Amplitude Delta Research Articles

The Atlantida 3.1_2014 Program for Earth Tide Prediction: New Version

The main distinctive features of ATLANTIDA3.1._2014, the first domestic program for the prediction of Earth tides, are discussed in comparison to similar programs of international authors, and some examples of the practical application of the program by different researchers are presented. The main functional features of the program are listed. Among them, the features for calculating amplitude delta factors of tidal waves for an oceanless Earth, as well as amplitude delta factors and phase shifts for an Earth with an ocean, tidal time series, and amplitudes and phases of the oceanic gravimetric effect, are especially distinguished. The theoretical developments included in the program are briefly described. The main differences of the latest version of the program are identified. The theoretical values of the amplitude delta factors for an inelastic self-gravitating rotating Earth, calculated with respect to the action of relative and Coriolis accelerations, as well as dissipation, are considered in detail. A total of 12 model variants are considered, which differ from each other by the inclusion or exclusion of separate factors affecting the result. The closeness of the results yielded by the program and the observations using the European superconducting gravimeters of the Global Geodynamic Project (GGP) is evaluated. It is shown that according to this criterion, our program surpasses the world’s most well-known counterparts. Tasks are listed that after their solution will expand the functional features of the program and clarify the results obtained so far.

TYC 3637-1152-1 – A high amplitude δ Scuti star with peculiar pulsational properties

In some δ Scuti stars, only one or two radial modes are excited (usually the fundamental mode and/or first overtone mode) and the observed peak-to-peak amplitudes exceed 0.3 mag (V). These stars are known as High Amplitude Delta Scuti (HADS) variables.We here present a detailed photometric and spectroscopic analysis of the HADS star TYC 3637-1152-1. We have derived a metallicity close to solar, a spectral type of F4 V and an age of logt=9.1. Employing archival time series data from different sources, two frequencies f0 = 10.034 c/d and f1 = 12.681 c/d and their harmonics and linear combinations were identified. The period ratio of f0/f1=0.791 puts this star into a peculiar position in the Petersen diagram, from which we conclude that TYC 3637-1152-1 is a unique object with peculiar pulsational properties that indicate a transitional state between HADS stars pulsating in the fundamental and first overtone modes and stars pulsating in higher overtones.

Electrophysiological underpinnings of response variability in the Go/NoGo task.

Response variability has been identified as a useful predictor of executive function and performance in non-clinical samples in the Go/NoGo task. The present study explores the utility of reaction time variability (RTV) and EEG measures as predictors of Go/NoGo performance outcomes and ERP component amplitudes. Forty-four young adults had EEG recorded across eyes-closed (EC) and eyes-open (EO) resting states, and during an auditory Go/NoGo task. The 18 individuals with the lowest/highest RTV were assessed for differences in behavioural outcomes. As expected, individuals with high RTV committed more Go/NoGo errors and had smaller Go P3b and NoGo P3a amplitudes, and greater Go Slow Wave positivity, reflecting inefficient decision-making and response control efforts underlying performance. When RTV and EEG measures were modelled as predictors of Go/NoGo responses, RTV and task-related changes in delta were identified as positive predictors of Go SW amplitude; while RTV and prestimulus delta amplitudes negatively predicted NoGo accuracy rates. Prestimulus delta was also found to solely predict Go mean RT and NoGo SW negativity; effects that were independent of RTV. As delta has been implicated in attention-related mechanisms, these findings suggest that inadequate attention and task engagement underpin the variability in Go/NoGo performance.

A diverted submarine channel of Early Cretaceous age revealed by high-resolution seismic data, SW Barents Sea

