CINGULATE, POSTERIOR ORBITAL, ANTERIOR INSULAR AND TEMPORAL 



POLE CORTEX 



135' 



that recorded in animals has been obtained on stimu- 

 lating points in the same regions as those outlined 

 above for the monkey, cat and dog. The responses 

 have been produced in patients under light pentothal 

 anesthesia from the anterior cingulate (132, 156, 198, 

 273) and posterior orbital surface (41, 42, 158) as 

 well as in the conscious patient from the same areas 

 and from the anterior insula (132) and the ventro- 

 medial aspect of the temporal pole, particularly in 

 the region of the uncus (93, 132, 156). Stimulation of 

 the lateral surface of the temporal pole in man has 

 so far not evoked any significant responses. It is possi- 

 ble that with the great development of the temporal 

 lobe in man the responsive cortex has been displaced 

 more ventromedially than in the monkey (132). Pa- 

 tients are able to overcome partly the respiratory 

 arrest when asking to count during the stimulation 

 (132). The cessation of breathing is frequently asso- 

 ciated with a feeling of tiredness and sleepiness and a 

 tendency to close the eyes (132) and with impaired 

 consciousness (132, 156). 



ACCELERATION OF RESPIRATORY MOVEMENTS. Accelera- 

 tion of breathing with increased, unaltered or de- 

 creased amplitude has been observed on stimulating 

 the motor cortex of the cat (fig. 2C), dog and monkey 

 (cf. 126). A second acceleratory area is found in the 

 anterior ectosylvian and sylvian gyri in the cat (126, 

 234, 254) and dog (126) (fig. 2C). This area appar- 

 ently coincides with the second somatosensory field 

 (126). A third acceleratory zone has been located in 

 the middle and anterior portion of the cingulate cor- 

 tex in the dog (126, 147, 240), cat (126) (fig. lE) and 

 man (198). This acceleratory area appears to be 

 located posterior to the zone yielding maximum 

 inhiiiitory effects. In the anesthetized monkey the 

 acceleratory response from the cingulate is very incon- 

 sistent, probably due to great susceptibility to anes- 

 thesia and to interference with the cerebral blood 

 flow (126). It is readily obtained in unanesthetized 

 animals (10) and in animals under light chloralose 

 or chloralose-urethane anesthesia (126, 240); it disap- 

 pears before the inhibitory effects which are the last 

 to succumb on deepening the anesthesia (126). Accele- 

 ration appears to be more readily produced in dogs 

 than in cats (126, 240) and monkeys (126). 



Finally, acceleration of breathing, usually asso- 

 ciated with a marked decrease in amplitude, has been 

 recorded on stimulation of the rostral part of the pyri- 

 form (periamygdaloid) cortex in cats (126, 144), dogs 

 (126) and monkeys (10, 166) in unanesthetized or 

 lightly anesthetized (urethane, chloralose-urethane) 

 preparations. The response can be converted into pure 



inhibition by additional administration of barbi- 

 turates (126). According to Koikegami & Fuse (144) 

 the effect is mediated through the subjacent lateral 

 amygdaloid nucleus and thence through the stria 

 terminalis. As stimulation of all these structures in 

 unanesthetized animals produces rapid sniffing (128), 

 manifesting itself inter alia with increased rate and 

 diminished respiratory amplitude, it is quite possible 

 that the acceleration of respiration from the peri- 

 amygdaloid cortex merely represents part of a com- 

 plex pattern related to olfaction. The same is prob- 

 ably true of various other types of respiratory effects 

 which can be produced upon stimulation of the 

 olfactory pathways (126, p. 57; 241 ). 



EFFECTS ON SPONTANEOUS, CORTICALLY AND REFLEXLY 

 INDUCED MOVEMENTS AND MUSCULAR TONE. In 1 944 



Bailey et al. (23) included the anterior cingular 

 region (area 24) in the so-called cortical 'suppressor' 

 areas. Previously five such areas (8s, 4s, 3s, 2s and 19s) 

 had been mapped on the lateral surface of the hemi- 

 sphere of the monkey and cat [cf. reviews by Kaada 

 (126, p. 93), Sloan & Jasper (230) and Druckman 

 (58)]. The motor and electrical responses resulting 

 from stimulation of these areas have been summarized 

 as follows (60, 161): a) inhibition of motor after- 

 discharges elicited by stimulation of any focus in the 

 sensory-motor cortex, b) relaxation of existing muscu- 

 lar contractions, c) a rise of threshold and reduction of 

 the motor response to stimulation of area 4, and d) a 

 transient diminution of the electrical activity of area 

 4 (61 ) and of the entire cerebral cortex (81 ). 



The two latter effects were characterized by a 

 remarkably long latency of several minutes whereas 

 the first two effects occurred rather promptly (82, 

 161), as did the cessation of spontaneous movements 

 and the reduction of muscular tone observed by Hines 

 (no) on stimulating area 4s. Later studies (58, 230) 

 have revealed that the long-latency motor and elec- 

 trical responses, which were originally elicited only 

 from the specific cortical 'suppressor' strips, are most 

 probably identical with the 'spreading depression' 

 of Leao (148), a phenomenon which is nonspecific in 

 the sense that it can be elicited from almost any 

 portion of the cerebral cortex. 



Eliminating the long-latency effects as characteris- 

 tic responses to excitation of the cortical 'suppressor' 

 areas, the prompt cessation of motor after-discharges 

 and relaxation of 'existing muscular contractions' 

 (including cessation of spontaneous movements) are 

 the only two of the above-mentioned responses which, 

 according to the literature, should be common to all 

 these areas when examined under anesthesia. [For 



