Sri Aurobindo translates Taittiriya Upanishad, Shikshavalli, chapter six: “Lo, this heaven of ether which is in the heart within, there dwelleth the Being who is all Mind, the radiant and golden Immortal. Between the two palates, this that hangeth down like the breast of a woman, is the womb of Indra; yea, where the hair at its end whirleth round like an eddy, there it divideth the skull and pusheth through it.”
“As Bhur He is established in Agni, as Bhuvar in Vayu, as Suvar in the Sun, as Mahas in the Eternal. He attaineth to the kingdom of Himself; He attaineth to be the Lord of Mind; He becometh Lord of Speech, Lord of Sight, Lord of Hearing, Lord of the Knowledge. Thereafter this too He becometh, — the Eternal whose body is all ethereal space, whose soul is Truth, whose bliss is in Mind, who taketh His ease in Prana, the Rich in Peace, the Immortal. As such, O son of the ancient Yoga, do thou adore Him.”
The first section of this chapter addresses yogic anatomy and psychology. The references to locations in the physical body are for orientation of the awareness, not representations of functions of the physical body; rather, they refer to the subtle body of the chakras and the nadis, or “channels” of energy of the subtle body. The yogic texts and the Upanishads and Bhagavad Gita all refer to the seat of the Atman as being in the heart. The primary channel of the flow of consciousness through the chakras is the Sushumna which begins at the base of the spine and moves upwards through the major chakras, and exits out the top of the head, as described here. It is said that at the time of death, if the consciousness exits through the locus at the top of the skull, the soul achieves liberation. In the interim, if the consciousness has been awakened, the energy flows through the Sushumna, activates the chakras and brings about union, yoga, between the individual Atman and the universal and transcendent consciousness.
The experience that follows the process of identifying with the Atman, opening of the subtle energy centers and flow of that energy through the Sushumna is one of a reversal of the normal human consciousness which is focused and originates in the physical body and life. The seeker identifies with the Atman and becomes master of mind, life and body, which become instruments of his interface and interaction with the world. Stationed in the Atman, one with the Brahman, the seeker becomes a soul of peace and oneness.