Abstract Mud-rich prograding sediment lobes make for most of the Barremian – Albian stratigraphic record in the SW Barents Sea. Submarine canyons and channels potentially represent key components of sediment transport from shelf to basin floor but geological evidences are lacking. We present high-resolution seismic data and scrutinize an elongated, ∼150-km long bright seismic amplitude and resistive anomaly located alongslope of a NW-sourced Barremian delta in the SW Barents Sea. Seismic interpretation is performed on a comprehensive database comprising 3D/2D high-resolution P-Cable and conventional seismic data, tied to three exploration wells to provide age-control on key horizons. Our results highlight that the elongated geophysical anomaly originates from a soft layer deposited over a harder, erosional surface. The erosive morphology displays three narrow, V-shaped incisions to the NE of the Hoop area which develop into a single, ∼6 km-wide, U-shaped channel towards the transition to the Fingerdjupet Subbasin. The geological feature is named Ceres and interpreted as a submarine channel carved in Aptian, a period of marked sea level rise and sediment starvation in the Hoop area. An evolutionary model of a diverted submarine channel is proposed where a flooded delta lobe acted as a topographic barrier, funneling bottom currents and thereby carving an alongslope, possibly contouritic channel. This is the first documented case of a submarine channel pathway – delta lobe interaction on the Norwegian continental shelf. To account for the geophysical expression of Ceres, two competing explanations are discussed: (1) hydrocarbon-bearing sands, and (2) organic-rich source rock. Both scenarios have important implications for petroleum prospectivity: a faulted stratigraphic trap holding large volumes of hydrocarbons or alternatively the channel-controlled distribution of mature Aptian source rock in the SW Barents Sea.

Sensory and movement evoked EEG patterns in the preterm neonate

Due to the similarities between EEG activity of humans during second trimester of gestation and the activity patterns of neonatal rodents, the latter became valuable model to study the mechanisms by which early patterns of activity may act as template for later-emerging functional maps [2] . In rodents, early EEG activity (Spindles Bursts [SB]) are generated within a complex neural network including the peripheral sensory organs, subcortical nuclei as well as cortical areas. In the barrel cortex, sensory evoked SB contain early gamma oscillations (EGO) that are primarily driven by rhythmic gamma excitation from the thalamus and enable precise temporal binding of the topographically aligned thalamic and cortical neurons. EGO support long-term dependent potentiation in the thalamo-cortical synapses [1] . Characteristic preterm EEG patterns of “Delta-brushes” (DBs) are spontaneous EEG activities and have been reported in the sensory cortices following sensory stimuli and spontaneous movements. Spatiotemporal analyses of the cortical auditory-evoked responses (AERs) using 32-electrode EEG recordings in healthy neonates aged 30 to 38 post-menstrual weeks (PMW) showed that AERs are characterized by a power spectrum increase at frequency bands ranging from delta to gamma on the electrodes overlaying temporal regions. Time-frequency wavelet analysis also showed that fast (alpha-gamma) oscillations co-occurred with the auditory-evoked delta wave from around 650 ms after the stimulus and lasted for nearly 700 ms. Stimulus locked averaging disclosed cortical auditory-evoked potentials (CAEP) with negative high amplitude delta waves peaking successively over middle and posterior temporal regions. Thus, auditory-evoked DBs in preterm neonates are slow delta waves nesting fast oscillations in the temporal regions and correspond to the late part of CAEPs, which is lost when using classical CAEP processing [3] . Decreasing from 30 to 38 PMW, this EEG pattern is thus associated with the prenatal development of sensory processing circuits and likely participate to the cortical maps maturation.

F89. Video-EEG monitoring in a patient with leptomeningeal carcinomatosis and transient neurological dysfunction

