“The yogis have said for ages that spiritual practice changes the brain, and they have a very systematic method for doing so… The Yoga Sutra is a manual for how to do this”. Joan Shivarpita Harrigan, director of Patanjali Kundalini Yoga Care(How to Boost Brain Power, Yoga Journal, October 2008)
According to Yogic tradition, a tree to enlightenment grows within us. By directing our life force energy or consciousness (the sacred serpent Kundalini) upwards from the root of our spine, to ascend the tree trunk (spinal cord), into the highest branches of our brain (the Ajna Chakra or third eye), we blossom into cosmic consciousness and realize our true nature as divine beings.
Does this yogic metaphor of ascension have a basis in our biology ? Today there is a great deal
of evidence to suggest that yoga directs cerebral energy and blood flow upwards from its oldest and most primitive roots, into its highest neural branches, the most highly evolved area of our brain, the pre-frontal lobes.
Can this be seen as “climbing the tree” of our brain’s reptilian and limbic systems? I believe so. In this series, I will explore how, by teaching us to harness the power of the pre-frontal cortex (or Ajna chakra), yoga trains us to overrule the stimulus response, action-reaction parts of the brain and initiates a “ biology of transcendence” that is our full evolutionary potential.
The Tree of Evolution
Only this newest system can organize the entire brain into a smoothly synchronous intention, linking all our lower instincts, as well as thinking and feeling, with higher fields of intelligence and translate all the higher human attributes such as love, empathy and creativity into daily action. Joseph Chilton Pearce, ”The Biology of Transcendence”
In order to understand yoga’s potential to evolve the brain, we must first understand that nature never abandons a system, but builds upon the old. Each epoch of animal life is still literally contained within our brain and develops in utero in the order of appearance in evolutionary history. Each of these structural regions corresponds to particular behaviours.
The reptilian brain or brainstem appeared with the dinosaurs approximately 500 million years ago. It takes shape in the first trimester of gestation, and is concerned with survival and reproduction. The reptile brain cannot think or feel; only react and becomes dominant when threatened by fear or anxiety.
The second brain is the mammalian brain or limbic system (approximately 200 years old), and it branches out of the brain stem in the second trimester. Our emotional mammalian brain gives us the ability to nurture and bond, as well as the herd instincts that create our social worlds. It is responsible for the body’s ability to heal itself. Hormonal function, the immune system, and even allergic responses are handled by our mammalian brain.
The neo-cortex (the human brain) first appeared 50 million years ago and it develops in the third trimester. This is where we lift ourselves out of our ancient animal instincts into a higher order of functioning. It is the source of our intellectual capacities to think, compute, reason, analyse, imagine and so on.
Sprouting up from the neo-cortex only a mere 100,000 years ago, the pre-frontal cortex makes its debut after birth. Considered the command center of the brain, it is the seat of concentration and focus. It grants us freewill, the ability to create intent, look at situations objectively, organize our thoughts, make a plan of action and follow through.
Neuroscientists have found that when we concentrate, the brain circuits associated with time, space, and feelings, and sensory perceptions of the body literally quiet down. In other words, when we focus on what we want, the pre-frontal can regulate the emotions of the mammalian brain and the survival reflexes of our ancient reptilian system, to stop our biology from distracting us.
The pre-frontals are considered a largely latent, fourth evolutionary system. Neuroscientist Antonio Damasio, points out that for most of us, the pre-frontal cortex remains largely silent, meaning little activity can be recorded there. Neuroscientist Marian Diamond states that because our older brains require far less energy to function, the prefrontal cortex is ”the laziest muscle in our body”.
Most often our attention in everyday life is divided among the three older brains (each with its own agenda) so we are thinking one thing, feeling something else and acting from impulses below our conscious awareness. In this distracted or conflicted state, the lower brain will hijack the emotional or higher brain whenever it deems necessary, usually when fear, feeding, sex or threats to social status are involved.
Even negative thoughts have been demonstrated to shift cerebral energy down from our thinking forebrain to the survival oriented hindbrain (and do so completely beneath our conscious awareness).
According to the pre-eminent neuroscientist Dr. Paul MacLean reptilian behaviours are identified with an obsession with sex, food, control, domination, aggressiveness, territoriality, greed, hoarding, conformity, deception, habitual repetition of the same patterns and never learning from error.
This shift into the reptilian brain can also throw our limbic system into the “flight or fight response”, drawing energy away from the healing systems of the body, and depressing the immune system for up to six hours. Studies also show that poor or low function in the pre-frontal cortex is linked to depression, addiction, anxiety disorders, and criminal behaviour.
It seems clear that when we are in the grip of the hindbrain we do not have access to evolutions highest intelligence and react on a primitive impulsive level. This is where yoga comes in. In Part Two, we explore how by exercising self-awareness and self-control, yoga grants us the freedom to transcend our lower instincts and harness the power of the pre-frontal cortex.
body divine yoga 
You have a fascinating blog here. Very concise and well articulated. Glad I stumbled upon it this morning!