1932] Poliak: Afferent Fiber Systems, Primate Cerebral Cortex 125 



Experiment V-a 



In this experiment the attempt was made to interrupt the macular 

 fibers of the visual radiation separately and to study their course, 

 position, and cortical termination with the help of Marchi's method. 



Fourteen days later the animal was killed. By a single, sharply 

 delimited lesion in the left hemisphere of a young Java monkey (small 

 coarsely dotted area in fig. 4 and L in fig. 13), beginning with a super- 

 ficial damage to the most posterior portion of the middle temporal 

 convolution, the intermediate or the perpendicular branch of the visual 

 radiation (vr in fig. 13) was inten-upted. (For reference to the 

 anterior part of the lesion in the same case, causing a portion of the 

 thalamo-cortical radiation to degenerate see Somato-sensory System, 

 Chapter V, Experiment V-a). The degenerated fibers, forming at 

 first a fairly sharply delimited segment within the vertical or per- 

 pendicular branch of the visual radiation {M in 2 and 3 of fig. 13), 

 were easily pursued — on sections of the continuous series, well stained 

 according to Marchi's method — along their course occipitalward to 

 their termination in the cortex of the occipital lobe (4, 5 and 6 of 

 fig. 13). They all enter the striate area, or field 17 of Brodmann, 

 exclusively, and only that portion of the field covering the lateral 

 face of the occipital lobe situated behind the ascending and descending 

 branches of the calcarine fissure (area of the occipital lobe in fig. 4 

 shaded with continuous and broken horizontal lines). A narrow zone 

 of the opercular striate cortex in the dorsal and the most anterior 

 part of the occipital operculum receives few or none of the degenerated 

 fibers in the present experiment (the narrow finely stippled triangular 

 zone of the occipital operculum in the upper figure of fig. 4). This 

 zone of the macular cortex with its afferent visual fibers remaining 

 normal, continues with the striate area lining the upper lip of the 

 calcarine fissure on the inner face of the hemisphere {Fcalc in fig. 4). 

 The striate area lining the floor and the lower lip of the calcarine 

 fissure is also completely devoid of any of the degenerated afferent 

 visual fibers. Of the entire striate cortex within the calcarine fissure, 

 the only portion where there are degenerated fibers is that portion 

 lining the ascending and descending branches of this fissure, especially 

 around the ascending branch; but even here only the striate cortex 

 behind the mentioned branches is filled with black dots and particles, 

 the rest of the striate cortex in front of both ascending and descending 



