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Updated: May 4, 2025
What practical difference ought it to make if, instead of saying naively that 'I' am active now in delivering this address, I say that a wider thinker is active, or that certain ideas are active, or that certain nerve-cells are active, in producing the result? This would be the pragmatic meaning of the three hypotheses. Let us take them in succession in seeking a reply.
The following are the principal points presented: In operations under inhalation anesthesia the nerve impulses from the trauma reach every part of the brain the cerebrum that is apparently anesthetized as well as the medulla that is known to remain awake the proof being the PHYSIOLOGIC exhaustion of and the PATHOLOGIC change in the nerve-cells.
More nerve-cells are necessary to control these more numerous muscular fibrils. The animal now moves with one end foremost, and that end first comes in contact with food, hindrances, or injurious surroundings. Here the sensory cells of feeling and their nerve fibrils multiply.
The neural action accompanying this occurrence consists of an impression upon the nerve-cells in the eye, the conduction of the nervous current back to the visual area of the brain, the transmission of the current over association neurones to the motor area, then its transmission over the motor neurones, down the spinal cord, to the muscles that enable you to dodge the missile.
Whether the energy of the brain be discharged by injury under anesthesia or by ordinary muscular exertion, identical morphologic changes are seen in the nerve-cells. It is quite clear that in each of these cases the altered function and form of the brain-cells are due to an *excessive discharge of nervous energy.
"There are two among the special groups of nerve-cells which produce directly opposite effects. One of these has the power of accelerating the action of the heart, while the other has the power of retarding or arresting this action. One acts as the spur, the other as the bridle. According as one or the other predominates, the action of the heart will be stimulated or restrained.
The nerve-cells governing each tentacle appear to have been able to learn by experience, but each group in the diffuse nervous system had to learn separately. The dawn of this much of intelligence far down in the animal kingdom would not be surprising, for the selection and grasping of food has always involved higher mental power than most of the actions of these lowest animals.
You may look in Browne Faber's book, if you like, and you will find that to the present day men of science are unable to account for the presence, or to specify the functions of a certain group of nerve-cells in the brain. That group is, as it were, land to let, a mere waste place for fanciful theories.
As might be expected, the two functions of impressibility and conductivity are aided by such an arrangement of the nerve-cells that the nervous current may pass over definitely laid pathways. These systems of pathways will be described in a later paragraph. The third property of nerve-cells which is important in study is modifiability. That is, impressions made upon the nerve-cells are retained.
The means of nourishing the body and brain being therefore insured as to supply, it is not reasonable to suppose that the nerve-cells of the rejuvenated man can fail to receive their proper nourishment for many succeeding years, and, passing by the rat as a fallacious parallel, we cannot see any good reason why the human body and brain, either under the guidance of self-control, or surgically safeguarded against the waste of excess, should not function at their best for fifty years of added life, with very possibly another fifty added to that.
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