1932] Poliak: Afferent Fiber Systems, Primate Cerelral Cortex 37 



cortical injury of the anterior portion of the frontal opercular region ; 

 in fig. 44, another thick bundle consisting of many fine callosal and 

 very fine cortico-caudate fibers degenerated, due to the injury L of 

 the frontal cortex.) 



That not only areas immediately neighboring the sulcus centralis, 

 that is, Brodmann's areas 1, 2, 3 and 4, receive afferent fibers, but 

 also the parietal region (in the narrow sense of that word, areas 5 

 and 7 of Brodniann), and the precentral area 6 of Brodmann is well 

 demonstrated by the accompanying illustrations (figs. 52-55, and 

 44, 45). A small number of degenerated fibers partly composing 

 the eingulum, as said before, also enter the cortex of the cingular 

 sulcus. The inferior parietal or the supramarginal convolution receives 

 only in its anterior half a somewhat larger number of thalamo-cortical 

 fibers, more so around the intraparietal (postcentral) sulcus, although 

 at the latter spot much less than in both central convolutions (figs. 49, 

 50). Caudalward, the number of afferent somato-sensory fibers in both 

 the inferior and superior parietal convolutions noticeably decreases 

 and finally they disappear entirely. A similar gradual decrease in 

 number and the final disappearance of afferent fibers can be seen also 

 toward the arcuate sulcus of the frontal lobe. 



The relation between the ventral thalamo-cortical fibers and the 

 acoustic radiation is the same as in Experiment I (fig. 51). The only 

 exception in the present experiment is a greater number of degenerated 

 fibers penetrating through the caudal portions of the putamen into 

 the external capsule. In fact, all the bundles by which several small 

 islets of the caudal putamen are separated, degenerated completely. 



Ventro-lateral fiber bundles entering from the ventral thalamic 

 region in the ventral portion of the internal capsule and forming 

 lateral bundles of the thalamo-cortical radiation can, in quite a con- 

 siderable number, be directl}^ followed along and through the putamen 

 and along the inner contour of the claustrum to their termination in 

 the operculum. Yet some of them closely follow the upper spur of 

 the claustrum and, turning laterally, penetrate into the cortex around 

 the doi-sal corner of the Sylvian fossa and lining the Sylvian sulcus 

 (figs. 48-54). The region of the cortex which receives these afferent 

 fibers belongs on more caudal levels to Brodmann 's areas 7 and 22, 

 that is, partly to the parietal and partly to the temporal region {x in 

 figs. 52-54). In the caudal portion of the Sylvian fossa (figs. 48-51) 

 this region forms a part of the inner dorsal wall of that fossa, main- 

 taining its connection with the acustic area proper {Ttr in figs. 50, 51) 



