326
Specialia
o b s e r v e d in an average of all 32 cells. The d i s p l a c e m e n t was e v i d e n t w i t h i n a s u b g r o u p of t h e 12 b e s t zoom cells9 These cells were chosen b a s e d on t h e a v e r a g e n e a r field e n l a r g e m e n t of t h e t w o d i m e n s i o n s , w i t h each cell h a v i n g m o r e t h a n 70% of t h e e n l a r g e m e n t p r e d i c t e d b y t h e zoom model. The eccentric d i s p l a c e m e n t of t h e n e a r r e c e p t i v e fields of t h e s e cells was a b o u t i t/2 t i m e s t h e d i s p l a c e m e n t of t h e far p l a n e r e c e p t i v e field. The c o m p a r a t i v e scale f a c t o r a v e r a g e d 0.36 -4- 0.13 s.e. The zoom effects we m e a s u r e d could n o t be a t t r i b u t e d to optical a c c o m o d a t i o n . I n t h e first place, a c c o m o d a t i o n could n o t a c c o u n t for a s i m u l t a n e o u s m a g n i f i c a t i o n a n d m i n i f i e a t i o n of t h e t w o d i m e n s i o n s of a r e c e p t i v e field. F u r t h e r m o r e , using t h e G u l l s t r a n d s c h e m a t i c eye one can calculate t h a t 3 d i o p t e r s of a c c o m m o d a t i o n r e s u l t in only a b o u t 1% m a g n i f i c a t i o n ~3 All of our r e c o r d i n g was d o n e in I e s p o n s e t o b i n o c u l a r s t i m u l a t i o n . I t is reasonable t o suggest t h a t n e a r field e n l a r g e m e n t m a y result f r o m f i x a t i o n d i s p a r i t y a n d t h e s h i f t i n g of t w o m o n o c u l a r rec e p t i v e fields. This is r u l e d o u t as t h e sole e x p l a n a t i o n since t h e m a j o r i t y of r e c e p t i v e fields h a v e c h a n g e s in t h e vertical dimension. I t a p p e a r s t h a t in c o n t r a d i c t i o n to i n d i r e c t evidence, m a n y cells in t h e p r i m a r y visual c o r t e x of t h e m o n k e y e x h i b i t zoom scaling t h a t m a y s u b s e r v e size c o n s t a n c y 14. Our results s u p p o r t t h e zoom m o d e l p r e d i c t i o n s for n e a r
EXPERIENTIA 31/3
field e n l a r g e m e n t of visual r e c e p t i v e fields. This r e c e p t i v e field z o o m m e c h a n i s m can p r o v i d e a s u b s t r a t e for size cons t a n c y in t h e visual s y s t e m ~.
Zusammen[assung. R e z e p t i v e F e l d e r v o n 32 Zellen i m prim/irvisuellen ~usseren Tell des Grosshirns u n b e t/iubter, a b g e r i c h t e t e r A f f e n w u r d e n a b g e s t e c k t . D a v o n zeigten 97~o d e r Zellen V e r g r S s s e r u n g d e r eckigen A b m e s s u n g e n auf der n a h e n Fl~tche. Diese Gr6sseE i n s t e l l u n g u n t e r s t t i t z t unsere V o r s t e l l u n g eines der G r 6 s s e n - K o n s t a n z . j . D. SMITH a n d E. MARG
School o~ Optometry, University o/Cali/ornia, Berkeley (Cali/ornia 94720, USA), 4 November 7974.
13 H. H. 2MSLEY, Visual Optics, 4th edn. (Hatton Press, London 1946), p. 526. 14 C. BLAKEMORE,2. T. GARNERand J. A. SWEET, Perception 1, 111 (1972). 15 This work was supported in part by N. I. H. training grant 5T01 EY00076-02, N. S. F. grants GB 33338, BMS 7500452 and BMS 7201970 and the Committee on Research at the University of California, Berkeley, USA.
