16 Functions of Brain in Aitareya Upanishad

Aitareya Upanishad, which is embedded within Rig Veda, mentions 16 higher cortical functions of human brain like language, vision, recognizing objects in space (visuospatial recognition), awareness etc.
Human brain is the most complex computer system, both in its organisation and operation.
16 Mind Functions

In western world, Hippocrates (460-370 BCE) was first person identify human brain as the ‘organ of intellect‘ or ‘the guiding spirit‘.
In later generations, philosopher-scientists like Herophilus (335-280 BCE) and Galen (129-210 CE) accepted the mystic nature of the brain and labelled it as the ‘seat of the soul‘.
Many centuries later, neuroscientists like Vesalius regarded the brain as a ‘highly developed sense organ‘, whereas Gall provided the psychological explanation in terms of phrenologyand attempted to localize each psychological function within different segments of the brain .
Others like Lashley, Luria, Sperry etc proposed multiple theories about human brain.
But ancient Indians have been able to describe higher cortical function of humanbrain. The major distinction is present in the usage of term, ‘manas’ or mind rather than brain.
Earliest found scriptures like Upanishads describe all the mental functions namely, cognition, emotion and volition have been examined and describedthrough the concept of mind.
Manas‘ is considered as the figment of consciousness. Further, consciousness is said to reveal itself in waking (Jagrita), dream (Swapna) and dreamless sleep (Sushupti) stages.
People like Sigmond Freud defined 3 levels of mind : Preconscious, Conscious, Unconscious mind based on above.
Prasnopanishad even went few steps ahead and described how ‘Dreams‘ are created by Manas, while in sleep (Swapna) state.
sleep dreams mind explained in Prasnopanishad

Aitareya Upanishad gives a list of 16 functions of mind which represent the single generic term ‘Prajnana’ orcognition.
These are :

  1. Samjnana‘ or awareness
  2. Ajnana‘ or comprehension
  3. Vignina‘ or understanding
  4. Prajnana‘ or knowledge
  5. Medha‘ or retentiveness
  6. Drishti‘ or insight
  7. Dhriti‘ or resolution
  8. Mati‘ or opinion
  9. Smriti‘ or memory
  10. Manisha‘ or reflection
  11. Juti‘ or impulse
  12. Samkalpa‘ or conception
  13. Kratu‘ or purpose
  14. Asu‘ or vigor
  15. Kaamah‘ or desire
  16. Vasha‘ or will.

Prasna Upanishad also term mental phenomenon as ‘Antahkarana‘ or internal sense which is constituted by four psychological faculties. These are: ‘Manas’, ‘Buddhi’, ‘Ahamkara’ and ‘Chitta‘. The ‘Manas‘ refers to that faculty which receives the external stimuli. The message is then passed to ‘Buddhi‘ or intellect which proceeds to analyse these stimuli with the power of discrimination.
Further, the message is passed to the ‘Ahamkara‘ or ego which renders unique properties to the incoming message through the ‘Chitta‘ or consciousness.
These are all psychological experiences and cannot be empirically proved.

Tantrik manuals of yoga describe the anatomy and physiology of the nervous system, mind and its various functions.
Shatchakra Nirupana‘ , ‘Shiva Samhita‘ and ‘Hatha YogaPradipika‘ have illustrated the physiological process of various ‘nadis‘ and ‘chakras‘ which govern the subtle functions of the body and mind.
14 major ‘nadis‘ are mentioned in these texts, out of which the three ‘Ida‘ , ‘Pingala‘ and ‘Sushumna‘ are important.
Ida‘ and ‘Pingala‘ are said to be situated on either side of Merudanda (spinalcolumn). The spinal column contains the ‘Sushumna’ (spinal cord).
At the ‘Sheershanta‘ (cephalic end) each passes into the ‘Kapala‘ (cranium) with the other opposite and forms the ‘Bhrukitichakra’ (Naso-ciliary plexus). From there, the ‘Ida‘ and ‘Pingala‘ proceed further to join the ‘Sushumma‘ (spinal cord) at the ‘Mastishka stambha‘ (brain stem).
Brahamachakra‘ (cerebrum) receives the ‘sushumna‘ through the ‘Talu‘ (foramen magnum) forming a ‘Sahasrara‘ or thousand branch plexus.
The ‘Kapalaguhika‘ (cranial cavity) is present at the ‘Sushumma‘ and is divided into two parts : the anterior and posterior.
The anterior fibres travel upwards and join the ‘Ajnachakra‘ (lobe of intelligence). This lobe is concerned with the control of the voluntary muscles, ligaments and joints.
The posterior bundle, on the other hand, travels towards the ‘Brahma Randhra‘ (ventricles of the brain), where soul is supposed to reside.
It is this portion of the brain thata student of yogic sciences tries to develop by a process of co-ordinating, the ‘Prana‘ (air which is breathed in) and ‘Aprana‘ (air which is breathed out.
Shiva Shakthi Kundalini Yoga

Shatchakra Nirupana mentions how the different psychological experiences are generated.
According to text, theentire central nervous system is divided into six chakras.
These are: ‘Muladhara’, ‘Swadhisthana’,’Manipura’, ‘Anahata’, ‘Visuddha’ and ‘Ajna‘.

Lotus at Sahasrara ChakraLotus at Crown Chakra

Brain (Mind) dimensions and functions in Bhagavad Gita, Tripura Rahasya

Lord Krishna describes Mind (Manah/Manas) and its various aspects in multiple slokas of Gita.
He defines 4 basic types of mind : Manas, Buddhi, Ahankar & Chitta which are Mind, Intellect, Ego & Intuition.
In general, 13 dimension of mind are defined as 5 panchendriya (5 sense organs which send signals to brain), 5 gnanendiya (5 senses which are decoded independent of sense organs), buddhi (intellect), chitta (intition of sixth sense) and ahankar (ego).
Tripura Rahasya, which was unfolded by Dattatreya to Parasurama, describes more emotions and functions of human mind.
Manas (mind) can do kalpana (imagination), can have kaama (desire) which gives birth to krodha (anger) and lobha (greed).
Kalpana (imagination or day dreaming) and Swapna (dreams during sleep) are different. One can be controlled, while the other is involuntary. Westeners mix both and call upon to dream big things and work towards realising dreams.
In reality, we can only work and make imagination into real.