The relation between monosynaptic spinal reflex amplitudes and some EEG alpha activity parameters

Tilburg University

The relation between monosynaptic spinal reflex amplitudes and some EEG alpha

activity parameters

van Boxtel, Anton

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Electroencephalography and clinical neurophysiology

Publication date:

1976

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Citation for published version (APA):

van Boxtel, A. (1976). The relation between monosynaptic spinal reflex amplitudes and some EEG alpha activity parameters. Electroencephalography and clinical neurophysiology, 40.

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© Elsevier S c i e n t i f i c P u b l i s h i n g C o m p a n y , A m s t e r d a m - - P r i n t e d in T h e N e t h e r l a n d s

THE R E L A T I O N BETWEEN MONOSYNAPTIC SPINAL R E F L E X AMPLITUDES AND SOME EEG ALPHA ACTIVITY PARAMETERS *

A. V A N B O X T E L

Tilburg University, Department of Psychology, Physiological Psychology Section, Tilburg (The Netherlands) ( A c c e p t e d for p u b l i c a t i o n : S e p t e m b e r 30, 1 9 7 5 )

It has been f o u n d t h a t in normal man the habituation is an adequate one, since it is reflex amplitude gradually decreases through- u n k n o w n whether the decrement exhibits o u t a series of continuously evoked spinal the parametric characteristics of habituation, t e n d o n (T) reflexes, when the subject is in as outlined for a variety of physiological and rest (Davis and Beaton 1968; Brunia 1971; behavioural responses by T h o m p s o n and Hollis 1971). The d e c r e m e n t was f o u n d to be Spencer (1966). It is u n k n o w n to w h a t e x t e n t stronger when the T reflexes were increased the decrement is of supraspinal origin. Neither by a sensori-motor task (Brunia 1971) or by Prosser and H u n t e r (1936) nor Spencer et al. a loud tone preceding each t e n d o n tap (Davis (1966) could observe depression of repetitive- and Beaton 1968). Coquery (1969) showed ly evoked m o n o s y n a p t i c reflexes in the spinal t h a t a warning sound in a reaction time ex- cat. Dimitrijevid and Nathan {1973), however, periment elevated the T reflex but t h a t the f o u n d a steady decrease of regularly elicited T elevation diminished during successive trials, reflexes in spinal man, and Farel et al. (1973) Clarke (1967a) f o u n d a facilitation of the T provided a model of m o n o s y n a p t i c depression reflex when the tap was preceded by 2 light in the isolated frog spinal cord, which con- flashes b u t no facilitation could be observed formed to the parametric relations character- when 30 flashes were given. Amplitude de- istic of habituation.

crease has also been f o u n d as the result of An argument against the T reflex decre- sustained muscular contraction. Clarke m e n t as a spinal process could be provided if (1967b) f o u n d t h a t a Jendrassik manoeuvre the reflex amplitude were to covary with had no effect on the T reflex when it was changes in activation at supraspinal level. Be- maintained during 10 sec preceding the ten- cause c o n c o m i t a n t variations in fusimotor and d o n tap, while a contraction of 1 sec duration cortical activity (von Euler and S~derberg had a facilitative effect. 1957; Buchwald and Eldred 1961; Hongo et These findings have in c o m m o n t h a t the al. 1963) exist, and since both are supposed T reflex is subject to a decrement with suc- to reflect the same activating reticular in- cessive trials that, according to some authors, fluences, we selected the EEG alpha activity m a y be called habituation and should be con- as an indication o f changes in supraspinal ac- sidered to be of supraspinal (reticular) origin, tivation. We hypothesized t h a t no T reflex de- One m a y question whether the concept of crement will be observed if the alpha param- eters remain constant. On the other hand a

* T h i s r e s e a r c h was s u p p o r t e d b y a g r a n t o f t h e change of alpha parameters, indicating a de-

2 9 8 A. V A N B O X T E L

Experiment 1 the recording electrodes the skin was grazed

over a very small surface to reduce the im- The first experiment investigated whether pedance.

