CINGULATE, POSTERIOR ORBITAL, ANTERIOR INSULAR AND TEMPORAL POLE CORTEX 1353 



FIG. 4. .-I.' Stippled regions represent areas of cat 

 brain from which inhibition of spontaneous move- 

 ments, 'chloralose jerks' and motor after-dis- 

 charges were obtained on stimulation. B. Shiver- 

 ing {sh) superimposed on 'chloralose jerlvs" of the 

 left leg elicited by intermittent tactile stimulation. 

 C: 'Chloralose jerks' only. Weak stimulation of 

 'area 19s' (a) and the pyriform cortex (A) inhibits 

 shivering. 'Chloralose jerks' inhibited from the 

 retrosplenial [e) and subcallosal (/) regions. No 

 effects on excitation of points (c), (d) and (g) out- 

 side the stippled fields. D: The left motor corte.x was 

 stimulated every 15 sec. (60 cps, 4 v., 3 sec.) and 

 the resulting dorsiflexion of the right ankle (at 

 arrows) was followed by local motor after-dis- 

 charges. Inhibition of these after-discharges re- 

 sults from concurrent stimulation of the orbital 

 gyrus (h). Motor after-discharges reappear after 

 end of stimulation. [From Kaada (126).] 



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to E and figure 4.-1 found to arrest spontaneous move- 

 ments and 'chloralose jerks' in anesthetized monkeys 

 and cats (126). The effects are less marked during 

 more violent movements. The accompanying electri- 

 cal after-discharges recorded from the motor cortex 

 are quite unaffected. The most effecti\e points are 

 located within the two medial and basal fields 

 yielding maximum inhibition of muscular tone and 

 spontaneous movements. 



c) Effects on cortically induced mcwements and spinal 

 reflexes. The most extensive studies dealing with this 

 topic are those of Hodes et al. {114, 185) on the 

 cingulate cortex and subcortical structures in cat 

 and of Kaada (1 26) on the cingulate and orbitoinsulo- 

 temporal areas in the cat and monkey. Excitation of 

 the medial and basal areas exerting a bilateral inhibi- 

 tory effect on spontaneous movements has been shown 

 to influence single contractions induced by stimula- 

 tion of the motor cortex and the knee jerk in three 



ways: by inhibition (fig. 5/)), facilitation (fig. 5C), 

 and facilitation changing to inhibition after brief 

 stimulation (fig. ^E) (126). This inhibition appears 

 rather promptly, attaining a maximum within a few 

 seconds, and thus should be clearly distinguished 

 from the long-latency response identified in the 

 literature as "suppression of motor response.' All three 

 types of responses are usually associated with inhibi- 

 tion of spontaneous movements, including respira- 

 tion; facilitation also appears with acceleration of 

 breathing (126). 



The areas inhibiting cortically and reflexly induced 

 movements approximately coincide with those 

 yielding strongest inhibition of respiratory and other 

 spontaneous movements and muscle tone, i.e. the 

 cortex surrounding the genu of the corpus callosum 

 (114, 126) and the orbitoinsulotemporal polar field 

 as outlined above (indicated by vertically hatched 

 areas in fig. 5.-1, B) (126). The third type of response, 



