which part of the brain specifically associate with the five senses? 
why are some people more alert to those things and others are not?
example: why people might think things are salty and others don't?

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Request for Question Clarification by mvguy-ga on 14 Nov 2002 07:56 PST

Hi!  Do the comments below sufficiently answer your question, or is
there more information you want?   Thanks!

For each of the senses, I am giving the corresponding area of brain
that processes this information. There are actually many brain
structures in the midbrain and hindbrain (eg pons and medulla) that
process information as well, but I will just give you the cortical
areas (what people commonly refer to as the cerebral cortex)
Vision - occipital lobe - the brain at the back of your head
Audition - the temporal lobes - sides of the brain
Sensation - parietal lobe - the top of the brain, just slightly
towards the back of your head
Taste - insular cortex - brain just towards the middle of the temporal
lobe
Smell - orbitofrontal lobe - the brain at the front and bottom, near
to your eyes and nose

These are gross simplifications. Many parts of the brain have access
to all of the information (eg prefrontal cortex, parietal cortex, the
medial temporal lobe).

Check out: http://www.sirinet.net/~jgjohnso/brain.html

As to why some are attuned to different sensations ... not an easy
question to answer. All of our brains and life experiences are
different. With respect to vision, some people just have better visual
acuity (their eyes are better). For sound and other sense, some people
may just have a bit more precision in their circuitry.

As for salty sensations, most people I've run into are all pretty
similar. Some people may regularly have high or low salt diets and
hence are accostomed to this (my guess is that ganglia, neurons in
between the brain and the tongue, are to some extent responsible for
this accomodation, as well as the brainstem and neocortex).

The ability to taste some specific things is also determined genetically.

bbombpig,

Certain conditions, illnesses or diseases -- or certain treatments for
them -- can also cause alteration in a person's sensory perception.

For instance, according to WebMD's website, Sjogren's Syndrome is a
"chronic disorder that causes insufficient moisture production in
certain glands of the body. It occurs when a person's normally
protective immune system attacks and destroys moisture-producing
glands, including salivary glands... " causing symptoms such as
"decreased sense of taste".
http://my.webmd.com/content/article/2945.503

"People with schizophrenia often suffer terrifying symptoms such as
hearing internal voices not heard by others, or believing that other
people are reading their minds... Although hallucinations can occur in
any sensory form -- auditory (sound), visual (sight), tactile (touch),
gustatory (taste), and olfactory (smell) -- hearing voices that other
people do not hear is the most common type of hallucination in
schizophrenia." (Educational Non-Sequitur of the Day: The word
"schizophrenia" is commonly used, MISTAKENLY, to refer to "multiple
personality disorder". They are NOT the same thing.)
http://my.webmd.com/content/article/1680.51905

"A woman's body goes through major changes to accommodate pregnancy...
hormones... are produced in abundance. This avalanche of hormones has
side effects, however. It is likely responsible for the sore breasts,
cramping, nausea, vomiting, and taste and smell changes experienced by
many women very early in pregnancy. "
http://my.webmd.com/content/article/1680.51791

"...loss of appetite is fairly common for people fighting cancer...
Taste alterations in many foods can also occur due to chemotherapy's
effects; the taste alterations that occur are different in every
individual..."
http://my.webmd.com/content/article/1680.50835

"Common Heart Failure Medications...Side effects may include coughing,
skin rashes, fluid retention, excess potassium in the bloodstream,
kidney problems, and an altered or lost sense of taste."
http://my.webmd.com/content/article/1680.50874

"Other sensory losses that accompany aging include changes in the
senses of taste, touch, and smell."
http://my.webmd.com/content/asset/miller_keane_1776

"Postnasal drip [from sinusitis] may lead to a bad taste in the
mouth..."
http://my.webmd.com/content/article/1680.51930

"Factors in the development of sensory-perceptual alterations may
arise... from an alteration in sensory reception and transmission,  as
in hearing loss,  aphasia, or impaired vision, or from integration of
incoming stimuli. Other causes include chemical changes in the
composition of blood and body fluids,  as in electrolyte imbalance and
hypoxia, and drugs affecting the central nervous system."
http://my.webmd.com/content/asset/miller_keane_30093

I hope that you find this additional information helpful.

Regards,

aceresearcher

This is not a direct answer to your question. 

Consider the fact that "five senses" is not a scientific concept.

While sight, smell, taste, touch and hearing certainly are "the 5
senses", humans and other creatures are connected to their environment
in many subtle ways that are not apparent in a discussion of "the 5
senses".

