Our ability to read and make maps, to orient ourselves spatially in three dimensions and to use the appropriate symbols - all of which are probably involved in the development if not the use of language - are severely impaired by lesions in the parietal lobes, near the top of the head.
One soldier who suffered a massive wartime penetration of the parietal lobe was for a full year unable to orient his feet into his slippers, much less find his bed in the hospital ward.A lesion of the angular gyrus of the neocortex, in the parietal lobe, results in alexia, the inability to recognize the printed word.
The parietal lobe appears to be involved in all human symbolic language and, of all the brain lesions, a lesion in the parietal lobe causes the greatest decline in intelligence as measured by activities in everyday life.
Chief among the neocortical abstractions are the human symbolic languages, particularly reading and writing and mathematics.
Carl Sagan
1934 - 1996