Influence of Superior Cervical Ganglion on Electroretinogram of the Rabbit The p r e s e n t i n v e s t i g a t i o n was m a d e to analyze t h e influence of t h e s u p e r i o r cervical ganglion on t h e E R G (electroretinogram) of tile r a b b i t . Only a r e p o r t deals w i t h such a p r o b l e m 1, while t h e effects of electrical s t i m u l a t i o n of superior cervical s y m p a t h e t i c t r u n k or ganglion on t h e blood circulation in t h e eye 2, a, on t h e i n t r a o c u l a r pressure, on t h e intrinsic eye m u s c u l a t u r e a n d t h e r e l a t i o n b e t w e e n autonomic nervous system and retina were investigated in p r e v i o u s works 4,5 On t h e o t h e r h a n d , some a u t h o r s a n a l y z e d t h e influences of v a r i a t i o n of t h e blood circulation, p u p i l l a r y d i a m e t e r a n d i n t r a o c u l a r p r e s s u r e on t h e E R G 6-11.
A
"
~ " = ~ " ~ . - ~ . ~ t ~'. .
T h i r t y - f i v e r a b b i t s u n d e r N e m b u t a l a n a e s t h e s i a (33 m g / kg) were p u t in a s t e r e o t a x i c a p p a r a t u s in dorsal position, t h e n were curarized a n d artificially v e n t i l a t e d . Subs e q u e n t l y t h e s u p e r i o r cervical ganglion was isolated. The i p s i l a t e r a l eye was a t r o p i n i z e d , t h e n i c t i t a t i n g m e m b r a n e was cut, an artificial p u p i l on t h e cornea l i m i t e d the light input; however, 5 rabbits underwent iridectomy in o r d e r t o e l i m i n a t e a n y possible v a r i a t i o n of t h e p u p i l diameter. The EIRG was elicited w i t h a DC Galileo electronic flash. E a c h single flash lasted 50 asec, t h e light i n t e n s i t y r a n g e d f r o m 20 to 800 lux a n d t h e f l a s h f r e q u e n c y w a s 1/sec. The a n i m a l s were m a i n t a i n e d 30 rain in d a r k n e s s before b e g i n n i n g t h e p h o t o s t i m u l a t i o n . The E R G was r e c o r d e d b y a H e w l e t t - P a c k a r d 5480 t w o c h a n n e l i n p u t analyzer, w h i c h a v e r a g e d usually 16 single responses. A f t e r n u m e r o u s n o r m a l E R G s were r e c o r d e d f r o m t h e r i g h t eye, t h e ipsilateral superior cervical g a n g l i o n or t h e t r u n k (after p r o x i m a l section) was electrically s t i m u l a t e d for 30 sec b y m e a n s Of silver b i p o l a r electrodes w i t h t h e following p a r a m e t e r s : 2 5 - t 0 0 / s e c , 8-15 V,
I G. G. I\{ASCETTI, Brain Res. 47, 221 (1972).
B
IV~. BEST, S. IVfASKET a n d A. Z. RAEINOWITZ, I n v e s t . Ophthal.
System o] Ophthalmology (Henry Kimpton, London 1968), vol. 4, p. 68. 4 j. DUCRETand S. t(oGo, Pfltigers Arch. ges. Physiol. 227, 71 (1931). 2. I7IAFTER, Pfltigers Arch. ges. Physiol. 229, 447 (1932). 6 j. FujiNO and D. I. HA•ASAKI, Arch. Ophthal. 78, 757 (1967). 7 G. P. IV[.HORSTENand J. E. WINCKEL~AN,Aeta physiol, pharmac. neerl. 6, 586 (1957). 8 G. E. JAYLE, R. L. BOYER and G. B. SARACCO, L'dlectrordtinographic (Masson et Cie., Paris, 1965), vol. 1, p. 77. K. SHIWA, Aeta Soc. Ophthal. Jap. 65, 1516 (1961). 10 IV[. ZEWI and L. VAINIO-M'ATTILA, A c t a ophthal., Copenh. 33, 53 (1955). xl 2. )/[ANNI, Boll. Soc. ital. Biol. sper. 3~, 35 (1965). 3 S. DUKE-ELDER,
Effect of the electrical stimulation of right superior cervical ganglion on the ipsilateral 2RG. Each trace represents the average of 16 responses9 A) normal ERG. B) 2RG after sympathetic stimulation (10 V; 25/see; 1 msee; train of 30 sec). Parameters: darkness adaptation, 30 rain; light stimulation: 200 lux, 50 [zsee, 1/sec. Time: 100 msec. Amplitude: 100 [xV.
it,
211 (1972).
