Chap. 16 CONDUCTION AND COORDINATION NERVOUS SYSTEM 307 



Destruction of this causes blindness, even though the eyes may be normal; a 

 blow on this part of the head makes one "see stars." The auditory area is 

 near the temple and injury to this causes deafness, loss of the interpretation 

 of sound although the sound receptors may be normal. Along and behind 

 the central fissure (Rolando) which extends from about the middle of the 

 head to the top of the ear is an area associated with various bodily sensations: 

 muscle sense, pressure, temperature, and pain. Patients are able to report 

 their sensations when this region is exposed and is stimulated by electricity. On 



Medulla 



Fig. 16.22. Outline of left half of the human brain with the mental functions 

 of certain areas indicated. For example, the visual association area contains the 

 cells essential to interpret and coordinate the objects seen. (After Morgan. Cour- 

 tesy, Boring, et al.: The Foundation of Psychology, New York, John Wiley and 

 Sons, 1948.) 



the opposite side of the central fissure is the motor area. When different 

 parts of this area are stimulated, movements of the fingers, legs, or throat 

 can be produced. A cerebral hemorrhage or "stroke" in this region on the 

 left side causes paralysis of muscles in the right side of the body and vice 

 versa. Both of these areas, the sensory and the motor, are laid out like a 

 map with different places representing different parts of the body. There are 

 also association centers, such as the auditory and visual ones, believed to 

 be concerned with the remembrance of things heard and seen; these regions 

 have been only partially explored. Although the whole cerebral cortex is 

 concerned with thinking, the capacity to direct it and to lay out plans of 

 living appears to be located in the front regions of the cerebrum. 



Brain Waves 



Several waves per second of electrical activity are produced by the brain 

 even when a person is resting. Recordings of brain waves are obtained by 

 fastening electrodes to different parts of the scalp by adhesive tape and 

 picking up the currents by a recording apparatus. The records (electro- 



