ABSTRACT
This paper describes a data-driven Decision Support System for Electroencephalography (EEG) signals acquisition, and parallel elaboration based on the integration of an Ambient Intelligent (AmI) [1] platform and a GRID enabled Infrastructure. The paper explores the analysis and design of the environment, the real-time data acquisition, the integration of the acquired data in dedicated EHR, and the EEG processing through parallel analysis algorithm available on the GRID infrastructure. After an overview of background concepts, the paper presents a brief description of the environment architecture, and a detailed analysis of the EEG algorithm. The challenge of the work presented is to effectively show how medical data can be shared and processed by exploiting the resources and capabilities of both the AmI platform and the GRID infrastructure. This particular Decision Support System, shows how it is possible to improve patient safety, quality of care, and efficiency in healthcare delivery.
Subject(s)
Algorithms , Decision Making, Computer-Assisted , Electroencephalography/instrumentation , Electroencephalography/methods , Signal Processing, Computer-Assisted/instrumentation , HumansSubject(s)
Brain Mapping , Down Syndrome/physiopathology , Evoked Potentials, Somatosensory , Hemiplegia/physiopathology , Myoclonic Epilepsies, Progressive/physiopathology , Adolescent , Adult , Aged , Child , Child, Preschool , Female , Fragile X Syndrome/physiopathology , Humans , Male , Median Nerve/physiology , Middle Aged , Reaction Time/physiology , Scalp , SoftwareABSTRACT
1. The inward rectification induced by membrane hyperpolarization was studied in adult guinea-pig rods by the perforated-patch-clamp technique. 2. CsCl blocked the rectification observed in both voltage- and current-clamp recordings at voltages negative to -60 mV, while BaCl2 blocked the inward relaxation observed at voltages positive to -60 mV. The current activated at -90 mV had a low selectivity between sodium and potassium and reversed at -31.0 mV. 3. These observations suggest that two inward rectifiers are present in guinea-pig rods: a hyperpolarization-activated (Ih) and a hyperpolarization-deactivated (Ikx) current. The functional roles of Ih and Ikx were evaluated by stimulating rods with currents sinusoidally modulated in time. 4. Rods behave like bandpass amplifiers, with a peak amplification of 1.5 at about 2 Hz. For hyperpolarizations that mainly gate Ikx, amplification and phase shifts are fully accounted for by a rod membrane analogue model that includes an inductance. For hyperpolarizations that also gate Ih, a harmonic distortion became apparent. 5. Bandpass filtering and amplification of rod signals, associated with Ih and Ikx gating by membrane hyperpolarization, are strategically located to extend, beyond the limits imposed by the slow phototransductive cascade, the temporal resolution of signals spreading to the rod synapse.
Subject(s)
Potassium Channels, Inwardly Rectifying , Retinal Rod Photoreceptor Cells/physiology , Animals , Barium/pharmacology , Cell Membrane/physiology , Cesium/pharmacology , Chlorides/pharmacology , Electric Stimulation , Guinea Pigs , Ion Channel Gating/drug effects , Ion Channel Gating/physiology , Membrane Potentials/drug effects , Models, Biological , Patch-Clamp Techniques , Potassium Channels/physiology , Tetraethylammonium/pharmacology , Time FactorsABSTRACT
A simple method for the quantitative description of sleep microstructure is proposed. This method is based on the computation of descriptors which provide a normalized measure of how the amplitude of the activity in a frequency band differs, at a given instant, from its background. The use of these descriptors makes it possible to identify epochs of transient increase in band activity, to measure their length, and to measure the time distance between two successive epochs.
Subject(s)
Electroencephalography/methods , Models, Neurological , Sleep/physiology , Adult , Humans , PeriodicityABSTRACT
A quantitative method was applied in order to assess variations in EEG activities during sleep. Three classes of variations were distinguished: variations connected with sleep-stage changes (class 1), higher-frequency variations described by the envelope of frequency-band activities (class 2), intermediate-frequency variations, corresponding to periods from 4 to 120 s (class 3). For each class, parameters characterizing the frequency spectra were computed. These parameters were mathematically simple and clear in their meaning, since they measured power, modulation index and mean squared frequency. A statistical comparison of the mean values of the parameters during different sleep stages evidenced a certain number of significant shifts in each of the three classes. The most important class-1 and class-2 variations were described by our parameters with high levels of significance. The results obtained for class 3 were in agreement with visual observations reported in the literature, such as the progressive increase in the interval between successive arousals from sleep onset to Stage 4 and the frequent occurrence of cyclic alternating patterns during Stage 2 epochs immediately preceding REM sleep.
ABSTRACT
The interhemispheric relationship during sleep in elderly subjects was studied throughout the night by a minute-by-minute computation of two linear correlation coefficients between right and left EEG activities. One of these coefficients (X delta) related to the 1-4-Hz band activity, and the other (X sigma) to the 12.5-14.5-Hz band activity. For five of the six subjects examined, it was found that the rapid-eye-movement (REM) mean values of both coefficients were significantly different from the nonrapid-eye-movement (NREM) values. A comparison between this elderly group and a control group of young subjects, examined previously, did not reveal any significant shift, either for the REM or for the NREM mean values of the coefficients.
Subject(s)
Aging/physiology , Brain/physiology , Sleep, REM/physiology , Aged , Electroencephalography , Humans , Methods , Middle AgedABSTRACT
EEG signals were recorded in 11 normal subjects from F4-C4, F3-C3, P4-O2 and P3-O1 during both stage 2 and the REM stage of each NREM/REM cycle. The logarithm of the right/left ratio for the power in the range of the various frequency bands showed a prevalent right-side asymmetry only with the fronto-central derivations. This trend, observed for all frequency bands, remained stable over the various NREM/REM cycles with the exception of the last one. These data indirectly support the hypothesis that the right hemisphere is more heavily involved in dreaming than the left, and suggest a prevalent involvement of the anterior regions.
Subject(s)
Sleep/physiology , Adult , Autoanalysis , Electroencephalography , Humans , Male , Reference Values , Sleep, REM/physiologyABSTRACT
The correlation coefficients between left and right activity in the various frequency bands of the EEG signal were computed during sleep for 11 normal adults. The values of the correlation during REM sleep were compared with those for NREM sleep. This comparison was performed 'locally,' i.e., during each period of the REM-NREM cycle, as well as over the whole night. For 9 out of the 11 examined subjects, both a visual comparison with the hypnogram and a statistical analysis showed the existence of cyclic variations during the night in the delta and/or sigma correlation coefficient. These variations lasted for the whole night and were synchronized with the REM-NREM cycle. A possible connection between these results and data on the interhemispheric relationship given by amplitude analysis is briefly discussed.