15.3. 1975
327
Specialia
pulse d u r a t i o n 1 msec. E R G s were r e c o r d e d d u r i n g or i m m e d i a t e l y a f t e r t h e e n d of electrical s y m p a t h e t i c s t i m u l a t i o n w i t h t h e s a m e flash p a r a m e t e r s of t h e c o n t r o l . I n 20 r a b b i t s t h e c o m p a r i s o n b e t w e e n t h e n o r m a l E R G a n d t h a t o b t a i n e d d u r i n g or i m m e d i a t e l y a f t e r electrical s t i m u l a t i o n of t h e s u p e r i o r cervical g a n g l i o n or t r u n k s h o w e d a n increase in t h e a m p l i t u d e of %' a n d ' b ' w a v e s (see Figure). T h e e n h a n c e m e n t was of a b o u t 15%. T h i s effect was e v i d e n t also a f t e r r e m o v a l of t h e c o r n e a a n d lens a n d in t h e i r i d e e t o m i z e d a n i m a l s . H o w e v e r , t h e s y m p a t h e t i c effect o n E R G failed t o a p p e a r w h e n t h e v a l u e s of t h e b l o o d p r e s s u r e were lower t h a n 70 m m Hg. I n 5 a n i m a l s t h e s u p e r i o r c e r v i c a l g a n g l i o n was a c u t e l y a b l a t e d a n d t h e i p s i l a t e r a l E R G was t h e n r e c o r d e d : u n d e r s u c h e x p e r i m e n t a l c o n d i t i o n s , a decrease of t h e ' a ' w a v e of a b o u t 17% a n d of t h e ' b ' w a v e s of a b o u t 3 4 % o c c u r r e d in c o m p a r i s o n w i t h t h e c o n t r a l a t e r a l E R G . I n 3 r a b b i t s , t h e r i g h t s u p e r i o r cervical g a n g l i o n was chronically r e m o v e d u n d e r N e m b u t a l a n a e s t h e s i a a n d asepsis. 2, 4 a n d 6 d a y s a f t e r t h e o p e r a t i o n , t h e i p s i l a t e r a l E R G e x h i b i t e d a decrease s i m i l a r t o t h a t d e s c r i b e d a f t e r a c u t e a b l a t i o n . O t h e r r a b b i t s u n d e r w e n t c h r o n i c l i g a t u r e of t h e r i g h t c o m m o n c a r o t i d arteries. Also u n d e r s u c h experim e n t a l c o n d i t i o n s t h e s t i m u l a t i o n of t h e g a n g l i o n was effective. T h e s y m p a t h e t i c i n f l u e n c e was also visible a f t e r i n j e c t i o n i n t o t h e f e m o r a l v e i n of t h e R e g i t i n - C i b a (e-blocking drug, 2 mg/kg), while it d i s a p p e a r e d a f t e r i n j e c t i o n of fl-blocking drug, since a s t r i k i n g decrease of b l o o d p r e s s u r e o c c u r r e d 12. T h e s y m p a t h e t i c a c t i v a t i o n of E R G %' a n d ' b ' w a v e s did n o t d e p e n d u p o n t h e c o n c o m i t a n t s y m p a t h e t i c influence o n t h e pupil, n i c t i t a t i n g m e m b r a n e a n d i n t r a o c u l a r pressure6-~0; in p a r t i c u l a r we o b s e r v e d a m o d e s t increase of a b o u t 5 m m t-Ig of e n d o o c u l a r p r e s s u r e w i t h i n 3 or 4 sec d u r i n g s y m p a t h e t i c s t i m u l a t i o n . T h e n a slow decrease o c c u r r e d followed b y a slow r e t u r n t o n o r m a l values.
Thus the conclusion can be reached that the superior cervical g a n g l i o n c a n influence t h e E R G p r o b a b l y t h r o u g h a m o d i f i c a t i o n in t h e a c t i v i t y of t h e r e t i n a l cells. T h e data obtained from ablation indicate a tonic sympathetic action. T h i s is s u p p o r t e d also b y t h e fact t h a t a - b l o c k i n g drug which removes the vascular sympathetic activity did n o t s u p p r e s s t h e s y m p a t h e t i c e n h a n c e m e n t of t h e ' a ' a n d ' b ' waves. H o w e v e r , a c i r c u l a t o r y c o m p o n e n t m u s t also be t a k e n i n t o a c c o u n t , since t h e s y m p a t h e t i c effects were n o t p r e s e n t w h e n t h e systolic b l o o d p r e s s u r e was low.