stability of alpha parameters would corre- The r e f l e x p o t e n t i a l s w e r e a m p l i f i e d ( H e l l i g e spond with stability of T reflex amplitudes. EE pre-amplifiers, input impedance 10 M ~ , Nineteen normal students, males and females, =-3 dB at 16 c/sec and 1 kc/sec) and stored aged between 18 and 29 years, volunteered on magnetic tape. The peak-to-peak ampli- as subjects for this experiment, tudes of M, H and T were measured digitally

off-line and punched in paper tape. Method

EEG

Reflexes EEG alpha parameters of interest were am-

The experiments were performed in a plitude, frequency and % of time alpha was s o u n d p r o o f electrically shielded cubicle, with present (alpha index). In order to attain the control and recording apparatus located in stability of these parameters during a 40 min an adjacent room. The subjects were seated period the subjects received feedback a b o u t c o m f o r t a b l y with eyes closed in a specially the degree of alpha presence. Because Kreit- designed chair that had supports for head, man and Shaw (1965) showed that auditory arms and legs. Legs and feet were fixed while stimuli p r o d u c e neither enhancement nor sup- knees and ankle joints were flexed a b o u t 120 ° pression of alpha activity, auditory feedback,

and 100 ° respectively, administered by headphones, was chosen.

During 40 min Achilles t e n d o n (T) and The EEG was derived from Fp2--O2. The H o f f m a n n (H) reflexes were evoked simul- signal was amplified (Hellige EE, --3 dB at 5.3 taneously at the rate of 1/10 sec, according to and 35 c/sec), led to an analogue feedback cir- the m e t h o d of Paillard (1955). Higher stimulus cuit consisting of a bandpass filter (- 3 dB at frequencies were avoided to eliminate low fre- 8.3 and 12 c/sec, 20 dB d o w n / o c t a v e ) and an quency depression (Cook 1968; Hollis 1971). audio-oscillator, and recorded on magnetic Tendon taps were delivered b y an electromag- tape.

. . . . ,8 I I A M P L I T U D E I~ ,8 A M P L I T U D E ~.j ,8 A M P L I T U D E >~ ACHILLES TENDON R E F L E X >~ I DIRECT MOTOR R E S P O N S E H O F F M A N N R E F L E X i - i I i N , N i N z ,4 ', z ,4 bJ W I W o ; - ' o ; + . . . . J 0

I

ii

- , 4 , - . 4 I - ,4 - , 8 . - , 8 - , 8 t ] i i £ _ L ~ L , L I J_ £ ~ i I l L J J L l ~ l 2 3 4 5 6 7 8 1 2 3 Z,, 5 6 '7 8 1 2 3 4 5 6 7 8

PERIODS OF 5 MIN PERIODS OF 5 MIN PERIODS OF 5 MIN.

o b c

100 ~ - - . . . _[

9 0 ~ TIME A L P H A ACTIVITY ~ ,8 AMPLITUDE ] ~ ~ ,8 ! WAVE PERIOD

i P R E S E N T ~ A L P H A A C T I V I T Y >~ ! A L P H A ACTIVITY Z 80 L I I I N N 70 5 0 i 0 , ~. ~ " ' "~- 4 0 4 0 30 ~ -.4 - . 4 " 2 0 - [ 10 ~- i - . 8 - , 8 i / / 1 2 3 4 5 6 7 8 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

PERIODS OF 5 MIN PERIODS OF 5 MIN PERIODS OF 5 MIN

d e f

Fig. 1. Mean values o f H and T reflex amplitudes and EEG alpha parameters of 19 subjects in a 40 rain rest exper- iment with alpha feedback. The values o f the individual subjects have been c o m p u t e d for periods o f 5 min. The vertical bars indicate the 95% confidence intervals.

min reasonably constant alpha, the experi- pected that the feedback procedure would ment was done. The subjects were n o t select- rather lead to stability of alpha parameters ed on alpha quantity, during the experiment.

