Cerebrocortical injuries such as stroke are a major source of disability. Maladaptive consequences can result from post-injury local reorganization of cortical circuits. For example, epilepsy is a ...common sequela of cortical stroke, but the mechanisms responsible for seizures following cortical injuries remain unknown. In addition to local reorganization, long-range, extra-cortical connections might be critical for seizure maintenance. In rats, we found that the thalamus, a structure that is remote from, but connected to, the injured cortex, was required to maintain cortical seizures. Thalamocortical neurons connected to the injured epileptic cortex underwent changes in HCN channel expression and became hyperexcitable. Targeting these neurons with a closed-loop optogenetic strategy revealed that reducing their activity in real-time was sufficient to immediately interrupt electrographic and behavioral seizures. This approach is of therapeutic interest for intractable epilepsy, as it spares cortical function between seizures, in contrast with existing treatments, such as surgical lesioning or drugs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
To determine continuous EEG (cEEG) patterns that may be unique to anti-NMDA receptor (NMDAR) encephalitis in a series of adult patients with this disorder.
We evaluated the clinical and EEG data of ...23 hospitalized adult patients with anti-NMDAR encephalitis who underwent cEEG monitoring between January 2005 and February 2011 at 2 large academic medical centers.
Twenty-three patients with anti-NMDAR encephalitis underwent a median of 7 (range 1-123) days of cEEG monitoring. The median length of hospitalization was 44 (range 2-200) days. Personality or behavioral changes (100%), movement disorders (82.6%), and seizures (78.3%) were the most common symptoms. Seven of 23 patients (30.4%) had a unique electrographic pattern, which we named "extreme delta brush" because of its resemblance to waveforms seen in premature infants. The presence of extreme delta brush was associated with a more prolonged hospitalization (mean 128.3 ± 47.5 vs 43.2 ± 39.0 days, p = 0.008) and increased days of cEEG monitoring (mean 27.6 ± 42.3 vs 6.2 ± 5.6 days, p = 0.012). The modified Rankin Scale score showed a trend toward worse scores in patients with the extreme delta brush pattern (mean 4.0 ± 0.8 vs 3.1 ± 1.1, p = 0.089).
Extreme delta brush is a novel EEG finding seen in many patients with anti-NMDAR encephalitis. The presence of this pattern is associated with a more prolonged illness. Although the specificity of this pattern is unclear, its presence should raise consideration of this syndrome.
Electronics that are capable of intimate, non-invasive integration with the soft, curvilinear surfaces of biological tissues offer important opportunities for diagnosing and treating disease and for ...improving brain/machine interfaces. This article describes a material strategy for a type of bio-interfaced system that relies on ultrathin electronics supported by bioresorbable substrates of silk fibroin. Mounting such devices on tissue and then allowing the silk to dissolve and resorb initiates a spontaneous, conformal wrapping process driven by capillary forces at the biotic/abiotic interface. Specialized mesh designs and ultrathin forms for the electronics ensure minimal stresses on the tissue and highly conformal coverage, even for complex curvilinear surfaces, as confirmed by experimental and theoretical studies. In vivo, neural mapping experiments on feline animal models illustrate one mode of use for this class of technology. These concepts provide new capabilities for implantable and surgical devices.
Arrays of electrodes for recording and stimulating the brain are used throughout clinical medicine and basic neuroscience research, yet are unable to sample large areas of the brain while maintaining ...high spatial resolution because of the need to individually wire each passive sensor at the electrode-tissue interface. To overcome this constraint, we developed new devices that integrate ultrathin and flexible silicon nanomembrane transistors into the electrode array, enabling new dense arrays of thousands of amplified and multiplexed sensors that are connected using fewer wires. We used this system to record spatial properties of cat brain activity in vivo, including sleep spindles, single-trial visual evoked responses and electrographic seizures. We found that seizures may manifest as recurrent spiral waves that propagate in the neocortex. The developments reported here herald a new generation of diagnostic and therapeutic brain-machine interface devices.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Cerebrocortical injuries, such as stroke, are a major source of disability. Maladaptive consequences can result from post-injury local reorganization of cortical circuits. For example, epilepsy is a ...common sequela of cortical stroke, yet mechanisms responsible for seizures following cortical injuries remain unknown. In addition to local reorganization, long-range, extra-cortical connections might be critical for seizure maintenance. Here we report in rats the first evidence that the thalamus – a structure remote from but connected to the injured cortex – is required to maintain cortical seizures. Thalamocortical neurons connected to the injured epileptic cortex undergo changes in HCN channel expression and become hyperexcitable. Targeting these neurons with a closed-loop optogenetic strategy demonstrates that reducing their activity in real-time is sufficient to immediately interrupt electrographic and behavioral seizures. This approach is of therapeutic interest for intractable epilepsy, since it spares cortical function between seizures, in contrast to existing treatments such as surgical lesioning or drugs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Thalamic relay neurons have well-characterized dual firing modes: bursting and tonic spiking. Studies in brain slices have led to a model in which rhythmic synchronized spiking (phasic firing) in a ...population of relay neurons leads to hyper-synchronous oscillatory cortico-thalamo-cortical rhythms that result in absence seizures. This model suggests that blocking thalamocortical phasic firing would treat absence seizures. However, recent in vivo studies in anesthetized animals have questioned this simple model. Here we resolve this issue by developing a real-time, mode-switching approach to drive thalamocortical neurons into or out of a phasic firing mode in two freely behaving genetic rodent models of absence epilepsy. Toggling between phasic and tonic firing in thalamocortical neurons launched and aborted absence seizures, respectively. Thus, a synchronous thalamocortical phasic firing state is required for absence seizures, and switching to tonic firing rapidly halts absences. This approach should be useful for modulating other networks that have mode-dependent behaviors.
