Low-frequency Activity Research Articles

Autonomic Activity in Overweight-Obese Children During the Morning Transition in Cardiac Circadian Regulation (P21-065-19)

ObjectivesRegulation of the autonomic nervous system is disturbed in obese children and adults. This dysregulation—which includes sympathetic nervous system (SNS) over activity and disruption of cardiac circadian rhythms—is of interest because of the negative impact of these effects on cognition, regulation of energy homeostasis, cardiovascular health, and metabolic functions. The present study evaluated heart rate (HR) measures during the first hours following awakening from sleep when circadian cardiac control transitions from an emphasis on parasympathetic nervous system activity (PNS) during sleep to an emphasis on SNS activity during wakefulness. MethodsResting HR recordings (5 min) were obtained from healthy normal weight (NW: BMI < 85th %ile; n = 47; 25 boys) and overweight-obese (OB: BMI > 95th %ile; n = 48; 24 boys) 10 yr olds enrolled in the ACNC’s Brain Food study. The first of two recording sessions (T1) took place 2 hrs after awakening (1 hr after a standardized breakfast), and the second (T2) 1 hr later. Recordings were processed for measures of sympathetic [low frequency (LF)] and parasympathetic [high frequency (HF); vagal tone (VT); root mean square of intervals between adjacent heart beats (RMSSD)] activities. ResultsSeparate ANOVAs (recording session by group by sex) were conducted for each measure. Previous reports of higher HR in girls than boys and in OB than NW groups were confirmed (both P ≤ 0.001) HR slowed significantly from T1 to T2 for OB (P = 0.021), but not NW. These effects were associated with T1 to T2 increases in SNS LF activity for both groups (both P ≤ 0.003), but significant increases in PNS measures (HF, RMSSD, VT; all P < 0.05) for only OB children. Increases in PNS activity across recording sessions for OB children attenuated group HR differences during T2 (T1: OB > NW, P = 0.008; T2: OB > NW, P = .051). Gender differences were consistent with faster HR in girls which was maintained across groups and recording sessions. ConclusionsThe results are the first to show that autonomic dysregulation in obese children modulates the shift in SNS-PNS balance characteristic of the transition from sleep to waking. These findings may inform the development of new early intervention strategies to attenuate obesity that consider the role played by circadian rhythms. Funding SourcesFunded by USDA-ARS Project 6026-51000-010-05S.

P65-F EEG evolution in a case of rapidly progressive dementia

Background Rapidly progressive dementia can be caused by several factors like neurodegenerative, toxic/metabolic, infectious, autoimmune or neoplastic disorders. Here I present a case of this type and the diagnostic process leading to diagnosis. Material and methods This case describes a woman in her sixties admitted to hospital with dementia and anxiety as initial symptoWithin 2 month progression of these symptoms and appearance of apraxia, visual affection and cerebellar gait. The diagnostic process is illustrated. including consecutive EEGs, PET, MRi, CSF markers. Results Initial MRi was considered normal and first EEG with normal posterior dominant rhythm and bi-fronto-temporal 2–3 Hz activity (leftsided dominance) and no paroxystic activity. Repeated tests revealed classic changes seen in sporadic CJD on MRi in the form of cortical ribbon sign and adynamic periodic paroxyms and low frequency activity (2–3 Hz) lateralized in the EEG. CSF with normal count of protein and normal count of White blood cells and elevated count of total tau 1200 (normal range Conclusions Even though a definite diagnosis of Creutzfeldt-Jacob disease (CJD) can only be manifest by brain autopsy or biopsy post mortem a possible or likely diagnosis can be established combining CSF markers, brain imaging and EEG. This case illustrates the importance of EEG and especially consecutive EEGs in the diagnostic process of rapidly progressive dementia.

Non-selective inhibition of inappropriate motor-tendencies during response-conflict by a fronto-subthalamic mechanism.

