EFFECT

OF

ON T H E

EXTERNAL

ENVIRONMENTAL

TEMPERATURE

N° A.

TEMPERATURE

SENSATION

Kokhanova

and

P.

N.

FUNCTION UDC 612.53/.55

Zhilin

An i n v e r s e r e l a t i o n s h i p e x i s t s b e t w e e n the a i r t e m p e r a t u r e , on the one hand, and the l a t e n t p e r i o d of the s e n s o m o t o r r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n and the t h r e s h o l d of t e m p e r a t u r e d i s c r i m i n a t i o n , on the o t h e r hand, in c h i l d r e n d u r i n g the s u m m e r vacation.

The s y s t e m for t e m p e r a t u r e s e n s a t i o n , with its i m p o r t a n t r o l e in m a i n t e n a n c e of the b a l a n c e b e t w e e n the o r g a n i s m and the e x t e r n a l e n v i r o n m e n t a l t e m p e r a t u r e , is in a state of c o n t i n u o u s activity [4, 5, 7, 8]. However, slight f l u c t u a t i o n s in e n v i r o n m e n t a l t e m p e r a t u r e u n d e r n a t u r a l conditions are f r e q u e n t l y u n n o t i c e d , e s p e c i a l l y by c h i l d r e n , although this is a s s o c i a t e d with changes in the state of the t e m p e r a t u r e s e n s o r y system. The I n v e s t i g a t i o n d e s c r i b e d below was c a r r i e d out on c h i l d r e n d u r i n g the s u m m e r v a c a t i o n when they spent v i r t u a l l y the whole day outside. Indices u s e d to define the state of t e m p e r a t u r e s e n s a t i o n were the late l a t e n t p e r i o d of the s e n s o m o t o r r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n and the t h r e s h o l d of t e m p e r a t u r e d i s c rimination. EXPERIMENTAL

METHOD

The t e m p e r a t u r e s t i m u l a t i o n d e t e c t o r was fixed to the m e d i a l s u r f a c e of the d i s t a l p o r t i o n of the f o r e a r m [1, 3]. Its t h e o r e t i c a l i n e r t i a was u n d e r 10 m s e c . T e m p e r a t u r e s e n s t i v i t y (in J / c m 2) was d e t e r m i n e d from the t h r e s h o l d l e v e l of t e m p e r a t u r e s t i m u l a t i o n . The c o m p u t e r p a r t of the a p p a r a t u s r e c o r d e d the latent p e r i o d of the r e s p o n s e in m i l l i s e c o n d s (time f r o m b e g i n n i n g of s t i m u l a t i o n to t i m e when the s u b j e c t TABLE 1. Latent P e r i o d of R e s p o n s e of C h i l d r e n of P r e s c h o o l Age (10 subjects) to T e m p e r a t u r e Stimulation d u r i n g Colder and W a r m e r P e r i o d s of July Index studied

Period and time of observation to--15 luly 24--29 July 8:00 A.M. I P.M. 8:00 A.M. 1 P.M.

p between 1st and 2nd ~eriods

Air temperature (in deg.) Limits of variants M ~m Latent perLod (in msec) Limits of variants . M~m .....

16.3--21,1 18,2--24,9 20,4--23,8 18,84-0,9 22,64-1,2 22,24-0,6 880--773 82O+--19

815--737 770± 14

796 --674 733~21

25,2-t=29,6 27,64-1,0

<0,05 <0,05

731--581 675 -- 27

<0,05 <0,05

L a b o r a t o r y of E r g o n o m i c s , Institute of Work Hygiene and Occupational D i s e a s e s , A c a d e m y of Medical Sciences of the USSR. D e p a r t m e n t of Hygiene of Town P l a n n i n g , F. F. E r i s m a n S c i e n t i f i c - R e s e a r c h I n s t i tute of Hygiene, Moscow. ( P r e s e n t e d by A c a d e m i c i a n of the A c a d e m y of Medical S c i e n c e s of the USSR A. P. Letavet.) T r a n s l a t e d from B y u l l e t e n ' F,k s p e r i m e n t a l ' n o i Biologil i Meditsiny, Vol. 70, No. 12, pp. 12-14, D e c e m b e r , 1970. O r i g i n a l a r t i c l e s u b m i t t e d March 16, 1970.

© 1971 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 10011. All rights reserved. This article cannot be reproduced [or any purpose whatsoever without permission o[ the publisher. A copy o[ this article is available [rom the publisher [or $15.00.

