John F. Fulton 



205 



Later studies by Dusser de Barenne, Garol and McCulloch,^ reported at 

 the meeting of the Association for Research in Nervous and Mental Disease 

 in December, 1940, indicate that there are other suppressor areas, notably 

 areas 8-s and 2-s (fig. 1). On stimulation, both regions may cause activation of 

 the caudate nucleus in a sharply circumscribed area, 8-s activating the anterior 



Fig. 1. A diagram of the cerebral cortex of the common Rhesus monkey {Macaca mulatto.) 

 showing the principal suppressor areas (8-s, 4-s. 2-s, 19-s) together with the primary motor 

 regions 4L (leg), 4A (arm), 4F (face). (From Dusser de Barenne, Garol and McCulloch: Jl. 

 Neurophysiol. 4:325, 1941) 



part of the caudate, 4-s the medial part, and 2-s the tail of the caudate. Thus 

 all of the suppressor areas of the cortex converge in a spatially oriented manner 

 upon the caudate nucleus. 



With regard to the other parts of the basal ganglia, it is no doubt significant 

 that, whereas areas 4 and 6 fail to project to the caudate, they do, when strych- 

 ninized, cause strong electrical activation of the putamen, and area 6 also 

 affects the external segment of the globus pallidus. Although the suppressor 

 regions exhibit an anteroposterior organization of their projections, there is 

 less precise localization within the putamen and globus pallidus. To quote 

 Dusser de Barenne, Garol and McCulloch: 



From a purely anatomical standpoint, that spatially separated areas 4 and 6 should project 

 to one structure, the putamen, while 4-s and 8-s project to another, the nucleus caudatus, is 

 truly surprising, for 4-s lies between 4 and 6, and 6 lies between 4-s and 8-s. On the other hand, 

 when one realizes that 4 and 6 are alike in giving motor responses and that 4-s and 8-s are 

 alike in giving suppression, it becomes highly probably that the projections from 4 and 6 

 may converge somewhere else, and it ceases to be so surprising to discover these discrete con- 

 vergences in the corpus striatiun. 