It is reported that, in the absence o f visual

stimulation, subjects do n o t learn to enhance Results

their alpha quantity above their baseline level

300 A. V A N B O X T E L

were expressed in z-scores, c o m p u t e d with amplitude (Dietrichson and S¢rbye 1971). reference to the mean of all reflexes in the ex- Period means and standard deviations were periment and to the within-periods variance c o m p u t e d for alpha amplitude (peak value estimate. For each 5 min period the mean z- histogram) and alpha wave period {primary score of all subjects and its 95% confidence zero crossings analysis) and transformed into interval were c o m p u t e d (Fig. 1,

a--c),

z-scores (Fig. 1, e and f). The alpha index To test whether M, H and T changed signi- values of the periods were averaged over sub- ficantly during the course of the experiment, jects (Fig. 1, d). Alpha amplitude and alpha on each o f them an analysis of variance was index did n o t show gross changes; they show- performed (two-factor design with repeated ed a slight increase in the second part of the measures on one factor and replications with- experiment.

in cells). None of the three variables showed To reveal the intra-individual relations be- a significant periods effect (P > 0.20). The tween the d e p e n d e n t variables, p r o d u c t - - percentage of total variance attributable to m o m e n t intercorrelations between H, T and the periods factor was respectively 0.59, 0.22 alpha parameters were c o m p u t e d for each and 0.14% for M, H and T. subject. Because it is n o t desirable to draw The square pulses, representing the force of conclusions from data of individual subjects, the tendon tap, and the alpha activity were a chi-square test of combined probabilities analysed off-line b y a DEC LAB 8/e computer, was used to evaluate the overall significance The period means of the tap force were ex- of the correlation coefficients (Guilford and pressed as a percentage of the value in period Fruchter 1973). In order to c o m p u t e the 1 and averaged over subjects. These values did probabilities of the correlation coefficients of n o t deviate more than 6% from the initial value individuals, this procedure requires that ex- in period 1 (0.73 N). Small fluctuations in pectations a b o u t the sign of the correlations stimulus intensity of this magnitude are with- were specified. Our expectations were based o u t detectable consequences for the reflex on the results of Jovanovid (1971) who found

T A B L E I

Chi-square t e s t o f c o m b i n e d p r o b a b i l i t i e s o f intra-individual i n t e r c o r r e l a t i o n s b e t w e e n T a n d H r e f l e x a m p l i t u d e s a n d E E G a l p h a p a r a m e t e r s .

P e a r s o n r E x p e c t - 40 m i n r e s t w i t h a l p h a 40 m i n r e s t w i t h o u t a l p h a

ed c o r r e - f e e d b a e k ( f o r all t e s t s corn- f e e d b a c k ( f o r all t e s t s e o m -

m _ _ W

AMPLITUDE LLI

3 '8 ~ .8 AMPLITUDE ,8 AMPLITUDE

.J

X DIRECT MOTOR RESPONSI ~ I HOFFMANN REFLEX X ACHILLES TENDON REFLEX

N I N N ~ ~ I o . 1 1 , o o r i -,4 - ,4 - , 4 i r

-,8

-.811

- , 8 1 L', i I I__ I L ] I i I [ • I I I__ ~ ; I l I I 1 2 4 5 6 7 8 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

PERIODS OF 5 MIN. PERIODS OF 5 MIN. PERIODS OF 8 MIN.

cl b c

100 I r

90 TIME ALPHA ACTIVITY ~j .8 ,L- AMPLITUDE ~.j ,8 WAVE PERIOD Z E ) ~ - PRESENT X, ~. ALPHA ACTIVITY X, ALPHA ACTIVITY

N / N 70 z , 4 - z ,4 6oF- ~ i ,,,< 40 F 2O ~- 10 - , 8 - , 8 ~- 1 2 3 Z4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 PERIODS OF 5 MIN. PERIODS OF 5 MIN PERIODS OF 5 MIN

d e f

Fig. 2. Mean values o f H and T r e f l e x a m p l i t u d e s and EEG alpha parameters o f 2 0 s u b j e c t s in a 4 0 rain rest exper- i m e n t w i t h o u t alpha f e e d b a c k . T h e values o f the individual subjects have b e e n c o m p u t e d for periods o f 5 min. T h e vertical bars indicate the 95% c o n f i d e n c e intervals.

