Page:Popular Science Monthly Volume 67.djvu/331

Rh old mechanism thrown out of its accustomed use, may have made ready another center and new tracts for the same use.

This hypothesis leads pretty directly to another which seems to be demanded by some of the facts of the case under examination. A more and more highly differentiated volitional control was obtained over the facial muscles; the stimulus of the various emotions, without the accompaniment of volition, met with a better response; and the sight of the condition of the facial muscles as afforded by a mirror was of help in gaining this increased control. All this experience would seem to prove beyond doubt that the higher cortical centers concerned in conscious volition, in emotion and in the perceptions of sight had somehow established the necessary new connections with the center, lower down, in control of the N. accessorius. In a word, whereas formerly, when the accessory nerve was only concerned in helping to lift the arm and shrug the shoulder, these volitional emotional, and visual centers, had paid little or no attention to their influence over the cortical center of this nerve, now that this center and this nerve were being called upon for unaccustomed and more elaborate functions, they found out a way to get into connection, and to bring the new apparatus under their control. But these volitional, emotional and visual centers are widely spread over the cortical area. About their special connections with one another, and especially with the center of the accessory nerve, under normal conditions, we are much in the dark. And how they could go to work to solve, in any length of time and even partially, the problem of readjusting their functional relations to the new and abnormal conditions, offers a problem as yet quite unanswerable by cerebral physiology.

There is one other assumption which would seem to be at once more simple, more sure, and more effective in explanation, than either of those hitherto made. What was the old cortical center for the control of the muscles of the face through the N. facialis doing all this time? We can scarcely suppose it to have been entirely idle or resting in indifference to the functions of which it had been so suddenly and rudely dispossessed. Indeed, it is as certain as anything about such matters can be that the cortical center of the facial nerve would not be allowed to rest. The fifth pair of nerves, whose function is to transmit the sensory impulses from the facial areas, was unimpaired; and since the discomfort from increased lachrymation, saliva and gathering food in the flaccid cheek was very great, this cortical center must have been perpetually sharply reminded of its neglect of duty. Moreover, every time the faradaic current was applied to the cheek, and the patient tried to get control over the facial muscles, helping himself meanwhile by looking in the mirror, there was undoubtedly a very excessive demand for activity made upon this now