To effectively interact with their environment, humans must often select actions from multiple incompatible options. Existing theories propose that during motoric response-conflict, inappropriate motor activity is actively (and perhaps non-selectively) suppressed by an inhibitory fronto-basal ganglia mechanism. We here tested this theory across three experiments. First, using scalp-EEG, we found that both outright action-stopping and response-conflict during action-selection invoke low-frequency activity of a common fronto-central source, whose activity relates to trial-by-trial behavioral indices of inhibition in both tasks. Second, using simultaneous intracranial recordings from the basal ganglia and motor cortex, we found that response-conflict increases the influence of the subthalamic nucleus on M1-representations of incorrect response-tendencies. Finally, using transcranial magnetic stimulation, we found that during the same time period when conflict-related STN-to-M1 communication is increased, cortico-spinal excitability is broadly suppressed. Together, these findings demonstrate that fronto-basal ganglia networks buttress action-selection under response-conflict by rapidly and non-selectively net-inhibiting inappropriate motor tendencies.

Associations between electroencephalography power and Alzheimer's disease in persons with Down syndrome.

It is complicated to diagnose dementia in persons with Down syndrome (DS). Older studies have, however, demonstrated low-frequency activity in electroencephalography (EEG) in persons with concurrent DS and Alzheimer's disease (DS-AD). The aim of this study was to examine whether it was possible to identify AD-associated changes (increased high-frequency power and decreased low-frequency power) in persons with DS-AD compared with DS. We included 21 persons with DS-AD and 16 with DS without cognitive deterioration assessed by the informant-based Dementia Screening Questionnaire in Intellectual Disability. EEG was recorded for all participants. Absolute power for each electrode and global power were calculated for all frequency bands for both eyes open and eyes closed. For global power in the eyes closed condition, we found an increased global slow-frequency activity and a decreased global high-frequency activity in DS-AD compared with DS. In addition, we found a significant difference in the global alpha/delta ratio with the largest difference found for global alpha power in DS-AD compared with DS. In the current study, we found that changes known to be associated with AD could also be identified when comparing DS-AD with DS using quantitative EEG. In general, these findings suggest that EEG might be a useful tool in diagnosing AD in persons with DS, but larger studies are needed.

Emotion regulation after acquired brain injury: a study of heart rate variability, attentional control, and psychophysiology

ABSTRACTPrimary objective: To examine the efficacy of heart rate variability biofeedback (HRV-BF) to treat emotional dysregulation in persons with acquired brain injury.Design: A secondary analysis of a quasi-experimental study which enrolled 13 individuals with severe chronic acquired brain injury participating in a community-based programme. Response-to-treatment was measured with two HRV resonance indices (low frequency activity [LF] and low frequency/high frequency ratio [LF/HF]).Main outcome: Behavior Rating Inventory of Executive Function-informant report (emotional control subscale [EC]).Results: Results show significant correlation between LF and EC with higher LF activity associated with greater emotional control; the association between LF/HF pre-post-change score and EC is not statistically significant. A moderation model, however, demonstrates a significant influence of attention on the relation between LF/HF change and EC when attention level is high, with an increase in LF/HF activity associated with greater emotional control.Conclusions: HRV-BF is associated with large increases in HRV, and it appears to be useful for the treatment of emotional dysregulation in individuals with severe acquired brain injury. Attention training may enhance an individual’s emotional control.

Continuous EEG Monitoring in a Consecutive Patient Cohort with Sepsis and Delirium.

Delirium is common during sepsis, although under-recognized. We aimed to assess the value of continuous electroencephalography (cEEG) to aid in the diagnosis of delirium in septic patients. We prospectively evaluated 102 consecutive patients in a medical intensive care unit (ICU), who had sepsis or septic shock, without evidence of acute primary central nervous system disease. We initiated cEEG recording immediately after identification. The median cEEG time per patient was 44h (interquartile range 21-99h). A total of 6723h of cEEG recordings were examined. The Confusion Assessment Method for the ICU (CAM-ICU) was administered six times daily to identify delirium. We analyzed the correlation between cEEG and delirium using 1252 two-minute EEG sequences recorded simultaneously with the CAM-ICU scorings. Of the 102 included patients, 66 (65%) had at least one delirium episode during their ICU stay, 30 (29%) remained delirium-free, and 6 (6%) were not assessable due to deep sedation or coma. The absence of delirium was independently associated with preserved high-frequency beta activity (> 13Hz) (P < 10-7) and cEEG reactivity (P < 0.001). Delirium was associated with preponderance of low-frequency cEEG activity and absence of high-frequency cEEG activity. Sporadic periodic cEEG discharges occurred in 15 patients, 13 of whom were delirious. No patient showed clinical or electrographic evidence of non-convulsive status epilepticus. Our findings indicate that cEEG can help distinguish septic patients with delirium from non-delirious patients.