that alpha index and amplitude decreased was found between the reflex amplitudes and

with increasing drowsiness while alpha wave alpha index or alpha amplitude. Only one of

period increased, and on results o f Coquery et the expectations about the relations between

al. (1965) w h o found a decrease of H and T the alpha parameters was confirmed: a posi-

reflexes under the same conditions. The ex- tive relationship between alpha index and

pectations and the results of the combined alpha amplitude was obtained. The relations

probabilities tests are shown in Table I. A between index and wave period, and ampli-

positive relationship was found between H tude and wave period, were not negative, as

and T reflexes. Both correlated negatively expected, but were shown to be significantly

302 A. VAN BOXTEL

E x p e r i m e n t 2 individual intercorrelations between reflex

amplitudes and alpha parameters. Al[relations The s e c o n d e x p e r i m e n t i n v e s t i g a t e d w h e t h e r were in accordance with the expectations. a change of alpha parameters, indicating a de-

crease of cortical activation, would be accom- Discussion panied by a decrease of reflex amplitudes.

T w e n t y normal students, males and females, The present experiments indicate that, un- aged between 18 and 27 years, volunteered der conditions of fairly stable alpha index and

in the experiment, amplitude, T and H reflex amplitudes do not

change significantly. But when the alpha

M e t h o d parameters reflect a decreasing cortical ac-

tivation, the reflex amplitudes decrease. The The subjects in this experiment did n o t re- results support the idea that the decrease of ceive alpha feedback. They were habituated the repetitively evoked T reflex is of supra- to the experimental situation before the ex- spinal origin. T h e y agree with the finding that periment was conducted. Despite the fact that the decrement is counteracted by systematic they were instructed to remain awake it was increase of the demand of an induced sensori- expected that, because of the m o n o t o n o u s m o t o r task (Brunia et al. 1973).

and restful situation, they would become The identical behaviour of T and H reflex drowsy which would entail a decrease of alpha in both experiment 1 and experiment 2 sug- amplitude, index and frequency. All m e t h o d s gests that during rest, when high levels of cor- and statistical procedures were identical to tical activation are avoided, the supraspinal

those in experiment 1. influences are mediated by alpha motoneu-

rones. Coquery et al. (1965) found parallel

Results changes of H and T during successive stages of

sleep. Pompeiano (1966) has reported similar The mean values and 95% confidence inter- variations of H and T during synchronized vals of M, H, T and alpha parameters are shown and desynchronized sleep in unrestrained, un- in Fig. 2. An analysis of variance revealed that anaesthetized cats.

the periods effect was significant for H and T The relations b e t w e e n alpha parameters (P < 0.001) while the M response did not and reflex amplitudes in experiment 2 are change significantly (P > 0.20). The percen- more clear-cut than in experiment 1. This is tage of total variance attributable to the pe- probably due to the fact that the range of riods factor was respectively 0.03, 0.49 and most d e p e n d e n t variables is smaller in experi- 1.45% for M, H and T. m e n t 1 than in experiment 2; the greater the The mean tendon tap force values did n o t range the higher the correlation, other things deviate more than 6% from the initial value being equal (Guilford and Fruchter 1973).

in period 1 (0.71 N). The alpha changes in experiment 2 can be

slight recovery of reflex amplitudes, alpha am- tively evoked t e n d o n reflexes decrease as the plitude and alpha index in the last periods of n u m b e r of evoked reflexes progresses. The the experiment, question whether this decrement is a spinal In experiment 1 seemingly paradoxical alpha p h e n o m e n o n or that it can be ascribed to changes have been observed: during the en- supraspinal influences that are related to the tire experiment alpha wave period increased degree of cortical activation was investigated while in the second half index and amplitude in two experiments designed to test whether increased somewhat. Jovanovid (1971)observ- a relation exists between the H o f f m a n n (H) ed similar results for m o n o p o l a r occipital, and Achilles t e n d o n {T) reflex amplitudes and parietal and frontal derivations in subjects EEG alpha activity parameters during a rest who relaxed. The waning of alpha t h a t is condition. The principal results can be sum- characteristic of sleep onset was often preced- marized as follows:

ed by this stage of alpha augmentation. 1. A constant alpha index was accompanied Kasamatsu and Hirai (1966) observed similar by stable reflex amplitudes.