1358

~

26

2~

ii"

22

22 ZO

•~ =

~.~

yyo

B%

~

o ~

~ .700

YO0

.~ = 7.50 r- ~

E..--6ooL "-"

"--"

~E

i a oL5 o'~ 445

~ :~

~

I

I

I

3

7

//

June

~'~ .~ :, 0/~'"

i

29

'

.V

'

II

-"~

t3

J

J

J

Z3

25

27

luly Fig. 1. Changes in a i r t e m p e r a t u r e , l a t e n t p e r i o d of r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n , and t h r e s h o l d of d i s c r i m i n a t i o n in c h i l d r e n of school age d u r i n g s u m m e r v a c a t i o n in the c o u n t r y n e a r M o s c o w (mean r e s u l t s for 14 c h i l dren). Continuous line r e p r e s e n t s m e a s u r e m e n t s at 9 A.M., b r o k e n l i n e m e a s u r e m e n t s at 1 P.M.

I

I

I5 I #

I

23

Ju 1),

Fig. 2. Changes in a i r t e m p e r a t u r e , l a t e n t p e r i o d of r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n (continuous line), and t h r e s h o l d of t e m p e r a t u r e d i s c r i m i n a tion (broken line) for c h i l d r e n of s c h o o l age during s u m m e r v a c a t i o n on the Black Sea c o a s t of the C a u c a s u s (mean r e s u l t s f o r s e v e n c h i l dren). M e a s u r e m e n t s m a d e at 9 A.M.

f e l t the heat and p r e s s e d the button). T e s t s w e r e c a r r i e d out on c h i l d r e n of p r e s c h o o l (6 y e a r s ) and school (10-13 y e a r s ) age, during t h e i r s u m m e r v a c a tion in the c o u n t r y n e a r Moscow and on the Black Sea c o a s t of the C a u c a s u s . O b s e r v a t i o n s on the Black Sea c o a s t continued f o r a month at the s a m e t i m e of day, the c h i l d r e n of the two age g r o u p s being t e s t e d on d i f f e r e n t days. In the c o u n t r y n e a r Moscow, o b s e r v a t i o n s w e r e made f o r 6-7 days at the beginning and at the end of the c h i l d r e n ' s s t a y in t h e i r P i o n e e r Camp. The m e t e o r o l o g i c a l conditions w e r e r e c o r d e d at the s a m e t i m e . The p h y s i o l o g i c a l and m e t e o r o l o g i c a l m e a s u r e m e n t s w e r e m a d e by d i [ [ e r e n t i n d i v i d u a l s .

EXPERIMENTAL

RESULTS

In the country near Moscow the air temperature during the period of investigation varied. In the less warm period (July 10-15) the latent period of the response to temperature stimulation was longer than in the warmer period (July 24-29), when the air temperature reached 25.2-29.6°C (Table i). Results obtained during tests on 14 children on vacation in the Pioneer Camp the following year are shown in Fig. i. In this case, at the beginning of each period of testing the children the air temperature was lower than at its end. The latent period of the response to temperature stimulation and the threshold of temperature discrimination varied during each period from higher to lower values. Changes in the studied indices also were observed during the day. In the morning (9 A.M.) a lower air temperature corresponded to higher values of the latent period and threshold of temperature discrimination compared with those recorded during the afternoon (i P.M.). Systematic observations on the air temperature, on the one hand, and the latent period and threshold of temperature discrimination, on the other hand, for a period of one month revealed the dynamic character of the relationship between these indices in the children of school age (Fig. 2) and of preschool age (Fig. 3) on vacation on the Black Sea coast of the Caucasus. These illustrations show that fluctuations of air temperature between days of testing were greater for the children of school age than for those of the preschool group. Correspondingly, the fluctuations in latent period and threshold of temperature discrimination were greater for the children of school age than for the preschool group.

