1354 HANDBOOK OF PHYSIOLOGV >— NEUROPHYSIOLOGY II 



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FIG. 5. Areas facilitating {hor- 

 irjmlal lines) or inhibiting (ver- 

 tical lines) cortically induced 

 movements and the knee jerk in 

 monkey {A) and cat (B). C to F: 

 Upper tracing, respiratory move- 

 ments; second tracing, the knee 

 jerk elicited every 2 sec. in cat. 

 Time, 10 sec. Respiratory in- 

 hibition associated with facili- 

 tation (C), inhibition (D), and 

 facilitation reversing to inhibi- 

 tion IF) of the knee jerk on stimu- 

 lating the orbital gyrus in differ- 

 ent experiments. D and F: 

 Stimulation of the central end 

 of the cut vagus nerve produces 

 identical effects in the respective 

 e.xperiments. [From Kaada 

 (126).] 



facilitation reversing to inhihiiion, was obtained from 

 the same zones (126). The extent of the areas inhib- 

 iting cortically induced movements was greater than 

 that reducing the knee jerk (i 14, 126). Facilitation has 

 usually been obtained from the horizontally hatched 

 regions in figure 5.-!, B outside these "inhibitory' areas, 

 i.e. from the regions producing the "awakening" or 

 'arousal' type of response in imanesthetized and 



lightly anesthetized animals, while occasionally facili- 

 tation (particularly of cortically induced movements) 

 also occurred, in quite an unpredictable manner, on 

 stimulation of the medial and basal 'inhibitory' zones 

 (126). The increase of the knee jerk was inconsistent 

 and usually less marked than the facilitation of 

 cortically induced movements. Thus, there were a 

 number of cortical points, particularly in the anterior 