Riassunto. L a s t i m o l a z i o n e e l e t t r i c a del ganglio cervicale superiore d e t e r m i n a u n i n c r e m e n t o delle o n d e
Specialia
o b s e r v e d in an average of all 32 cells. The d i s p l a c e m e n t was e v i d e n t w i t h i n a s u b g r o u p of t h e 12 b e s t zoom cells9 These cells were chosen b a s e d on t h e a v e r a g e n e a r field e n l a r g e m e n t of t h e t w o d i m e n s i o n s , w i t h each cell h a v i n g m o r e t h a n 70% of t h e e n l a r g e m e n t p r e d i c t e d b y t h e zoom model. The eccentric d i s p l a c e m e n t of t h e n e a r r e c e p t i v e fields of t h e s e cells was a b o u t i t/2 t i m e s t h e d i s p l a c e m e n t of t h e far p l a n e r e c e p t i v e field. The c o m p a r a t i v e scale f a c t o r a v e r a g e d 0.36 -4- 0.13 s.e. The zoom effects we m e a s u r e d could n o t be a t t r i b u t e d to optical a c c o m o d a t i o n . I n t h e first place, a c c o m o d a t i o n could n o t a c c o u n t for a s i m u l t a n e o u s m a g n i f i c a t i o n a n d m i n i f i e a t i o n of t h e t w o d i m e n s i o n s of a r e c e p t i v e field. F u r t h e r m o r e , using t h e G u l l s t r a n d s c h e m a t i c eye one can calculate t h a t 3 d i o p t e r s of a c c o m m o d a t i o n r e s u l t in only a b o u t 1% m a g n i f i c a t i o n ~3 All of our r e c o r d i n g was d o n e in I e s p o n s e t o b i n o c u l a r s t i m u l a t i o n . I t is reasonable t o suggest t h a t n e a r field e n l a r g e m e n t m a y result f r o m f i x a t i o n d i s p a r i t y a n d t h e s h i f t i n g of t w o m o n o c u l a r rec e p t i v e fields. This is r u l e d o u t as t h e sole e x p l a n a t i o n since t h e m a j o r i t y of r e c e p t i v e fields h a v e c h a n g e s in t h e vertical dimension. I t a p p e a r s t h a t in c o n t r a d i c t i o n to i n d i r e c t evidence, m a n y cells in t h e p r i m a r y visual c o r t e x of t h e m o n k e y e x h i b i t zoom scaling t h a t m a y s u b s e r v e size c o n s t a n c y 14. Our results s u p p o r t t h e zoom m o d e l p r e d i c t i o n s for n e a r
EXPERIENTIA 31/3
field e n l a r g e m e n t of visual r e c e p t i v e fields. This r e c e p t i v e field z o o m m e c h a n i s m can p r o v i d e a s u b s t r a t e for size cons t a n c y in t h e visual s y s t e m ~.
Zusammen[assung. R e z e p t i v e F e l d e r v o n 32 Zellen i m prim/irvisuellen ~usseren Tell des Grosshirns u n b e t/iubter, a b g e r i c h t e t e r A f f e n w u r d e n a b g e s t e c k t . D a v o n zeigten 97~o d e r Zellen V e r g r S s s e r u n g d e r eckigen A b m e s s u n g e n auf der n a h e n Fl~tche. Diese Gr6sseE i n s t e l l u n g u n t e r s t t i t z t unsere V o r s t e l l u n g eines der G r 6 s s e n - K o n s t a n z . j . D. SMITH a n d E. MARG
School o~ Optometry, University o/Cali/ornia, Berkeley (Cali/ornia 94720, USA), 4 November 7974.
13 H. H. 2MSLEY, Visual Optics, 4th edn. (Hatton Press, London 1946), p. 526. 14 C. BLAKEMORE,2. T. GARNERand J. A. SWEET, Perception 1, 111 (1972). 15 This work was supported in part by N. I. H. training grant 5T01 EY00076-02, N. S. F. grants GB 33338, BMS 7500452 and BMS 7201970 and the Committee on Research at the University of California, Berkeley, USA.
Influence of Superior Cervical Ganglion on Electroretinogram of the Rabbit The p r e s e n t i n v e s t i g a t i o n was m a d e to analyze t h e influence of t h e s u p e r i o r cervical ganglion on t h e E R G (electroretinogram) of tile r a b b i t . Only a r e p o r t deals w i t h such a p r o b l e m 1, while t h e effects of electrical s t i m u l a t i o n of superior cervical s y m p a t h e t i c t r u n k or ganglion on t h e blood circulation in t h e eye 2, a, on t h e i n t r a o c u l a r pressure, on t h e intrinsic eye m u s c u l a t u r e a n d t h e r e l a t i o n b e t w e e n autonomic nervous system and retina were investigated in p r e v i o u s works 4,5 On t h e o t h e r h a n d , some a u t h o r s a n a l y z e d t h e influences of v a r i a t i o n of t h e blood circulation, p u p i l l a r y d i a m e t e r a n d i n t r a o c u l a r p r e s s u r e on t h e E R G 6-11.
