Dominant Rhythm Research Articles

Continuous Electroencephalography After Moderate to Severe Traumatic Brain Injury.

After traumatic brain injury, continuous electroencephalography is widely used to detect electrographic seizures. With the development of standardized continuous electroencephalography terminology, we aimed to describe the prevalence and burden of ictal-interictal patterns, including electrographic seizures after moderate-to-severe traumatic brain injury and to correlate continuous electroencephalography features with functional outcome. Post hoc analysis of the prospective, randomized controlled phase 2 multicenter INTREPID study (ClinicalTrials.gov: NCT00805818). Continuous electroencephalography was initiated upon admission to the ICU. The primary outcome was the 3-month Glasgow Outcome Scale-Extended. Consensus electroencephalography reviews were performed by raters certified in standardized continuous electroencephalography terminology blinded to clinical data. Rhythmic, periodic, or ictal patterns were referred to as "ictal-interictal continuum"; severe ictal-interictal continuum was defined as greater than or equal to 1.5 Hz lateralized rhythmic delta activity or generalized periodic discharges and any lateralized periodic discharges or electrographic seizures. Twenty U.S. level I trauma centers. Patients with nonpenetrating traumatic brain injury and postresuscitation Glasgow Coma Scale score of 4-12 were included. None. Among 152 patients with continuous electroencephalography (age 34 ± 14 yr; 88% male), 22 (14%) had severe ictal-interictal continuum including electrographic seizures in four (2.6%). Severe ictal-interictal continuum burden correlated with initial prognostic scores, including the International Mission for Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury (r = 0.51; p = 0.01) and Injury Severity Score (r = 0.49; p = 0.01), but not with functional outcome. After controlling clinical covariates, unfavorable outcome was independently associated with absence of posterior dominant rhythm (common odds ratio, 3.38; 95% CI, 1.30-9.09), absence of N2 sleep transients (3.69; 1.69-8.20), predominant delta activity (2.82; 1.32-6.10), and discontinuous background (5.33; 2.28-12.96) within the first 72 hours of monitoring. Severe ictal-interictal continuum patterns, including electrographic seizures, were associated with clinical markers of injury severity but not functional outcome in this prospective cohort of patients with moderate-to-severe traumatic brain injury. Importantly, continuous electroencephalography background features were independently associated with functional outcome and improved the area under the curve of existing, validated predictive models.

Theta/delta coupling across cortical laminae contributes to semantic cognition

Rhythmic activity in populations of neurons is associated with cognitive and motor function. Our understanding of the neuronal mechanisms underlying these core brain functions has benefitted from demonstrations of cellular, synaptic, and network phenomena, leading to the generation of discrete rhythms at the local network level. However, discrete frequencies of rhythmic activity rarely occur alone. Despite this, little is known about why multiple rhythms are generated together or what mechanisms underlie their interaction to promote brain function. One overarching theory is that different temporal scales of rhythmic activity correspond to communication between brain regions separated by different spatial scales. To test this, we quantified the cross-frequency interactions between two dominant rhythms-theta and delta activity-manifested during magnetoencephalography recordings of subjects performing a word-pair semantic decision task. Semantic processing has been suggested to involve the formation of functional links between anatomically disparate neuronal populations over a range of spatial scales, and a distributed network was manifest in the profile of theta-delta coupling seen. Furthermore, differences in the pattern of theta-delta coupling significantly correlated with semantic outcome. Using an established experimental model of concurrent delta and theta rhythms in neocortex, we show that these outcome-dependent dynamics could be reproduced in a manner determined by the strength of cholinergic neuromodulation. Theta-delta coupling correlated with discrete neuronal activity motifs segregated by the cortical layer, neuronal intrinsic properties, and long-range axonal targets. Thus, the model suggested that local, interlaminar neocortical theta-delta coupling may serve to coordinate both cortico-cortical and cortico-subcortical computations during distributed network activity. NEW & NOTEWORTHY Here, we show, for the first time, that a network of spatially distributed brain regions can be revealed by cross-frequency coupling between delta and theta frequencies in subjects using magnetoencephalography recording during a semantic decision task. A biological model of this cross-frequency coupling suggested an interlaminar, cell-specific division of labor within the neocortex may serve to route the flow of cortico-cortical and cortico-subcortical information to promote such spatially distributed, functional networks.

