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A method is proposed to determine components of evoked scalp potentials, in terms of times of occurrence (latency) and location on the scalp (topography). The scalp field distributions were evoked by checkerboard reversal and were recorded simultaneously in 47 channels. Component latencies are defined as times of maximal values of the electrical power of(More)
  • W Skrandies
  • 1998
According to the 'semantic differential technique' the affective meaning of words can be quantified in statistically defined, independent dimensions where every word is uniquely located on the three dimensions evaluation ('good-bad'), potency ('strong-weak'), and activity ('active-passive'). Two experiments were performed on a total of 52 adults: first, 162(More)
Steps in brain information processing are reflected on the scalp as changes of the electric potential which is evoked by the stimulus. However, for a given recording point on the scalp, there is no absolute amplitude or phase information of the electric brain potential. This means that the shape of an evoked potential waveform which is recorded from a given(More)
The perception of dynamic random-dot stereograms (RDS) depends on the physiological fusion of horizontally disparate binocular visual input. Thus, the use of RDS offers the possibility to study selectively cortical processing of visual information in man. We investigated the influence of horizontal disparity on the scalp topography of RDS evoked brain(More)
A group of 24 patients with Parkinson's disease (PD) with normal fundi and normal visual acuities was examined electrophysiologically. Checkerboard reversal VEPs and ERGs (P-ERGs) at various contrast levels as well as photopic and scotopic luminance ERGs were recorded and compared with an age-matched group of controls. Earlier reported latency increases of(More)
Scalp potential fields in human subjects were evoked by checkerboard reversals to the upper and lower hermiretinae, using 1.6 and 3.2 reversals/s. Averaged fields were sampled along a saggital midline row of electrodes (field profiles) in 20 subjects, and from a 47 electrode array (field maps) in five subjects. In five subjects, profile peaks and troughs(More)
Multichannel records of responses to large and small hemiretinal stimuli were obtained from 6 healthy subjects. Scalp distribution maps were constructed for all conditions at all post-stimulus times and component latencies were objectively determined by computing a reference-independent measure of field power. This procedure identified 2 components (at 100(More)
Electroencephalographic data recorded for topographical analysis constitute multidimensional observations, and the present paper illustrates methods of data analysis of multichannel recordings where components of evoked brain activity are identified quantitatively. The computation of potential field strength (Global Field Power, GFP) is used for component(More)
Eye movement-related brain activity was studied in 14 subjects by recording EEG topographically in 16 channels over the occipital brain areas. Potential fields obtained with or without the simultaneous presentation of a visual stimulus during the time course of horizontal saccades were compared. Without visual stimulation, eye movements were followed at a(More)
The affective meaning of words can be quantified statistically by the 'semantic differential technique'. We studied a total of 55 Chinese adults in two experiments: first, 210 nouns were rated by 32 subjects. Factor analysis on these data yielded three independent semantic dimensions. Semantically unique words were used in electrophysiological experiments(More)