PHYSIOLOGICAL TOPOGRAPHY OF SURFACE OF CEREBRUM. 8oi 



In cases of epilepsy marked excitation of the sensorial centers, mani- 

 fested by excessive subjective impressions, often in association with 

 psychic irritative disorders, for example the appearance of definite 

 thoughts, has been observed as an irritative accompaniment of the con- 

 vulsive seizure. Such excitation may appear even without accompany- 

 ing convulsions as so-called sensory epilepsy, which may be partial, 

 that is unilateral and confined to individual impressions, in the latter 

 event without loss of consciousness. In cases of congenital inactivity 

 of a psychosensorial center hallucinations in this region never develop. 



Epileptoid hallucinations of the character described occur without convul- 

 sions but accompanied only by brief derangement of consciousness (absence). 

 Under such circumstances amaurosis has also been observed, gradually disappear- 

 ing later and being replaced by a concentric contraction of the visual field. Occa- 

 sionally only the psychic cortical centers are affected, preepileptic and postepi- 

 leptic insanity, loss of memory for certain periods of time, derangement of con- 

 sciousness resulting. Cases are extremely rare in which epilepsy occurs with 

 loss of consciousness but without convulsions, and so also are cases in which the 

 convulsions occur without derangement of consciousness. 



The nerve-fibers passing from the sensorial and sensory organs to the 

 psychosensorial cortical centers traverse the posterior third of the pos- 

 terior limb of the internal capsule (Fig. 263). Destruction at this point 

 causes, therefore, anesthesia on the contralateral half of the body. Only 

 the viscera retain their sensibility. Also contralateral loss of hearing, 

 of smell, and of taste, as well as hemiopia, appear. Whether the visceral 

 sensations, sensations of internal processes associated with pleasure or 

 displeasure, are localized in the cerebral cortex or in the midbrain is 

 undetermined. 



Pathological. In human beings with more or less complete injury or degenera- 

 tion of this tract, more or less well-marked loss of the pressure-sense and the temper- 

 ature-sense, of cutaneous and of muscular sensibility, of taste, smell, and hearing is 

 accordingly found. The eye is rarely entirely blind, but visual acuity is greatly 

 impaired, the visual field is contracted and the color-sense may be partially or 

 totally abolished. The eye upon the same side may suffer alone in lesser degree. 

 In addition to material lesions of the brain, sensory anesthesia is observed also 

 as a functional disorder in association with hysteria, neuroses, and psychoses. 

 With reference to the mutual relations of the individual conducting paths within 

 the internal capsule Redlich maintains that behind the pyramidal tracts there 

 pass first the fibers for muscular sense, then those for cutaneous sensibility, 

 and finally the visual fibers. 



Cases of injury in the anterior frontal region without motor and sen- 

 sory disorders have been collected in large number by Charcot, Pitres, 

 Ferrier, and others. On the other hand, enfeeblement of intelligence 

 and idiocy have been observed in connection with acquired or congenital 

 deficiencies of the frontal region. According to Flechsig, there is no 

 doubt, in accordance with clinical observation, that the frontal lobe and 

 the temporo-occipital zone bear an intimate relation to mental processes, 

 particularly those of a higher order, which disappear largely in the old 

 and in epileptics. 



The anterior portions of the first and second frontal convolutions, portions 

 of the third and of the gyrus rectus in the frontal lobe, the island of Reil, the 

 first and second parietal convolutions, the second and third temporal convolu- 

 tions, the occipitotemporal gyrus, and the precuneus are association-centers. 

 They connect the various sense-spheres and they have the function of associating 

 irritative states of various sense-spheres. 



Situation of the Cerebral .Regions in the Skull. In order to indicate the posi- 

 tion of the principal fissures and convolutions in the uninjured head various 