Rapports de la ponctuation avec la construction grammaticale

Antiquity it was treated sometimes in generic terms (for distinctio is a grammatical operation), sometimes and more often in a rhetorical context. During the Middle Ages, more and more theorists appeal to grammar and use syntactic terminology to explain their own conception of punctuation. From the XIIth century onwards, difficulties in combining stylistics with grammatical analysis led these theorists to rely more on syntax to understand punctuation terms and to structure the texts. Conversely, in stylistics, defining punctuation pauses as marks of dependance, sufficiency and finitude leads to codify the rules of dictamen according to principles that are almost as grammatical as they are stylistic, with a dominant threefold rhythm in agreement with the triads of punctuation.

Association of Biological Rhythm Impairment with Levels of Anxiety, Depression, Dream Anxiety and Other Sociodemographic Correlates in Turkish Medical Students

Purpose In this study, we investigate association of biological rhythm impairment with levels of anxiety, depression and dream anxiety and other sociodemographic correlates of Baskent University medical students. Methods 193 students who accepted to participate in the study from Baskent University School of Medicine Grades 1, 2, 3, 4 and 5, were enrolled to our study. Participants were administered the Beck Anxiety Inventory, Beck Depression Inventory, Dream Anxiety Scale, Biological Rhythm Scale and Sociodemographic Data Form. Results Participants’ biological rhythm (impairment) scores were found to be significantly associated with the Dream Anxiety Scale, Beck Depression Inventory and Beck Anxiety Inventory scores. Female students were found to have higher biological rhythm, activity rhythm, sleep rhythm, anxiety and dream anxiety scores, which means that they have higher anxiety levels and more impaired biological rhythms. Students who drowse in the lectures were found to have higher sleep, activity, social and dominant rhythm patterns with higher levels of dream anxiety and Beck Depression Inventory scores as well. Conclusions Biological rhythm impairment is related to dream anxiety, anxiety and increased depression levels. Smoking, alcohol consumption and having pet are factors negatively effecting biorhythms and increasing dream anxiety in medical students. Drowsing during the lectures is a common complaint of medical students and can be a sign of irregularity in the biological rhythms and psychiatric disorders like anxiety and depression as well. Encouraging medical students for having more regular biorhythms can help them ensuring their own mental health.

Intraoperative neurophysiological monitoring: reliability and usefulness in pediatrics

This review presents a number of literature data on the use of the bispectral index (BIS) in children. It is shown that extrapolation of data obtained in adults to children can not be sufficiently justified because of the different methods of anesthesia in pediatrics, the changed pharmacology of anesthetics, the features of the maturation of the brain and the developing psychology of children. The use of encephalographic technologies to measure depression in pediatrics requires not only the validity of these methods, but also a more significant study and understanding of neurophysiology in a given population.The bispectral index was suggested for use in children, but many studies have not confirmed their effectiveness for young children. As you know, EEG reflects the functional activity of the brain, which depends on the degree of maturity of the brain structures. Therefore, it is obvious that as the various departments of the central nervous system mature, the bioelectrical activity of the brain changes (as the gradual transition of the dominant brain rhythm from low-frequency to higher-frequency brain becomes more frequent), the EEG picture changes very much with the child's age. The concept of the general age norm in electroencephalography also can not be considered strictly defined, as in young children the individual differences in EEG are significantly expressed. In older children, physiology, anatomy and clinical observation indicate that the performance of BIS monitors may be similar to that in adults, although the clinical significance of the results may be different.

Experience of dynamic magnetotherapy in neuroreabilitation of patients in intermediate period of light traumatic brain injury

