Connectivity Alterations in Emotional and Cognitive Networks During a Manic State Induced by Direct Electrical Stimulation.

Mania is characterized by affective and cognitive alterations, with heightened external and self-awareness that are opposite to the alteration of awareness during epileptic seizures. Electrical stimulations carried out routinely during stereotactic intracerebral EEG (SEEG) recordings for presurgical evaluation of epilepsy may represent a unique opportunity to study the pathophysiology of such complex emotional-behavioral phenomenon, particularly difficult to reproduce in experimental setting. We investigated SEEG signals-based functional connectivity between different brain regions involved in emotions and in consciousness processing during a manic state induced by electrical stimulation in a patient with drug-resistant focal epilepsy. The stimulation inducing manic state and an asymptomatic stimulation of the same site, as well as a seizure with alteration of awareness (AOA) were analyzed. Functional connectivity analysis was performed by measuring interdependencies (nonlinear regression analysis based on the h2 coefficient) between broadband SEEG signals and within typical sub-bands, before and after stimulation, or before and during the seizure with AOA, respectively. Stimulation of the right lateral prefrontal cortex induced a manic state lasting several hours. Its onset was associated with significant increase of broadband-signal functional coupling between the right hemispheric limbic nodes, the temporal pole and the claustrum, whereas significant decorrelation between the right lateral prefrontal and the anterior cingulate cortex was observed in theta-band. In contrast, ictal alteration of awareness was associated with increased broadband and sub-bands synchronization within and between the internal and external awareness networks, including the anterior and middle cingulate, the mesial and lateral prefrontal, the inferior parietal and the temporopolar cortex. Our data suggest the existence of network- and frequency-specific functional connectivity patterns during manic state. A transient desynchronization of theta activity between the external and internal awareness network hubs is likely to increase awareness, with potential therapeutic effect.

Population of resonance and metastable atoms in a cylindrical volume of finite size.

A solution method of the Holstein-Biberman equation in the case of two-dimensional finite-size geometry by means of transformation of the integral operator to a four-dimensional matrix is presented. Using this matrix the array of two-dimensional eigenvalues and eigenfunctions of the radiation transport operator in the case of finite cylinder is determined. The exact two-dimensional characteristics have been compared with approximate functions determined as a combination of corresponding eigenvalues and eigenfunctions for the one-dimensional problems (cylinder of infinite length and slab). The spatiotemporal evolution of excited atom densities for two typical forms of the excitation source in a nonequilibrium plasma has been analyzed. The reasons for the distinct difference in the formation of spatiotemporal distributions of resonance and metastable atoms in the case when the spatial distribution of the excitation source does not coincide with the fundamental mode are discussed. Resonance atoms follow the excitation source while the diffusion effectively takes metastable atoms out from the excitation source. Rearrangement of metastable atoms to the fundamental mode during their decay lasts about one effective diffusion lifetime while the corresponding process for the resonance atoms takes much longer (several effective lifetimes). The differences are caused by the effective suppression of higher diffusion modes compared with radiation modes. The developed solution method treats the radiation transport processes at the same accuracy level as diffusion transport of other plasma components and it is suitable for a self-consistent modeling of nonequilibrium plasmas.

High-frequency oscillations and spikes running down after SEEG-guided thermocoagulations in the epileptogenic network of periventricular nodular heterotopia.

OBJECTIVE: Epilepsy associated with periventricular nodular heterotopia (PNH) is characterized by complex relationships between the heterotopic and the normotopic cortex during the interictal state and at seizure onset. High-frequency oscillations (HFO) have been proposed as a marker of epileptogenicity that might reflect disease activity. The effects of thermocoagulations on epileptogenicity in this context remain unknown. We aimed to investigate the interictal HFO- and spike profiles of different cortical structures before and after two consecutive SEEG-guided thermocoagulations, in correlation with seizure outcome, in a patient with PNH-related drug-resistant epilepsy. METHODS: The epileptogenic zone (EZ) was defined by SEEG analysis based on the Epileptogenicity Index. Interictal spikes, ripples (80-250 Hz) and fast ripples (FR, 250-330 Hz) were analyzed within the heterotopia, the temporal neocortex and the hippocampus. RESULTS: The SEEG recordings revealed a distributed EZ involving the heterotopia and the posterior temporal neocortex. Both structures were targeted by thermocoagulations. Background spikes, ripples and FR-rates were significantly higher in PNH compared to the normotopic cortex. A drastic reduction of spikes (by over 80%) and absence of FR were demonstrated both in the PNH and in the neocortex during the second SEEG exploration 6 months after the first thermocoagulation, whereas no significant difference was observed in the posterior hippocampus. Ripples were significantly reduced by the first and suppressed by the second thermocoagulation within the three structures. Seizures relapsed after two months but decreased in frequency after the first thermocoagulation. Sustained seizure-freedom was achieved only after the second procedure. CONCLUSIONS: Our data demonstrate the running down of interictal HFO and spikes within the epileptogenic network following thermocoagulations of heterotopic and normotopic sites involved at seizure onset. This dynamics was in good correlation with significantly improved seizure control. SIGNIFICANCE: Combination of ictal and different interictal markers of epileptogenicity, including HFO and spike analysis, is important to get the full picture of the epileptogenic zone and could help to evaluate the disease activity.

Uranium transport in acidic brines under reducing conditions.

The behavior of uranium in environments, ranging from those of natural systems responsible for the formation of uranium deposits to those of nuclear reactors providing 11% of the world's electricity, is governed by processes involving high-temperature aqueous solutions. It has been well documented that uranium is mobile in aqueous solutions in its oxidized, U6+ state, whereas in its reduced, U4+ state, uranium has been assumed to be immobile. Here, we present experimental evidence from high temperature (>100 °C) acidic brines that invalidates this assumption. Our experiments have identified a new uranium chloride species (UCl4°) that is more stable under reducing than oxidized conditions. These results indicate that uranium is mobile under reducing conditions and necessitate a re-evaluation of the mobility of uranium, particularly in ore deposit models involving this metal. Regardless of the scenario considered, reducing conditions can no longer be considered a guarantee of uranium immobility.

Atonic seizures in children with surgically remediable epilepsy: a motor system seizure phenotype?

Atonic seizures are common in some epileptic syndromes beginning in infancy or early childhood but they are rarely described in epilepsy with focal seizures of structural aetiology. We aimed to characterize the electroclinical features of atonic seizures in surgically remediable paediatric patients and to study the spatiotemporal organization of the underlying epileptogenic networks. We retrospectively analysed two consecutive, longitudinally evaluated and surgically treated paediatric patients presenting with atonic seizures as a manifestation of pharmacoresistant epilepsy of structural aetiology, evidenced by scalp- and stereotactic intracerebral video-EEG-recordings. A quantitative analysis of the epileptogenic zone organization was performed using the "epileptogenicity index". Long-lasting generalized ictal atonia, occurring in infancy, was a predominant clinical feature in both patients, with some hints of focal origin present in one case. The seizure phenotype evolved at later age into subtle segmental atonia, associated with prominent positive motor signs. The epileptogenic zone was localized within the dorsolateral or mesiolateral premotor region. Its spatial organization was focal, matching the lesional cortex in one and distributed involving several lesional and non-lesional structures in the other case. The emergence of atonic semiology temporally correlated with involvement of both lateral and mesial premotor, as well as primary motor areas. We hypothesize that atonic seizures may be considered as a motor system seizure phenotype in the setting of structural epilepsy. Complete removal of the epileptogenic area provided excellent seizure control.