Brain question?

[Dean Mullen]

I was just wondering, how does the brain when it receives signals from the senses about the body, how does it give us the ability to determine where those signals are coming from? for example how do we determine that when we experience pain it is coming from our finger other than seeing it, how does the brain interpret where these signals are coming from for us then?

[Blahah]

In the postcentral gyrus of the parietal lobe, different areas of the brain tissue correspond to different areas of the body. This mapped part of the lobe is called the sensory homunculus. The amount of space in the homunculus which is apportioned to each part of the body corresponds to the amount of nerve endings in that part of the body, and therefore the sensitivity of the somatosense of that region.

 

In simple language - in a part of your brain where all the nerves end, there is a little map of the human body made of brain tissue. The nerves for your arm end in the arm part of this area, so when you feel arm pain it travels along the nerve to this part of your brain, and when the signals in your brain originate from this piece of brain tissue you know it's your arm hurting.

[thinker_jeff]

In short, the brain cortex has a map for your body on which the nerves from each piece of body project to a specific location of cortex.

You may search the internet to have tones of answers like that.

Edited February 16, 2011 by thinker_jeff

[SMF]

Blahah and Thinker_Jeff are referring to the labeled line theory. SM

[Blahah]

No, the labeled line theory suggests that different types of sensory information (not sensory information from different places) are encoded and transported uniquely. So for example, labeled line theory suggests that the sensation of heat is carried from specific heat sensors along a specific heat nerve pathway, and that's how we know it's heat. In contrast, pattern theory suggests that different sensations are encoded by the patterns of electrical nerve signals sent along the same nerve pathway, rather than being physically separated.

 

The sensory homunculus derives from experimental observation that nerves from parts of the body correspond to parts of the postcentral gyrus. It is not the same as labeled line theory.

 

Of course, even if this system is accurate it doesn't completely answer your question Dean. If we know that nerves connected to specific parts of the brain mapped to body parts, we still don't understand how this translates to the experience of pain, because we don't understand precisely how conscious perception arises. Is that what you were getting at?

Edited February 17, 2011 by Blahah

[SMF]

Blahah, you misunderstand the concept. Labeled lines maintain different types of information separate in different pathways, or within an array of axons in a pathway, such that the information at the source is reconstructed at the termination. For the senses, this information can be a large variety of sensory qualities, and one important quality is spatial relationships within the receptor surface. A homunculus is a construct of spatial representation. SM

[Blahah]

Hmm OK so I see how the homunculus could be subsumed under labeled lines, but your description is my understanding of the concept. Actually, I shouldn't have said "not sensory information from different places". The homunculus idea is not part of labeled line theory, it can just be included in it, but it also works fine with any competing theory (since it's true).

Edited February 17, 2011 by Blahah