Background. The high prevalence of minor craniocerebral injuries, a decrease in the labor activity of the victims, and disappointing data from long-term forecasts give the problem an important medical and social significance.
 Aim. Is to develop a method of sanatorium and spa treatment of patients with the consequences of light traumatic brain injury (LTBI) using radono- and dynamic magnetotherapy.
 Methods. Under supervision there were 150 patients in the intermediate period of LTBI at the age of 18 to 55 years old who were included in 3 randomized groups of 50 people in each: the 1st main group (MG1) was prescribed radon baths and magnetotherapy suboccipital; the 2nd MG was prescribed radon baths and magnetic therapy transcranially; the control group (CG) had only radon baths.
 Results. The patients of the MG2 had an improvement in brain biolectrogenesis in the form of a statistically significant (p 0.01) increase in the number of patients with dominant (alpha) rhythm, with diffuse-flattened type of EEG, a decrease in the number of EEG with conditional epileptiform phenomena and diffuse slow wave activity.
 There has been detected a statistically significant (p 0.01) increase in the number of patients with high functional activity of the cerebral cortex; whereas the analysis of EEG data among the patients of MG1 showed a statistically little efficacy in using radon baths and MT of cervical spine for bioelectric brain activity, which was clearly correlated with the physical and mental components of quality of life.
 Conclusion. The analysis of the studied data makes it possible to speak about the inclusion of running magnetic field transcranially and suboccipital in the process of neuroreabilitation of patients in the intermediate period of LTBI as a control factor that provides a targeted distribution of the flow of general afferent effects on tropical brain structures.

A CASE OF MASSIVE PULMONARY EMBOLISM CAUSING VENTRICULAR FIBRILLATION AND CARDIAC ARREST

SESSION TITLE: Critical Care 1 SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Massive Pulmonary Embolism (PE) is a known noncardiac cause of circulatory arrest, it is associated with very poor outcomes and high mortality. We herein report a unique case of cardiac arrest due to massive PE that presented with a dominant rhythm of Ventricular Fibrillation (VF). CASE PRESENTATION: A 42-year-old male with past medical history of morbid obesity and chronic back pain; presented to our hospital with acute on chronic low back pain and inability to ambulate. On admission, vital signs were normal. Physical examination showed signs of left lower extremity radiculopathy. Often times and because of the pain severity, patient used to refuse to participate in physical therapy and assisted ambulation. Given that, patient was on appropriate pharmacological deep venous thrombosis prophylaxis. During hospitalization, the patient was found unresponsive and pulseless, code blue was activated and cardiopulmonary resuscitation was started. Upon connecting it, the cardiac monitor showed VF rhythm (Image 1) for which a shock was delivered. After few minutes, return of spontaneous circulation achieved. A 12-lead electrocardiogram demonstrated sinus tachycardia and new right bundle branch block (Image 2) and that triggered the suspicion of PE. A stat bedside echocardiogram revealed dilatation of the right ventricle. Computed Tomography of chest with intravenous contrast (PE protocol) confirmed the diagnosis of PE in the left and right main pulmonary arteries(Image 3). As a result, systemic thrombolytic therapy was initiated. Few hours later, the patient went into three successive episodes of cardiac arrest in which VF was the recurrent rhythm and multiple shocks were delivered. DISCUSSION: PE is the third most common cause of hospital-related death[1]. The vast majority of VF cases are strongly linked to cardiac events; mainly coronary artery disease due to ischemia[2]. On the other hand, PE with circulatory arrest is highly associated with pulseless electric activity (PEA) followed by asystole[3]. For VF to be the dominant rhythm in the setting of cardiac arrest due to massive PE and without any evidence of myocardial ischemia is unreported. This case highlights the importance of considering PE in the differential diagnosis of cardiac arrest causes when the presenting and the dominant rhythm is VF particularly in the absence of myocardial ischemia. CONCLUSIONS: To our knowledge, this is the first case in the literature to provide a direct link between PE and VF in the context of circulatory arrest. It is crucial to recognize the initial rhythm that is associated with the cardiac arrest as it may guide toward the etiology of the arrest. While, PEA and asystole are by far the most common rhythms in massive PE with cardiac arrest, our case should encourage physicians to also consider PE as a possible cause of cardiac arrest when VF is the main rhythm and no signs of cardiac ischemia exist. Reference #1: Lindblad B, Eriksson A, Bergqvist D. Autopsy-verified pulmonary embolism in a surgical department: analysis of the period from 1951 to 1988. Br J Surg. 1991;78:849–852. [PubMed] Reference #2: Warnes CA, Roberts WC. Sudden coronary death: relation of amount and distribution of coronary narrowing at necropsy to previous symptoms of myocardial ischemia, left ventricular scarring and heart weight. Am J Cardiol. 1984 Jul 1. 54(1):65-73. Reference #3: Kürkciyan I, Meron G, Sterz F, Janata K, Domanovits H, Holzer M, Berzlanovich A, Bankl HC, Laggner AN. Pulmonary Embolism as Cause of Cardiac ArrestPresentation and Outcome. Arch Intern Med.2000;160(10):1529–1535. https://doi.org/10.1001/archinte.160.10.1529 DISCLOSURES: No relevant relationships by Michel Chalhoub, source=Web Response No relevant relationships by halim el hage, source=Web Response No relevant relationships by Cheikh Talal El Imad, source=Web Response No relevant relationships by Ahmad Itani, source=Web Response No relevant relationships by boutros karam, source=Web Response No relevant relationships by Ahmed Mahgoub, source=Web Response No relevant relationships by chadi salmane, source=Web Response No relevant relationships by Jay Solanki, source=Web Response