•TC output is synchronized, phasic, and rhythmic during spontaneous SWDs•Unilaterally toggling TC phasic spiking via eNpHR induces bilateral SWDs•Unilaterally toggling TC tonic spiking via SSFO bilaterally aborts SWDs•Unilaterally suppressing TC output via eNpHR bilaterally shortens SWDs
Here Sorokin et al. investigate the roles of phasic and tonic firing modes of thalamocortical relay cells in absence epilepsy and discover that unilaterally toggling TC phasic firing initiates bilateral absence seizures, while switching to tonic aborts seizures in real time.
Ethylene vinyl acetate (EVA) composites, including two different carbonaceous conductive fillers, carbon black (CB) and commercially available graphene (G), were fabricated by solvent-casting and ...melt compounding methods. The effect of additives and process conditions on electrical and thermal properties of composites was investigated. The dielectric responses of EVA composites were characterized by a percolation threshold of 15 wt % for EVA/G prepared by solvent-casting. However, as the EVA/G15% was also subsequently extruded, the applied shear stress induced by extrusion caused deterioration of the electrical network and reduced the composite's electrical conductivity. A percolating network was found for the EVA composites containing CB at around 5–7 wt % with 10 orders of magnitude increase in electrical conductivity with respect to the neat EVA. The thermal conductivity of EVA/CB7% and EVA/G15% increased 16 and 22% respectively, in comparison to the neat EVA. Both additives increased the electrical and thermal conductivity of composites to be appropriate as jackets for high-voltage cables.
•Electrical and thermal conductivity of EVA composites with two conductive additives were investigated.•A percolation threshold was characterized by broadband spectroscopy for EVA/G at 15% filler content.•EVA composites with CB filler was found to be conductive at 7 wt% CB filler content.•Addition of graphene and carbon black enhanced the thermal conductivity and dynamic mechanical properties of the composite.
The work of Berezinskii, Kosterlitz and Thouless in the 1970s
revealed exotic phases of matter governed by the topological properties of low-dimensional materials such as thin films of superfluids ...and superconductors. A hallmark of this phenomenon is the appearance and interaction of vortices and antivortices in an angular degree of freedom-typified by the classical XY model-owing to thermal fluctuations. In the two-dimensional Ising model this angular degree of freedom is absent in the classical case, but with the addition of a transverse field it can emerge from the interplay between frustration and quantum fluctuations. Consequently, a Kosterlitz-Thouless phase transition has been predicted in the quantum system-the two-dimensional transverse-field Ising model-by theory and simulation
. Here we demonstrate a large-scale quantum simulation of this phenomenon in a network of 1,800 in situ programmable superconducting niobium flux qubits whose pairwise couplings are arranged in a fully frustrated square-octagonal lattice. Essential to the critical behaviour, we observe the emergence of a complex order parameter with continuous rotational symmetry, and the onset of quasi-long-range order as the system approaches a critical temperature. We describe and use a simple approach to statistical estimation with an annealing-based quantum processor that performs Monte Carlo sampling in a chain of reverse quantum annealing protocols. Observations are consistent with classical simulations across a range of Hamiltonian parameters. We anticipate that our approach of using a quantum processor as a programmable magnetic lattice will find widespread use in the simulation and development of exotic materials.
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