Theli

Something I've been wondering about...
If we were to take a complete human body, and start chopping of peices (like hands, arms and legs) we would find that the conciousness would still exist. Assuming ofcourse that we can keep the brain alive. So obviously, the consciousness doesn't exist in the whole body.

Now... if we were to erase the memory in the brain, would the consciousness still be there?
How far would we have to go before all that is left of the body is the parts that make the consciousness?
What will remain?

Ted Hoffman

Theli,
Consciousness is merely awareness, especially of what is happening around you and the totality of one’s thoughts, feelings, and impressions. People in a coma for example lack consciousness but their brains might be otherwise fully functional with their memory completely intact.
The part of the brain behind consciousness is the the reticular activating system (RAS) in the brainstem, which is a collection of several thousand neurons dispersed throughout a large portion of the midbrain, pons, and medulla that seems to act like a light switch -- when the switch is on the "light" (consciousness) is on, off is "dark" (un-consciousness -- which if persistent, is coma).
The RAS both does the "filtering" (remember the example of a sleeping woman who hears the voice of her crying baby in noisy traffic) and the electrical stimulation.

Memory has got NOTHING to do with consciousness. Information (read memory) is first processed and kept in the hippocampus for several weeks, before being transferred to the cerebral cortex for permanent storage.

This explains why people with brain damage to their hippocampal region retain previous memories of faces and places, which are stored in the cortex, but have difficulty forming new short-term memories.

Because the hippocampus is part of the limbic system, it also has a role in the emotion system of a person, and its part of the temporal lobe.

To answer your question:
Now... if we were to erase the memory in the brain, would the consciousness still be there?

Yes.

How far would we have to go before all that is left of the body is the parts that make the consciousness?
The RAS does not work in isolation because we have parts of the brain responsible for olfactory senses, auditory, speeck, balance, memory, emotion etc: the RAS wires them together to have a being who is both intelligent and able.

I have heard of lobotomy experiments of subjects who were fully aware but without memory or very poor memory after surgical removal of the hippocampus. Meaning consciousness can be present in the absence of regions concerned with memory. Alzheimers victims also indicate the same.

<a href="http://isd.saginaw.k12.mi.us/~mobility/hippocam.htm" target="_blank">This site</a> says:

What will remain?
What will remain of course will be what you leave (after your chopping excercise).
What will remain in order to sustain consciousness? The RAS, whose constituent neurons are dispersed all over the midbrain, for it to maintain arousal, attention, and awareness, will require other parts of the brain to give it biofeedback - the thalamus, the cortex, neurohormones, energy etc. But the memory sections should not be critical for consciousness.

[ August 15, 2002: Message edited by: Intensity ]</p>

Theli

Thanks for the info, Intensity.

Ted Hoffman

You, Theli, are very welcome.

Ierrellus

Theli,

There are many case studies of patients who have lost limbs but still have consciousness of feelings in nonexistent toes or fingers. If you are interested, there are theories about this phenomenon.

Ierrellus
PAX

Mageth

There are also case studies of brain-injured patients who lose awareness of parts of their body, such as their left leg, even though the appendage is still present and the nerves intact.

The mind is a strange beast.

[ August 15, 2002: Message edited by: Mageth ]</p>