800 PHYSIOLOGICAL TOPOGRAPHY OF SURFACE OF CEREBRUM. 



as the active areas. Complete deafness occurs only on destruction of 

 the latter areas on both sides. Word-deafness is followed by secondary 

 atrophy of the motor speech-center. 



Verbal blindness and deafness may be included clinically in the group of 

 aphasic disorders, in so far as they resemble the amnesic variety. The word-deaf 

 or the word-blind patient resembles an individual who in early youth had learned 

 a foreign language, which in later life he has completely forgotten. He 

 hears, therefore, or he reads well the words and the symbols of writing and he is 

 able also to repeat the words spoken to him and to write them on dictation, but 

 he has entirely lost comprehension of the signs. While, therefore, the amnesic 

 aphasic has lost only the key of the door to his speech-mechanism, the word-deaf 

 or word-blind patient has lost this mechanism itself. From a case in which 

 recovery took place it is known that the word sounds to the patient like a confused 

 murmur. In left-handed persons destruction of the left temporal lobe is not 

 followed by word-deafness, as in them the center is probably situated on the right 

 side. The hallucinations of hearing induced by irritation of the psycho-auditory 

 center appear usually in the right ear, although they may appear in both. Occa- 

 sionally they are at the same time different in content and character in both ears. 

 Huguenin observed atrophy of the temporal lobe after deafness of long standing. 



Agra'phia also may be due to word-blindness, the patient being unable to 

 write from copy, although he can write spontaneously or on dictation; and like- 

 wise to word-deafness, the patient being unable to write on dictation, although 

 he can write spontaneously or from copy. 



According to Flechsig the psycho-osmic center or the olfactory sphere 

 comprises the entire posterior margin of the base of the frontal lobe and 

 the basal portion of the fornicate gyrus, the uncinate gyrus, and a portion 

 of the adjacent inner pole of the temporal lobe. The psychogeusic 

 center or the gustatory sphere is supposed by Flechsig to be situated within 

 or at the margin of the center for bodily sensations or the olfactory sphere. 



Subjective sensations of taste or smell in the insane and in epileptics are due 

 to abnormal irritation in these regions, destruction of which will cause loss 

 of the corresponding functions. In the new-born the olfactory center appears 

 to be one of the earliest to enter upon functional activity. It degenerates after 

 destruction of the olfactory tract. 



The sphere for bodily sensation, psycho-esthetic and psycho-algic center, 

 comprises the area between the fossa of Sylvius and the corpus callosum, 

 including the central convolutions, the foot of all of the frontal convolu- 

 tions, the paracentral lobule, and the gyrus fornicatus, especially in its 

 middle third. The superficial tactile impressions and the sensations of 

 movement are impaired after destruction of the central convolutions, 

 while painful, thermic, and pressure sensations are preserved. After 

 destruction of the fornicate gyrus and the hippocampal gyrus, tactile 

 and thermic and common sensibility are partially lost. Destruction of 

 certain regions (marginal gyrus) cause failure to recognize objects through 

 the sense of touch. 



On electric stimulation in a trephined human being sensory impres- 

 sions (creeping) were observed in peripheral portions of the skin. All 

 sensory impulses that rise from the posterior spinal roots pass through 

 the lateral nucleus of the optic thalamus and from here they reach the 

 central convolutions, which therefore are connected with the sensory 

 nuclei of the posterior and lateral columns of the spinal cord. 



Irritative disorders of sensibility occur in consequence of cortical irritation, 

 including hallucinations of tactile, motor, and visceral sensations, the sensation 

 of itching, prickling, and burning, which may reach a painful degree, as in epileptics 

 and hysterics. Some cases of migraine, especially those associated with epilepsy, 

 may be due to cortical irritation. 



