Nonperturbative treatment of giant atoms using chain transformations

Superconducting circuits coupled to acoustic waveguides have extended the range of phenomena that can be experimentally studied using tools from quantum optics. In particular giant artificial atoms permit the investigation of systems in which the electric dipole approximation breaks down and pronounced non-Markovian effects become important. While previous studies of giant atoms focused on the realm of the rotating-wave approximation, we go beyond this and perform a numerically exact analysis of giant atoms strongly coupled to their environment, in regimes where counterrotating terms cannot be neglected. To achieve this, we use a Lanczos transformation to cast the field Hamiltonian into the form of a one-dimensional chain and employ matrix-product state simulations. This approach yields access to a wide range of system-bath observables and to previously unexplored parameter regimes.Comment: 8+5 pages, 8+2 figures, 1+1 tables. v3: update published versio

Interictal rhythmical midline theta differentiates frontal from temporal lobe epilepsies

PURPOSE: We evaluated the role of interictal rhythmical midline theta (RMT) in the identification of frontal lobe epilepsy (FLE) and its differentiation from temporal lobe epilepsy (TLE) and nonepileptic controls. METHODS: We included 162 individuals in the study: 54 FLE patients, 54 TLE patients, and 54 nonepileptic controls. Continuous electroencephalographic (EEG)-video monitoring was performed in all individuals. Interictal RMT was included only if it occurred during definite awake states. RMT associated with drowsiness or mental activation and ictal RMT was excluded. RESULTS: We identified RMT significantly more frequently in FLE patients (48.1%, 26 of 54) than in TLE patients (3.7%, 2 of 54) (p < 0.01), and not in the control group. The average frequency was 6 Hz (range 5-7 Hz), and the average RMT bursts lasted 8 s (3-12 s). Interestingly, all mesial FLE patients (n = 4) (as established by invasive EEG recordings) showed RMT, whereas this was less frequently the case in the other FLE patients (44%, 22 of 50) (p = 0.03). Thirteen of our 54 patients with FLE (24%) did not have any interictal epileptiform discharges (IEDs), but RMT was observed in the majority of these patients (62%, 8 of 13). CONCLUSION: Interictal RMT is common and has a localizing value in patients with FLE, provided that conditions such as drowsiness and mental activation as confounding factors for RMT are excluded. RMT should be included in the evaluation of patients considered for resective epilepsy surgery

Hypersomnia associated with bilateral posterior hypothalamic lesion - A polysomnographic case study

We examined an obese 58-year-old patient with a bilateral posterior hypothalamic lesion of unknown etiology. A 24-hour polysomnography revealed a markedly increased total sleep time (17.6 h). During daytime, only 3 continuous wake phases occurred. REM periods occurred only between 5 p.m. and 6 a.m. We conclude from our results that, similar to the results from animal experiments, the posterior hypothalamus in humans plays a critical role in the maintenance of wakefulness. Copyright (C) 2003 S. Karger AG, Basel

The human thalamus orchestrates neocortical oscillations during NREM sleep

A hallmark of non-rapid eye movement sleep is the coordinated interplay of slow oscillations (SOs) and sleep spindles. Traditionally, a cortico-thalamo-cortical loop is suggested to coordinate these rhythms: neocortically-generated SOs trigger spindles in the thalamus that are projected back to neocortex. Here, we used intrathalamic recordings from human epilepsy patients to test this canonical interplay. We show that SOs in the anterior thalamus precede neocortical SOs (peak −50 ms), whereas concurrently-recorded SOs in the mediodorsal thalamus are led by neocortical SOs (peak +50 ms). Sleep spindles, detected in both thalamic nuclei, preceded their neocortical counterparts (peak −100 ms) and were initiated during early phases of thalamic SOs. Our findings indicate an active role of the anterior thalamus in organizing sleep rhythms in the neocortex and highlight the functional diversity of thalamic nuclei in humans. The thalamic coordination of sleep oscillations could have broad implications for the mechanisms underlying memory consolidation

The human thalamus orchestrates neocortical oscillations during NREM sleep

A hallmark of non-rapid eye movement (NREM) sleep is the coordinated interplay of slow oscillations (SOs) and sleep spindles. Traditionally, a cortico-thalamo-cortical loop is suggested to coordinate these rhythms: neocortically-generated SOs trigger spindles in the thalamus that are projected back to neocortex. Here, we used direct intrathalamic recordings from human epilepsy patients to test this canonical interplay. We show that SOs in the anterior thalamus precede neocortical SOs, whereas concurrently-recorded SOs in the mediodorsal thalamus are led by neocortical SOs. Furthermore, sleep spindles, detected in both thalamic nuclei, preceded their neocortical counterparts and were initiated during early phases of thalamic SOs. Our findings indicate an active role of the anterior thalamus in organizing the cardinal sleep rhythms in the neocortex and highlight the functional diversity of specific thalamic nuclei in humans. The concurrent coordination of sleep oscillations by the thalamus could have broad implications for the mechanisms underlying memory consolidation

