Incessant Regeneration of Brain Tissue

If we love, hate, think, feel, worship, at the expense of actual physical effort on the part of the brain, and consequent waste of tissue, how enormous must be the labour of that organ with which we, in fact, do everything, even many of those acts whose final execution falls to the hands or feet!  It is true:  and to repair this excessive waste, the brain consumes the lion’s share of the nourishment provided for the body.  As we have already seen, fully a sixth or a fifth of all the blood in the body goes to repair the waste in the king’s house; in other words, new brain tissue is being constantly formed at a startlingly rapid rate:  one wonders at what age the child has no longer any part left of that brain with which he was born.

The new tissue repeats the old, but not quite exactly.  Just as a new muscular growth adapts itself to any new exercise required of it, so the new brain tissue is supposed to ‘grow to’ any habit of thought in force during the time of growth – ‘thought’ here including, of course, every exercise of mind and soul.  “The cerebrum of man grows to the modes of thought in which it is habitually exercised,”[1] says an able physiologist; or, in the words of Dr Carpenter, “Any sequence of mental action which has been frequently repeated, tends to perpetuate itself; so that we find ourselves automatically prompted to think, feel, or do what we have been before accustomed to think, feel, or do, under like circumstances, without any consciously formed purpose or anticipation of results.  For there is no reason to regard the cerebrum as an exception to the general principle, that whilst each part of the organism tends to form itself in accordance with the mode in which it is habitually exercised, this tendency will be specially strong in the nervous apparatus, in virtue of that incessant regeneration which is the very condition of its functional activity.  It scarcely, indeed, admits of a doubt, that every state of ideational consciousness which is either very strong or is habitually repeated, leaves an organic impression on the cerebrum, in virtue of which the same state may be reproduced at any future time in correspondence to a suggestion fitted to excite it.”[2]