Intracranial Recordings and Computational Modeling of Music Reveal the Time Course of Prediction Error Signaling in Frontal and Temporal Cortices.

Prediction is held to be a fundamental process underpinning perception, action, and cognition. To examine the time course of prediction error signaling, we recorded intracranial EEG activity from nine presurgical epileptic patients while they listened to melodies whose information theoretical predictability had been characterized using a computational model. We examined oscillatory activity in the superior temporal gyrus (STG), the middle temporal gyrus (MTG), and the pars orbitalis of the inferior frontal gyrus, lateral cortical areas previously implicated in auditory predictive processing. We also examined activity in anterior cingulate gyrus (ACG), insula, and amygdala to determine whether signatures of prediction error signaling may also be observable in these subcortical areas. Our results demonstrate that the information content (a measure of unexpectedness) of musical notes modulates the amplitude of low-frequency oscillatory activity (theta to beta power) in bilateral STG and right MTG from within 100 and 200 msec of note onset, respectively. Our results also show this cortical activity to be accompanied by low-frequency oscillatory modulation in ACG and insula-areas previously associated with mediating physiological arousal. Finally, we showed that modulation of low-frequency activity is followed by that of high-frequency (gamma) power from approximately 200 msec in the STG, between 300 and 400 msec in the left insula, and between 400 and 500 msec in the ACG. We discuss these results with respect to models of neural processing that emphasize gamma activity as an index of prediction error signaling and highlight the usefulness of musical stimuli in revealing the wide-reaching neural consequences of predictive processing.

Establishing the objective sleep phenotype in hypersomnolence disorder with and without comorbid major depression.

To clarify whether hypersomnolence disorder is associated with a specific sleep phenotype and altered neurophysiological function in persons with and without hypersomnolence disorder and major depressive disorder (MDD). Eighty-three unmedicated persons with and without hypersomnolence disorder and/or MDD underwent ad libitum high-density EEG polysomnography. Clinical and sleep architecture variables were compared between groups. Topographic patterns of slow-wave activity (SWA) relative to healthy controls were compared, with correlations between topographic SWA and daytime sleepiness assessed. Reductions in SWA in hypersomnolence disorder were mapped to specific cortical areas using source localization. Regardless of the presence or absence of comorbid MDD, persons with hypersomnolence disorder had increased sleep duration relative to both controls and persons with MDD without hypersomnolence. Participants with hypersomnolence disorder also demonstrated reduced bilateral centroparietal low-frequency activity during nonrapid eye movement sleep relative to controls, a pattern not observed in persons with MDD but without hypersomnolence. SWA in these regions was negatively correlated with subjective measures of daytime sleepiness. Source localization demonstrated reductions in SWA in the supramarginal gyrus, somatosensory, and transverse temporal cortex in participants with hypersomnolence disorder. Hypersomnolence disorder is characterized by increased sleep duration with normal sleep continuity, regardless of the presence or absence of comorbid depression. Reduced local SWA may be a specific neurophysiological finding in hypersomnolence disorder. Further research is warranted to elucidate the mechanisms through which these cortical changes are related to clinical complaints of daytime sleepiness.

Sequential Neural Activity in Primary Motor Cortex during Sleep.

