Meditation is a process to still the Mind, by divesting thoughts and their impressions on the Mind. The process is to still the Mind, by not allowing it to go after sense objects. Mind is always a churning pot of Thoughts, reflections and residues of emotions. Mind is always in a State of flux.

Brain Mind and Intellect and Chitta ( as desired by Yoga) are not one and the same.

Brain is the physical organ that receives stimuli and reacts under directions.By Whom?

Mind, as directed by Intellect.

Mind classifies information into various headings, also assigns as to what causes/ caused us pleasure and pain in the past and regulates our emotions and they in turn affect our Mind, thought processes and thus a vicious cycle is formed.While Brain collects information ,Mind classifies information just as CPU.

Mind through its instrument,Intellect ,Buddhi classifies information as Right or Wrong ( Value judgement) ,as Correct or incorrect ( Factual).

We can put it this way. Brain is the physical organ that receives the Stimuli,while Mind is the Activity of the Brain that collates classifies. Thoughts form in the Mind and it’s counter part also is formed in the mind. These leaves their residues after an act or thought is completed.

The Intellect is directed by Chitta a higher plane over Mind. This Chitta ,at the ultimate Level in Gnana,Pure Knowledge. Reality is Sat,Chit and Amanda.Sat,Being; Chit,Pure Knowledge and Ananda Bliss.

Chitta is influenced by one’s past and immediate Karma,actions and their reactions. The remnants of these influence Chitta and Chitta, thus influenced, directs Intellect,then throught it the Mind.

Thus Chitta influences the Mind. And cessation of modifications of Chitta is Yoga. ‘ Yogaha Chittavrutthi Nirododadha’ Patanjali Yoga Sutra 1.

How the whole thing affects human Body and Brain and how it is mapped by science?

The Study on Influence of Meditation on Brain.

• In a 2012 study, researchers compared brain images from 50 adults who meditate and 50 adults who don’t meditate. Results suggested that people who practiced meditation for many years have more folds in the outer layer of the brain. This process (called gyrification) may increase the brain’s ability to process information.
• A 2013 review of three studies suggests that meditation may slow, stall, or even reverse changes that take place in the brain due to normal aging.
• Results from a 2012 NCCIH-funded study suggest that meditation can affect activity in the amygdala (a part of the brain involved in processing emotions), and that different types of meditation can affect the amygdala differently even when the person is not meditating.
• Research about meditation’s ability to reduce pain has produced mixed results. However, in some studies scientists suggest that meditation activates certain areas of the brain in response to pain.

Who should be careful in practising Meditation.

• Meditation is generally considered to be safe for healthy people.
• People with physical limitations may not be able to participate in certain meditative practices involving movement. People with physical health conditions should speak with their health care providers before starting a meditative practice, and make their meditation instructor aware of their condition.
• There have been rare reports that meditation could cause or worsen symptoms in people with certain psychiatric problems like anxiety and depression. People with existing mental health conditions should speak with their health care providers before starting a meditative practice, and make their meditation instructor aware of their condition.   Source. https://www.nccih.nih.gov/

Meditation is a tool of Yoga.

Yoga is defined as the cessation of the modification of  Chitta, that is the cessation of the thought waves at the level of Chitta.

Activity of thr Brain is the mind, which is akin to CPU that receives inputs with  no say in choosing  stimulii/action..

Intellect is the instrument which decides what is correct/incorrect,Right/Wrong.

Higher than this is Chitta which guides the Intellect as to what to do in tune with the natural disposition of  the individual.

As thoughts are innumerable, control over thoughts becomes difficult.

To control thoughts medi is used.

In this process , the brain is slowly guided into moving to Delta wave zone.( we normally operate on Alpha-waking,Beta,sleeping,Theeta,deep sleep).

At this level, the mind is divested of all multifarious thoughts and remains fixed on a single thought.

This changes the structure of the Brain.

Story:

Participating in an 8-week mindfulness meditation program appears to make measurable changes in brain regions associated with memory, sense of self, empathy and stress. In a study that will appear in the January 30 issue of Psychiatry Research: Neuroimaging, a team led by Massachusetts General Hospital (MGH) researchers report the results of their study, the first to document meditation-produced changes over time in the brain’s grey matter.Meditation group participants reported spending an average of 27 minutes each day practicing mindfulness exercises, and their responses to a mindfulness questionnaire indicated significant improvements compared with pre-participation responses. The analysis of MR images, which focused on areas where meditation-associated differences were seen in earlier studies, found increased grey-matter density in the hippocampus, known to be important for learning and memory, and in structures associated with self-awareness, compassion and introspection. Participant-reported reductions in stress also were correlated with decreased grey-matter density in the amygdala, which is known to play an important role in anxiety and stress. Although no change was seen in a self-awareness-associated structure called the insula, which had been identified in earlier studies, the authors suggest that longer-term meditation practice might be needed to produce changes in that area. None of these changes were seen in the control group, indicating that they had not resulted merely from the passage of time.  https://ramanisblog.in/2011/01/22/meditation-changes-brains-structurefor-the-better/

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