INFLUENCE OF CHANGES IN TEMPERATURE AND 

 PRESSURE ON THE NERVE FIBERS 



IcHiJi Tasaki and Constantine S. Spyropoulos, Laboratory of 

 Neurophtjsiology, National Institutes of Health, 

 Bethesda, Maryland 



I 



F NERVOUS ACTIVITY depends on biochemical reactions, the rates of vari- 

 ous phases of this activity should, in general, be modified by changes in 

 temperature and pressure. Although the demonstration of a marked tem- 

 perature or pressure dependence of a biological process may not prove 

 that this process is carried out by chemical reactions, it does serve to dis- 

 tinguish it from other processes having different types of temperature or 

 pressure dependence. 



The effects of temperature changes upon various phases of nervous ac- 

 tivity have been investigated by a great number of workers. In 1908, Keith 

 Lucas (1) showed that conduction velocity in the frog motor nerve de- 

 creased with a fall in temperature; the Qio he obtained was approximately 

 L8. This result was confirmed by many recent investigators. In 1912, Ad- 

 rian (2) found that the duration of both the absolute refractory period 

 and of the electric response of the frog nerve varies with temperature with 

 a Qio of approximatelv 3. A little later, Gasser (3) made a series of classi- 

 cal observations on the effects of temperature upon various phases of the 

 action potential of the frog nerve. More recently the effects of tempera- 

 ture changes upon the frog nerve fiber have been investigated by Bremer 

 and Titeca (4), Schoepfle and Erlanger (5j, Lorente de No (6), Lundberg 

 (7), Tasaki (8-10), and many others. The temperature effects on the iso- 

 lated invertebrate axon have been reported by Cardot and Arvanitaki 

 (11), Hodgkin and Katz (12) and others. 



Investigations on the effects of pressure changes upon the nerve are very 

 scarce. Grundfest and Cattell (13) in this country and Ebbecke and 

 Schaefer (14) in Germany made some pioneer observations in this field. 

 The investigation along this line was, however, comjiletely interrupted 

 for almost two decades. 



This article is a review of the experimental studies on the effects of 

 temperature and pressure changes upon the isolated myelinated nerve 

 fiber of the frog and toad and upon the isolated giant axon of the squid. 



^ Part of the work presented in this article was carried out at tlie Marine Biological 

 Laboratory, Woods Hole, Massachusetts. 



201 



