When does actual senses (smell, taste, touching, etc)go into

**brumans** · 08-12-2004 06:40 PM

Hey..
When do actual senses go into dreams. I have had a few dreams where I recognized a certain SMELL, or could FEEL something against me or slamming down on me.. but these are rare..

I'm assuming when you are lucid that these are all common and happen..
so does it go with the level of awareness.. or what causes these to happen in normal dreams or dreams in general?

thanks

**O'nus** · 08-12-2004 08:01 PM

This is quite the interesting phenomena.

Through all of the studies of dreaming, the most important aspect to keep in mind is that the mind will shut off external influences and input from the periphery to avoid self-injury. Of course it cannot do it completely and the levels in which the mind works to keep it at this cataleptic state alter (when you have to literally hit someone to wake them up, or just whisper).

The neurotransmitters that are responsible for carrying information from the external periphery (the cerebral peduncles, corticospinal tract, medulla, etc.) are dramatically reduced in activity during sleep in which the monoamine neurotransmitters (such as norepinphrine, serotonin, and histamine). However, the thalamus and midbrain is still active (of course) through out sleep which is where the dreaming takes place.

There are two major reasons how and why senses are still active during sleep.

The first way is best elucidated is to think of it like this: when you smell something, you will immediately wonder where the smell came from, what created it, and you will remember the smell of hot dogs. When you hear something along with a certain object, that too will be retained within your memory that jackhammers are loud as hell. This ocurrs for each sense. So, within dreaming, these are inverted and projected from memory! You will smell the hotdogs because you remember what they smell like, and you will hear the jackhammer because you remember what it sounds like! Hopefully that is easy to understand.

Also, when actual senses are in play, this is even simpler to understand. Even during sleep, your senses are all still active, primarily controlled by the reticular activation system (RAS) - within the brainstem, that which is responsible for waking you up and what creates you to have those "WTF?!" awakenings. You still receive information from the external, however it is usually disregarded or the information simply does not make it to thalamus. The RAS will still register all the activity from sounds as it is still received from the auditory nerves and through the cerebral peduncles, however, it will not always be incorporated into dreams. The most common reaction to receiving auditory information is either to wake up and turn off that bloody stereo, or the sounds will be incorporated into the dreams in some significant fashion (this also has a lot of psychoanalysis behind it in why your mind chooses to incorporate the song as the song must have some sentimental attachment). I'd really rather not get into that psychoanalysis as this post is already extensive.. lol.

The reason sight is never incorporated is simple - your eyes are shut and Meyer's loop (the line of information from the lateral geniculate nucleus, the retina, etc. that process visual information) is not active.

Smell is not commonly brought into dreams from the external... and can only be during awakening. Although the olfactory complex is quite the independant system and travels throughout the limbic system a distance before reaching actual thalamus, there are two major reasons why smell cannot be registered from the external during deep stages of sleep. First, the neurotransmitter gamma-amino butyric acid is produced at a dramatic incidental rate which is incapable of bringing the smell from the parietal lobe to thalamus. Second, even if there was enough activity to bring it to thalamus, the thalamus is shut off from receiving any inforation from the parietal lobe because all the dendrites are shut off completely. The thalamus is far occupied with acetylcholine activity.

I'm not sure I worded that very well and it was all from memory.. so I apologise if I am not very clear. But I hope that helps. Of course, I imagine there may be questions, and I look forward to them. Until then..

Hope I have been enlightening.