1359

The r e s u l t s of t h i s i n v e s t i g a t i o n thus showed that the l a t e n t p e r i o d of the r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n and the t h r e s hold of t e m p e r a t u r e d i s c r i m i n a t i o n a r e highly l a b i l e and t h a t they v a r y with c h a n g e s in the e x t e r n a l e n v i r o n m e n t a l t e m p e r a t u r e . An i n v e r s e r e l a t i o n s h i p e x i s t s b e t w e e n t h e a i r t e m p e r a t u r e and the i n d i c e s studied.

g asob~

,.= .,n

,..a~

b June

July

Fig. 3. Changes in a i r t e m p e r a t u r e , l a t e n t p e r i o d of r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n (continuous line), and t h r e s h o l d of t e m p e r a t u r e d i s c r i m i n a tion (broken line) in c h i l d r e n of p r e school age d u r i n g t h e i r s u m m e r v a c a tion on the B l a c k Sea c o a s t of the C a u c a s u s (mean r e s u l t s for 12 c h i l d r e n ) . M e a s u r e m e n t s made at 9 A.M.

Changes in the a c t i v i t y of the s y s t e m for t e m p e r a t u r e s e n s a t i o n in r e s p o n s e to a d e q u a t e s t i m u l a t i o n a r e r e f l e c t e d in changes in the f r e q u e n c y of i m p u l s e s g e n e r a t e d by the t h e r m o r e c e p t o r s , the l e v e l of which is fixed at a given t e m p e r a t u r e , and t h e r e a r e c o r r e s p o n d i n g c h a n g e s in the flow of i m p u l s e s to c e n t r a l s t r u c t u r e s u n d e r t h e s e s a m e conditions [6, 10]. As a r e s u l t , the functional s t a t e of the s y s t e m f o r t e m p e r a t u r e s e n s a t i o n a s a whole is m o d i f i e d , a s r e f l e c t e d in c h a n g e s in the t h r e s h o l d of t e m p e r a t u r e s e n s a t i o n and c h a n g e s in the l a t e n t p e r i o d of the r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n . This e x p l a n a tion is a l s o c o n f i r m e d by the fact that the c h a n g e s in l a t e n t p e riod of the s e n s o m o t o r r e s p o n s e in m a n a r e c l o s e l y c o n n e c t e d with, and in the s a m e d i r e c t i o n a s , c h a n g e s in e l e c t r i c a l a c t i v i t y of that a r e a of the c o r t e x to which the i n f o r m a t i o n is a d d r e s s e d [2, 9].

The c h a n g e s in the l a t e n t p e r i o d of the r e s p o n s e to t e m p e r a t u r e s t i m u l a t i o n and in the t h r e s h o l d of t e m p e r a t u r e d i s c r i m i n a t i o n u n d e r n a t u r a l c o n d i t i o n s d i s c o v e r e d b y t h e s e e x p e r i m e n t s i n d i c a t e a c o n s t a n t fluctuation in the l e v e l of function of the s y s t e m for t e m p e r a t u r e s e n s a t i o n in a c c o r d a n c e with e x t e r n a l t e m p e r a t u r e c o n d i tions. They also i n d i c a t e a c o n s t a n t i n t e r a c t i o n b e t w e e n the o r g a n i s m and the e x t e r n a l e n v i r o n m e n t , a i m e d at m a i n t a i n i n g e q u i l i b r i u m . LITERATURE 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

1360

CITED

S . I . Gorshkov, in: M o d e r n Methods of I n v e s t i g a t i o n in Hygiene [in R u s s i a n ] , Moscow (1964), p. 9. M . P . Ivanova, Byull. E k s p e r i m . Biol. i Med., No. 3, 3 (1967). N . A . Kokhanova, Byull. E k s p e r i . Biol. i Med., No. 12, 10 (1965). S . L . L i b e r m a n and V. M. Romko, in: T r a n s a c t i o n s of the D e p a r t m e n t of P h y s i o l o g y , Kazakh I n s t i t u t e of P h y s i c a l C u l t u r e [in R u s s i a n ] , No. 2, A l m a - A t a (1957), p. 288. P . G . Snyaldn, The F u n c t i o n a l M o b i l i t y Method in C l i n i c a l and E x p e r i m e n t a l R e s e a r c h [in Russian] Moscow (1959). H. Hensel and Y. Z o t t e r m a n , A c t a P h y s i o l . Scand., 2._33, 291 (1951). H. Hensel, A. Iggo, and I. Wit*, J. P h y s i o l . (London), 153, 113 (1960). R. M e l z a c k , G. R o s e , and D. M c I n t y r e , Exptl. N e u r o l . , 6, 300 (1962). F. Morrei1 and M. R o s s , A r c h . Neurol. P s y c h i a t . , 70, 611 (1953). Y. Z o t t e r m a n , Ann. Rev. P h y s i o l . , 1_~5,357 (1953).