THE GUSTATORY RELAY IN THE MEDULLA 



385 



of the mouth and tongue at a level 5 mm anterior to the obex, 3-0 to 

 5-0 mm lateral to the midhne, and at a depth of 2 + mm. Our chemically 

 sensitive region lies at the same level but just dorsal and medial to the 

 tongue tactile region. Thus, the gustatory area, somatotopically considered, 



^^v^ 



'^WA! 



W 



^Hi 



H^O .3 NaCI 



-w^' 



rJ\A^ 



ij^V^ 



Vvx/ 



HoO 



n 



Cool 



Fig. 3. Summated neural response to different stimuli. The entire record 

 represents a continuous recording in a single preparation extending over 21|niin. 

 The upward deflections of the mariners under the record indicate duration of 

 stimulus flow over the tongue, the downward deflections represent duration 

 of the wash, and the lines connecting the two represent the time during which 

 the solution rests on the tongue. The numbers refer to the molarity of the 

 solutions. Q is quinine hydrochloride and R is Ringer's solution. The 

 temperature of all solutions was approximately 28 C except for warm, distilled 

 water at approximately 38'C, and cool, distilled water at approximately 18°C, 

 as indicated. Time mark in upper left corner above the trace indicates 1 min. 



borders and overlaps the tongue tactile zone but the two sensitivities are 

 not coextensive. This agrees with the observations just described for the 

 rat, in which both soinesthetic and taste sensitivity were systematically 

 mapped in the same animal. 



Frozen sections of the medullas were made at 15, 25, or 50 /i and stained 

 with Luxol blue and cresyl violet (Kliiver and Barrera, 1953). This com- 

 bined stain made it possible to differentiate the medial and lateral subnuclei 



