The neurones of the second order, the cells of which form the internal nuclear layer, and their processes form synapses in the internal molecular layer with 3.
The neurones of the third order, the cells of which form the ganglionic layer and their neuraxons constitute the fibres of the optic nerve which end in the optic lobes of the brain.
Parker's neurones of the first order, is very much longer than in Petromyzon or in any vertebrate, for the external molecular layer (6, Fig.
In the optic lobe the axones of the neurones of the optic tract meet neuroneswhose axones pass in turn to the motor neurones of the muscles moving the eyeballs, and also to other motor neurones.
This stripe results from a layer of nerve-fibres, many of which are axones from the neurones of the lateral geniculate body and the pulvinar, the grey masses directly connected with the optic nerve-fibres.
That is, the neurones are laid in conductive series, the far end of one apposed to the near end of its precursor.
The chains of neurones passing through the cortex are more complex and connected with greater numbers of associate complex chains than are those of the spinal centres.
The optic nerve and tract constitute the second link in the chain of neurones joining the retina to the brain.
But from certain limited regions of the cortex such stimulation does evoke muscular acts, and one of these regions is that to which the neurones forming the third link of the conductive chain from the retina pass.
From this geniculate body a number ofneurones extend to the pallial portion of the cerebrum, for in the reptilian brain the pallium is present.
In mammals this visual region of the cortex is distinguished in its microscopic features from the cortex elsewhere by a layer of myelinate nerve-fibres, many of which are the axones of neurones of the geniculate body and pulvinar.
They may therefore be regarded as the equivalent of an intraspinal tract connecting the deep ends of the afferent neurones from the skin with higher nervous centres.
The peculiar configuration of symptoms shown in cases with the physical shell-shock or its equivalent, is perhaps dependent upon what neurones are locally affected.
He also believes that the controlling neurones in the intermedio-lateral tracts that have to do with the sympathetic system, would be affected just as anterior horn cells are.
It is decidedly doubtful whether the hypothesis of microscopic or larger hemorrhages, or of local areas of destruction of neurones will suffice for the explanation of true Shell-shock.
If there has been good evidence of near-by explosion or of wound, it will be especially important to learn just what parts of the nervous system and just what synergic neurones and other structures were affected.
He thinks that small hemorrhages, inflammatory processes, and degenerative processes affect the neurones unfavorably, and permit the psychogenic effects to occur more readily.
The jar would thus be communicated to the neuronic cells of origin of two types: spinomuscular and preganglionic, leaving the gangliospinal neurones relatively intact.
Where there are central neurones in the arc, their branching axons aid in distributing the excitation; and so we get a big movement in response to a minute, though intense stimulus.
We have good evidence, as already outlined, for growth of the neurones and their branches through exercise.
Both rods and cones connect at their base withneurones that pass the activity along through the optic nerve to the brain.
A reflex is a native reaction, and it is taken care of by a team of neurones in the way just stated.
A nerve current is supposed to pass along this pair of neurones in the direction of the arrow.
Exercise, then, has the same general effect on neurones that it has on muscles; it causes them to grow and it probably also improves their internal condition so that they act more readily and more strongly.
The way nerve currents must go shooting around the brain from one center or group of neurones to another, keeping it up for a long time without requiring any fresh peripheral stimulus, is remarkable.
Streams of electrons that had coursed in familiar paths through chains of neurones find easier paths through the poison-thinned cell-walls.
The big nerve cells and the glia of their lateral vestibular apparatus were analyzed, since the Deiters neurones present in this structure are directly connected to the middle ear.
Changes in the RNA composition of neurones and glia of the brainstem occur during a learning situation.
The neurones of each such group must be conceived as being so intimately connected with one another that the excitement of any part of the group at once spreads through the whole group or disposition, so that it always functions as a unit.
Some neurones in the human body, although visible only under the compound microscope, give rise to axons several feet in length.
At the base of these hairs are found neurones which send axons inward to the central nervous system.
The essential differences in the effects of destructive lesions of upper and lower neurones may be indicated thus:-- Upper Neurone Lesion.
Neurones in different stages of development, from a to e.
Here also the neurones are crossing, or changing sides, so that those which pass up the right side of the cord finally connect with the left side of the brain, and vice versa.
The training of the nervous system consists finally, then, in the development and coördination of the neurones of which it is composed.
True, the neurones are held in place, and perhaps insulated, by a kind of soft cement called neuroglia.
In the medulla, the unmedullated neurones which comprise the center of the cord are passing to the outside, and the medullated to the inside, thus taking the positions they occupy in the cerebrum.
On the brain side this involves producing in the appropriate neurones the activities which, when repeated again later, cause the fact to be recalled.
It is accomplished through the law of habit working in the neurones of the cortex.
The number of the microscopic neurones required to make up the mass of the brain, cord and peripheral nervous system is far beyond our mental grasp.
The very structure and arrangement of theneurones is such that we are obliged to make some movement in response to objects affecting our sense organs.
For example, when you see, smell, taste and touch an orange, the corresponding areas in the brain act in conjunction and are associated by means of the association neurones connecting them.
It is important to note that neurones never act singly; they always act in groups, the nervous current passing from neurone to neurone.
The association neurones have the further function of connecting one sensory area in the brain with another.
They are called association neurones and transmit the nervous current from sensory areas to motor areas or from one sensory area to another.
Some of the neurones are as long as three feet; others measure but a fraction of an inch in length.
They are called sensory neurones and their function is to carry messages inward to the brain.
The area in the brain, where these neurones emerge, is near the top of the brain in the area marked Motor on the diagram.
In all these places we find ends of neurones which converge at the spinal cord and travel to the brain.
The nerve-cells in this group are called motor neurones and their function is to carry messages from the brain out to the muscles, for a muscle ordinarily does not act without a nervous current to set it off.
Thence it pushes on, over association neurones in the brain to motor neurones, over which it passes down the spinal cord again to muscles, and ends in some movement.
If we could see exactly the structure of the brain itself, we should find it to consist of millions of similar neurones each resembling a bit of string frayed out at both ends and here and there along its course.
Neurones which are easily impressed and retain their impression simply because they are so made are the gift of nature and the corner stone of a good memory.
It is determined by the character of the neurones and varies with different brains.
In order for conduct or feeling or intellect to be present, at least two neuronesmust be active, and in all but a few of the human activities many more are involved.
The meeting places of these neurones are the synapses.
The possibility of conduct or intelligence depends upon the connections at the synapses,--upon the possibility of the current affecting neurones in a certain definite way.
All neurones have the three characteristics of sensitivity, conductivity, and modifiability.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "neurones" in a variety of sentences. We hope that you will now be able to make sentences using this word.
