bade parameters of the static burst discharge of lingual cold receptors in the cat

8/9/2019 Bade Parameters of the Static Burst Discharge of Lingual Cold Receptors in the Cat

1/5

Pflfigers Arch. 382, 1 -5 (1979)

P f l f i g e r s r c h i v

u r o p e a n J o u r n a l

of hysiology

9 by Springer-Verlag 1979

Pa ra m eters o f th e S ta t i c u rs t D i s ch a rg e o f L i n g u a l Co l d Recep to rs in th e Ca t

H . B a d e , H . A . B r a u n , a n d H . H e n s e l

Physi01ogisches Institut der Unive rsidit Ma rburg, Deutschhausstrasse 2, D -3550 M arburg, F ederal Re public of Germ any

A b s t r a c t . T h e r m a l s t i m u l i w e r e a p p l i e d t o t h e u p p e r

s u r f a c e o f th e t o n g u e o f t h e c a t . T h e s t i m u l i r a n g e d

f i 'o m 4 0 ~ t o 1 0 ~ a n d w e r e c h a n g e d in c o l d s t e p s o f

5 ~C , e a c h t e m p e r a t u r e l a s t i n g 2 m i n . A f f e r e n t i m p u l s e s

o f s i n g le s p e c i f i c c o l d f i b e r s f r o m t h e l i n g u a l n e r v e w e r e

a n a l y s e d b y a c o m p u t e r p r o g r a m . A b o u t 9 0 % o f t h e

f i b e r s s h o w e d b u r s t s u n d e r s t a t i c c o n d i t i o n s . T h e b u r s t s

b e g a n a s d o u b l e t s a t t h e t e m p e r a t u r e o f m a x i m a l

a v e r a g e f r e q u e n c y . T h i s t e m p e r a t u r e v a r i e d f r o m 4 0 ~C

t o 1 5 ~ i n d i f f e r e n t f i b e rs , t h e a v e r a g e b e i n g 3 0 ~C . T h e

p a r a m e t e r s b u r s t p e r i o d , b u r s t d u r a t i o n , p a u s e d u -

r a t i o n , i n t r a b u r s t i n t e r v a l a n d s p i k e s p e r b u r s t i n -

c r e a s e d m o n o t o n i c a l l y f r o m 3 0 ~ t o 1 5 ~ T h e p o s -

s i b l e p h y s i o l o g i c a l s i g n i f i c a n c e o f t h e b u r s t p a t t e r n i s

d i scu ssed .

K e y w o r d s : C o l d r e c e p t o r - B u r s t p a r a m e t e r s -

L i n g u a l n e r v e - S t a t i c d i s c h a r g e .

I n t r o d u c t i o n

G r o u p e d d i s c h a r g e s w e r e f ir s t d e s c r i b e d f o r c o l d f i be r s

i n t h e l i n g u a l n e r v e o f t h e c a t . T h e s e g r o u p e d d i s c h a r g e s

w e r e f o u n d t o s t a r t a t c o n s t a n t t e m p e r a t u r e s l o w e r t h a n

t h o s e a t w h i c h t h e s t a t i c a c t i v i t y o f c o l d f i b e r s b e g a n

( H e n s e l a n d Z o t t e r m a n , 1 95 1) . A t t e m p e r a t u r e s b e l o w

1 5 ~ t h e g r o u p e d p a t t e r n d is a p p e a r e d a n d t h e d is -

c h a r g e o f im p u l s e s b e c a m e m o r e r e g u l a r a g a in . D o d t

( 1 9 5 3 ) f o u n d a n i n v e r s e r e l a t i o n s h i p b e t w e e n g r o u p

f r e q u e n c y a n d c o n s t a n t t e m p e r a t u r e .

