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Scalp electric potentials (electroencephalogram; EEG) are contingent to the impressed current density unleashed by cortical pyramidal neurons undergoing post-synaptic processes. EEG neuroimaging consists of estimating the cortical current density from scalp recordings. We report a solution to this inverse problem that attains exact localization: exact(More)
STUDY OBJECTIVES Functional significance of stage 2 sleep spindle activity for declarative memory consolidation. DESIGN Randomized, within-subject, multicenter. SETTING Weekly sleep laboratory visits, actigraphy, and sleep diary (4 weeks). PARTICIPANTS Twenty-four healthy subjects (12 men) aged between 20 and 30 years. INTERVENTIONS Declarative(More)
Event-related potentials (ERPs) were recorded at 17 leads in an auditory oddball paradigm in 172 normal healthy subjects aged between 20 and 88 years. With advancing age, N1 latency increased parietally (0.12 ms/year), P2 latency increased frontally (0.34 ms/ year) and N2 and P300 latencies increased all over the scalp (0.37 ms/year for N2; 0.92 ms/year for(More)
Analyses of scalp-recorded sleep spindles have demonstrated topographically distinct slow and fast spindle waves. In the present paper, the electrical activity in the brain corresponding to different types of sleep spindles was estimated by means of low-resolution electromagnetic tomography. In its new implementation, this method is based on realistic head(More)
Topographic brain mapping of the electroencephalogram (EEG) is a promising new method in neuropsychiatry and neuropsychopharmacology. Rapid advances in computer technology allow on-line analysis by means of micro-computers. This paper describes an acquisition and signal analysis system for studying neurophysiological and neuropsychopharmacological aspects(More)
The P300 event-related potential (ERP) is considered to be closely related to cognitive processes. In normal aging, P300 scalp latencies increase, parietal P300 scalp amplitudes decrease and the scalp potential field shifts to a relatively more frontal distribution. Based on ERPs recorded in 172 normal healthy subjects aged between 20 and 88 years in an(More)
The application of an automatic sleep spindle detection procedure allowed the documentation of the topographic distribution of spindle characteristics, such as number, amplitude, frequency and duration, as a function of sleep depth and of recording time. Multichannel all-night EEG recordings were performed in 10 normal healthy subjects aged 20-35 years.(More)
Studies of psychiatric disorders have traditionally focused on emotional symptoms such as depression, anxiety and hallucinations. However, poorly controlled cognitive deficits are equally prominent and severely compromise quality of life, including social and professional integration. Consequently, intensive efforts are being made to characterize the(More)
The paper describes a reliable and valid method for the automatic detection of sleep spindles in whole night polygraphy. The recording of a multi-channel EEG during sleep polysomnography was performed in 10 healthy volunteers aged 20-35 years. This objective method should improve the time-consuming and subjective visual evaluation by increasing the accuracy(More)
The topographic distributions of absolute delta and theta powers were used to classify demented patients and normals by means of z statistics, discriminant analysis and artificial neural networks (NN). The data were taken from two psychopharmacological studies in mildly to moderately demented patients (111 and 96 patients for studies I and II, respectively)(More)