"left" and "right" neurons

[gib65]

Are there centers in the brain for our perception or "feel" for left and right? I ask because I remember learning in school that there are but my current text book mentions nothing of this.

 

I've also heard of people neglecting certain sides of the world, like one case in which the person would not eat the left half of his plate, wouldn't colm the left half of his hair, wouldn't fully put on his shirt on the left side, etc.

 

I've also heard of an autistic girl who would avoid facing north. The care giver would spin around with her in a circle, and evertime she faced north, she'd duck her head. Of course, this is not left and right, but north, east, west and south. Still, the question is similar: Are there parts of the brain for our experiences of left and right, or just orientation in general?

[CharonY]

What you describe is basically tied to whole brain areas, not individual neurons.

The brain consists basically of two hemispheres (left and right) which control (and get information) from the opposite body part. So roughly your left body parts are controlled by the right brain hemisphere and vice versa (there are small cross-overs, e.g. in the visual pathway, but I will neglect it here).

Generally all the signals are integrated by means of the corpus callosum, which is a broad band connecting both hemispheres.

Now the persons you describe typically have a severed corpus callosum, meaning that each brain hemisphere can only work with the data it receives and cannot exchange information with the other half. So if such a so-called brain-split patient sees something with his left eye (sending information to the visual area in the right hemisphere) he will only be able to point at it with his left hand (also controlled by the right hemisphere). The other half of the brain is totally unaware of it.

[sabbath]

There is also a tendency towards handedness, left handedness and right handedness. Nurturing and culture plays a role in this. It may be that we are born with right or left tendencies but due to culture (for example, right handedness is the majority) these tendencies can be changed. It is also said that some people view the world with a tendency in the right, or left. Like seeing details more in the right side than in the left. Others are ambidextrous however, and have both sides of the brain more or less equally developed.

[Edtharan]

I am on odd case in Left/Right/Ambidexterity. I started off writing right handed, but changed to left handed in the middle of a word (you can acutually see it on the page) and I have been strongly left handed since. However I still retain the skill I had in writing with my right hand at the same skill as I had when I switched. This puts me as ambidextrous, but I am still strongly left handed.

 

I am also much stronger with my right hand and leg, but I am more generally dexterous with my left hand. However I do use a computer right handed (I developed this on my own and was not taught to use a computer right handed), and eat right handedly. But these are isolated cases.

 

Another odd thing is that people who are strongly left right dominant also usually (but not alwase) have a dominant eye. Infact most people have a noticable dominance in one eye or the other, but I don't. In many tests on eye dominance I alwayse come out with equal dominance in my eyes, and yet show a fairly clear dominance in one side or the other for other tests (dexterity and strength).

 

I haven't been tested for brain dominance, but I would find that interesting to see.

[ashennell]

I've also heard of people neglecting certain sides of the world, like one case in which the person would not eat the left half of his plate, wouldn't colm the left half of his hair, wouldn't fully put on his shirt on the left side, etc.

 

Neglecting half of your visual field is called hemispatial neglect. The individual often only has partial access to information from one side - they are not conscious of this area of space existing (but don't notice that it is missing) but in certain circumstances can use information that comes from the neglected area. It is most commonly caused by damage to the thalamus.

 

Interestingly the neglect can have different frames of reference, so for example if you have three pictures arranged horizontally in a line, then only one half of each would be percieved. So , for example :

 

-**- -**- -**-

 

may be percieved as

 

-* -* -*

 

which, is pretty wierd.

[imelda]

can anyone tell me what it actually means if you've had a test and the right and left hemisphere's of your brain are found to be equally dominant.I am ambidextrous, as i play three instrument's , but at eighteen i accidentally realized that i could write with my left hand, although not in the normal sense but in perfect mirror image, the one letter that i seem to get confused at is the letter J . Does anyone know anything about this type of thing?[