Introduction Leptomeningeal carcinomatosis (LMC) refers to diffuse or multifocal seeding of the leptomeninges by neoplastic cells. Patients with LMC can have transient neurological dysfunction due to seizures or plateau waves from paroxysmal elevation of intracranial pressure (ICP). There are very few descriptions of the clinical and EEG correlates of plateau waves in patients with LMC. We present the video-EEG findings in a patient with LMC and episodes of transient anisocoria and unresponsiveness. Methods Case report. Results A 20-year-old man with history of colorectal cancer treated with surgery and chemotherapy four years earlier, presented to an outside hospital with severe headache, diplopia, fever and neck rigidity. Brain MRI showed mild meningeal enhancement. Serum and CSF evaluation was normal except for positive Lyme antibodies. He was treated with intravenous ceftriaxone for Lyme meningitis, but showed no improvement. On transfer to our hospital, spine MRI revealed multiple enhancing lesions. Lumbar puncture showed opening pressure > 55 cm H20 and atypical tumor cells positive for AE1/AE3 and CK20, consistent with LMC from a colorectal adenocarcinoma with raised ICP. He had multiple episodes of impaired consciousness and tremulous arm movements with pupillary anisocoria (right pupil dilated and nonreactive, left pupil normal size and reactive). The episodes lasted for 5–10 min followed by spontaneous recovery. Video-EEG monitoring was performed. Background EEG revealed continuous, diffuse, moderate amplitude, polymorphic theta/delta activity. One recorded event was characterized by pupillary anisocoria, unresponsiveness, left sided tremulous movements and repetitive mouth movements. EEG changes preceded the clinical event by a few seconds and consisted of diffuse, high amplitude, rhythmic delta activity. This lasted for 7 min and gradually returned to baseline with clinical improvement. There were no epileptiform discharges. EKG showed bradycardia but no asystole or arrhythmias during the event. A ventriculoperitoneal shunt was placed. The patient was given intraventricular chemotherapy with methotrexate and gemcitabine through an Ommaya reservoir. He had improvement of headache and episodes of transient neurological dysfunction. Subsequent EEGs showed only diffuse polymorphic slowing. Conclusion In patients with LMC, clinical distinction between epileptic seizures and plateau waves resulting from raised ICP as the etiology of transient neurological dysfunction can be difficult. Video-EEG monitoring is helpful not only to rule out seizures but also to identify the electrographic correlates of plateau waves, consisting of diffuse, high amplitude delta activity. It can also be useful in monitoring the response to treatment.

3.3 DISTURBANCES IN NEURAL OSCILLATIONS, GLUTAMATE, AND GABA: EFFECTS OF KETAMINE AND COMPARISON TO SCHIZOPHRENIA

BackgroundIn schizophrenia (SCH), proton MRS studies of the medial prefrontal cortex (MPFC) show elevated glutamine (Gln) or the combination of Glu and Gln (Glx) in unmedicated patients. Studies in healthy human subjects demonstrate ketamine-induced acute increases in MPFC Glu or Gln. Together, these findings raise the question of potential disturbances in excitation-inhibition balance in the illness, possibly arising from NMDA receptor deficits in GABAergic interneurons. We investigated these questions following acute ketamine administration by using repeated 15-minute MRS acquisitions of Glx and GABA with simultaneous EEG and comparing the results with the same modalities acquired in SCH.MethodsWe enrolled 11 healthy volunteers (age 18–55) who were given a constant i.v. infusion of ketamine 0.5 mg/kg over 40 min during a combined EEG and 1H MRS study. Glx and GABA were acquired in the pregenual MPFC using a 3T GE system and a J-edited PRESS sequence. Sequential MRS acquisitions each of 15 min duration (90 min total) were obtained before, during, and following the infusion. EEG was recorded using an MRI-compatible 64-channel system with direct current BrainAmp MR amplifiers (Brain Products GmbH). Post-ketamine EEG data were analyzed in frontal electrodes for gamma and delta alterations. EEG and MRS data were also acquired in 12 patients with SCH with these systems.ResultsNeurochemicals Glx and GABA showed acute increases within 15–30 minutes following the initiation of ketamine infusion, more pronounced for GABA (13% increase, p = .04 by paired t test). Gamma amplitude in left and right frontal electrodes increased in the first 15-minute average after initiation of ketamine (p < .05), with no evidence of earlier gamma decrease. Left delta amplitude decreased linearly following ketamine (p < .01). Peak GABA concentration correlated inversely with average left delta amplitude in the immediately subsequent 15-minute acquisition. Data in SCH showed similar elevations in GABA and gamma amplitude.DiscussionThese data show the feasibility of attaining time resolution of Glx and GABA changes in the several-minutes range with standard PRESS J-edited 1H MRS, and simultaneous sub-second resolution with EEG. There were no indications in these frontal electrodes of very early GABAergic inhibition leading to disinhibition of Glx, which may occur in other brain regions following ketamine administration. The GABA, Glx, and EEG alterations found here following ketamine administration are consistent with stable alterations reported in unmedicated patients with SCH and are compatible with an NMDA receptor deficit mechanism in the illness. They show homeostatic rebalancing at elevated levels as found in SCH itself. Excitation-inhibition rebalancing at abnormally elevated levels may pose a risk of neuronal damage that persists in untreated psychosis.