I g g o ( 1 9 6 9 ) g a v e a m o r e d e t a i l e d a n a l y s i s o f t h e

g r o u p e d d i s c h a rg e i n t h e s k in o f m o n k e y a n d d o g ,

d e f i n i n g th e t e r m ' b u r s t ' a s a p a t t e r n w i t h a n i n t e r b u r s t

i n t e r v a l a t l e a s t t w i c e a s l o n g a s t h e i n t r a b u r s t i n t e r v a l ,

w h i c h i s r e p e a t e d i n a r e g u l a r m a n n e r . W h i l e t h e

e n d o f f p r h ~ t r e q u e s t s t o H. Hensel at the above address

a v e r a g e s t a t i c f r e q u e n c y o f c o l d f i b e r s s h o w e d a

m a x i m u m a t a c e r t a in t e m p e r a t u r e , m o s t o f t h e b u r s t

p a r a m e t e r s , s u c h a s b u r s t f r e q u e n c y o r n u m b e r o f

i m p u l s e s p e r b u r s t , i n c r e a s e d m o n o t o n i c a l l y w i t h d e -

c r e a s i n g c o n s t a n t t e m p e r a t u r e i n t h e b u r s t i n g r a n g e

( I g g o , 1 9 6 9 ; Po u lo s , 1 9 7 1 , 1 9 7 5 ; I g g o an d Y o u n g ,

1 9 7 5; D y k e s , 1 9 7 5 ; D u b n e r e t a l. , 1 97 5 ; K e n s h a l o a n d

D u c l a u x , 1 9 7 7 ) . T h e b u r s t p a t t e r n a p p e a r e d a t t e m -

p e r a t u r e s n e a r t h e m a x i m a l s e n s i t i v i ty o f a c o l d r e-

cep to r ( I g g o , 1 9 6 5 ; Po u lo s , 1 9 7 5 ) .

I t w a s a s s u m e d t h a t t h e b u r s t p a t t e r n c o u l d c o n -

s t it u t e a c o d e t o g i v e u n a m b i g u o u s i n f o r m a t i o n a b o u t

s t e a d y t e m p e r a t u r e f r o m t h e s t a r t i n g t e m p e r a t u r e o f

c o l d f i b er a c t iv i t y d o w n t o l o w t e m p e r a t u r e s w h e r e t h e

b u r s t p a t t e r n d i s a p p e a r s a g a i n ( Ig g o a n d Y o u n g , 1 9 75 ;

D y k e s , 1 9 7 5 ; P o u l o s a n d M o l t , 1 9 7 6 ) .

T h e a i m o f o u r i n v e st i g a ti o n s w a s t o c o m p a r e t h e

b u r s t p a r a m e t e r s o f c o l d fi b e r s i n t h e l i n g u a l n e r v e o f

t h e c a t a t c o n s t a n t t e m p e r a t u r e s w i t h t h e r e s p e c t i v e

p a r a m e t e r s i n t h e s k i n o f m o n k e y a n d d o g . I n c o n t r a s t

t o t h e s k i n , t h e c a t ' s t o n g u e , u n d e r n a t u r a l c o n d i t i o n s ,

i s n e v e r e x p o s e d t o l o w s t a t i c t e m p e r a t u r e s w h e r e t h e

b u r s t d i s c h a r g e m a y b e c o m e s i g n i f i c a n t a s a d d i t i o n a l

i n f o r m a t i o n p a r a m e t e r . A c o m p a r i s o n o f r e la t iv e n u m -

b e r a n d p r o p e r t i e s o f c o l d f i b e rs in t h e t o n g u e a n d

i n

t h e

e x t e r n a l s k i n w a s e x p e c t e d t o c o n t r i b u t e t o t h e d i s -

c u s s i o n o f t h e p h y s i o l o g i c a l s i g n if i c a n c e o f t h e b u r s t

d i s c h a r g e . I n a d d i t i o n , t h e t o n g u e i s p a r t i c u l a r l y s u i t e d

f o r t h e s t u d y o f c o l d r e c e p t o rs u n d e r e x t e r n a ll y a n d

i n t e r n a l l y c o n t r o l l e d c o n d i t i o n s , i n c l u d i n g i n t r a a r t e r i a l

a d m i n i s t r a t i o n o f s u b s t a n c e s a n d a r t i f i c ia l p e r f u s i o n . I t

s e e m e d t h e r e f o r e d e s i r ab l e t o o b t a i n d e t a i le d i n f o r m a -

t i o n a b o u t t h e p r o p e r t i e s o f t h e l in g u a l c o l d r e c e p t o r

p o p u l a t i o n .