Locally induced neuronal synchrony precisely propagates to specific cortical areas without rhythm distortion

Propagation of oscillatory spike firing activity at specific frequencies plays an important role in distributed cortical networks. However, there is limited evidence for how such frequency-specific signals are induced or how the signal spectra of the propagating signals are modulated during across-layer (radial) and inter-areal (tangential) neuronal interactions. To directly evaluate the direction specificity of spectral changes in a spiking cortical network, we selectively photostimulated infragranular excitatory neurons in the rat primary visual cortex (V1) at a supra-threshold level with various frequencies, and recorded local field potentials (LFPs) at the infragranular stimulation site, the cortical surface site immediately above the stimulation site in V1, and cortical surface sites outside V1. We found a significant reduction of LFP powers during radial propagation, especially at high-frequency stimulation conditions. Moreover, low-gamma-band dominant rhythms were transiently induced during radial propagation. Contrastingly, inter-areal LFP propagation, directed to specific cortical sites, accompanied no significant signal reduction nor gamma-band power induction. We propose an anisotropic mechanism for signal processing in the spiking cortical network, in which the neuronal rhythms are locally induced/modulated along the radial direction, and then propagate without distortion via intrinsic horizontal connections for spatiotemporally precise, inter-areal communication.

Predictive values and specificity of electroencephalographic findings in autoimmune encephalitis diagnosis

ObjectiveEarly diagnosis of autoimmune encephalitis (AE) to not delay treatment is challenging but needed in practice. Most previous evidences of electroencephalographic (EEG) findings in AE were derived from descriptive studies. Given paucity of evidence of specific EEG findings to help with early diagnosis of AE, this study aimed to ascertain specific EEG findings and assess their predictive values in diagnosis of AE. MethodsWe included all cases with AE in our institution from January 2013 to June 2017. Cases were matched with controls by age and level of consciousness (1:2 ratio). Potential confounders for EEG findings collected as baseline characteristics were compared. Two epileptologists independently reviewed EEGs. Standardized terminology, definitions, and scoring system of EEG findings were employed. Logistic regression analysis was performed, and diagnostic performance of significant EEG features was assessed. ResultsTwenty cases and 40 controls were included in this study. Poorly sustained posterior dominant rhythm (PDR) was significantly associated with AE (p = 0.007) and even more predictive in anti-N-methyl-d-aspartate (NMDA) encephalitis. Inter-rater agreement (kappa) was 0.714. None of the cases had normal EEG nor Grand Total EEG (GTE) score < 4 (negative predictive value (NPV) of 100%). Specificity of well sustained PDR to exclude the diagnosis of anti-NMDA encephalitis was high (91.67%). ConclusionsSimple EEG assessment can be used to help exclude AE. When AE is suspected, careful assessment of the sustainment of the PDR is warranted. The NPV of GTE score < 4 and specificity of well sustained PDR can be simply used to differentiate many conditions from AE.

F81. Diagnosis of dementia and subtype classification by digital EEG: Is it also endorsed by automatic EEG analysis?