The peculiarities of brain bioelectrical activity in infants who suffered from stress due to military conflict depending on type of feeding

The aim of the research is to study the peculiarities of brain electrical activity in infants who suffered from stress due to military conflict and who were on different types of feeding.&#x0D; An electroencephalographic study was conducted in 68 infants who were in the military conflict zone and formed the main group. These infants were divided into 2 subgroups. Subgroup Ia included 36 infants who were breastfeeding. Subgroup Ib included 32 infants who were on artificial feeding. EEG was also made to 88 children who made up a control group and were outside the zone of military conflict. Of these, 47 children were breastfed, who entered the subgroup IIa and 41 children were on artificial feeding, included in subgroup IIb.&#x0D; The study was carried out with the help of a hardware-software complex for recording and processing electroencephalograms and evoked potentials DX-NT 32.&#x0D; The most pronounced physiological changes in brain bioelectrical activity were detected in the group of children undergoing stress of war and being on artificial feeding, which were manifested by lower parameters of the amplitude, frequency and time index of alpha and beta rhythms, increased amplitude, frequency and time index of delta and theta rhythms.

Ongoing Electroencephalographic Activity Associated with Cortical Arousal in Transgenic PDAPP Mice (hAPP V717F).

It has been shown that theta (6-10 Hz) and delta (1-6 Hz) ongoing electroencephalographic (EEG) rhythms revealed variations in the cortical arousal in C57 Wild Type (WT) mice during cage exploration (active condition) compared to awake quiet behavior (passive condition; IMI PharmaCog project, www.pharmacog.eu). The objective was to test if these EEG rhythms might be abnormal in old PDAPP mice modeling Alzheimer's disease (AD) with a hAPP Indiana V717F mutation (They show abnormal neural transmission, cognitive deficits, and brain accumulation of Aβ1-42). Ongoing EEG rhythms were recorded by a frontoparietal bipolar channel in 15 PDAPP and 23 WT C57 male mice (mean age of 22.8 months ±0.4 and 0.3 standard error, respectively). EEG absolute power (density) was calculated. Frequency and amplitude of individual delta and theta frequency (IDF and ITF) peaks were considered during passive and active states in the wakefulness. Compared with the WT group, the PDAPP group showed higher frequency of the IDF during the passive condition and lower frequency of the ITF during the active state. Furthermore, the WT but not PDAPP group showed significant changes in the frontoparietal EEG power (IDF, ITF) during active over passive state. PDAPP mice were characterized by less changes in the brain arousal during an active state as revealed by frontoparietal EEG rhythms. Future studies will have to cross-validate the present results on large animal groups, clarify the neurophysiological underpinning of the effect, and test if the disease modifying drugs against AD amyloidosis normalize those candiate EEG biomarkers in PDAPP mice.

The Vitamin E Preventive Effect on Taxol-Induced Neuropathy Among Patients With Breast Cancer: A Randomized Clinical Trial

Background: Chemotherapy-induced neuropathy is one of the most severe complications of cancer drug therapies causing a number of problems for patients and making treatment limitation decisions problematic. One of the most important drugs used in breast cancer chemotherapy regimens, Taxol is considered as the most common cause of neuropathy in such cases. The aim of this study was to evaluate the effect of vitamin E on reducing the Taxol-induced neuropathy development among patients with breast cancer. Methods: The randomized clinical trial (RCT) included 70 patients with breast cancer who received Taxol chemotherapy regimens. They were assigned to one of the two groups: a group without vitamin E feeding (Group I) and a group with vitamin E treatment at a daily dose of 400 IU bid (Group II). Electrophysiological testing of all patients was performed before starting medications and again 3 months post-treatment. The data were compared between the groups. Results: Vitamin E feeding had no significant effect on amplitude, latency, and CV of tibial and peroneal nerves (P > 0.05), while the delta amplitude of sural nerve was significantly lower among patients taking vitamin E supplements (P = 0.007). Conclusion: We suggest the inhibitory effect of vitamin E on the progression of Taxol-induced neuropathy, by slowing the speed of progression, among breast cancer patients by improving the function of the nervous system.

