232 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



and thus brought into relation with the motor system to the cord 

 known as the rubrospinal tract. Lesions of the nucleus caudatus 

 are accompanied by marked disturbances in heat regulation, so 

 that many authors assume the existence of a heat-regulating center 

 in this nucleus. Others have suggested that the corpus striatum 

 constitutes a regulating center for the control of the more primitive 

 or automatic movements, such as walking, posture, etc., and have 

 described a motor or pallidal system arising chiefly in the large 

 cells of the globus pallidus through which these motions are 

 mediated. According to Hunt,* pathological lesions (atrophy) of 

 the cells of the globus pallidus are followed by paralysis agitans, 

 while lesions of the other nuclei manifest themselves in choreic 

 movements. With regard to the various nuclei of the thalamus, it 

 is known that they form abundant connections with the sensory 

 areas of the cortex cerebri, and from this standpoint they may be 

 regarded as consisting of subcenters, with a probability, however, 

 that reflexes may occur through them (subcortical reflexes) inde- 

 pendently of the cortex. Numerous fibers have been traced from 

 the thalamus to the body sense area (Flechsig) . Sachs f states that 

 the thalamus may be considered as being composed of two prac- 

 tically independent parts: an inner division, which has relation 

 with the nucleus caudatus and the rhinencephalon, and an outer 

 division, which, on the one hand, serves as a terminus for the fibers 

 of the lemniscus and of the superior cerebellar peduncle, and, on the 

 other hand, is connected by afferent and efferent paths with the 

 cortex of the Rolandic region. It is evident, from these relations 

 and from the proximity of the internal capsule, that lesions in the 

 thalamus may occasion symptoms of a very diverse character. 

 Among these symptoms, we should expect to find hemianesthesia 

 on the opposite side, owing to the fact that the thalamus serves 

 as a substation for the fibers of the lemniscus. 



* Hunt, "Brain," 1917, 40, 58. 

 t Sachs, "Brain," 1909, 1. 