Introduction Precise diagnosis of subtypes of dementia is essential in daily medical practice. Electroencephalography (EEG) is a less expensive and non-invasive examination, but is not used for the diagnosis of dementia and its subtype classification because of lack of clear evidence. Therefore, we aimed at delineating clinical utility of EEG for this matter for Alzheimer disease (AD), dementia with Lewy body (DLB) and Parkinson disease with dementia (PDD). Methods We retrospectively analyzed the EEG data of 16 patients of AD (mean age ad SD = 67 ± 9.1-years, 6 male and 10 female) and 22 of synucleinopathy including 12 DLB and 10 PDD (72 ± 9.1-years, 17 male and 7 female) at Kyoto University Hospital from 2008 to 2015. First, by visual analysis we compared the posterior dominant rhythm (PDR) frequency and the ratio of generalized and regional slow waves between AD and synucleinopathy. Then, by automatic analysis we employed automatic EEG interpretation software (QP270 Nihonkoden) to investigate the same EEG parameters. Finally, we compared the results of visual analysis and automatic analysis in all patients. Results (1) With respect to the visual analysis, patients with synucleinopathy showed significantly lower PDR frequency (7.8 ± 1.0 Hz) than that of AD (9.2 ± 0.91 Hz) (p Conclusion In the visual analysis, EEG provides the information to differentiate AD from synucleinopathy by means of PDR, occipital slow waves and GS. The result of automatic analysis of EEG well matched with the visual analysis and there is a possibility that automatic EEG analysis was a useful tool to endorse the visual findings.

T60. Continuous EEG after moderate to severe traumatic brain injury: Seizures, ictal-interictal patterns and neurophysiologic predictors of functional outcome

Traumatic brain injury is common and the leading source of disability in the US. International guidelines for the use of EEG in those requiring ICU admission include indications to detect nonconvulsive seizures in those with altered mental status or in those at high-risk, although evidence is lacking for which patients might be at risk. Further, there is no evidence for the prognostic importance of continuous EEG (cEEG) in the context of established clinical indicators. We performed a post hoc analysis of data from the INTREPD2566 study (NCT00805818), a randomized controlled clinical trial of NNZ-2566, a synthetic neurotrophic IGF-1 derivative for moderate to severe TBI, defined as a Glasgow Coma Scale (GCS) score 4–12. This study failed to achieve its secondary end-point of modifying EEG. Per protocol, all patients received study drug or placebo within 8 h of injury; cEEG was initiated as soon as possible and continued for 72 h. Glasgow Outcome Scale-Extended data were collected at 3 months and dichotomized as good (GOSE 5–8) or poor (GOSE 1–4). A total n = 261 were initially enrolled; n = 38 were subsequently excluded from the study and n = 141/222 (63.5%) underwent cEEG monitoring. The mean age was 34 ± 15 years and 127/141 (90.1%) were men. The median post-resuscitation GCS was 7 (Interquartile Range 6–8) with a mean Injury Severity Score (ISS) of 23.6 ± 13.3. Mortality was 8.5% (12/141) at 3 months. The mean time from trauma to cEEG was 13.8 ± 9.8 h. Of those with data at 72 h, n = 24/120 (20%) had electrographic seizures, lateralized periodic discharges, or lateralized rhythmic discharges (SZ/LD); 4/120 had seizures alone. Only the presence of mass lesion on CT was associated with SZ/LD (OR 4.0, 95 CI 0.05–0.58; p = 0.01). Although n = 3/4 patients with seizures had poor outcome, there was no statistical association with outcome (OR2.9, 95 CI 0.22–154.60; NS); similarly, SZ/LD were observed equally between those with good and poor outcome. By contrast, the presence of a posterior dominant rhythm or sleep transients were associated with good outcome, while background delta frequencies were associated with poor outcome; superimposed background alpha/beta and burst-suppression (usually associated with sedation) were not associated with outcome. On multivariate analysis, only the ISS (OR 1.05, 95 CI 1.02–1.09) and an absence of sleep transients within 24 h (OR 4.61, 95 CI 2.14–9.94) were independently associated with poor outcome; the odds for poor outcome increased to 6.19 (95 CI 2.54–15.07) at 72 h without sleep transients. In this prospective cohort, we confirmed the incidence of seizures and focal periodic or rhythmic discharges and found an association with mass lesions on initial imaging. While seizures did not predict poor functional outcome, we found an independent association with the absence of identifiable sleep transients at 24 and 72 h.