Unilateral Blinking: Insights from Stereo-EEG and Tractography

To study the neuroanatomical correlate of involuntary unilateral blinking in humans, using the example of patients with focal epilepsy. Patients with drug resistant focal epilepsy undergoing presurgical evaluation with stereotactically implanted EEG-electrodes (sEEG) were recruited from the local epilepsy monitoring unit. Only patients showing ictal unilateral blinking or unilateral blinking elicited by direct electrical stimulation were included (n = 16). MRI and CT data were used for visualization of the electrode positions. In two patients, probabilistic tractography with seeding from the respective electrodes was additionally performed. Three main findings were made: (1) involuntary unilateral blinking was associated with activation of the anterior temporal region, (2) tractography showed widespread projections to the ipsilateral frontal, pericentral, occipital, limbic and cerebellar regions and (3) blinking was observed predominantly in female patients with temporal lobe epilepsies. Unilateral blinking was found to be associated with an ipsilateral activation of the anterior temporal region. We suggest that the identified network is not part of the primary blinking control but might have modulating influence on ipsilateral blinking by integrating contextual information

Hormonal contraceptive exposure relates to changes in resting state functional connectivity of anterior cingulate cortex and amygdala

IntroductionHormonal contraceptives (HCs), nowadays one of the most used contraceptive methods, downregulate endogenous ovarian hormones, which have multiple plastic effects in the adult brain. HCs usually contain a synthetic estrogen, ethinyl-estradiol, and a synthetic progestin, which can be classified as androgenic or anti-androgenic, depending on their interaction with androgen receptors. Both the anterior cingulate cortex (ACC) and the amygdala express steroid receptors and have shown differential functionality depending on the hormonal status of the participant and the use of HC. In this work, we investigated for the first time the relationship between ACC and amygdala resting state functional connectivity (rs-FC) and HC use duration, while controlling for progestin androgenicity.MethodsA total of 231 healthy young women participated in five different magnetic resonance imaging studies and were included in the final analysis. The relation between HC use duration and (i) gray matter volume, (ii) fractional amplitude of low-frequency fluctuations, and (iii) seed-based connectivity during resting state in the amygdalae and ACC was investigated in this large sample of women.ResultsIn general, rs-FC of the amygdalae with frontal areas, and between the ACC and temporoparietal areas, decreased the longer the HC exposure and independently of the progestin’s androgenicity. The type of HC’s progestin did show a differential effect in the gray matter volume of left ACC and the connectivity between bilateral ACC and the right inferior frontal gyrus

Ictal SPECT in Sturge-Weber syndrome

We report on a patient with right-sided Sturge-Weber syndrome (SWS), in whom earlier functional hemispherectomy failed. Subtraction of ictal and interictal single-photon-emission-computed-tomography (SPECT) superimposed on individual MRI showed a right fronto-orbital hyperperfusion, with a left-sided EEG seizure pattern. Ictal SPECT supported our assumption that right frontal originated seizure pattern propagated to left hemisphere via the remaining right frontal bridge. Right orbito-frontal resection and disconnection from corpus callosum resulted in seizure freedom

Kopfschmerz bei Parietal- und Okzipitallappenepilepsien

Epilepsiepatienten leiden überdurchschnittlich häufig unter Kopfschmerzen. Dies gilt insbesondere für Patienten mit idiopathisch generalisierten und parietookzipitalen Epilepsien. Die Häufigkeit des gemeinsamen Auftretens von Kopfschmerzen und Epilepsie überschreitet dabei die rechnerische Koinzidenz, sodass von einer Komorbidität beider Syndrome auszugehen ist. Bestärkt wird diese Hypothese durch überlappende genetische Veränderungen sowie gemeinsame pathophysiologische Mechanismen. Bis zu 62 % der Patienten mit z. B. Parietal- und Okzipitallappenepilepsie (POLE) geben Kopfschmerzen an. Diese treten v. a. nach dem Anfall (postiktal) auf und manifestieren sich am häufigsten als Migräne-ähnlicher Kopfschmerz oder Spannungskopfschmerz. Seltener kommt es zu Kopfschmerzen vor (periiktal), während (iktal) oder zwischen (interiktal) epileptischen Anfällen. Bei transienten neurologischen Ausfallsymptomen mit begleitenden Kopfschmerzen ist differenzialdiagnostisch neben der Migräne an vaskuläre Ereignisse wie Synkopen oder eine transiente ischämische Attacke zu denken.The prevalence of headache in epilepsy patients is above average compared to the general population. This is especially true for patients with idiopathic generalized and parieto-occipital epilepsies. Comorbidity of both syndromes is suspected as the frequency of the joint occurrence of headache and epilepsy exceeds the statistical coincidence rate. This hypothesis is supported by data on shared genetic variants as well as overlapping pathophysiological mechanisms. Up to 62% of patients with parietal and occipital lobe epilepsy (POLE) report headaches. These occur especially following seizures (postictally) and with migraine-like or tension-type characteristics. Less frequently, headache manifests before (preictal), during (ictal) or between (interictal) epileptic seizures. The most relevant differential diagnoses for paroxysmal events with neurological deficits and accompanying headache are migraine and vascular events, such as syncope and transient ischemic attacks