Sequential firing of neurons during sleep is thought to play a role in the consolidation of learning. However, direct evidence for such sequence replay is limited to only a few brain areas and sleep states mainly in rodents. Using a custom-designed wearable neural data logger and chronically implanted electrodes, we made long-term recordings of neural activity in the primary motor cortex of two female nonhuman primates during free behavior and natural sleep. We used the local field potential (LFP) spectrogram to characterize sleep cycles, and examined firing rates, correlations, and sequential firing of neurons at different frequency bands through the cycle. Slow-wave sleep (SWS) was characterized by low neural firing rates and high synchrony, reflecting slow oscillations between cortical down and up states. However, the order in which neurons entered up states was similar to the sequence of neural activity observed at low frequencies during waking behavior. In addition, we found evidence of brief bursts of theta oscillation, associated with non-SWS states, during which neurons fired in strikingly regular sequential order phase-locked to the LFP. Theta sequences were preserved between waking and sleep, but appeared not to resemble the order of neural activity observed at lower frequencies. The sequential firing of neurons during slow oscillations and theta bursts may contribute to the consolidation of procedural memories during sleep.SIGNIFICANCE STATEMENT Replay of sequential neural activity during sleep is believed to support consolidation of daytime learning. Despite a wealth of studies investigating sequential replay in association with episodic and spatial memory, it is unknown whether similar sequences occur in motor areas during sleep. Within long-term neural recordings from monkey motor cortex, we found two distinct patterns of sequential activity during different phases of the natural sleep cycle. Slow-wave sleep was associated with delta-band sequences that resembled low-frequency activity during movement, while occasional brief bursts of theta oscillation were associated with a different order of sequential firing. Our results are the first report of sequential sleep replay in the motor cortex, which may play an important role in consolidation of procedural learning.

Quasi-periodic patterns contribute to functional connectivity in the brain

Functional connectivity is widely used to study the coordination of activity between brain regions over time. Functional connectivity in the default mode and task positive networks is particularly important for normal brain function. However, the processes that give rise to functional connectivity in the brain are not fully understood. It has been postulated that low-frequency neural activity plays a key role in establishing the functional architecture of the brain. Quasi-periodic patterns (QPPs) are a reliably observable form of low-frequency neural activity that involve the default mode and task positive networks. Here, QPPs from resting-state and working memory task-performing individuals were acquired. The spatiotemporal pattern, strength, and frequency of the QPPs between the two groups were compared and the contribution of QPPs to functional connectivity in the brain was measured. In task-performing individuals, the spatiotemporal pattern of the QPP changes, particularly in task-relevant regions, and the QPP tends to occur with greater strength and frequency. Differences in the QPPs between the two groups could partially account for the variance in functional connectivity between resting-state and task-performing individuals. The QPPs contribute strongly to connectivity in the default mode and task positive networks and to the strength of anti-correlation seen between the two networks. Many of the connections affected by QPPs are also disrupted during several neurological disorders. These findings contribute to understanding the dynamic neural processes that give rise to functional connectivity in the brain and how they may be disrupted during disease.

Subthalamic and pallidal oscillatory activity in patients with Neurodegeneration with Brain Iron Accumulation type I (NBIA-I)

ObjectivesNeurodegeneration with Brain Iron Accumulation type I (NBIA-I) is a rare hereditary neurodegenerative disorder with pallidal degeneration leading to disabling generalized dystonia and parkinsonism. Pallidal or subthalamic deep brain stimulation can partially alleviate motor symptoms. Disease-specific patterns of abnormally enhanced oscillatory neuronal activity recorded from the basal ganglia have been described in patients with movement disorders undergoing deep brain stimulation (DBS). Here we studied oscillatory activity recorded from the internal globus pallidus (GPi) and the subthalamic nucleus (STN) to characterize neuronal activity patterns in NBIA-I. MethodsWe recorded local field potentials (LFP) from DBS electrodes in 6 juvenile patients with NBIA-I who underwent functional neurosurgery. Four patients were implanted in the STN and two patients in the GPi. Recordings were performed during wakeful rest. An FFT-based approach was used to analyze the power spectrum in the target area. ResultsIn all patients we found distinct peaks in the low frequency (7–12 Hz) and in 5 out 6 also in the beta frequency range (15–30 Hz) with the largest beta peak in the patient that presented with the most prominent bradykinesia. No distinct peaks occurred in the gamma frequency range (35–100 Hz). The oscillatory pattern did not differ between STN and GPi. ConclusionsHere we show for the first time the oscillatory activity pattern in the STN and the GPi in juvenile patients with dystonia plus syndrome due to NBIA-I. The low frequency peak we found is in line with previous studies in patients with isolated idiopathic dystonia. In our cohort, the pallidal beta band activity may be related to more severe motor slowing in dystonia plus syndrome such as NBIA-I. SignificanceOur results further support the link between hyperkinetic motor symptoms such as dystonia and enhanced basal ganglia low frequency activity irrespective of the underlying etiology of dystonia.