Effect of mother's voice on neonatal respiratory activity and EEG delta amplitude.

While the influence of the mother's voice on neonatal heart‐rate response and its relevant activity on cerebral cortex and the autonomic nervous system (ANS) are well known, few studies have assessed its influence on respiratory activity. We investigated the relationship among the respiration rate, the delta wave amplitudes through electroencephalography, and the basal state of ANS through the respiratory variability index while 22 full‐term neonates hear their mother's voice and an unknown voice. It was found that when respiratory variability was large, a transient (<5 s) change in respiration rates was observed in response to an unknown voice, while a greater increase in the delta wave amplitude was observed in the frontal lobe than the parietal one in response to the mother's voice. Conversely, when respiratory variability was small, a sustained increase (>10 s) in respiration rates was observed in response to the mother's voice, while a greater increase in the delta wave amplitude was found in both the frontal and parietal lobes. These results suggest that the basal state of ANS influences the latency of increases in respiration rates. Furthermore, induced by the mother's voice, transient increases in respiration rates are reduced in association with frontal lobe activity, and sustained increases in respiration rates are promoted in association with frontal and parietal lobe activities.

Tidal Amplitude Delta Factors and Phase Shifts for an Oceanic Earth

M.S. Molodenskiy’s problem, which describes the state of an elastic self-gravitating compressible sphere, is generalized to the case of a biaxial hydrostatically equilibrium rotating elliptical inelastic shell. The system of sixth-order equations is supplemented with corrections due to the relative and Coriolis accelerations. The ordinary and load Love numbers of degree 2 are calculated with allowance for their latitude dependence and dissipation for different models of the Earth’s structure (the AK135, IASP91, and PREM models). The problem is solved by Love’s method. The theoretical amplitude delta factors and phase shifts of second-order tidal waves for an oceanic Earth are compared with their most recent empirical counterparts obtained by the GGP network superconducting gravimeters. In particular, it is shown that a good matching (up to the fourth decimal place) of the theoretical and observed amplitude factors of semidiurnal tides does not require the application of the nonhydrostatic theory.

P 125 Ring chromosome 20 Epilepsy syndrome in children Variable EEG- and electro-clinical pattern

Background Children with ring chromosome 20 epilepsy syndrome (rchr20es) typically show severe, drug-resistant focal epilepsies characterized by frontal semiology, high susceptibility for non-convulsive status epilepticus (NCSE) and epilepsy-associated cognitive and behavioral deteriorations. EEG has been reported to show frequent or continuous subclinical seizure patterns together with characteristic rhythmic theta waves (Caneveni et al. 1998). Here, we report on clinical and EEG data in four patients. Patients and methods Retrospective analysis of clinical and video-EEG-long-term-monitoring data of four patients (all female) with rchr20es. Age at onset of epilepsy ranged from 5 to 8 years, the number of antiepileptic drugs already used ranged from 6 to 10, and all four patients had suffered NCSE previously. Semiology: all four patients showed auras (epigastric: 2, fear: 2, visual: 1, somatosensory: 1) and seizures (hypermotor: 3, tonic: 3, dialeptic: 2, psychomotor: 2). Clinical epilepsy syndromes were frontal lobe epilepsies (n = 3) and frontal/ temporal lobe epilepsy (n = 1). EEG showed regional abnormalities in frontal (n = 4), temporal (n = 3) and parieto-occiptal (n = 1) areas, with subclinical seizure patterns and/ or EEG-status elements (with serial spikes, polyspikes, sharp waves, or spike wave complexes; n = 3), rhythmic theta (n = 2), 1–2 Hz slow sharp wave complexes (n = 1), spike wave complexes/low amplitude fast activity +high amplitude delta burst (n = 1), alpha/theta seizure activity (n = 1). MRI was essentially normal in all patients, with minor abnormalities in frontal (2) or temporal areas (2). Conclusion Consistent with the literature, our patients showed severe drug-resistant epilepsies with an electro-clinical complex of a fronto-temporal epilepsy with frequent, long-lasting or continuous subclinical seizure patterns and/or NCSE. Rhythmic theta as a “characteristic” EEG pattern was, however, only observed in 2/4 of our patients. Therefore, a rchr20es should be suspected in such patients also in the absence of this EEG feature. This information will help in an early identification of rchr20es, which is especially important since, without this specific diagnosis, many affected patients are considered candidates for pre-surgical diagnostics or even epilepsy surgery.

