I. OLDS AND M. E. OLDS 



155 



3V 

 TRANSFORMER 



I 1000 Jl 



'^ POTENTIOMETER 



C R 



Self-stimulation experiment. Animal's lever response causes i-second cut-off device to deliver 

 60-cycle current as long as lever is depressed up to ^-second maximum, atter v^'hich the animal 

 must release and press again for more current. Current causes cumulative recorder to register 

 response (thereby converting response rate into the slope of a graph) and causes via transformer 

 and potentiometer a stimulus to the rat's brain which passes on the way through a constant 

 resistor across which it is measured by cathode-ray oscilloscope. Rats respond with rates up to 

 12,000 responses per hour with electrodes in medial-forebrain-bundle regions. 



HPTH 



Fig. 2 

 Map of self-stimulation and some escape points in rat's brain. The former arc 

 indicated by cross hatching, the latter by stippling. Self-stimulation region 

 extends from baso-medial areas of tegmentum through baso-lateral hypotha- 

 lamic areas into telencephalon and then up through the basal ganglia to the 

 whole palaeocortical system. Escape regions plotted here include the dorsal 

 posterior hypothalamus and similarly placed points in the gementum. The 

 escape system is now known to extend forward too. 