Age-related cortical signatures of human sleep electroencephalography

Accumulating evidence demonstrates a direct relationship between impaired neural integrity and disrupted sleep physiology in normal and pathological aging. However, previous work has focus almost exclusively on nonrapid eye movement sleep electroencephalography as a proxy of cortical integrity with aging. Whether this relationship holds true for rapid eye movement sleep electroencephalography is unknown. Our results show that age-related reduction in low-frequency delta activity during both rapid eye movement and nonrapid eye movement sleep was statistically mediated by the thinning of the medial frontal and anterior cingulate cortices. These findings (1) support the potential role of the medial frontal and cingulate cortices, major hubs of the human brain, in synchronizing neuronal assemblies during sleep, and (2) suggest that, with age, a reduction in cortical integrity within this frontal network mediates the loss of delta power during sleep. Further work will determine whether cortical thinning and delta loss may interact and contribute to cognitive decline with aging.

Differential recordings of local field potential: A genuine tool to quantify functional connectivity

Local field potential (LFP) recording is a very useful electrophysiological method to study brain processes. However, this method is criticized for recording low frequency activity in a large area of extracellular space potentially contaminated by distal activity. Here, we theoretically and experimentally compare ground-referenced (RR) with differential recordings (DR). We analyze electrical activity in the rat cortex with these two methods. Compared with RR, DR reveals the importance of local phasic oscillatory activities and their coherence between cortical areas. Finally, we show that DR provides a more faithful assessment of functional connectivity caused by an increase in the signal to noise ratio, and of the delay in the propagation of information between two cortical structures.

Implanted Battery-Free Direct-Current Micro-Power Supply from in Vivo Breath Energy Harvesting.

In vivo biomechanical energy harvesting by implanted nanogenerators (i-NGs) is promising for self-powered implantable medical devices (IMDs). One critical challenge to reach practical applications is the requirement of continuous direct-current (dc) output, while the low-frequency body activities typically generate discrete electrical pulses. Here, we developed an ultrastretchable micrograting i-NG system that could function as a battery-free dc micro-power supply. Packaged by a soft silicone elastomer with a cavity design, the i-NG exhibited an ultralow Young's modulus of ∼45 kPa and a high biocompatibility to soft biological tissues. The i-NG was implanted inside the abdominal cavity of Sprague Dawley adult rats and directly converted the slow diaphragm movement during normal respiration into a high-frequency alternative current electrical output, which was readily transmitted into a continuous ∼2.2 V dc output after being integrated with a basic electrical circuit. A light-emitting diode was constantly operated by the breath-driven i-NG without the aid of any battery component. This solely biomechanical energy-driven dc micro-power supply offers a promising solution for the development of self-powered IMDs.

Dissociating the effect of flavor and nicotine in smokeless tobacco products using electroencephalography: The case of wintergreen flavors

The increased consumption of tobacco products in recent years has been linked, among other factors, to the presence of added flavors. Although flavors are important in explaining consumption, their effects in the brain have until now been unexplored. In the present study, we investigated how electrophysiology can serve to dissociate the effects of nicotine and flavor. Participants attended 4 sessions (2-by-2 factorial design, with flavor and nicotine as within-subject factors), in each session an oddball task was performed before and after smokeless tobacco consumption.We explored the dissociation of neural responses to flavor and nicotine. While event-related potentials did not show modulation due to flavors, time-frequency showed a flavor-nicotine dissociation. Low-frequency activity (delta, theta and alpha) showed only effects of nicotine, and high-frequency activity (beta1, beta2 and gamma) showed effects only susceptible to flavor. Flavors in smokeless tobacco not only made the product more desirable but also triggered the allocation of cognitive resources. This long-lasting effect of flavor may enhance the addictive potential of the tobacco product. Further research is being developed to determine the precise role of flavors in contributing to addiction.This is the first study investigating the neural effects of flavor (specifically wintergreen) in smokeless tobacco products. By understanding the effects of flavors in the brain we can explain the precipitants of tobacco consumption behaviors, and the addictive potential of flavors. Regulators will be able to determine if and in which amount flavors should be allowed in tobacco products.

