Atita Bhavanga - Calana Bhavanga - Pacceua Bhavanga
In order to really understand the subtlety of Buddha's system of meditation, that was quite different than all that had gone before, it is really necessary to understand the psychological processes involved in his meditation beneath the Rose-apple tree when he was a young man and had completed his formal education.
It is not easy to understand nor correctly practice and many practitioners and teachers believe they are doing fine when really they have not fully understood the subtlety involved.
Everything from an external or internal source that enters the human afferent path, eventually becoming conscious, interrupts a passive state which was termed "Vibrating Bhavanga" (Calana), which we can consider as continual two-moment pulses which occur below the level of consciousness.
The immediate past Bhavanga was called Atita, while the present was termed Pacceua. You can imagine this like the continual background which is interrupted by a stimulus.
Dvaravajjhana - Panca Vinnana - Cokkhu Vinnana
The interruption, which we call in psychology an Irritation, is captured by the Sense Door Consciousness, which we can consider the Pure Mindfulness in which nothing is known about the stimulus, but only that there is an interruption as an object of irritation has entered the mind. This continual functioning is passed to the Right Hemisphere, telling the system that Mindfulness without knowing the stimulus or object is correctly active.
Next there arises Sense Consciousness, Panca Vinnana. We can best consider this pair, the Sense Door Consciousness and the Sense Consciousness, as the consciousness of the sense organ, followed by information of its irritation. Then there arises another very special event. It is the signal that "Sensing is taking place by all of the organs". This is called Cokkhu Vinnana and this information is also passed to the right hemisphere.
There is no need to remember these six events, as they are given only so that you can understand the complete process at a level that is not just cognitive.
Sampaticchanna - Adhimokka - Manasikara - Vitakka - Vicara - Ekagatta
We enter now the important phase of the Receiving Consciousness, Sampaticchanna, which we can consider as a conscious "Alert of Interruption". This is followed by Adhimokka, which is an element which is a form of selection declaring, according to the Abhidhamma, "give unwavering attention to just this event." Then there arises Manasikara, which "turns the mind towards that particular object".
It is then that there occurs the important Vitakka, "Applied Attention," and then Vicara, "Sustained Attention."
Immediately after the object of attention is sustained then the important Ekagatta, "One-pointedness of Concentration," occurs.
Phassa - Vedana - Sanna - Cetana
Then in normal conditions there arises Sensation, Phassa; Discrimination, Vedana; Perception, Sanna, and finally Volition, Cetana, where all the major work of the left-hemisphere cognition takes place.