M e t h o d s

Cats were initially anesthetized with pentobarbital i.p. (25 mg/kg);

anesthesia was m aintained by intravenous application. The trachea

was cannulated. The head o f the animal was fixed and the tongue

0 0 3 1 - 6 7 6 8 / 7 9 / 0 3 8 2 / 0 0 0 1 / $ 0 1 . 0 0


2/5

2 P f l / i g e r s A r c h . 3 8 2 1 9 7 9 )

u p p e r s i de d o w n - w a s p la c e d o n a m e t a l t h e r m o d e o f 2 . 5 c m

d i a m e t e r c o v e r i n g t h e w h o l e f o r e p a r t o f t h e t o n g u e . T h e t h e r m o d e

w a s a l t e r n a t i v e l y c i r c n l a t e d w i t h w a t e r f r o m 7 t h e r m o s t a t s k e p t a t

c o n s t a n t t e m p e r a t u r e s . S t i m u l u s t e m p e r a t u r e s w e r e m e a s u r e d b y a 4 0 ~

t h e r m o c o u p l e s o l d e r ed t o t h e b o t t o m o f th e t h e r m o d e , d i s p la y e d o n

a n o s c i l l o s c o p e a n d r e c o r d e d o n t a p e a n d f i l m .

T h e d i st a l p a r t o f t h e l in g u a l n e r v e w a s e x p o s e d a n d p r o x i m a l l y

c u t . A f t e r t e s t i n g t h e r e c e p t i v e f i e l d b y m e c h a n i c a l s t i m u l a t i o n ,

s u i t a b l e b u n d l e s w e r e c h o s e n f o r s i n g l e - fi b e r p r e p a r a t i o n s o f s p e c i fi c 3 5 ~

c o l d f i be r s . A c t i o n p o t e n t i a ls w e r e r e c o r d e d w i t h R i n g e r - s o a k e d w i c k

e l e c t r o d e s . T h e a m p l i f i e d a c t i o n p o t e n t i a l s w e r e d i s p l a y e d o n a n

o s c i l l o s c o p e a n d r e c o r d e d o n t a p e a n d f i l m . S i n g l e f i b e r s r e s p o n d i n g

t o m e c h a n i c a l s t i m u l a t i o n w e re n o t u s e d . F u r t h e r m o r e , a c o l d st e p o f

2 5 ~ C t o 2 0 ~ C w a s a p p l i e d i n o r d e r t o e l i m i n a t e f i b e r s w i t h r e c e p ti v e 3 0 o C

f i e ld s o n t h e l o w e r s i d e o f t h e t o n g u e . T h e s e f i b e r s g iv e a d e l a y e d

r e s p o n s e t o t h e c o l d s t e p H e n s e l a n d W i t t , 1 95 9 ) . S e v e n s t i m u l u s

t e m p e r a t u r e s f r o m 4 0 ~ t o 1 0 ~ i n s t e p s o f 5 ~ w e r e a p p l i e d f o r

2 m i n e a c h . I n t h i s t i m e t h e d i s c h a r g e a d a p t e d t o t h e s t a t i c v a l u e s .

A f t e r t r a n s f o r m i n g t h e s p i k e s b y a w i n d o w d i s c r im i n a t o r , d a t a w e r e 2 5 o C

p r o c e s s e d b y m e a n s o f a c o m p u t e r p r o g r a m f o r b u r s t i d en t i f ic a t i o n

a n d a n a l y s i s o n a P D P 1 2.

Resu l t s

T h i r t y - f o u r s i n g l e c o l d f i b e r s w e r e i n v e s t i g a t e d , o f

w h i c h 2 7 c o u l d b e t e st e d o v e r th e w h o l e t e m p e r a t u r e

r a n g e . F i g u r e 1 s h o w s t h e s t a t i c a c t i v i t y o f a s i n g le c o l d

f i b e r a t v a r i o u s t e m p e r a t u r e s . A t h i g h e r t e m p e r a t u r e s , a

r e g u l a r s e q u e n c e o f s i n g le s p i k e s is se e n . W h e n l o w e r i n g

t h e c o n s t a n t t e m p e r a t u r e , s p o r a d i c b u r st s ( d o u b l e t s )

a p p e a r . A t 3 0 ~C , a r e g u l a r b u r s t d i s c h a r g e o c c u r s . W i t h

f u r t h e r d e c r e a se i n t e m p e r a t u r e , b u r s t d u r a t i o n , p a u s e

d u r a t i o n , i n t r a b u r s t i n t e r v a l, a n d n u m b e r o f s p ik e s p e r

b u r s t i n c r e a s e . F i n a l l y , t h e d i s c h a r g e b e c o m e s m o r e

i r r egu la r .

