The hypothesis that the brain works using glial-neuronal networks that are responsible for sensory, motor and cognitive processes has been proposed in the neuroscience literature. Graph theory offers mathematical models to describe these complex networks from simple abstractions such as nodes and connecting edges. In this work, using signal processing techniques to the analysis of functional connectivity between neuronal ensembles derived from EEG measurements through theory graph. Procedures for the analysis of connectivity are described, from multichannel record processing and conditioning, computation of wideband power spectral density, determination of connectivity measures between electrodes, and parameter estimation of the resulting complex networks. EEG recordings from fifty subjects were analyzed in intervals before (pre) and during repeated photostimulation (Rph). Based on the statistical significance of the response during Rph, desynchronization/synchronization (D/S) in alfa band, and its wide distribution in cortical areas, the participants were divided into three groups: G1 , G2 and G3. The slope D/S in alfa band was significant in 16 of 16 regions (G1), 12 of 16 (G2) and 5 of 16 (G3). The functional connectivity depicted the same trend as these changes, whereas in the delta, theta and beta bands occurred no modifications. D is related to activation and S with inhibition, supporting the hypothesis of alfa-band’s participation in the cognitive process of habituation to photostimulation.

A quasi-floating gate (QFG) “super-follower” is presented. The high resistance used by the QFG transistor is constructed by two diodes connected back-to-back, leading to a simple-, temperature-stable- and small-area solution. Expressions for the behavior of the follower are introduced and verified by circuit simulations in LTSPICE using 0.5[Formula: see text][Formula: see text]m CMOS process models, which show an improved performance of the proposed circuit with respect to the original super-follower. To prove the principle, a test cell was fabricated in the same 0.5[Formula: see text][Formula: see text]m CMOS technology and characterized. Measurement results show a gain-bandwidth product of 10[Formula: see text]MHz and power consumption of 120[Formula: see text][Formula: see text]W with a 1.5[Formula: see text]V single supply.

Background: Oscillations, action, and postsynaptic potentials in glial-neuronal ensembles integrate the spectral power (SP) of

In recent years, inverter-based sigma-delta ( ) modulators have received great attention as a suitable approach for the design of low-voltage, low-power, switched-capacitor . This method uses digital inverters as the active elements to construct the integrators in the loop. In some applications, a reduced silicon area implementation is an important constraint; this demands the use of only one inverter in the integrator. This paper proposes to use the common-source amplifier as the building block to achieve the operation of integration instead of the digital inverter. This leads to the operation of the amplifier in strong inversion combined with low-voltage supply and compact chip area. The idea was confirmed with a prototype fabricated in a 0.5-μm CMOS technology available through Metal Oxide Semiconductor Implementation Service (MOSIS). Using 250 kHz of sampling frequency, measurement results show a signal-to-noise and distortion ratio of 70 dB over a bandwidth of 125 Hz. The circuit consumes 38 μW when powered from a single 1.5-V supply voltage and uses 200 × 260 μm of active area. Circuit simulations in SPICE show the potential of this method to work with 450 mV of power supply in a 50-nm CMOS technology.Résumé-Au cours des dernières années, les modulateurs sigma-delta ( ) à onduleur ont reçu une grande attention comme une approche appropriée pour la conception de condensateur de commutation basse tension, basse puissance. Cette méthode utilise des onduleurs numériques comme éléments actifs pour construire les intégrateurs dans la boucle . Dans certaines applications, l'implémentation de la zone réduite du silicium est une contrainte importante; ceci exige l'utilisation, uniquement, d'un seul onduleur dans l'intégrateur. Cet article propose d'utiliser l'amplificateur source commune comme bloc de construction pour réaliser la fonction d'intégration au lieu de l'onduleur numérique. Cela conduit au fonctionnement de l'amplificateur en forte inversion combiné avec une alimentation basse tension et une zone compacte de la puce. L'idée a été confirmée avec un prototype fabriqué dans une technologie CMOS de 0,5-μm disponible par le biais de Metal Oxide Semiconductor Implementation Service (MOSIS). En utilisant 250 kHz de fréquence d'échantillonnage, les résultats de mesure montrent un rapport signal-bruit et une distorsion de 70 dB sur une bande passante de 125 Hz. Le circuit consomme 38 μW lorsqu'il est alimenté à partir d'une seule source d'alimentation de tension 1,5 V et utilise 200 × 260 μm de la zone active. Les simulations du circuit dans SPICE montrent le potentiel de cette méthode à fonctionner avec 450 mV de tension d'alimentation dans une technologie CMOS 50-nm.

Introduction. TBI is associated with alterations in cortico-subcortical connectivity. However, little attention has been paid to its clinical characteristics and functional connectivity in pediatric patients with chronic TBI. Objective. To evaluate the cognitive performance and spectral coherence of a group of children with TBI in non-acute phase. Method. Cross-sectional study of 15 children with chronic TBI and 17 healthy children. The Neuropsychological Assessment of Children (Evaluación Neuropsicológica Infantil, ENI) was used and the resting activity of the EEG with eyes-closed was recorded. Offline, two-second epochs of the EEG of each participant were chosen and the spectral coherence was estimated in a range of 1.6 to 30 Hz. The cognitive performance between groups was compared with T-test/Mann-Whitney U Test and MANOVA for the coherence values. Results. The TBI group showed a lower performance (p ≤ 0.05) in metalinguistic, visuospatial skills, attention, memory, non-verbal flexibility, planning, and organization. Differences (p ≤ 0.000) were found both inter and intrahemispherically in the spectral coherence between the groups, particularly on F1-F3 (95% CI: 0.543 - 0.557) over the whole frequency range and F3-C3 (95% CI: 0.503 - 0.515) in delta, theta, alpha2, and beta frequencies. Discussion and conclusión. Our findings suggest alterations of hypo and hyper functional connectivity, particularly on the frontal and parietal lobes of both hemispheres, even after several years of a TBI. It is possible that a subtle difference in the degree of connectivity is crucial in the genesis or successful development of attentional, mnesic, executive, and visuospatial processes.