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CEAN-computerized EEG analysis
Electroencephalography and Clinical Neurophysiology, 1 9 7 7 , 4 2 : 7 4 1 - - 7 4 3
741
© E l s e v i e r / N o r t h - H o l l a n d Scientific Publishers Ltd.
BOOK REVIEWS edited by H. PETSCHE
and J O H N
R. HUGHES
CEAN-computerized EEG analysis; --Dolce, G. and Kiinkel, H. (editors), (Gustav Fischer-Verlag, Stuttgart, 1975, 466 p., 40 Tables, 267 Fig. DM 120.--) In April 1974 a s y m p o s i u m was held in K r o n b e r g , Germany, around the subject of quantitative EEG analysis with t h e goal to survey the field a n d assess its status. Participants, c o m i n g f r o m E u r o p e a n d USA, were invited to t h e s y m p o s i u m a n d asked to p r e s e n t w r i t t e n papers in advance. T h e m a j o r p a r t of the 2.5 days was d e v o t e d to discussions a r o u n d these papers. This is r e f l e c t e d in the m o n o g r a p h w h i c h c o n t a i n s , a p a r t f r o m 32 papers, edited e x t r a c t s f r o m t h e discussions. This, I t h i n k , greatly adds to t h e value o f t h e book. In a review it seems a d v a n t a g e o u s to discuss t h e c o n t e n t in t h e f o l l o w i n g categories: E E G activity, e q u i p m e n t , d a t a processing a n d applications. T h e e m p h a s i s is o n d a t a processing a n d a p p l i c a t i o n s b u t c o n s i d e r a b l e i n f o r m a t i o n is also given o n t h e o t h e r items. It is n a t u r a l t h a t the s t a t i o n a r y E E G activity plays a d o m i n a n t role, o n w h i c h various f o r m s o f spectral analysis are based. Several papers also deal with transient and non-stationary phenomena and a few e x a m p l e s are given of e v o k e d p o t e n t i a l s . In c o n n e c t i o n s w i t h r e c o r d i n g EEG signals t h e t e c h n i q u e s o f dealing w i t h a r t e f a c t s a n d e q u i p m e n t defects are essential, a n d valuable c o m m e n t s are given in several papers. It is i n t e r e s t i n g to see t h a t m o s t o f the analysis were carried o u t o n r e a s o n a b l y sized m i n i c o m p u t e r installations. In c e r t a i n cases this has b e e n c o m b i n e d w i t h analogue e q u i p m e n t to m a k e it a h y b r i d installation. O n data processing m o s t e f f o r t was s p e n t o n spectral analysis, w h e r e we find Fast F o u r i e r T r a n s f o r m ( F F T ) , applied filtering t e c h n i q u e , interval analysis, analysis w i t h p a r a m e t r i c m o d e l s a n d analysis o f spectral m o m e n t s . The use o f F F T is very well established in m o s t research groups a n d it is t o d a y standard t e c h n i q u e for E E G analysis. Several impressive a p p l i c a t i o n s were r e p o r t e d . Interval analysis is t h e c o m p e t i n g t e c h n i q u e ; it m a y be simpler t o implem e n t o n a c o m p u t e r a l t h o u g h it is inferior f r o m a t h e o r e t i c a l p o i n t o f view. It has f o u n d p a r t i c u l a r a p p l i c a t i o n in p s y c h o - p h a r m a c o l o g i c a l research. Spectral analysis b y m e a n s o f p a r a m e t r i c (autoregressive) m o d e l s is applied in o n e p a p e r for m u l t i c h a n n e l analysis. T h e e x t r a c t i o n of spectral m o m e n t s p r o p o s e d b y
H j o r t h has several s u p p o r t e r s . T h e review of this technique, its possibilities a n d l i m i t a t i o n s is a valuable c o n t r i b u t i o n to t h e s y m p o s i u m . T h e s t a t i o n a r i t y r e q u i r e m e n t s i m p o s e d by spectral analysis c o n c e r n several p a r t i c i p a n t s and we find here, I t h i n k , the b e g i n n i n g o f a n e w b r a n c h of E E G analysis. I n t e r e s t i n g c o n t r i b u t i o n s are given o n analysing changes in s p e c t r a l p r o p e r t i e s a n d o n d e t e c t i o n o f spikes. A n o t h e r m e t h o d o l o g i c a l field o f increasing i n t e r e s t is m u l t i v a r i a n t analysis applied for diagnostic p u r p o s e s a n