T h e f o l l o w i n g d e f i n i t i o n s ( s e e a l s o F i g . 3 ) w e r e u s e d

f o r t h e c la s s if i c a ti o n o f b u r s t p a r a m e t e r s : B D , b u r s t

d u r a t i o n ; P D , p a u s e d u r a t i o n ; B P , b u r s t p e r i o d ( B D

+ P D ) ; B I , i n t r a b u r s t i n t e r v a l ; A B I , a v e r a g e i n t r a b u r s t

i n t e r v a l ; S B , s p i k e s / b u r s t ; A F , a v e r a g e i m p u l s e f r e -

q u e n c y ; B B , b e g i n n i n g o f th e r e g u l a r b u r s t p a t t e r n .

S i n c e t h e c h a n g e f r o m s i n g l e s p i k e s t o r e g u l a r b u r s t i n g

w a s g r a d u a l , B B w a s d e f i n e d a s t h a t s t a t e a t w h i c h m o r e

t h a n 5 0 o f t h e s p i k e s a p p e a r e d i n b u r s t s .

I n a p o p u l a t i o n o f 2 7 f i be r s t h e t e m p e r a t u r e o f B B

w a s 4 0 ~ t o 1 5 ~ w i t h a c c u m u l a t i o n i n t h e r a n g e

b e t w e e n 2 0 ~ t o 3 5 ~ C . T h e a v e r a g e t e m p e r a t u r e o f B B

w a s 3 0 ~ A r e c r u i t m e n t o f b u r s t i n g f i b er s o c c u r r e d

w h e n l o w e r i n g t h e t e m p e r a t u r e f r o m 4 0 ~ C t o 2 5 ~ C . A t

2 5 ~ 9 2 .5 o f t h e p o p u l a t i o n w a s b u r s t in g .

F i b e r s h a v i n g t h e s a m e t e m p e r a t u r e o f B B w e r e

g r o u p e d t o g e t h e r a n d t h e i r A F w a s p l o t t e d a s fu n c t i o n

o f t e m p e r a t u r e ( F ig . 2 ). A c o r r e l a t i o n b e t w e e n B B a n d

m a x i m a l A F c a n b e s e e n i n f i b e r s w i t h B B a t 3 5 ~

30 ~ C , 25 ~ C an d 20 ~C , w h e r e a s t h i s c o r r e l a t i o n d o e s n o t

h o l d f o r B B a t t h e m o r e e x t r e m e t e m p e r a t u r e s o f 4 0 ~ C

a n d 1 5 ~

I f , h o w e v e r , a v e r a g e v a l u e s f o r t h e w h o l e p o p u -

l a t i o n o f c o l d re c e p t o r s a r e c a l c u la t e d , t h e m a x i m a l A F

2 o C

1 5 o c

I M P U L S E D I S C H A R G E

IIIIIIIllllll[llllllllllllllllllilll[llll[llillllillllllll

I00 S E C 1

I N S T A N T A N E O U S F R E Q U E N C Y

I l l l l l l l l l l l i l l l l l l l l l 3l l l l I I I I I l l l l l l l l i l l l l l l

1 0 0

i 2 3

I I I I l l l l l t I I I I I I I I I I I I I I I I I I I I I

1 0 0

0 i 2 3 4

I I I I I I I I l l I I

1 0 0

o ~

0 2 3 4

I [ [ l l l l [ [ I I l

1 0 0 ! S E c ' I

o I _ k ~ 8 9 I _

1

2 3 4

T I M E S E C

n

~ 1 7 6I

~o II HISTOGR M

Im N WroTHSMSEC

~ o : 1 o . 2 o : a o ~ 4 o ~s

0 . . . . . . . . . .

0 al 0 2 o,3 0/. o,5

1 0 0

5 O

0 9 ~ ' ~ . . . . . . .