A
"
~ " = ~ " ~ . - ~ . ~ t ~'. .
T h i r t y - f i v e r a b b i t s u n d e r N e m b u t a l a n a e s t h e s i a (33 m g / kg) were p u t in a s t e r e o t a x i c a p p a r a t u s in dorsal position, t h e n were curarized a n d artificially v e n t i l a t e d . Subs e q u e n t l y t h e s u p e r i o r cervical ganglion was isolated. The i p s i l a t e r a l eye was a t r o p i n i z e d , t h e n i c t i t a t i n g m e m b r a n e was cut, an artificial p u p i l on t h e cornea l i m i t e d the light input; however, 5 rabbits underwent iridectomy in o r d e r t o e l i m i n a t e a n y possible v a r i a t i o n of t h e p u p i l diameter. The EIRG was elicited w i t h a DC Galileo electronic flash. E a c h single flash lasted 50 asec, t h e light i n t e n s i t y r a n g e d f r o m 20 to 800 lux a n d t h e f l a s h f r e q u e n c y w a s 1/sec. The a n i m a l s were m a i n t a i n e d 30 rain in d a r k n e s s before b e g i n n i n g t h e p h o t o s t i m u l a t i o n . The E R G was r e c o r d e d b y a H e w l e t t - P a c k a r d 5480 t w o c h a n n e l i n p u t analyzer, w h i c h a v e r a g e d usually 16 single responses. A f t e r n u m e r o u s n o r m a l E R G s were r e c o r d e d f r o m t h e r i g h t eye, t h e ipsilateral superior cervical g a n g l i o n or t h e t r u n k (after p r o x i m a l section) was electrically s t i m u l a t e d for 30 sec b y m e a n s Of silver b i p o l a r electrodes w i t h t h e following p a r a m e t e r s : 2 5 - t 0 0 / s e c , 8-15 V,
I G. G. I\{ASCETTI, Brain Res. 47, 221 (1972).
B
IV~. BEST, S. IVfASKET a n d A. Z. RAEINOWITZ, I n v e s t . Ophthal.
System o] Ophthalmology (Henry Kimpton, London 1968), vol. 4, p. 68. 4 j. DUCRETand S. t(oGo, Pfltigers Arch. ges. Physiol. 227, 71 (1931). 2. I7IAFTER, Pfltigers Arch. ges. Physiol. 229, 447 (1932). 6 j. FujiNO and D. I. HA•ASAKI, Arch. Ophthal. 78, 757 (1967). 7 G. P. IV[.HORSTENand J. E. WINCKEL~AN,Aeta physiol, pharmac. neerl. 6, 586 (1957). 8 G. E. JAYLE, R. L. BOYER and G. B. SARACCO, L'dlectrordtinographic (Masson et Cie., Paris, 1965), vol. 1, p. 77. K. SHIWA, Aeta Soc. Ophthal. Jap. 65, 1516 (1961). 10 IV[. ZEWI and L. VAINIO-M'ATTILA, A c t a ophthal., Copenh. 33, 53 (1955). xl 2. )/[ANNI, Boll. Soc. ital. Biol. sper. 3~, 35 (1965). 3 S. DUKE-ELDER,
Effect of the electrical stimulation of right superior cervical ganglion on the ipsilateral 2RG. Each trace represents the average of 16 responses9 A) normal ERG. B) 2RG after sympathetic stimulation (10 V; 25/see; 1 msee; train of 30 sec). Parameters: darkness adaptation, 30 rain; light stimulation: 200 lux, 50 [zsee, 1/sec. Time: 100 msec. Amplitude: 100 [xV.
it,
211 (1972).
