Seems two concepts here - one about breathing, one about amnesia.
Here's some thoughts to share, happy to hear other's views on mine...
on breath - agree with the focus on breath meditation - this is a key.
I usually do some deep breathing ex prior to going, along the lines of max inhale, hold 3-5 secs - ram more air in with a few forced sniffs, let basal alveoli expand to max out lung volumes, full exhale (and I mean full) use arms to squish chest - centralise any mucus in the bronchial tree - cough any gunk out before you go.
Other thoughts - I suspect a great deal of electrical activity is going on in the brain / body during a journey, I can sense the oxygen debt and feel my metabolic rates skyrocket - I have become aware that poor nutrition reduces the brain/mind machines 'top speed' potential, thus I suppliment with heaps of serotonin rich foods, (banannas & walnuts) Q10 and broad B group vitamins - to help ensure mitochondria and neurons have enough fuel to get into orbit...
Try a berocca 1/2 an hour before you go.... the neurons go turbo...
One experiment I am waiting to do is to max out on O2 before I go.
Breathing & mucus - seems that sometimes spice causes the body to detoxify, I hear the ahaywaska(?) makes you vomit out toxins, seems also that various mucus cells along lung and nasal passages try to expell the crap - as snot / mucus. this can make it hard to breath. I notice my skin is also expelling more gunk than it used to, and I am starting to feel much 'cleaner' inside. My guess is the gunk are all part of living in the city, its in the air, the food, the water.
Try to cleanse environment and self - ritually - before you go, it will empower the experience as well. A good gargle / nasal gargle might help you continue to breath.
Re the amnesia - sounds like either too much - check dosages as recommended in the spirit molecule - per body kg... or you are thinking too much / too stuck in own thoughts and blocking. I think that message about looking in the gaps, in the silence, between thoughts, to be pretty spot on. Also the bit about just letting go, try to ride the sensorium and observe, but don't analyse.
Given you are probably contacting an infinite intelligence, maybe not be so surprised that there is more information than simple human can contain.
I'm happy if I come back with one gem at a time.
Eg- My last was a very interesting conception of how the consciousness field creates reality - and how we as self programming swarm intelligences - actual whirlwinds in this mind field can mould-create-influence it.
This was not a hocus pocus - it was superstring physics minus the visual representation of the equations, akin to a living fractal bio-psycho-social entity that is the cosmos. Here's a similar concept by PHd John Hagelin if that didn't make any sense to you.
http://www.youtube.com/watch?v=OrcWntw9juMThe gem was that the fundamental 'particle-proccess' of the cosmos is AGAPE LOVE and we as self aware entities in this cosmos can access this infinite love, with or WITHOUT spice, at any time....
I dream of what I'd call a "no spice" or "endogenous spice" tech....
these are some of the keys I've found so far.
ritual prep - self and environment, sensory dep or suitable vibe music
(you-tube entheogenic-pagan dream machine... or the OMMMMMMMMMMMM - Both are powerful boosters), breath control, body temp room, recline in absolute darkness
respect for what is sacred..... these things are SOME, I'm sure there's more / simpler / better - lots of us seem to be developing these 'techs'.
If you have to think, coz your mind won't shut up,
maybe have a mantra related to your mission.....
- even doing nothing / just observing can be considered the 'mission'
Feel free to try a favorite of mine - a gem I was given on my first real journey.
"Love is the word and the word is love "