Etiopathogenetic neuroreparative therapy of encephalopathies

The possibility of neural tissue regeneration in encephalopathies of various genesis by influencing brain cell pool with reduced functional activity in the state of parabiosis is discussed. The use of a neuroprotective agent rekognan (citicoline) is a justified etiopathogenetic therapy realizing its effects through mechanisms of synthesis of membrane phospholipids, inhibition of synthesis of phospholipase A2, restoration of Na+/K+-adenosine triphosphate functioning, blocking of oxidative stress and apoptosis, modulation of choline, dopamine and glutamatergic neurotransmission. Electroencephalography study was made in order to investigate reactivity of a brain in 12 patients (6 men and 6 women, average age 57±11 years) with encephalopathies to treatment with the Rekognan. The relative index - K α/θ spectra of electroencephalogram power - was used to assess the dynamics of the functional state of a brain before and after the course of treatment with a neuroprotective agent. The majority of patients (9 patients) had a statistically significant positive electrophysiological dynamics with an average increase of K α/θ by 64%. Deprivation of the focus of irrigation in the form of a «running» of reduced acute waves in the right temporal region was recorded in one case, revealed during the test with hyperventilation. An additional prescription for the main therapy of the course of the recognan is associated with an increase in the power of electroencephalogram spectra in a frequency of the dominant alpha rhythm in 75% of patients with encephalopathies of different etiology. Favorable dynamics K α/θ spectra of electroencephalogram power testifies to the involvement of the cerebral reserve due to the neuroreparative effect of recognan.

Diagnostic yield of standard-wake and sleep EEG recordings

ObjectiveTo investigate whether Posterior Dominant Rhythm (PDR) can be reliably assessed in sleep-EEG recordings and to investigate the diagnostic yield of standard-wake and sleep-recordings. MethodsEEG recordings of 303 consecutive patients aged 18–88 years were analyzed. All patients had both standard-wake and sleep-recordings, including patients who had abnormal standard recordings. Melatonin was used in 6% of sleep EEGs, and sleep deprivation in 94%. The mean duration of sleep was 41 min. We measured the PDR frequency in standard and sleep-recordings, both before and after sleep. We compared the diagnostic yield of standard-wake and sleep EEG recordings. ResultsCompared to standard EEG, sleep-recordings showed a significantly lower PDR frequency, both when measured before and after sleep (p < 0.001). One-hundred-fifty-six patients (51%) had normal standard recordings, and 35 of them (22%) had abnormal findings in the sleep-recording. One-hundred-forty-seven patients had abnormal standard recordings and in 16 of them (11%) these abnormalities were not present in sleep-recording. ConclusionsPDR is significantly slower in the wake periods of sleep-recordings, compared to standard wake recordings. SignificanceSleep and standard wake recordings are complementary.

High-density EEG characterization of brain responses to auditory rhythmic stimuli during wakefulness and NREM sleep

Auditory rhythmic sensory stimulation modulates brain oscillations by increasing phase-locking to the temporal structure of the stimuli and by increasing the power of specific frequency bands, resulting in Auditory Steady State Responses (ASSR). The ASSR is altered in different diseases of the central nervous system such as schizophrenia. However, in order to use the ASSR as biological markers for disease states, it needs to be understood how different vigilance states and underlying brain activity affect the ASSR. Here, we compared the effects of auditory rhythmic stimuli on EEG brain activity during wake and NREM sleep, investigated the influence of the presence of dominant sleep rhythms on the ASSR, and delineated the topographical distribution of these modulations. Participants (14 healthy males, 20-33 years) completed on the same day a 60 min nap session and two 30 min wakefulness sessions (before and after the nap). During these sessions, amplitude modulated (AM) white noise auditory stimuli at different frequencies were applied. High-density EEG was continuously recorded and time-frequency analyses were performed to assess ASSR during wakefulness and NREM periods. Our analysis revealed that depending on the electrode location, stimulation frequency applied and window/frequencies analysed the ASSR was significantly modulated by sleep pressure (before and after sleep), vigilance state (wake vs. NREM sleep), and the presence of slow wave activity and sleep spindles. Furthermore, AM stimuli increased spindle activity during NREM sleep but not during wakefulness. Thus, (1) electrode location, sleep history, vigilance state and ongoing brain activity needs to be carefully considered when investigating ASSR and (2) auditory rhythmic stimuli during sleep might represent a powerful tool to boost sleep spindles.

The Encephalophone: A Novel Musical Biofeedback Device using Conscious Control of Electroencephalogram (EEG).

