THE DORSAL COLUMN NUCLEI 423 







+ 1 



^■■^ mm -"-O 



Fig. 5. — Luxol-fast section through brain stem at level of inferior olive, showing 



the amount of tissue remaining after the transection. The overlying medial 



lemniscus tissue was effectively transected, as revealed by a comparison of 



sections at various levels through this region. 



reticular formation are involved (Kuypers, 1958a). In any event, it is evident 

 that activation of certain fibers coursing out from the pericruciate cortex 

 ultimately leads to a decrease in the excitability of units in the dorsal column 

 nuclei, as evidenced by the responsiveness of cuneate and gracile units to 

 both monosynaptic and multisynaptic cutaneous inputs. The simphcity of the 

 anatomical arrangement in this preparation makes it ideal for the further 

 analysis of inhibition at higher levels of the central nervous system than the 

 spinal cord. 



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