The Brain Makes Us Aware
What would it be like if you "saw" all the
radio signals in the world? There is short-wave radio, AM, FM. There is
communication among pilots and airports, military communications,
satellite uplinks and downlinks. If we could see all that, we would go
crazy. Fortunately, our brains are wired to see only what we have to see
for effective operation in this world. We don't need to see radio
signals, but we do need to see objects that we would otherwise walk
into.
Similar things could be said about sound. The point is
that we are aware of only part of what is "out there" in the
world.
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This diagram is intended to make the point that our
sensory systems detect only a fraction of the information in the
world. And of the part that is detected, even smaller amounts
reach our consciousness and still smaller amounts get
remembered. |
We humans have detector cells for:
- Light waves (eyes)
- Sound waves (ears)
- Chemicals that we smell (sensors in the nose)
- Chemicals that we taste (tongue sensors)
- Physical forces (touch, pressure, cold, heat) (skin
sensors)
- Muscle tone and limb position (sensors in muscles)
Two things to remember about these sensations:
1. They tend to be mapped in our brains. That is
mapped in terms of location outside of our body or location inside our
body, depending on where the sensation is coming from.
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View of the brain from the ventral
(bottom) side. Blue lines show paths taken by nerve fibers leaving
each eye. Note that half of the fibers cross over to the other
side.
The lateral geniculate body is a relay station
in the brainstem. Some processing of visual information occurs at
this level, but conscious evaluation of what you see occurs in the visual cortex.
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Mapping can be very specific. For example, neurons in
the visual cortex (see above) respond to a line on a TV screen, but the
degree of response depends on the orientation of the line (vertical,
horizontal, angular) and the line's location in the field of view. Click
here to perform an on-line simulation that illustrates this.
2. We can be consciously aware of many of these
stimuli. That is, we not only know this information, we are aware that
we are aware of it.
Brain Makes Us Conscious
Where Does Consciousness Come From?
It comes from the interaction between:
- the cerebral cortex (outer part of the brain)
- a cluster of cells in the core of the brainstem
Lower animals do not have nearly as many cells in
their cortex as we do. Therefore, they cannot operate at the same high
level of consciousness as we do. In both lower and higher animals, the
brainstem core is crucial. Damage in this area can cause permanent coma.
Language is Important for Our Thinking
We think most clearly and precisely with language. We
remember best with pictures.
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Age and Learning A Second
Language
Foreigners who come here as young children can learn English as
well as U.S.-born children. But children who come here in the 8th
grade or higher have a much more difficult time.
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