d p a t t e r n r e c o g n i t i o n . Several r e a d a b l e c o n t r i b u t i o n s are r e p o r t e d . C o m p u t e r analysis p r o d u c e s a lot o f d a t a and the p r e s e n t a t i o n o f results is a n essential item. We see e x a m p l e s o f t h r e e - d i m e n s i o n a l spectral plots a n d t o p o g r a p h i c p l o t s o f s p e c t r a a n d p o t e n t i a l fields. A large n u m b e r o f a p p l i c a t i o n s were d e a l t w i t h and n o t all can be m e n t i o n e d . Several investigations were r e p o r t e d o n t h e n e u r o p h y s i o l o g i c a l m e c h a n i s m s o f g e n e r a t i o n o f E E G , w h i c h I t h i n k is a n essential s u b j e c t for f u t u r e d e v e l o p m e n t o f E E G analysis. T h e r e l a t i o n b e t w e e n E E G a n d changes in physiological variables is discussed in m a n y papers. A good a n d r e a d a b l e survey is given o f E E G analysis applied to the s t u d y o f p s y c h i a t r y a n d b e h a v i o u r a l states (in particular schizophrenia) and to psychopharmacology. Epilepsy a n d sleep E E G are fields w h e r e E E G analysis has b e e n applied w i t h success. Much m o r e difficult is its use for clinical purposes. T h e v o l u m e c o n t a i n s six p a p e r s d e v o t e d to this s u b j e c t ; p r o m i s i n g progress b e i n g r e p o r t e d . T o e n t e r the field d o E E G analysis f r o m an engineering p o i n t o f view has its points. T h e r e is still m u c h m i s u n d e r s t a n d i n g a b o u t data processing m e t h o d o l o g y a m o n g t h o s e clinically t r a i n e d b u t t h e situat i o n steadily improves. In this respect I find t h e discussions valuable. T h e s y m p o s i u m m o n o g r a p h gives valuable i n f o r m a t i o n b o t h for engineers and neurophysiologists and I feel t h a t it m a y serve t h e p u r p o s e , o f b e c o m i n g a r e f e r e n c e m a n u a l o n t h e s u b j e c t , for w h i c h t h e e d i t o r s i n t e n d e d it.
L.H. Z E T T E R B E R G The Royal Institute of Technology, Stockholm (Sweden)
741
© E l s e v i e r / N o r t h - H o l l a n d Scientific Publishers Ltd.
BOOK REVIEWS edited by H. PETSCHE
and J O H N
R. HUGHES
CEAN-computerized EEG analysis; --Dolce, G. and Kiinkel, H. (editors), (Gustav Fischer-Verlag, Stuttgart, 1975, 466 p., 40 Tables, 267 Fig. DM 120.--) In April 1974 a s y m p o s i u m was held in K r o n b e r g , Germany, around the subject of quantitative EEG analysis with t h e goal to survey the field a n d assess its status. Participants, c o m i n g f r o m E u r o p e a n d USA, were invited to t h e s y m p o s i u m a n d asked to p r e s e n t w r i t t e n papers in advance. T h e m a j o r p a r t of the 2.5 days was d e v o t e d to discussions a r o u n d these papers. This is r e f l e c t e d in the m o n o g r a p h w h i c h c o n t a i n s , a p a r t f r o m 32 papers, edited e x t r a c t s f r o m t h e discussions. This, I t h i n k , greatly adds to t h e value o f t h e book. In a review it seems a d v a n t a g e o u s to discuss t h e c o n t e n t in t h e f o l l o w i n g categories: E E G activity, e q u i p m e n t , d a t a processing a n d applications. T h e e m p h a s i s is o n d a t a processing a n d a p p l i c a t i o n s b u t c o n s i d e r a b l e i n f o r m a t i o n is also given o n t h e o t h e r items. It is n a t u r a l t h a t the s t a t i o n a r y E E G activity plays a d o m i n a n t role, o n w h i c h various f o r m s o f spectral analysis are based. Several papers also deal with transient and non-stationary phenomena and a few e x a m p l e s are given of e v o k e d p o t e n t i a l s . In c o n n e c t i o n s w i t h r e c o r d i n g EEG signals t h e t e c h n i q u e s o f dealing w i t h a r t e f a c t s a n d e q u i p m e n t defects are essential, a n d valuable c o m m e n t s are given in several papers. It is i n t e r e s t i n g to see t h a t m o s t o f the analysis were carried o u t o n r e a s o n a b l y sized