EVIDENCE OF A MOTOR PALLIUM IN THE FORE- 

 BRAIN OF REPTILES! 



J. B. JOHNSTON 



University of Minnesota 



OXE FIGURE 



At the title indicates, the purpose of this note is not to describe 

 the structure of the reptiUan motor cortex nor to discuss the 

 locaHzation of function within this area. The purpose is onh' 

 to give such evidence as is now at hand that a speciaHzed area 

 comparable to the mammalian motor cortex probably exists 

 in the reptilian brain and to indicate the general ]-)osition and 

 extent of this area. 



The writer has indicated in a jirevious i)a])er ('15 b) that the 

 rostral portion of the dorsal pallium in the turtle differs structur- 

 ally from the rest and has suggested the possibility that this 

 area may correspond to the motor cortical area in the mammalian 

 brain. 



This hy])()thesis is being tested by degeneration methods and 

 by cortical stimulation. Sufficiently definite results have been 

 obtained by the latter method to indicate that motor and siMisory 

 fields can be (hstinguished in the reptilian ])allium. 



Three species of turtle (Chelydra serpentina, Cistudo Carolina, 

 and Chrysemys marginata) and one lizard (Gerrhonotus) have 

 been studied. Two methods of stimulation were used : induction 

 shocks with two-])oint electrodes, the two i)oints closely approxi- 

 mated; induction shocks with one point electrode, the second 

 electrode being formed by a copper plate covered with moist 

 cloth on which the body of the animal rested. 



An important factor in the experiments is the degi'ee of anaes- 

 thesia employed. The clearest results have been obtained with 

 very deep anaesthesia. Some of the turtles were given a dose 

 of morphine by hypodermic injection, and all were anaesthet- 



' Neurological Studies, University of Minnesota, no. 22. June 29, 1916. 



47.") 