0 9 0 '1 0 ' 2 0 , 3 0 , 4 0 , 5

5 0

0 9 , ' f ~ . . . . . . .

o o j o 2 o 3 o 4 0 5

O O l

0

0 0 , 1 0 . 2 q 3 0 . 4 0 '5

r~

0

0 0,1 0,2 0,3 0/~ 0,5

I N T E R V A L S E e

F i g . 1 . I m p u l s e d i s c h a r g e , i n s t a n t a n e o u s f r e q u e n c y a n d i n t e rv a l

h i s t o g r a m s o f a s i n g le c o l d f ib e r a t v a r i o u s c o n s t a n t t e m p e r a t u r e s

a n d B B m u s t n o t n e c e s s a r i ly c o in c i d e . F o r a p o p u l a t i o n

o f 2 7 c o ld r e c e p t o r s , th e m e a n t e m p e r a t u r e o f B B w a s

30 ~C , w h i le t h e t e m p e r a t u r e o f m a x i m a l A F w a s 2 5 ~C .

H o w e v e r , a t 3 0 ~C , A F w a s o n l y s l i g h t ly l o w e r (9 7 )

t h a n t h e m a x i m a l v a l u e .

T h e p a r a m e t e r s B P , B D a n d P D d i d n o t s ig n if i-

c a n t l y d i f f e r i n f i b e r s o f d i f f e r e n t t e m p e r a t u r e s o f B B .

T h e r e f o r e t h e v a l u e s o f a l l f i b e r g r o u p s i n F i g . 3 w e r e

p u t t o g e t h e r . B P , B D a n d P D i n c r e a s e d m o n o t o n i c a l l y

w i t h d e c r e a s i n g t e m p e r a t u r e , t h e v a r i a t i o n o f si n g le

v a l u e s b e c o m i n g l a r g e r i n th e l o w e r t h e r m a l r a n g e . I n

c o n t r a s t t o t h e s e p a r a m e t e r s , t h e a v e r a g e i n t e rv a l h a d a

m i n i m u m a t 2 5 ~ T h i s c u r v e d e p i c ts t h e r e c i p r o c a l

v a l u e o f th e b e l l - s h a p e d f r e q u e n c y - t e m p e r a t u r e c u rv e

o f c o l d r e c e p t o r s .

W h e n t h e s t a t i c t e m p e r a t u r e w a s l o w e r e d , t h e

p a r a m e t e r S B i n c r e a s e d m o n o t o n i c a l l y ( F ig . 4 ). F o r

f i b e r g r o u p s w i t h B B o t h e r t h a n 3 0 ~C , t h e c u r v e s r u n

p a r a l l e l w i t h t h a t s h o w n i n F i g . 4 .

i s cus s i on

T h e b u r s t p a t t e r n o f c o l d fi b e rs f r o m t h e c a t ' s t o n g u e

s h o w s a s i m i l a r d e p e n d e n c y o n t e m p e r a t u r e t o t h a t o f


3/5

H. Bade et al. : Burst Parameters of Lingual Cold Receptors

20

Fig 2

Average frequency of single cold fibers as function

of temperature. BB, beginning of bursts, n, number

of fibers in each group. Bars indicate S.E.M.

1 5

i

LLI

L/3

>.-

(..)

z 1 0

ILl

0

W

n,,

LL

~

Ll

~BoB ~ / B B 3 5 o c

I [ o : 8

J / / .~ \ ~ o o c

i B ,

1 0 1 5 2 0 2 5 3 0 3 1 5 ~ O 0 c

T E M P E R A T U R E

6 0 0

m s e c

BP - BI i .

5 0 0

L o _

n~ 3

2

to

10 0 B D ~ x . ~ ' , _ . . . . . . . ~ ~ .

- T_

0

1 5 2 0 2 5 3 0 3 5 ~


Fig. 3. Average burst parameters and mean spike interval as function

of constant temperature.

BD,

burst duration;

PD,

pause duration;

BP,

burst period;

BI,

intraburst interval;

ABI,

average intraburst

interval, n, number of cold fibers. Bars indicate S.E.M.

3

E

m

1 5 2 0 2 5 3 0 ~ 3 5


Fig.4. Number of spikes/burst SB) for a group of cold fibers with

beginning of bursts at 30~C as function of temperature, n, number of

fibers

cold fibers in the monk ey s skin, perior al units in the

dog and cold fibers in the scrotal skin of the rat. The

values for several burst parameters in various species

are given in Table 1.

