Brain Research on Lizards 
3 
MONKEY 
(After Parent & 01 ivier) 
Figure 3. Shaded areas indicate how a stain for cholinesterase distinguishes the greater part of the R-com- 
plex in animals ranging from reptiles to primates. With the fluorescent technique of Falck and Hillarp, 
the same areas shown above would glow a bright green because of the high content of dopamine (Juorio and 
Vogt, 1967). The pallidal part of the striatal complex does not fluoresce. No existing reptiles represent the 
forerunners of mammals. Birds are an offshoot from the Archosauria (“ruling reptiles”) (from MacLean, 
1973c, and adapted from Parent and Olivier, 1970). 
that some animals evolved in the direction 
of birds, while others went the mammalian 
way. The critical area lies near the ventro- 
lateral base of what J.B. Johnston in 1916 
called the dorsal ventricular ridge, presum- 
ably because it reminded him of a mountain 
ridge. In an extension of Johnston’s analogy, 
the proliferating hypopallial area might be 
imagined as comparable to a turbulent vol- 
canic zone. In birds, its continued eruption 
appears to have resulted in a piling up of 
ganglia upon ganglia, whereas its explosion 
in mammals was responsible for the mush- 
rooming of neocortex forming the dorso- 
lateral part of the brain. Ventromedial to the 
hypopallial zone is the striatal complex that 
continues to be firmly embedded in the brains 
of reptiles, birds, and mammals. The R- 
complex is as much the bedrock of the fore- 
brain as the Laurentian shield is to the 
North American continent. 
We now come to the heart of the matter 
regarding our special interest in the striatal 
complex. Twenty years ago when planning 
began for the present facility, almost as little 
was known about the functions of these 
structures as at the beginning of the century. 
In his Text-Book of Physiology published 
in 1900, E.A. Schafer wrote: “The corpus 
striatum is generally believed to act as a 
centre for the higher reflex movements, and 
to be in close association with the Rolandic 
area, but the experimental grounds of this 
belief are still lacking” (p. 778). Sixty years 
later Crosby et al. stated: “At present , . . 
in spite of numerous experimental studies 
