Higher Level Projection
With enough control over the chakras, the energy for these higher levels can be produced. The production of one particular type of energy will raise the consciousness to that level and energise the corresponding subtle body. This is usually done by consciousness raising meditation and advanced energy work on the chakras. The consciousness can then experience that level of existence. If enough energy is available, and conditions are right, the meditator can project that particular subtle body directly into its natural dimension.
Depending on the skill and natural ability of the operator, if a higher body is energised and projected so, usually, are the lower ones. The astral body contains within it all the other subtle bodies and can, during a projection, project the mental body into the mental dimension and so on. This will sometimes give multiple sets of memories from the one projection. The general rule is, whichever subtle body contains the greatest amount of energy, will have the strongest memories. These dominant memories will be the ones retained by the physical mind upon its return to the waking state.
Projecting consciously into levels higher than the astral dimension takes a high level of skill. You need to be proficient in both consciousness raising and chakra control, but it is achievable. I have, so far, projected into the Astral, Mental, Buddhic and Atmic levels of existence. It is commonly believed that it is only possible for a human to project into the Astral, Mental and Buddhic levels and not possible to project into the higher Adi and Anupadaka.
These dimensions have been named, and are described, so someone must have been there or they would be unknown. If you realise the true nature of the mind you will understand there are no limits. It was also once said that the sound barrier would never be broken.
BTW: These dimensions don't have signposts on them saying Welcome to the Astral dimension, ta...daa! or Mental dimension, watch your mind!. So I will describe the higher levels I have been to using these accepted names.