P337 The failure of a rhythm…not always cortical…

Objective To present two cases illustrating non-epileptic paroxysms only detected in a long-term video-electroencephalography (LTVEEG). Methods Case report. Results Case 1: 40 years-old, female, followed in an epilepsy clinic. She described a stereotyped ascending epigastric sensation, palpitations and blurred vision with a simultaneous dreaming state “as watching movie frames”. These sensations were brief, without subsequent confusion. It began at 12 years-old with a variable frequency, without remission although antiepileptic drugs. Routine electroencephalogram (EEG) revealed a doubtful right focal epileptiform temporal activity. MRI showed a cystic lesion in the right mesial temporal region. Electrocardiography (ECG) Holter was normal. During LTVEEG it was recorded two usual episodes with concomitant complete atrioventricular block with syncopal EEG features. Case 2: 20 years-old, female, with generalized tonic-clonic seizures since 9 years-old. At 19 years-old, she developed paroxysms described as a fainting sensation accompanied by a lower limbs tremor. LTVEEG showed a generalized epileptiform activity and a variable RR interval. It was recorded a fainting episode while collecting blood samples. Simultaneous ECG revealed a progressive increment of the RR interval ending in a ten seconds asystolia and EEG showed alpha depression, followed by a low voltage fast activity and subsequent generalized high amplitude delta. Discussion These two cases emphasize the usefulness of the LTVEEG in the differential diagnosis of epilepsy mimics. Cardiac dysrhythmias are probably underestimated mimic and it is essential to search carefully ECG abnormalities. Conclusion In case of doubtful phenomenology or drug-resistant epilepsy, LTVEEG with ECG recording is crucial to a definitive diagnosis.

Oscillatory EEG dynamics underlying automatic chunking during sentence processing

Sentences are easier to remember than random word sequences, likely because linguistic regularities facilitate chunking of words into meaningful groups. The present electroencephalography study investigated the neural oscillations modulated by this so-called sentence superiority effect during the encoding and maintenance of sentence fragments versus word lists. We hypothesized a chunking-related modulation of neural processing during the encoding and retention of sentences (i.e., sentence fragments) as compared to word lists. Time–frequency analysis revealed a two-fold oscillatory pattern for the memorization of sentences: Sentence encoding was accompanied by higher delta amplitude (4Hz), originating both from regions processing syntax as well as semantics (bilateral superior/middle temporal regions and fusiform gyrus). Subsequent sentence retention was reflected in decreased theta (6Hz) and beta/gamma (27–32Hz) amplitude instead. Notably, whether participants simply read or properly memorized the sentences did not impact chunking-related activity during encoding. Therefore, we argue that the sentence superiority effect is grounded in highly automatized language processing mechanisms, which generate meaningful memory chunks irrespective of task demands.

Locking of length scales in two-band superconductors

A model of a clean two-band s-wave superconductor with cylindrical Fermi surfaces, different Fermi velocities v_{1,2}, and a general 2x2 coupling matrix V_{alpha beta} is used to study the order parameter distribution in vortex lattices. The Eilenberger weak coupling formalism is used to calculate numerically the spatial distributions of the pairing amplitudes Delta_1_ and Delta_2_ of the two bands for vortices parallel to the Fermi cylinders. For generic values of the interband coupling V_{12}, it is shown that, independently of the couplings V_{alpha beta}, of the ratio v_1 /v_2, of the temperature, and the applied field, the length scales of spatial variation of Delta_1 and of Delta_2 are the same within the accuracy of our calculations. The only exception from this single length-scale behavior is found for V_{12} --> 0, i.e., for nearly decoupled bands.