Slow periodic activity in the longitudinal hippocampal slice can self-propagate non-synaptically by a mechanism consistent with ephaptic coupling.

Slow periodic activity can propagate with speeds around 0.1ms-1 and be modulated by weak electric fields. Slow periodic activity in the longitudinal hippocampal slice can propagate without chemical synaptic transmission or gap junctions, but can generate electric fields which in turn activate neighbouring cells. Applying local extracellular electric fields with amplitude in the range of endogenous fields is sufficient to modulate or block the propagation of this activity both in the in silico and in the in vitro models. Results support the hypothesis that endogenous electric fields, previously thought to be too small to trigger neural activity, play a significant role in the self-propagation of slow periodic activity in the hippocampus. Experiments indicate that a neural network can give rise to sustained self-propagating waves by ephaptic coupling, suggesting a novel propagation mechanism for neural activity under normal physiological conditions. Slow oscillations are a standard feature observed in the cortex and the hippocampus during slow wave sleep. Slow oscillations are characterized by low-frequency periodic activity (<1Hz) and are thought to be related to memory consolidation. These waves are assumed to be a reflection of the underlying neural activity, but it is not known if they can, by themselves, be self-sustained and propagate. Previous studies have shown that slow periodic activity can be reproduced in the in vitro preparation to mimic in vivo slow oscillations. Slow periodic activity can propagate with speeds around 0.1ms-1 and be modulated by weak electric fields. In the present study, we show that slow periodic activity in the longitudinal hippocampal slice is a self-regenerating wave which can propagate with and without chemical or electrical synaptic transmission at the same speeds. We also show that applying local extracellular electric fields can modulate or even block the propagation of this wave in both in silico and in vitro models. Our results support the notion that ephaptic coupling plays a significant role in the propagation of the slow hippocampal periodic activity. Moreover, these results indicate that a neural network can give rise to sustained self-propagating waves by ephaptic coupling, suggesting a novel propagation mechanism for neural activity under normal physiological conditions.

The Influence of Fetal Head Circumference and Fetal Weight Measurement Assessed By Intrapartum Ultrasound on Labor Outcome

Background: labor is a clinical diagnosis characterized by regular, painful uterine that increase in frequency and intensity is associated with progressive cervical effacement or dilatation. More specifically, it is associated with a change in the myometrial contractility pattern from irregular contractures (long-lasting, low-frequency activity) to regular contractions (high-intensity, high frequency activity). Aim of the work: it was to determine if fetal head circumference and fetal weight could predict the rate of caesarian section and operative vaginal deliveries in nulliparous women in labor. Patients and Methods: this study was carried out at Al Alamein Hospital from January 2017 to January 2018 on two hundred (200) primigravida women; their ages ranged from 20 to 30 years and the gestational ages ranged from 38-40 weeks with normal singleton pregnancy with cephalic presentation in labor. Results: there were highly statistically significant relations between mode of delivery and fetal head circumference and estimated fetal weight as p value (0.001).it was found that large fetal head circumference relative to maternal pelvic diameter is the main cause of prolonged labor and therefor increased risk of primary caesarian section. Conclusion: the numerical data have a significant relation between intra partum head circumference and fetal weight and the incidence of primary caesarian section, maternal and fetal complications. Recommendations: according to numerical results obtained from this study. The study recommends strict labor monitoring by partogram in cases where fetal head circumference is more than 35cm or fetal weight is more than 3950gms.

