1932] Poliak: Afferent Fiber Systems, Primate Cerebral Cortex 175 



The projection of various retinal quadrants upon the occipital lobe 

 expounded in the above lines stands in good accord with the distribu- 

 tion of excitable points for conjugate eye movements in the occipital 

 lobe of the monkey found by Schafer, Mott-Schafer, Lewandowsky- 

 Simons, Levinson, Baranyi-Vogt, and with the results of the electrical 

 stimulation of various portions of the striate area in man undertaken 

 by Foerster, 1929, and Foerster-Penfield. 



The anatomical facts found here, physiological experiments (Munk) 

 and clinical observations (Laqueur, Lenz, Henschen, Holmes, Foerster 

 1929, Souques-Odier, Brouwer, R. A. Pfeifer, et al.) all compel us to 

 conclude that the macula, or better, both the homonymous hemimacu- 

 lae, must be represented in the posterior portion of the striate area 

 around the pole and occipital operculum and not in its anterior portion 

 (fig. 23). The maeula.r segment of the external geniculate body, as 

 found by R<)nne (1914) and by Brouwer-Zeeman (1926), represents a 

 large portion of that nucleus, perhaps more than half of it. The fibers 

 which originate in this segment, as we obser\'ed, constitute a con- 

 siderable portion of the visual radiation, nearly half of it, namely the 



Fig. 23. A diagram to illustrate the projection of various quadrants of the 

 visual fields and of both retinae upon the external geniculate bodies, upon the 

 visual radiation, and upon the visual projection area of the cerebral cortex 

 (area striata), as determined by the present experiments, combined with those 

 of Brouwer-Zeeman. Left (S) and right {B) sides of the visual fields and of 

 the afferent visual apparatus. Number 1 represents both fields of vision with their 

 upper {s) and lower (f), nasal and temporal halves; the smaller inner circles 

 represent the "central" or macular portions (their relative size in comparison 

 witli the perimacular portion is somewhat exaggerated); the large circles repre- 

 sent the peri- or extramacular portions of the binocular visual fields; the outer- 

 most lightly shaded sickle-shaped zones represent the monocular portions of the 

 visual fields. Number 2 represents left and riglht retinae with tlieir upper {s) 

 and lower (i), nasal and temporal halves; smaller and larger circles and the 

 monocular portions as above. Number 3 represents a schematic cross section 

 through the left and right geniculate bodies; tlieir internal margins (m) close to 

 the thalamus; their external margins {I); their concave contours in the figure 

 facing upward represent their ventral margins. Number 4 represents cross 

 sections through the left and right visual radiation (external sagittal strata of 

 the parietooccipital lobes); their dorsal horizontal branches {d) , their ventral 

 horizontal branches (v) with perpendicular or vertical branches (in the figure 

 horizontal) connecting both horizontal branches. Number 5 represents the left 

 and right visual projection cortex, the area striata of Elliot Smith, field 17 of 

 Brodmann, each subdivided into an upper {Is) and a lower half {li) corresponding 

 with the upper and lower lips of the calcarine fissures. The dividing lines, vertical 

 in the figure, and terminating at the letters x and y, correspond in their upper 

 parts to the bottom of the calcarine fissures and to the horizontal meridians of 

 both visual fields dividing the upper from the lower extramacular quadrants; 

 in their lower parts (lower in the figure) these lines correspond to horizontal 

 meridians dividing the upper from lower macular quadrants. The points where 

 these lines reach the posterior limits of both striate areas, marked by the 

 letters x and y in the figure, correspond to both points of fixation in the visual 

 fields. The vertical lines or meridians dividing the left- from the right homonymous 

 halves of the macular portion of the visual fields correspond to the posterior 

 (lower in the figure) circumference of the striate areas close to the letters 

 X and V. 



