Nervous Systems 



839 



lobes of the forebrain have specific functions: occipital lobe— vision; tem- 

 poral lobe— hearing; parietal lobe (post-central gyrus)— proprioceptive and 

 exteroceptive sense; frontal lobe (precentral gyrus)— motor control. The func- 

 tions named are not restricted to their lobes and in each part of the cortex 

 there are also areas of integration. The sensory areas have been mapped by 



/'"^^ — posta)^ial 

 /leg,' 



FACE I 



FACE II 



ARM 



INSULA 



POSTAXIAL — 7 



TRUNK 



^VISUAL I 

 ,' FACE I \\ "n 



-W-VISUAL 11 



Fig. 312. Maps of the somatic sensory, auditory, and visual areas of the cerebral cortex 

 of monkey, cat, and rabbit as determined by action potentials. I primary, II secondary 

 areas for each sensory modality. Hatched lines, ipsilateral face areas. A M B in auditory 

 areas indicate projection of apical, middle, and basal turns of cochlea. In diagram of 

 monkey brain the sylvian fissure is represented as spread apart to reveal the insula. 

 Redrawn from Woolsey.*^ 



local application of strychnine in animals, by electrical stimulation in con- 

 scious humans, by extirpation and observation of sensory deficiencies, and by 

 recording electrical responses to sensory stimulation. To a localized sensory 

 stimulus there are usually two or more cortical regions of response, primary 

 and secondary (Fig. 31 2).^'^'^ The retina is represented point for point on the 



