluntary contraction force. We report here on voluntary force and sEMG responses during isometric elbow contractions across consecutive recording sessions, spread over 12 weeks in three segments, starting with a preliminary session performed just prior to the BT injection. At predetermined time points, we conducted additional clinical assessments and we also recorded from the contralateral limbs of our stroke cohort. Eight subjects were studied for approximately 86 experimental recording sessions on both stroke-affected and contralateral sides.ResultsWe recorded an initial reduction in force and sEMG in all subjects, followed by a trajectory with a progressive return to baseline over a maximum of 12 weeks, although the minimum sEMG and minimum force were not always recorded at the same time point. Three participants were able to complete only one to two segments. Slope values of the sEMG-force relations were also found to vary across the different time segments. While sEMG-force slopes provide assessments of force generation capacity of the BT injected muscle, amplitude histograms from novel sEMG recordings during the voluntary tasks provide additional insights about differential actions of BT on the overall motor unit (MU) population over time.ConclusionsThe results of our study indicate that there are potential short term as well as long term decrements in muscle control and activation properties after BT administration on the affected side of chronic stroke survivors. Muscle activation levels as recorded using sEMG, did not routinely return to baseline even at three months’ post injection. The concurrent clinical measures also did not follow the same time course, nor did they provide the same resolution as our experimental measures. It follows that even 12 weeks after intramuscular BT injections muscle recovery may not be complete, and may thereby contribute to pre-existing paresis.

Long-term labeling of microelectrode tracks with fluorescent latex microspheres

BackgroundAfter physiological recordings are performed in behaving animals, it is valuable to identify microelectrode tracks in histological sections so that neuronal responses can be correlated with brain anatomy. However, no good method currently exists for long-term labeling, so that microelectrode tracks can be recovered months or even years after recording sessions. New MethodPenetrations were made into the brains of mice with microelectrodes coated with fluorescent dyes packaged into 0.2 μm polystyrene microspheres, followed by survival periods of 3 days, 2, 4, or 6 months. Sections were examined by fluorescence microscopy before and after cytochrome oxidase histochemistry to identify microelectrode tracks. ResultsAfter all 4 survival periods, 0.2 μm fluorescent microspheres clearly marked the tracks of microelectrode penetrations. Comparison with Existing MethodsFluorescent microspheres label microelectrode penetrations for longer than do fluorescent lipophilic dyes, such as FM 1−43FX. The label appears punctate, and resistant to degradation, because it is protected by the barrier of the polystyrene micro-container. ConclusionsCoating of microelectrodes with fluorescent microspheres allows one to identify the penetration track in histological sections half a year later. This technique may be useful when electrophysiological recording sessions are being carried out in behaving animals, with plans to identify electrode tracks in histological sections many months later.

Disentangled Adversarial Transfer Learning for Physiological Biosignals.

Recent developments in wearable sensors demonstrate promising results for monitoring physiological status in effective and comfortable ways. One major challenge of physiological status assessment is the problem of transfer learning caused by the domain inconsistency of biosignals across users or different recording sessions from the same user. We propose an adversarial inference approach for transfer learning to extract disentangled nuisance-robust representations from physiological biosignal data in stress status level assessment. We exploit the trade-off between task-related features and person-discriminative information by using both an adversary network and a nuisance network to jointly manipulate and disentangle the learned latent representations by the encoder, which are then input to a discriminative classifier. Results on cross-subjects transfer evaluations demonstrate the benefits of the proposed adversarial framework, and thus show its capabilities to adapt to a broader range of subjects. Finally we highlight that our proposed adversarial transfer learning approach is also applicable to other deep feature learning frameworks.

Multidimensional Tuning in Motor Cortical Neurons during Active Behavior.

A region within songbird cortex, dorsal intermediate arcopallium (AId), is functionally analogous to motor cortex in mammals and has been implicated in song learning during development. Non-vocal factors such as visual and social cues are known to mediate song learning and performance, yet previous chronic-recording studies of regions important for song behavior have focused exclusively on neural activity in relation to song production. Thus, we have little understanding of the range of non-vocal information that single neurons may encode. We made chronic recordings in AId of freely behaving juvenile zebra finches and evaluated neural activity during diverse motor behaviors throughout entire recording sessions, including song production as well as hopping, pecking, preening, fluff-ups, beak interactions, scratching, and stretching. These movements are part of natural behavioral repertoires and are important components of both song learning and courtship behavior. A large population of AId neurons showed significant modulation of activity during singing. In addition, single neurons demonstrated heterogeneous response patterns during multiple movements (including excitation during one movement type and suppression during another), and some neurons showed differential activity depending on the context in which movements occurred. Moreover, we found evidence of neurons that did not respond during discrete movements but were nonetheless modulated during active behavioral states compared with quiescence. Our results suggest that AId neurons process both vocal and non-vocal information, highlighting the importance of considering the variety of multimodal factors that can contribute to vocal motor learning during development.