Читать книгу Fear - A. Mosso - Страница 13

Table of Contents

The analysis of memory better than anything else shows us the connection between the various parts of the brain which enter into activity in order to provide us with the elements that form speech.

We must distinguish two kinds of memory:

1. The fixation of impressions, whether these be images, or representations of movements, words, sounds or sensations.

2. The re-awakening of these impressions as recollection.

The phenomena of memory remain quite incomprehensible if we do not admit their intimate connection with physical changes of the nerve substance. An external impression acting upon receptive nerve-cells is retained by them permanently, as though it were photographed, if it be allowable to explain the unknown by a comparison with the known. It is the blood which carries those substances to the brain which are necessary to the functions of memory. Attention cannot be developed in all its intensity without causing considerable alterations in the circulation. Now when we are absent-minded, images leave no lasting impression on the memory, as no provision is then made by the physical changes in the organism accompanying attention for a more rapid circulation of blood in the cerebral hemispheres.

The old notion that the brain was a storehouse in which each idea had its nook where it might stay till needed, is truer than it appears. Modern science has proved that the matter is much more complicated than one thinks. It suffices that the blood should coagulate in the artery which carries it to some convolution, or that a tumour should destroy a part of the brain, for us to lose, as it were, a province of memory.

Let us first consider verbal memory. That region of the brain in which it is placed is, generally speaking, the parietal region of the left side; so that anyone who has had a blow on the temple at that side nearly always loses his speech, although he still remembers things and can pronounce their names when they are repeated to him by others, a sufficient proof that the movements of the tongue are not impeded. Sometimes it happens that a person in this condition looks in the dictionary for the missing word, in order to recover the pronunciation of it.

In learning a language, we believe that certain cells undertake functions which they did not before possess, that connections with other cells are established, like very intricate nets in which the impressions of nouns and verbs, the graphic representations of ideas and words, are collected. As we exercise ourselves in the language, the blood carries new elements to these cells, and the greater our attention, the stronger become the impressions. Oxidation does not destroy the impression once received, but it weakens it. If we have had no practice for some years in speaking a language, we meet with great difficulties, our communications being made in set, stiff words; but after a few days one regains the former fluency.

We might quote cases in which, through illness, a man has completely forgotten a language, recovering it as health returned. Others have forgotten several languages in the order of succession in which they had learnt them, regaining them later in the inverse order to that of acquisition.

When groping in the dim recesses of memory, we always perceive that there are associations and intimate connections amongst the phenomena of thought. The blood, making its way into certain parts of the brain, is like the light of a torch penetrating subterranean passages, on the walls of which are painted pictures of things we know. Often the blood-vessels do not yield, and we then wander in vain in that labyrinth, retracing our steps, roaming hither and thither, until suddenly we see an opening, and what we were seeking appears unexpectedly before us. The supposition that we here have to do with an effect of the blood, an expansion or contraction of the vessels, and with phenomena of nutrition, seems to be strengthened by the circumstance that sometimes, in consequence of violent emotion, a succession of things which before seemed totally forgotten suddenly reappears in our memory.

The link between physical phenomena and phenomena of memory is more apparent during fatigue and the refreshing state of repose. Memory may fail entirely from anæmia, from poisoning by narcotics, innutrition of the brain, and in old age; for we all know how much better we remember the events of our youth than those of later occurrence.

Men who have had wounds or contusions on the head have been known to forget that they had children; authors have forgotten even the titles of their works; but as soon as the fever had passed, or the wound healed, they regained their memory. Others, during a fever, have related events and remembered names which they had quite forgotten previously, and which they were unable to recall after recovery.