A novel musical instrument and biofeedback device was created using electroencephalogram (EEG) posterior dominant rhythm (PDR) or mu rhythm to control a synthesized piano, which we call the Encephalophone. Alpha-frequency (8–12 Hz) signal power from PDR in the visual cortex or from mu rhythm in the motor cortex was used to create a power scale which was then converted into a musical scale, which could be manipulated by the individual in real time. Subjects could then generate different notes of the scale by activation (event-related synchronization) or de-activation (event-related desynchronization) of the PDR or mu rhythms in visual or motor cortex, respectively. Fifteen novice normal subjects were tested in their ability to hit target notes presented within a 5-min trial period. All 15 subjects were able to perform more accurately (average of 27.4 hits, 67.1% accuracy for visual cortex/PDR signaling; average of 20.6 hits, 57.1% accuracy for mu signaling) than a random note generation (19.03% accuracy). Moreover, PDR control was significantly more accurate than mu control. This shows that novice healthy individuals can control music with better accuracy than random, with no prior training on the device, and that PDR control is more accurate than mu control for these novices. Individuals with more years of musical training showed a moderate positive correlation with more PDR accuracy, but not mu accuracy. The Encephalophone may have potential applications both as a novel musical instrument without requiring movement, as well as a potential therapeutic biofeedback device for patients suffering from motor deficits (e.g., amyotrophic lateral sclerosis (ALS), brainstem stroke, traumatic amputation).

Traumatic brain injury: An EEG point of view.

Traumatic brain injury (TBI) is a silent epidemic. Mild traumatic brain injury (mTBI) causes brain injury that results in electrophysiologic abnormalities visible on electroencephalography (EEG) recordings. The purpose of this brief review was to discuss the importance of EEG findings in traumatic brain injury. Relevant articles published during the 1996-2016 period were retrieved from Medline (PubMed). The keywords were in English and included "traumatic brain injury", "EEG" and "quantitative EEG". We found 460 articles, analyzed 52 and selected 13 articles. EEG after TBI shows slowing of the posterior dominant rhythm and increased diffuse theta slowing, which may revert to normal within hours or may clear more slowly over many weeks. There are no clear EEG or quantitative EEG (qEEG) features unique to mild traumatic brain injury. Although the literature indicates the promise of qEEG in reaching a diagnosis and indicating prognosis of mTBI, further study is needed to corroborate and refine these methods.

Three decades of continuous wrist-activity recording: analysis of sleep duration.

Motor activity recording by a wrist-worn device is a common method to monitor the rest-activity cycle. The first author wore an actimeter continuously for more than three decades, starting in 1982 at the age of 43.5years. Until November 2006 analysis was performed on a 15-min time base, and subsequently on a 2-min time base. The timing of night-time sleep was determined from the cessation and re-occurrence of daytime-level activity. Sleep duration declined from an initial 6.8 to 6h in 2004. The declining trend was reversed upon retirement, whereas the variance of sleep duration declined throughout the recording period. Before retirement, a dominant 7-day rhythm of sleep duration as well as an annual periodicity was revealed by spectral analysis. These variations were attenuated or vanished during the years after retirement. We demonstrate the feasibility of continuous long-term motor activity recordings to study age-related variations of the rest-activity cycle. Here we show that the embeddedness in a professional environment imparts a temporal structure to sleep duration.

Bursting Neurons in the Hippocampal Formation Encode Features of LFP Rhythms.

Burst spike patterns are common in regions of the hippocampal formation such as the subiculum and medial entorhinal cortex (MEC). Neurons in these areas are immersed in extracellular electrical potential fluctuations often recorded as the local field potential (LFP). LFP rhythms within different frequency bands are linked to different behavioral states. For example, delta rhythms are often associated with slow-wave sleep, inactivity and anesthesia; whereas theta rhythms are prominent during awake exploratory behavior and REM sleep. Recent evidence suggests that bursting neurons in the hippocampal formation can encode LFP features. We explored this hypothesis using a two-compartment model of a bursting pyramidal neuron driven by time-varying input signals containing spectral peaks at either delta or theta rhythms. The model predicted a neural code in which bursts represented the instantaneous value, phase, slope and amplitude of the driving signal both in their timing and size (spike number). To verify whether this code is employed in vivo, we examined electrophysiological recordings from the subiculum of anesthetized rats and the MEC of a behaving rat containing prevalent delta or theta rhythms, respectively. In both areas, we found bursting cells that encoded information about the instantaneous voltage, phase, slope and/or amplitude of the dominant LFP rhythm with essentially the same neural code as the simulated neurons. A fraction of the cells encoded part of the information in burst size, in agreement with model predictions. These results provide in-vivo evidence that the output of bursting neurons in the mammalian brain is tuned to features of the LFP.