For cold receptors in the monk ey s skin, Poulos

(1975) mentioned a certain correlation between the

temperature of BB and that of the static maximum of

AF. In his sample of 7cold fibers, the maximal AF

occurs at 29~ and the burst pattern with SB = 2 at

33 ~C. Similar results were reported by I ggo and Y oun g

(1975); in a sample of 12 cold fibers, the maxim al A F

was fou nd a t 27 ~ C, while the burst patte rn with SB = 2

occurred at 31~ The corre spondin g values foun d by

Dykes (1975) were 24~ and 26 -2 8~ respectively.

Alth ough the average temperatu re of BB is higher than

the temperature of the maximal AF, the results of these

authors show a correlation between both parameters:

the higher the temperature of the maximal AF, the

higher the temperature at which the regular burst

pattern begins.

Accord ing to our measurements, the temperature of

the cat s tongue does not drop to constant levels below

35~ even at ambients as low as 5~ while the skin

temperature of the nose can easily reach co nstant levels

between 30~ and 15~ where the burst parameters

are highly dependent on temperature. For example, the

average nasal temperature of cats was found to be 15~

at ambients of 5~ (Hensel and gch~fer, 1979).


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a b l e

1 . B u rs t p a ra m e t e r s o f c o l d f i b e r s i n v a r i o u s sp e ci es

Pfl i igers Arch . 382 (1979)

A u t h o r N e r v e

S p i k e s / b u rs t B u r s t d u r a t i o n B u r s t p e r i o d R a n g e

(SB ) (B D) (B P) o f r e g u l a r

b u r s t p a t t e r n

n ms ms ~C

I g g o ( 1 96 9 ) M o n k e y , N . m e d i a n u s 2 - 4

Po u l o s (1 97 1 ) ~ M o n k e y , N. t r i g e mi n u s 2 -5

D y k e s ( 19 75 ) M o n k e y , N . m e d i a n u s 2 - 4

He l l o n e t a l. (1 97 5 ) R a t , N . p u d e n d u s 2 -4

O u r d a t a C a t , N . l in g u a li s 2 - 4

2 8 5 - - 6 5 0 3 1 - 2 1

2 0 - 1 0 0 1 3 0 - 3 40 3 3 - 2 1

1 2 - 2 2 0 2 4 0 -- 6 00 2 6 - 2 0

2 7 - - 2 0

1 5 - - 1 00 1 6 0 - 5 20 3 0 - 1 5

Pa r t i a l l y e x t ra p o l a t e d d a t a

However, in contrast to the lingual cold receptors with

more than 90 bursting units, only 28 of the nasal

cold fibers were bursting at constant temperatures of

15 ~C. If the burst discharge is decisive for the detection

of low static temperatures, it is difficult to understand

why in a receptive field never exposed to such tempera-

ture levels nearly all cold fibers are bursting, whereas

only a relatively small fraction of bursting units is found

in a region which, under natural conditions, can

frequently reach low constant temperatures. In the

range below 20 ~C, additional thermal information may

be conveyed by recently discovered nasal receptors

activated at very low constant temperatures (Duclaux,

Sch/ifer and Hensel, unpublished).

The average temperature of the furred skin in the

cat changes from about 34 ~C at 25 ~C ambient tempera-

ture to 31~ at -5 ~ ambient temperature (Hensel

and Banet, 1977). There is only limited information

available about cutaneous cold receptors in the trunk

and proximal parts of the extremities in cats (Witt and

Hensel, 1959; Hensel et al., 1960). Assuming that their

response characteristics are similar to those o f the nasal

cold receptors, AF alone could give sufficient infor-

mation for the thermoregulatory system in this tem-

perature range.

The burst parameters of cold fibers from the

monkey's hand do not agree with static temperature

sensation in the human hand. According to Beste and

Hensel (1977), human subjects are not able to discrim-

inate constant temperatures applied to the hand in the

range between 28~ and 22~ whereas the burst

parameters of cold receptors in the monkey's hand are

highly dependent on temperature particularly in this

range (Dykes, 1975). On the other hand, human

sensory discrimination improves at constant tempera-

tures below 20 ~C, but in the monkey no regular burst

pattern is seen in this range.

