According to Rajyoga The mind takes the impression farther
in, and presents it to the determinative faculty -- buddhi -- which reacts.
Along with this reaction flashes the idea of egoism. Then this mixture of action and reaction is presented to the
Purusha, the real Soul, who perceives an object in this mixture. The organs
(Indriyas), together with the mind (Manas), the determinative faculty
(Buddhi), and egoism (Ahamkara), form the group called the Antahkarana
(the internal instrument). They are but various processes in the mind - stuff,
This is the feeling mind and is also rooted in the cerebellum. It is the field of sensations, called vedana. This powerful part of the mind responds to the good or bad judgement made by the buddhi by releasing a stream of chemicals in to the body. For example, if we taste something we like or see someone we love, our buddhi recognizes this as positive and in response our citta responds by flooding our system with chemicals such as endorphins, seratonin or melatonin that in turn give a pleasant sensation understood as something we like. Similarly if we come into contact with something that the buddhi tells us is bad, such as a rotten smell or someone shouting at us, the citta impulse triggers the release of peptides or cortisones, unpleasant sensations that we understand as disliking. The speed of the mind’s processing power is mind boggling. One neuron processes the equivalent data of 12 computers. Buddha teaches that 10 to the power of 12 x 250 ( more than 1000 billion) chittas are produced every second and in turn 100, 000 chemicals are released into the blood stream in 1/27th second. The body produces more than 4 million chemicals. In the duration of watching a hollywood film, imagine how many pleasant and unpleasant chemicals are released in the body! The chitta is continuously fed by the sense doors and creates waves of excitement and depression throughout our days. The unconscious mind reacts to the citta and stores these reactions as sankharas at RNA/ DNA level. Chitta is the only part of the mind that operates in the present and so it is at this level of the mind that we work using raja yoga, the science of deconditioning.
The sub-conscious mind is rooted in the cerebellum. It is the recognizing part of the mind and it functions after cognition occurs in the conscious mind. This is where perception takes place. The buddhi recognizes an object and immediately makes a good or bad judgement about it by retrieving from a vast database of past impressions. For this reason it is considered to function in the past as it is based on past conditioning. The buddhi is the intellect and it decides in which direction the senses and the mind go. The analogy is often given of the buddhi being the charioteer controlling the six senses (including the mind), i.e. the horses. The buddhi can be positively conditioned and in fact all the learning that takes place, all the skills that we develop throughout our lives are due to the conditioning of the buddhi. Buddhi is called Sanna by Buddha. It is the first part of the vinnanamaya kosha.
The conscious mind is rooted in the cerebrum, in the frontal lobe. The conscious mind controls conscious thought, all voluntary actions, will-power, logic and empathy and is highly developed in humans unlike other species. It is the cognizing part of the mind and it’s entire field is consciousness. It cognizes through the senses and comprises of sight consciousness, sound consciousness, smell consciousness, taste consciousness, touch consciousness and mind consciousness, i.e. consciousness of thoughts. The manas is behind every sense door and without it we are not conscious of them. For example, we can be eating something but if our mind is distracted, we are not really tasting it. We can switch off if we are not interested in listening to someone speaking for example and their words do not register. Likewise when we are asleep, our ears are ‘open’ yet we do not hear because the conscious mind is cut off. The conscious mind dwells in pure consciousness referred to as atma, or soul and for that reason it is considered to be an entirely wholesome mind. It is the observing mind in meditation, known as dhrashta. It is also called chetana manas, jnatha, hridaya and kshetragna. Buddha calls the conscious mind vinnana. This is the manomayakosha.
Aham is the deepest root level of the unconscious mind, the ego, the store-house of all reactions. It is the oldest and most primitive part of the brain that dates back 14.5 million years to when evolution began. It is sometimes referred to as the reptilian brain and is situated in the medulla oblangata. It constantly reacts to the pleasant or unpleasant sensations produced by the chemistry of the citta and in turn prompts an outward bodily reaction. The citta and unconscious mind are always in active contact with each other 24 hours a day. This part of the mind reacts much faster to sensations, i.e. citta than the conscious mind and therefore reactions take place at an unconscious level before they even come to our attention. For example, if we have an itch, i.e. an unpleasant sensation, our hand goes to scratch it before we are even consciously aware. Likewise if someone insults us prompting an unpleasant citta/ sensation, our fight or flight mechanism has kicked in before we consciously even register our anger or dismay. The bodily reaction is automatic, if someone praises us we smile or go and hug them and if someone yells at us we might yell back, hit them or run away. These responses are unconscious as the ego is strongly dominating the conscious mind whenever we are in a state of excitement and in fact 24 hours a day. The unconscious mind’s direct connection to the body is so strong that even in sleep, when our conscious mind is cut off, our unconscious mind reacts to discomfort and makes our bodies roll from side to side. This happens without the knowledge or permission of our conscious mind. In sanskrit the ego is called sankhara, ahamkhara or kamma bija that literally means karma seed. It is the hard disk that stores past reactions at the level of RNA/ DNA as cellular memories. These stored reactions, known in Sanskrit as sankhara or samskara in Pali, are the seeds of future karmic fruit. The entire journey in yoga culminates in the removal of these stored reactions through the observation of the citta by the conscious mind during meditation.