changes in Zen masters after t h e y started 2. A decreasing alpha index was accom- meditation. Jovanovid (1971) f o u n d a more panied by decreasing reflex amplitudes. pronounced increase of alpha in frontal than 3. A positive relation was found between H in occipital or parietal regions. Rubin (1938) and T reflex amplitudes.

f o u n d that index changes m a y be nonpropor- 4. A positive relation was f o u n d between tional for the two hemispheres. These results alpha index and alpha amplitude.

imply t h a t the relations between alpha param- 5. No circumscribed relation was f o u n d be- eters and reflex amplitudes m a y depend on tween the alpha wave period on the one side the derivations t h a t are studied, and the alpha index and amplitude on the It should be emphasized t h a t the variability other side. Apparently these relations are de- of the intra-individual alpha-reflex correla- p e n d e n t on the state of activation of the sub- tions was considerable. Also the course of the ject.

reflex amplitudes with time was partly a 6. The relations between the reflex ampli- unique property of the subject. The subjects-- tudes and the alpha parameters showed great periods interaction was significant in experi- interindividual differences.

m e n t 1 and experiment 2 (P < 0.001) for both H and T. In both experiments the inter-

action contributed more to the total variance R~sum~ than the periods effect. The variance attrib-

utable to the interaction in experiment 1 was: Relation entre l'amplitude des rdflexes mono- H 10.1%, T 1.9% and in experiment 2: H synaptiques et quelques paramdtres de l'acti- 2.0%, T 6.6% (in both experiments the greater vitd EEG alpha

part of the variance was due to the subjects

304 A. VAN BOXTEL

l ' a c t i v i t 6 E E G a l p h a e n 6 t a t d e r e p o s d ' a u t r e phasic reflex response to parameters of a mechani-

part. Les r6sultats principaux se r6sument cal stimulus as an index of muscle-spindle sensitivi- ty. Med. biol. Engng., 1973, 11: 597--602.

ainsi: Cook, W.A. Effects of low frequency stimulation on

1. P o u r u n p o u r c e n t a g e d e t e m p s d ' a c t i - the m o n o s y n a p t i c reflex (H reflex) in man. Neuro- v i t 6 a l p h a c o n s t a n t , l ' a m p l i t u d e d e s r 6 f l e x e s logy (Minneap.), 1968, 18: 47--51.

n e changeait pas significativement. Coquery, J.M. A t t i t u d e pr~paratoire et variations de 2. U n e d i m i n u t i o n d e c e p o u r c e n t a g e s ' e s t l'excitabilit~ spinale induites par un son. Physiol. a c c o m p a g n 6 e d ' u n e r 6 d u c t i o n d e s a m p l i t u d e s Behav., 1969, 4: 297--302.

Coquery, J.M., Fressy, J., Paillard, J. et Vittini, F.

d e s r ~ f l e x e s . Evolution des r~flexes monosynaptiques au cours

3. I1 a 6t6 6 t a b l i u n e r e l a t i o n p o s i t i v e e n t r e du sommeil nocturne chez l'homme. C.R. Soc. l ' a m p l i t u d e d e s r 6 f l e x e s d e H o f f m a n n e t c e l l e Biol. (Paris), 1965, 159: 436--440.

des r6flexes tendineux. Davis, C.M. and Beaton, R.D. Facilitation and adapta- 4. I1 a 6t6 6 t a b l i u n e r e l a t i o n p o s i t i v e e n t r e tion of the human quadriceps stretch reflex pro- duced by auditory stimulation. J. comp. physiol. le p o u r c e n t a g e d e t e m p s a l p h a e t l ' a m p l i - Psychol., 1968, 65: 483--487.

r u d e a l p h a . Dietrichson, P. and S~brbye, R. Clinical method for

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