Interrelationships of EEG spectral analysis, visual EP and photic driving between subjects

290

J. Gruzelier, rd. / Psychophysiologv

Socre~ uhstracts, 1984

An alternate definition of component considers the topographical structure of the fields and disregards amplitude as absolute strength of the signal may be irrelevant for functional significance. Different field configurations mean different generator populations. Accordingly, a sequence of field maps indicates a new component, when the locations of the major characteristics (i.e. minimal and maximal values) change.

THE RELATION BETWEEN THE BRAIN’S RESPONSE SUSCEPTIBILITY AND SPONTANEOUS ACTIVITY Erol BASAR Medical Unic’ersity Luheck, Institute of Ph_vsdogy,

Lubeck. F. R. G

Several different nomenclature systems have evolved for denoting brain evoked potential components. Usually, a number of components have been labelled according to their polarity (N or P) and/or their ordinal position in the particular sequence under investigation. The major waves of the auditory evoked potentials are usually called, P50, NlOO, P170 and N200. Unfortunately, there does not exist any classification of evoked potentials which is based’on the state of EEG prior to sensory stimulation. In our earlier studies we were able to show a fundamental relation between EEG prior to stimulation and the event-related potentials by studying single sets of EEG-EP recordings and by comparing their characteristics in frequency and time domains by using a combined analysis procedure of EEG and evoked potentials. By using this procedure it has been possible to show that the waves P50, NlOO, P170 and N200 reflect mainly enhanced alpha, theta and delta activities of the brain in the 2215 Hz frequency range. The middle latency components reflected mostly enhancement of the 40 Hz activity. Accordingly, in order to decide objectively on the existence of event-related response components in the brain potential records we suggest performing an analysis of EEG activity prior to stimulation, especially in psychophysiological experiments where the background activity (especially the alpha activity) can be drastically changed due to emotion, motivation, attention or pain.

INTERRELATIONSHIPS OF EEG SPECTRAL ANALYSIS, AND PHOTIC DRIVING BETWEEN SUBJECTS

VISUAL

J.F. GOLDING Clinical Psychopharmcrcologv

Unit, The Medical School, Uniuersiry of Newcmrle

upon Tyne, U.K

EP

J. Gruzelier, ed. / Psychophysiolo~

Socwty abstracts, I984

291

EEG (spectral analysis; eyes open and closed), visual (flash) EP and photic driving at 16 and 26 Hz were investigated in young healthy student volunteers (n = 45). The d ata was reduced to 13 variables and factor analysis carried out (SPSS variation rotated). A five factor description was produced. FACTOR 1: Reactivity alpha, reactivity (alpha)/(delta + theta), (alpha)/(delta + theta); FACTOR 2: VEP latencies Pl, Nl, P2, VEP amplitude PlNl; FACTOR 3: VEP amplitudes NlP2, and PlNl, dominant alpha frequency; FACTOR 4; Reactivity (beta 2)/(beta efficiencies 16 Hz and 26 Hz, reactivity (alpha)/(delta + theta). Within the limitations of between ~ subject variation and over ranges of ‘moderate situational arousal’ it is suggested: (a) That systematic relationships exist between some electrocortical measures; (b) that the majority of these relationships are consistent in ‘direction’, forming ‘arousal-arousability’ dimensions; (c) that, by default, no support is offered to the concept of a unitary electrocortical ‘arousal-arousability’ dimension.

TIME SERIES ANALYSIS Chairman:

R.I. KITNEY

Contributors R.J. KITNEY SAMPLING AND SPECTRAL ESTIMATION R.E. CHALLIS CORRELATION, CONVOLUTION AND FILTERING R. E. CHALLIS TWO CASE STUDIES: EPs and GUT EMG H. TALHAMI . ANALYSIS OF BLOOD VELOCITY WAVEFORMS M. HATHORN RESPIRATORY OSCILLATIONS IN THE NEWBORN R.I. KITNEY ANALYSIS OF HEART RATE VARIABILITY AND BLOOD PRESSURE