Resting-State Functional Connectivity Magnetic Resonance Imaging and Outcome After Acute Stroke

Background and Purpose- Physiological effects of stroke are best assessed over entire brain networks rather than just focally at the site of structural damage. Resting-state functional magnetic resonance imaging can map functional-anatomic networks by analyzing spontaneously correlated low-frequency activity fluctuations across the brain, but its potential usefulness in predicting functional outcome after acute stroke remains unknown. We assessed the ability of resting-state functional magnetic resonance imaging to predict functional outcome after acute stroke. Methods- We scanned 37 consecutive reperfused stroke patients (age, 69±14 years; 14 females; 3-day National Institutes of Health Stroke Scale score, 6±5) on day 3 after symptom onset. After imaging preprocessing, we used a whole-brain mask to calculate the correlation coefficient matrices for every paired region using the Harvard-Oxford probabilistic atlas. To evaluate functional outcome, we applied the modified Rankin Scale at 90 days. We used region of interest analyses to explore the functional connectivity between regions and graph-computation analysis to detect differences in functional connectivity between patients with good functional outcome (modified Rankin Scale score ≤2) and those with poor outcome (modified Rankin Scale score >2). Results- Patients with good outcome had greater functional connectivity than patients with poor outcome. Although 3-day National Institutes of Health Stroke Scale score was the most accurate independent predictor of 90-day modified Rankin Scale (84.2%), adding functional connectivity increased accuracy to 94.7%. Preserved bilateral interhemispheric connectivity between the anterior inferior temporal gyrus and superior frontal gyrus and decreased connectivity between the caudate and anterior inferior temporal gyrus in the left hemisphere had the greatest impact in favoring good prognosis. Conclusions- These data suggest that information about functional connectivity from resting-state functional magnetic resonance imaging may help predict 90-day stroke outcome.

Acute effects of meditation training on the waking and sleeping brain: Is it all about homeostasis?

Our recent finding of a meditation-related increase in low-frequency NREM sleep EEG oscillatory activities peaking in the theta-alpha range (4-12Hz) was not predicted. From a consolidated body of research on sleep homeostasis, we would expect a change peaking in slow wave activity (1-4Hz) following an intense meditation session. Here we compared these changes in sleep with the post-meditation changes in waking rest scalp power to further characterize their functional significance. High-density EEG recordings were acquired from 27 long-term meditators (LTM) on three separate days at baseline and following two 8-hr sessions of either mindfulness or compassion-and-loving-kindness meditation. Thirty-one meditation-naïve participants (MNP) were recorded at the same time points. As a common effect of meditation practice, we found increases in low and fast waking EEG oscillations for LTM only, peaking at eight and 15Hz respectively, over prefrontal, and left centro-parietal electrodes. Paralleling our previous findings in sleep, there was no significant difference between meditation styles in LTM as well as no difference between matched sessions in MNP. Meditation-related changes in wakefulness and NREM sleep were correlated across space and frequency. A significant correlation was found in the EEG low frequencies (<12Hz). Since the peak of coupling was observed in the theta-alpha oscillatory range, sleep homeostatic response to meditation practice is not sufficient to explain our findings. Another likely phenomenon into play is a reverberation of meditation-related processes during subsequent sleep. Future studies should ascertain the interplay between these processes in promoting the beneficial effects of meditation practice.

Correlation of Synaptic Inputs in the Visual Cortex of Awake, Behaving Mice

The subthreshold mechanisms that underlie neuronal correlations in awake animals are poorly understood. Here, we perform dual whole-cell recordings in the visual cortex (V1) of awake mice to investigate membrane potential (Vm) correlations between upper-layer sensory neurons. We find that the membrane potentials of neighboring neurons display large, correlated fluctuations during quiet wakefulness, including pairs of cells with disparate tuning properties. These fluctuations are driven by correlated barrages of excitation followed closely by inhibition (∼5-ms lag). During visual stimulation, low-frequency activity is diminished, and coherent high-frequency oscillations appear, even for non-preferred stimuli. These oscillations are generated by alternating excitatory and inhibitory inputs at a similar lag. The temporal sequence of depolarization for pairs of neurons is conserved during both spontaneous- and visually-evoked activity, suggesting a stereotyped flow of activation that may function to produce temporally precise "windows of opportunity" for additional synaptic inputs.