276 



BIOPHYSICAL STUDIES ON NERVE AND MUSCLE 



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Figure 10-7. The Synapse or Junction Between Two Nerve Endings (con- 

 ceptual and schematic). As the impulse reaches the end of the nerve, acetyl- 

 choline (ACh) is released in quantity from the little (~300 A) vesicles contained 

 in the presynaptic nerve ending. This ACh depolarizes the membrane, and free 

 flow of K + out and Na + in, on the presynaptic ending, and of ACh across the 

 gap, occurs. 



The neuromuscular junction, shown and described later, is similar to the 

 neuron-neuron junction in many ways. 



Synapses are apparently very sensitive to ionizing radiations, for Livshits 

 and others in the Russian school have observed changes in the EEG pattern 

 during even very weak (1 r/hr) X- or 7-irradiation, although peripheral 

 nerve is relatively quite insensitive. The subtle psychological effects which 

 result from such interference with, or modification of, the normal pulsating 

 activity of the brain can therefore be considered as due to electrochemical 

 noise generating by radiations from outside. Noise in our reckoning system, 

 produced by such stresses from without, is considered a bit more fully in the 

 next chapter. Noise from within — disordered inputs from crossed neural 

 circuits, from the physical apparatus of memory, and from the metaphysical 

 parts of mind, intelligence, and will — is the basis for further psychological 

 stresses and disorders. Memory-stimulation by electric shocks applied to 

 the interpretive cortex of the brain seems to be another experimental avenue 

 by which man can apply biophysical methods to the study of this wonderful 

 organ. The uninitiated but interested reader is referred to the well-illus- 

 trated review by Penfield. 8 



Entering the brain are several trunk lines, each main line being many- 

 stranded, and every strand insulated electrically from every other so that 

 many signals may pass simultaneously down the trunk line. In the case of 