Increased frontal electroencephalogram theta amplitude in patients with anorexia nervosa compared to healthy controls.

ObjectiveTo conduct a blind study of quantitative electroencephalogram-band amplitudes in patients with anorexia nervosa (AN) and healthy controls.MethodsTwenty-one patients with AN and 24 controls were examined with eyes-closed 16-channel electroencephalogram. Main variables were absolute alpha, theta, and delta amplitudes in frontal, temporal, and posterior regions.ResultsThere were no significant differences between the AN patients and controls regarding absolute regional band amplitudes in μV. Borderline significance was found for anterior theta (P=0.051). Significantly increased left and right frontal electrode theta amplitude was found in AN patients (F3, P=0.014; F4, P=0.038) compared to controls. Significant differences were also observed for secondary variables: lower values for relative parietooccipital delta and frontocentral alpha activity among AN patients than among controls.ConclusionWe observed slight excess frontal theta and lower relative alpha and delta amplitudes among AN patients than among controls. This pattern is possibly related to a slight frontal lobe dysfunction in AN, or it may reflect increased attention/vigilance or another state-related change in patients with AN compared to healthy controls.

How dissipation and selection of the Earth model on the quality of the Earth tidal prediction

The influence exerted by dissipation and mass correction when calculating the gravimetric ocean effect, as well as by selection of the Earth model, on the degree of closeness of the predicted parameter values of the Earth’s tidal parameters to the observed values computed by the network of superconducting gravimeters is estimated. The role of the latitude dependence of the loading delta factors and the applicability of the hybrid model of the latitude dependence of the amplitude delta factors for an elastic oceanless Earth is briefly discussed.

Supine posture inhibits cortical activity: Evidence from Delta and Alpha EEG bands

Past studies have shown consistent evidence that body position significantly affects brain activity, revealing that both head-down and horizontal bed-rest are associated with cortical inhibition and altered perceptual and cognitive processing. The present study investigates the effects of body position on spontaneous, open-eyes, resting-state EEG cortical activity in 32 young women randomly assigned to one of two conditions, seated position (SP) or horizontal bed rest (BR). A between-group repeated-measure experimental design was used, EEG recordings were made from 38 scalp locations, and low-frequency (delta and alpha) amplitudes of the two groups were compared in four different conditions: when both groups (a) were seated (T0), (b) assumed two different body positions (seated vs. supine conditions, immediate [T1] and 120min later [T2]), and (c) were seated again (T3). Overall, the results showed no a priori between-group differences (T0) before experimental manipulation. As expected, delta amplitude, an index of cortical inhibition in awake resting participants, was significantly increased in group BR, revealing both rapid (T1) and mid-term (T2) inhibitory effects of supine or horizontal positions. Instead, the alpha band was highly sensitive to postural transitions, perhaps due to baroreceptor intervention and, unlike the delta band, underwent habituation and decreased after a 2-h bed rest. These results indicate clear-cut differences at rest between the seated and supine positions, thus supporting the view that the role of body position in the differences found between brain metabolic methods (fMRI and PET) in which participants lie horizontally, and EEG-MEG-TMS techniques with participants in a seated position, has been largely underestimated so far.

Sleep in ring chromosome 20 syndrome: a peculiar electroencephalographic pattern

Ring chromosome 20 [r(20)] syndrome is a chromosomal disorder characterized by epilepsy and intellectual disability. Distinctive electroclinical features and wakefulness EEG patterns have been described. The EEG features of sleep have not yet been evaluated. We studied the pattern of sleep in six patients aged 2-59 years who underwent at least one polysomnographic recording. Their sleep pattern evolution is described as deterioration ranging from normal to destructured NREM/REM sleep. NREM sleep alterations were observed from childhood and were more evident in adulthood. EEG abnormalities detected during wakefulness persisted, with morphological changes, during sleep. During NREM sleep all the subjects presented high amplitude delta sequences with a sharply contoured or notched appearance, prevalent over frontal regions. The theta rhythm of wakefulness was seen to persist during REM sleep. Ring chromosome 20 syndrome shows sleep alterations that seem to be age-related. A potential role of cortical and thalamocortical dysfunction is discussed.