PHASE OF REFLECTION OR EMISSION OF THE PROCESSES OF CEREBRAL ACTIVITY.
Period. Motor Processes.—In the state ment we have just made, we have seen that the processes of cerebral activity, which consist first of all in an impression upon the sensorium of external origin, resolve themselves into various reactions on the part of the cerebral apparatuses which are roused into activity, and into a sort of intra-cerebral radiation of the exci ting movement.
Now this impression, which has arrived in the form of an incident excitation, is a living force in act of trans formation ; this force is implanted in the sensoriztm ; it becomes reinforced and concentrated according as it is evolved ; it is necessary that it shall still continue in motion, and that, under one form or another, it shall pass out of the organism, by discharging itself upon other organs designed to serve it as gates of exit.
From this new stand-point we shall henceforward consider the phenomena of cerebral activity, at the moment in which, in their third phase of evolution, they finish their last stage and reveal themselves in various reactions. These, however varied their appear ances, nevertheless represent in the external world the reverberation of a former sensorial impression emanating from this external world.
Once upon their outward course, the processes of cere bral activity take two different routes, according to the variable conditions of receptivity of the cerebral medium in which they are developed, the nature of the individual, and his manner of feeling.
Thus they are sometimes reflected towards the different departments of vegetative life. They do not make their exit from the organism, and in that special sphere they produce secondary commotions of a more or less apparent kind ; their reflection takes place in an entirely automatic manner, and in spite of voluntary action (return shock of mental emotions upon the physical constitution).
Sometimes, on the contrary, they appear externally, and reveal themselves by the help of various means of expression—phonetic sounds, graphic signs, appropriate gestures. The external sensorial excitation, radiating from the external world that gave it birth, is in this case directly returned to this external world.