For example, we have organs that detect gravity (more accurately, not
just gravity, but any acceleration of our head in any direction). But
none of "The-Five-Senses" detect gravity. In spite of the fact that
ever speaks of the 5 senses, everbody alos immediately recalls that
gravity is detected in the inner ear (many people who have an ear
infection will report that they are wobbley -- they have trouble
keeping their balance -- that's often precisely because their gravity
detecting organs aren't working well, although there are other
potential causes). Although our gravity-sense is ear-related, it has
nothing to do with hearing, of course. I don't know which part of the
brain processes information related to our gravity-sense.

Since your question made reference to "areas of the brain", I should
mention that one of the most fascinating areas of the brain is that
part related to Proprioception. Proprioception is certainly not one of
the 5 senses, but I would argue it is a "sense" (however, the case may
be made that it isn't a "sense"). Proprioception connects us to the
form and location of our various external body parts. It isn't enough
to have "touch" to know where your hand is... there is special area of
the brain (I'm not sure where) that keeps us posted about the presense
of each (external) body part and it's position relative to the rest of
our bodies. Any complex activity (and possible even simple activities)
would be impossible wihtout this "sense". Sometimes, when a body part
is amputated, that part of the brain keeps us innapropriately informed
-- hence "phantom limb" sensations.

Sight is an extremely complex "Sense". It's so complex that it should
be broken down into a variety of senses. For example, an extremely
important component of our sense of sight keeps our eye steady when we
turn our head. However, this "sense" has nothing to do with light and
dark. Arguably it's only a reflex -- but an extraordinarily complex
reflex. This "sense" is tied into our Proprioception-sense (ie it
"knows" what our neck is doing to our head) as well as to our
"gravity-sense". Without this un-named sense, your vision would be
severely impaired whenever your head moved. By the way, the effect
that this sense causes in your eye (ie the tracking-effect) is called
"nystagmus". There is another cause of nystagmous: the image you are
looking at moves. An important component of your Sight-sense, detects
that teh image is moving (when your head isn't moving) and causes your
eye to track the image as it moves. This has nothing to do with either
proprioception nor your gravity-sense. Instead, it's purely a
visual-processing sense (again -- arguably a it's just a "reflex", but
again it's an extremely complex reflex that probably doens't deserve
to be categorized with a "knee-jerk reaction"). This latter form of
nystagmus is called visual-nystagmus while the first mentioend form is
called vestibular-nystagmus. Note that Visual-nystagmous depends on
light and dark while vestibular nystagmous can occur in the complete
absense of any visual stimulous.  Given the complexity and
effectiveness and necessity of these sense (ie we can see very well in
spite of the fact that our heads and/or the images we are looking at
may be moving), I claim that these two "senses" should be recognized
as full fledge senses. They aren't recognized, however, because they
are so subtle. I wouldn't know what to call these senses anyway!

Simplifications are often used to make complex systems easier to
understand. While the notion of The-Five-Senses certainly simplifies a
complex system, it does so in a way that too greatly obscures the
truth of our senses. Bear that in mind, when you hear this commonly
used phrase.

As for your example of "Saltiness" -- being able to detect saltiness
is a pretty important tool for any creature's survival. So it is
likely that all humans (and other creatures) experience similar levels
of saltiness in similar ways. Differences in salty-perception from
person to person very likely just come down to how accustomed an
individual is to salt in their daily diet (ie personal preference).
Given that, it is likely that the areas of the brain involved that
explain differences from person to person are those areas that are
associated with the very highest brain functions -- the frontal lobes.
Areas of the brain most closely associated with the sense of taste
(I'm not sure where that is, I'm afraid), are likely NOT associated
with differences in salty-perception from person to person. That is,
areas of the brain most closely associated with taste are likely very
nearly identical from person to person. (I should admit that this is
pure speculation on my part). This is likely true of all the areas of
the brain most closely associated our senses: they are likely
identical from person to person. Even parts of the brain associated
with higher functions are very similar from person to person.

So why are preferences and personalities different from person to
person? I don't want to answer that! : )

I hope you find this of interest.

bbombpig,
let me try and give u short and simple answers:
(a) the whole brain, while different parts takes care of processing
the in-coming signals from your "sense" organs, your whole brain makes
decision pertaining to the information received.
(b) Alertness is a behavioral trait - this can be achieved through
training, ofcos there will always be natural adepts at any trait.  It
comes back to your main brain making decision what sort of things it
like to track.  For folks brought up in the laps of luxury, usually
their alertness is dulled as they don't really need it, but for folks
living in a live of constant danger, this trait would be hone to a
great sharpness.
(c) Saltiness is an Opinion - your body would be able to detect salt
(unless the signals there have been jammed by sickness or genes), but
the level of saltiness is an opinion brought about by your own
experiences and training.  Yes, it is potentially possible to train
folks until they eat so much salt that they die of it, and like
anorexia, these folks would still insist that you don't give them
enough salt.