IHE HIPPOCAMPUS 



'375 



COLONNE 

 HORIZONTALE" 



PRECOM 

 FOR ■' 



PRE 



COM POST 



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CORPUS CALLOSUM 



PSALTERIUW 





SUaiCULUM 



ENTORHINAL 

 CORTEX \ 

 R nSSURE 



FIG. 2. Diagrams of the hip- 

 pocampus of the cat. A: Draw- 

 ing of dissection from the left 

 side. B: Same from the front. C: 

 Same as A but showing some of 

 the conduction paths j MFB, 

 median forebrain bundle; RF, 

 reticular formation. D: Termina- 

 tion of afferents about a hippo- 

 campal pyramid: /) from the 

 alveus, 2} from dentate granule 

 cells and 3) from the temporo- 

 ammonic tract. E: Schematic 

 cross section at level shown in C, 

 showing /) aflferents from the 

 fimbria to the dentate gyrus, 2) 

 axons of pyramidal cells, 3) 

 dentatopyramidal fibers, 4) tem- 

 poroammonic fibers and j) fibers 

 from colonne horizonlale and psal- 

 terium; hi to A5 show the approxi- 

 mate locations of pyramidal 

 neuron fields. The rudimentary 

 supracallosal hippocampus is 

 omitted for simplicity. 



campus in different species easy to understand. The 

 corpus callosum, then, is conceived to grow through 

 the hippocampal primordium-paraterminal body; in 

 this way, fibers to and from tlie hippocampus can be 

 loimd above and below the corpus callosum and also 

 incorporated within it. As a result of this growth of the 

 corpus callosum and the burgeoning of the cerebral 

 hemispheres, the hippocampus gradually retreats into 

 the temporal lobe. 



General Anatotm 



The primitive position of the hippocampal pri- 

 mordium helps to explain the afferent and efferent 

 connections of Amnion's horn. Before the develop- 

 ment of the neocortex, the hippocampus establishes 

 connections with the brain stem. These connections 

 are made through the region of the paraterminal 

 body to the hypothalamic and other diencephalic 

 areas, as well as toward the striatum. Thus, Herrick 