EEG epochs with less alpha rhythm improve discrimination of mild Alzheimer's

Background and objectiveEyes-closed-awake electroencephalogram (EEG) is a useful tool in the diagnosis of Alzheimer's. However, there is eyes-closed-awake EEG with dominant or rare alpha rhythm. In this paper, we show that random selection of EEG epochs disregarding the alpha rhythm will lead to bias concerning EEG-based Alzheimer's Disease diagnosis. MethodsWe compared EEG epochs with more than 30% and with less than 30% alpha rhythm of mild Alzheimer's Disease patients and healthy elderly. We classified epochs as dominant alpha scenario and rare alpha scenario according to alpha rhythm (8–13 Hz) percentage in O1, O2 and Oz channels. Accordingly, we divided the probands into four groups: 17 dominant alpha scenario controls, 15 mild Alzheimer's patients with dominant alpha scenario epochs, 12 rare alpha scenario healthy elderly and 15 mild Alzheimer's Disease patients with rare alpha scenario epochs. We looked for group differences using one-way ANOVA tests followed by post-hoc multiple comparisons (p < 0.05) over normalized energy values (%) on the other four well-known frequency bands (delta, theta, beta and gamma) using two different electrode configurations (parieto-occipital and central). ResultsAfter carrying out post-hoc multiple comparisons, for both electrode configurations we found significant differences between mild Alzheimer's patients and healthy elderly on beta- and theta-energy (%) only for the rare alpha scenario. No differences were found for the dominant alpha scenario in any of the five frequency bands. ConclusionsThis is the first study of Alzheimer's awake-EEG reporting the influence of alpha rhythm on epoch selection, where our results revealed that, contrarily to what was most likely expected, less synchronized EEG epochs (rare alpha scenario) better discriminated mild Alzheimer's than those presenting abundant alpha (dominant alpha scenario). In addition, we find out that epoch selection is a very sensitive issue in qEEG research. Consequently, for Alzheimer's studies dealing with resting state EEG, we propose that epoch selection strategies should always be cautiously designed and thoroughly explained.

Causal Interactions between Frontal(θ) - Parieto-Occipital(α2) Predict Performance on a Mental Arithmetic Task.

Many neuroimaging studies have demonstrated the different functional contributions of spatially distinct brain areas to working memory (WM) subsystems in cognitive tasks that demand both local information processing and interregional coordination. In WM cognitive task paradigms employing electroencephalography (EEG), brain rhythms such as θ and α have been linked to specific functional roles over given brain areas, but their functional coupling has not been extensively studied. Here we analyzed an arithmetic task with five cognitive workload levels (CWLs) and demonstrated functional/effective coupling between the two WM subsystems: the central executive located over frontal (F) brain areas that oscillates on the dominant θ rhythm (Frontalθ/Fθ) and the storage buffer located over parieto-occipital (PO) brain areas that operates on the α2 dominant brain rhythm (Parieto-Occipitalα2/POα2). We focused on important differences between and within WM subsystems in relation to behavioral performance. A repertoire of brain connectivity estimators was employed to elucidate the distinct roles of amplitude, phase within and between frequencies, and the hierarchical role of functionally specialized brain areas related to the task. Specifically, for each CWL, we conducted a) a conventional signal power analysis within both frequency bands at Fθ and POα2, b) the intra- and inter-frequency phase interactions between Fθ and POα2, and c) their causal phase and amplitude relationship. We found no significant statistical difference of signal power or phase interactions between correct and wrong answers. Interestingly, the study of causal interactions between Fθ and POα2 revealed frontal brain region(s) as the leader, while the strength differentiated between correct and wrong responses in every CWL with absolute accuracy. Additionally, zero time-lag between bilateral Fθ and right POa2 could serve as an indicator of mental calculation failure. Overall, our study highlights the significant role of coordinated activity between Fθ and POα2 via their causal interactions and the timing for arithmetic performance.