The union of praanan, manas and aatman is one type of realization. Better watch closely the sequence of events that take place in the event described above.

Aatman stays at III ventricle. manas is nothing but aatman, but only a part of it sent down to conduct the bodily metabolism with praanan. When merger takes place, manas, even if momentarily, loses its identity; and when this happens, there is only the aatman. Praanan never loses its identity but just stays by the side of aatman. When manas is gone, then our individual identity is also gone. Where then is our mind for us to claim that I am so and so and that this is my body etc. This merger demolishes my separate identity, the \91I\92, \91My\92 and \91Me\92 are all demolished. What remains is only the aatman. aatman stands as my \91I\92. In fact, I become aatman. Aatman becomes my reality and identity. 

This unexplainable experience, that I am aatman alone, is what is known as aatma-saakshaatkaara. It is, I am that. This fantastic event is to be directly experienced and the oneness achieved. Otherwise, claiming verbally that I am that becomes simply nonsensical.
 

This unique experience is supposed to happen to me on daily basis. But, alas, this may better be hoped for than actually achieved.

This is the one part of self-actualization, wherein aatman is realized.

Buddhi blossoms, jnaana dawns and chitta and ahamkaara bloat. Man the animal becomes man the human. We become human from now. Earlier we were a form of animality.