m i n i c o m p u t e r installations. In c e r t a i n cases this has b e e n c o m b i n e d w i t h analogue e q u i p m e n t to m a k e it a h y b r i d installation. O n data processing m o s t e f f o r t was s p e n t o n spectral analysis, w h e r e we find Fast F o u r i e r T r a n s f o r m ( F F T ) , applied filtering t e c h n i q u e , interval analysis, analysis w i t h p a r a m e t r i c m o d e l s a n d analysis o f spectral m o m e n t s . The use o f F F T is very well established in m o s t research groups a n d it is t o d a y standard t e c h n i q u e for E E G analysis. Several impressive a p p l i c a t i o n s were r e p o r t e d . Interval analysis is t h e c o m p e t i n g t e c h n i q u e ; it m a y be simpler t o implem e n t o n a c o m p u t e r a l t h o u g h it is inferior f r o m a t h e o r e t i c a l p o i n t o f view. It has f o u n d p a r t i c u l a r a p p l i c a t i o n in p s y c h o - p h a r m a c o l o g i c a l research. Spectral analysis b y m e a n s o f p a r a m e t r i c (autoregressive) m o d e l s is applied in o n e p a p e r for m u l t i c h a n n e l analysis. T h e e x t r a c t i o n of spectral m o m e n t s p r o p o s e d b y
H j o r t h has several s u p p o r t e r s . T h e review of this technique, its possibilities a n d l i m i t a t i o n s is a valuable c o n t r i b u t i o n to t h e s y m p o s i u m . T h e s t a t i o n a r i t y r e q u i r e m e n t s i m p o s e d by spectral analysis c o n c e r n several p a r t i c i p a n t s and we find here, I t h i n k , the b e g i n n i n g o f a n e w b r a n c h of E E G analysis. I n t e r e s t i n g c o n t r i b u t i o n s are given o n analysing changes in s p e c t r a l p r o p e r t i e s a n d o n d e t e c t i o n o f spikes. A n o t h e r m e t h o d o l o g i c a l field o f increasing i n t e r e s t is m u l t i v a r i a n t analysis applied for diagnostic p u r p o s e s a n d p a t t e r n r e c o g n i t i o n . Several r e a d a b l e c o n t r i b u t i o n s are r e p o r t e d . C o m p u t e r analysis p r o d u c e s a lot o f d a t a and the p r e s e n t a t i o n o f results is a n essential item. We see e x a m p l e s o f t h r e e - d i m e n s i o n a l spectral plots a n d t o p o g r a p h i c p l o t s o f s p e c t r a a n d p o t e n t i a l fields. A large n u m b e r o f a p p l i c a t i o n s were d e a l t w i t h and n o t all can be m e n t i o n e d . Several investigations were r e p o r t e d o n t h e n e u r o p h y s i o l o g i c a l m e c h a n i s m s o f g e n e r a t i o n o f E E G , w h i c h I t h i n k is a n essential s u b j e c t for f u t u r e d e v e l o p m e n t o f E E G analysis. T h e r e l a t i o n b e t w e e n E E G a n d changes in physiological variables is discussed in m a n y papers. A good a n d r e a d a b l e survey is given o f E E G analysis applied to the s t u d y o f p s y c h i a t r y a n d b e h a v i o u r a l states (in particular schizophrenia) and to psychopharmacology. Epilepsy a n d sleep E E G are fields w h e r e E E G analysis has b e e n applied w i t h success. Much m o r e difficult is its use for clinical purposes. T h e v o l u m e c o n t a i n s six p a p e r s d e v o t e d to this s u b j e c t ; p r o m i s i n g progress b e i n g r e p o r t e d . T o e n t e r the field d o E E G analysis f r o m an engineering p o i n t o f view has its points. T h e r e is still m u c h m i s u n d e r s t a n d i n g a b o u t data processing m e t h o d o l o g y a m o n g t h o s e clinically t r a i n e d b u t t h e situat i o n steadily improves. In this respect I find t h e discussions valuable. T h e s y m p o s i u m m o n o g r a p h gives valuable i n f o r m a t i o n b o t h for engineers and neurophysiologists and I feel t h a t it m a y serve t h e p u r p o s e , o f b e c o m i n g a r e f e r e n c e m a n u a l o n t h e s u b j e c t , for w h i c h t h e e d i t o r s i n t e n d e d it.
L.H. Z E T T E R B E R G The Royal Institute of Technology, Stockholm (Sweden)