Journal ArticleDOI
Intracerebral dipole sources of EEG FFT power maps
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TLDR
The described method opens a way to compute intracerebral source localizations of ongoing EEG activity by constructing a sine-cosine diagram of the Fourier-transformed data, which is the least error compromise landscape of all possible landscapes during the paradigmatic cycle of the given FFT frequency.Abstract:
The described method opens a way to compute intracerebral source localizations of ongoing EEG activity. A sine-cosine diagram of the Fourier-transformed data is constructed for each frequency point, forming a "FFT constellation" of entries. Into the FFT constellation of each diagram, a straight line is fitted which produces the least squared deviation sum between the original entry positions and their orthogonal projections onto that line. The map landscape described by the voltages between the projected positions ("FFT approximation") is the least error compromise landscape of all possible landscapes during the paradigmatic cycle of the given FFT frequency. The map thus constructed can be used in the usual dipole source localization procedures. There is one for each FFT frequency point. The squared forward solution of the fitted dipole source and the squared FFT approximation map are "power maps" which are very similar to the original power map. For an average-reference power map with two peaks, the source tends to lie between the peaks; a power map with one peak might show closely neighboring maximal and minimal potential values in the FFT approximation, indicative of a tangential source close to the surface.read more
Citations
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Journal ArticleDOI
Human auditory steady-state responses.
TL;DR: Auditory steady-state responses are generated throughout the auditory nervous system, with cortical regions contributing more than brainstem generators to responses at lower modulation frequencies, and are useful for objectively evaluating auditory thresholds, assessing suprathreshold hearing, and monitoring the state of arousal during anesthesia.
Journal ArticleDOI
Discrimination of Alzheimer's disease and mild cognitive impairment by equivalent EEG sources: a cross-sectional and longitudinal study.
TL;DR: It is concluded that localization and amplitude of equivalent EEG sources could be promising markers of early Alzheimer's disease and healthy aging.
Journal ArticleDOI
Intracerebral sources of human auditory steady-state responses.
Anthony T. Herdman,Otavio G. Lins,Patricia Van Roon,David R. Stapells,Michael Scherg,Terence W. Picton +5 more
TL;DR: The results suggest that the whole auditory nervous system is activated by modulated tones, with the cortex being more sensitive to slower modulation frequencies.
Book ChapterDOI
Electroencephalography and high-density electrophysiological source localization
TL;DR: In 1924, Hans Berger, a German psychiatrist, performed the first electroencephalographic recording in humans and was among the first to suggest that the periodic fluctuations of the human EEG may be associated with mental processes, including arousal, memory, and consciousness.
Journal ArticleDOI
3D statistical parametric mapping of EEG source spectra by means of variable resolution electromagnetic tomography (VARETA)
Jorge Bosch-Bayard,Pedro A. Valdes-Sosa,Trinidad Virues-Alba,Eduardo Aubert-Vazquez,E. Roy John,Thalía Harmony,J. Riera-Diaz,Nelson J. Trujillo-Barreto +7 more
TL;DR: A new method for 3D QEEG tomography in the frequency domain using a variant of Statistical Parametric Mapping is presented for source log spectra and the statistical issues involved are addressed by the use of extreme value statistics.
References
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Journal ArticleDOI
Reference-free identification of components of checkerboard-evoked multichannel potential fields
TL;DR: A method is proposed to determine components of evoked scalp potentials, in terms of times of occurrence (latency) and location on the scalp (topography), suggesting a stable localization of the generating process in depth.
Journal ArticleDOI
Evoked dipole source potentials of the human auditory cortex
Michael Scherg,D.Y. von Cramon +1 more
TL;DR: The normal dipole source potentials in the intact hemisphere fully explained scalp distributions in these patients, and presence of late dipole sources potentials, which were delayed by 20-30 msec, probably reflected cortical activation via commissural fibres.
Journal ArticleDOI
Tonotopic organization of the human auditory cortex revealed by transient auditory evoked magnetic fields.
Christo Pantev,Manfried Hoke,Klaus Lehnertz,Bernd Lütkenhöner,George Anogianakis,W. Wittkowski +5 more
TL;DR: The tonotopic organization of the human auditory cortex has been investigated by systematic measurements of magnetic fields evoked by tone-bursts with carrier frequencies of 250, 500, 1000, 2000 and 4000 Hz and suggest that the equivalent current dipoles of both the 100m and the 160m component are located in the transverse temporal gyri.
Journal ArticleDOI
Evaluation of Methods for Three-Dimensional Localization of Electrical Sources in the Human Brain
TL;DR: The results establish the technical feasibility of finding equivalent dipoles in the visual cortex for human visually evoked scalp potentials (VESP's), as well as the potential for the detection of multiple sources.