15.3. 1975
327
Specialia
pulse d u r a t i o n 1 msec. E R G s were r e c o r d e d d u r i n g or i m m e d i a t e l y a f t e r t h e e n d of electrical s y m p a t h e t i c s t i m u l a t i o n w i t h t h e s a m e flash p a r a m e t e r s of t h e c o n t r o l . I n 20 r a b b i t s t h e c o m p a r i s o n b e t w e e n t h e n o r m a l E R G a n d t h a t o b t a i n e d d u r i n g or i m m e d i a t e l y a f t e r electrical s t i m u l a t i o n of t h e s u p e r i o r cervical g a n g l i o n or t r u n k s h o w e d a n increase in t h e a m p l i t u d e of %' a n d ' b ' w a v e s (see Figure). T h e e n h a n c e m e n t was of a b o u t 15%. T h i s effect was e v i d e n t also a f t e r r e m o v a l of t h e c o r n e a a n d lens a n d in t h e i r i d e e t o m i z e d a n i m a l s . H o w e v e r , t h e s y m p a t h e t i c effect o n E R G failed t o a p p e a r w h e n t h e v a l u e s of t h e b l o o d p r e s s u r e were lower t h a n 70 m m Hg. I n 5 a n i m a l s t h e s u p e r i o r c e r v i c a l g a n g l i o n was a c u t e l y a b l a t e d a n d t h e i p s i l a t e r a l E R G was t h e n r e c o r d e d : u n d e r s u c h e x p e r i m e n t a l c o n d i t i o n s , a decrease of t h e ' a ' w a v e of a b o u t 17% a n d of t h e ' b ' w a v e s of a b o u t 3 4 % o c c u r r e d in c o m p a r i s o n w i t h t h e c o n t r a l a t e r a l E R G . I n 3 r a b b i t s , t h e r i g h t s u p e r i o r cervical g a n g l i o n was chronically r e m o v e d u n d e r N e m b u t a l a n a e s t h e s i a a n d asepsis. 2, 4 a n d 6 d a y s a f t e r t h e o p e r a t i o n , t h e i p s i l a t e r a l E R G e x h i b i t e d a decrease s i m i l a r t o t h a t d e s c r i b e d a f t e r a c u t e a b l a t i o n . O t h e r r a b b i t s u n d e r w e n t c h r o n i c l i g a t u r e of t h e r i g h t c o m m o n c a r o t i d arteries. Also u n d e r s u c h experim e n t a l c o n d i t i o n s t h e s t i m u l a t i o n of t h e g a n g l i o n was effective. T h e s y m p a t h e t i c i n f l u e n c e was also visible a f t e r i n j e c t i o n i n t o t h e f e m o r a l v e i n of t h e R e g i t i n - C i b a (e-blocking drug, 2 mg/kg), while it d i s a p p e a r e d a f t e r i n j e c t i o n of fl-blocking drug, since a s t r i k i n g decrease of b l o o d p r e s s u r e o c c u r r e d 12. T h e s y m p a t h e t i c a c t i v a t i o n of E R G %' a n d ' b ' w a v e s did n o t d e p e n d u p o n t h e c o n c o m i t a n t s y m p a t h e t i c influence o n t h e pupil, n i c t i t a t i n g m e m b r a n e a n d i n t r a o c u l a r pressure6-~0; in p a r t i c u l a r we o b s e r v e d a m o d e s t increase of a b o u t 5 m m t-Ig of e n d o o c u l a r p r e s s u r e w i t h i n 3 or 4 sec d u r i n g s y m p a t h e t i c s t i m u l a t i o n . T h e n a slow decrease o c c u r r e d followed b y a slow r e t u r n t o n o r m a l values.
Thus the conclusion can be reached that the superior cervical g a n g l i o n c a n influence t h e E R G p r o b a b l y t h r o u g h a m o d i f i c a t i o n in t h e a c t i v i t y of t h e r e t i n a l cells. T h e data obtained from ablation indicate a tonic sympathetic action. T h i s is s u p p o r t e d also b y t h e fact t h a t a - b l o c k i n g drug which removes the vascular sympathetic activity did n o t s u p p r e s s t h e s y m p a t h e t i c e n h a n c e m e n t of t h e ' a ' a n d ' b ' waves. H o w e v e r , a c i r c u l a t o r y c o m p o n e n t m u s t also be t a k e n i n t o a c c o u n t , since t h e s y m p a t h e t i c effects were n o t p r e s e n t w h e n t h e systolic b l o o d p r e s s u r e was low.
Riassunto. L a s t i m o l a z i o n e e l e t t r i c a del ganglio cervicale superiore d e t e r m i n a u n i n c r e m e n t o delle o n d e
