Spinal dog
From Infictive
From Human Behavior By Walter S. Hunter 1919 University of Chicago Press
"a spinal dog, e.g., is one whose spinal cord has been transected, or cut across, just below the mudulla, thus freeing the reflex activities controlled by the cord from the influence of the brain. In animals like the dog the reflex functions of the cord persist unimpaired by the operation. In the dog the scratch reflex has been most throughly studied (Sherrington)."
"If any point in the saddle shapped area of the spinal dog shown in figure 39 is stimulated, the hind leg on the side is alterntely flexed and extended in the typical scratch activity. Only allied harmonious reflexes are active at any one moment. The rate of reflex is constant (4.5 beats per second) no matter what the intensity of the stimulus. The scratch rhythm proceeds practically unmodfied by variation of the rhythmof the stimulation of the skin. This partly depends on the fact that each reflex has a refractory period during which, even apart from fatigue, it cannot be fully re-excited. If the intensity of the stated stimulus is gradually increased, the phenomenon of spread occurs, i.e.. more and more reflexes are aroused, due to the irradiation of nervous impulses in the cord, until the whole dog is active."
"Again, other things being equal, the protective reflexes--those aroused by injurious noxious stimuli--have the right of way over other reflexes."
