I I 14 HANDBtJOK OF PHYSIOLOGY ^ NEUROPHYSIOLOGY II 



\\\ 



^ TrM. t^ 



1mm 



FIG. 2. Diagonal section tlnrough the anterior brain stem of the adult cat sliowing respiratory 

 reactions to electrical stimulation. In the upper lejt corner the plane of the diagonal section is indicated 

 on a frontal section. ^ indicates an increase in respiratory activity, i.e. in the rate and amplitude 

 of respiration, /v indicates a decrease in respiratory activity. Dolled symbols represent points lying 

 I mm medial to the plotted plane; interrupted symbols represent points lying i to 2 mm lateral to 

 the plotted plane. Aq., aqueductus sylvii; C.a., commissura anterior; C ].d., columna fornicis descen- 

 dens; Ch., chiasma opticus; Col.s., coUiculus superior; C.p., commissura posterior; ,Vcr., nucleus 

 ruber; Po.. pons; T.o., tuberculum olfactorium; Tr.M., tractus Meynert; ///., ventriculus tertius. 

 [Modified from Hess (gi).] 



diencephalon it is located in the dorsal part of the 

 hypothalamus and the ventral part of the thalamus. 

 At the anterior end of the midbrain it is located in the 

 vicinity of the central o;'"ay matter, surrounding the 

 transition from the third ventricle to the cerebral 

 aqueduct." According to investigations on the iinanes- 

 thetized cat with electrical stimulation and electro- 

 lytic tissue destruction (96), the region from which 

 panting can be elicited seems to be rather extensive. 

 It is more or less identical with those areas from which, 

 in the mesencephalon, diencephalon and the supra- 

 optic region, general respiratory activation is ob- 

 tained. 



Cortical and Cerebellar Injluenee on Respiratorx Activity 



The known fact that respiratory activity can be 

 voluntarily controlled — in voluntarv breath-holdinsr, 



hyperventilation, speech and singing — stimulated, 

 towards the end of the last century, a series of in- 

 vestigations of the cortical influences on respiration 

 (6g, 137, 179). From the already extensive literature 

 dealing with the subject [for reviews see Dell (55), 

 Kaada (107) and Smith (177)], one can, to begin with, 

 conclude that the results of stimulation are to a large 

 extent dependent on the depth and type of narcosis, 

 on the type of current used as stimulus, and on the 

 animal species. In spite of this, it would seem that the 

 oral region of the frontal lobe is that part of the brain 

 from which the respiration can be influenced without 

 strong concomitant motor and vegetative effects (55, 

 93, 108). Less constantly obtained are respiratory 

 changes initiated through stimulation of the \entral 

 surfaces of the temporal lobe (157). On the other 

 hand, circumscribed regions of the premotor area 

 powcrfulK- influence respiration, ijut their stimulation 