There is no evidence that the burst pattern of cold

receptors is maintained through synaptic transmission

in the situation of convergence (Landgren, 1957, 1960;

Poulos, 1975; Iggo and Young, 1976 ; Iggo and

Ramsey, 1976; Schmidt, 1976; Dostrovsky and Hellon,

1978).

Neither is there any evidence of an indirect trans-

mission of the burst parameters, the frequency-

temperature characteristics of higher order neurons

showing a bell-shaped curve similar to that of periph-

eral cold receptors (Poulos, 1971; Poulos and Molt,

1976; Dostrovsky and Hellon, 1978). This does not

necessarily exclude any significance of the burst patte rn

for synaptic transmission but such a function remains

to be demonstrated.

Acknowledgements Th e a u t h o rs a re g re a t l y i n d e b t e d t o P ro f . H .

F r u h s t o r f e r a n d h i s c o - w o r k e r s D r . W . G . S c h m i d t a n d M r . P .

L a n g a n k e f o r t h e i r v a l u a b le h e l p in p r o g r a m m i n g t h e P D P - 1 2 a n d t o

M rs . H. B e s t g e n fo r t e c h n i c a l a s s is t a n c e .

S u p p o r t e d b y t h e D e u t s c h e F o r s c h u n g s g e m e i n s c h af t .

Re f e r en c e s

B e st e, R . , H e n se l , H . : Su b j e c t iv e e s t i ma t i o n o f s t a t i c t e mp e ra t u re s a t

t h e p a l m i n h u ma n s . P f l f i g e rs Arc h . 3 6 8, Su p p l . , R 4 7 (1 97 7 )

D o d t , E . : T h e b e h a v i o u r o f t h e r m o r e c e p t o r s a t l o w a n d h i g h

t e mp e ra t u re s wi t h sp e c i a l r e fe re n c e t o Eb b e c k e ' s t e mp e ra t u re

p h e n o me n a . Ac t a Ph y s i o l . Sc a n d . 2 7 , 2 9 5 -3 1 4 (1 9 5 3 )

Do s t ro v sk y , J . O . , H e l l o n , R . F . : Th e re p re se n t a t i o n o f f a c i a l

t e mp e ra t u re i n t h e c a u d a l t r i g e mi n a l n u c l e u s o f t h e c a t . J .

Ph y s i o l . (Lo n d . ) 2 7 7 , 2 9 -4 7 (1 9 7 8 )

Du b n e r , R . , Su mi n o , R . , Wo o d , W. J . : A p e r i p h e ra l c o l d f i b e r

p o p u l a t i o n r e s p o ns i v e t o i n n o c u o u s a n d n o x i o u s t h e r m a l s t i m u l i

a p p l i e d t o mo n k e y ' s f a c e . J . Ne u ro p h y s i o l . 3 8 , 1 3 7 3 -1 3 8 9

(1975)

Dy k e s , R . W. : C o d i n g o f s t e a d y a n d t ra n s i e n t t e mp e ra t u re s b y

c u t a n e o u s c o l d f i b e r s s e rv i n g t h e h a n d o f mo n k e y s . B ra i n R e s .

9 8 , 4 8 5 -5 0 0 (1 9 7 5 )

He l l o n , R . F . , He n se l , H . , Sc h f ife r, K . : Th e rm a l re c e p t o rs i n t h e

sc ro t u m o f t h e rat . J . Ph y s i ol . (Lo n d . ) 2 4 8 , 3 4 9 -3 5 7 (1 97 5 )

He n se l , H . : C o r re l a t i o n s o f t e m p e ra t u re se n s i t iv i t y i n ma n a n d

mo n k e y . In : Se n so ry fu n c t i o n s i n t h e sk i n o f p r i ma t e s , (Y.

Zo t t e rma n , e d . ) , p p . 3 3 1 - 3 5 4 . Ox fo rd : Pe rg a mo n Pre s s 1 9 7 6

H e n s e l, H . B a n e t , M . : F u r g r o w t h a n d m e t a b o l i s m in c o l d a n d w a r m

ada pted ca ts . Pfl t igers Ar ch . 368 , Suppl . , R28 (1977)


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