Brain over body: Hacking the stress system to let your psychology influence your physiology

There are people who show incredible resistance to extremes of temperature. Think of Buddhist monks who can calmly withstand being draped in freezing towels or the so-called “Iceman” Wim Hof, who can remain submerged in ice water for long periods of time without trouble.

These people tend to be viewed as superhuman or special in some way. If they truly are, then their feats are simply entertaining but irrelevant vaudevillian acts. What if they’re not freaks, though, but have trained their brains and bodies with self-modification techniques that give them cold resistance? Could anyone do the same?

As two neuroscientists who have studied how the human brain responds to exposure to cold, we are intrigued by what happens in the brain during such resistance. Our research, and that of others, is beginning to suggest these kinds of “superpowers” may indeed result from systematically practicing techniques that modify one’s brain or body. These modifications may be relevant for behavioral and mental health, and can potentially be harnessed by anyone.

The body’s drive for balance

Behavioral modification techniques like yoga and mindfulness seek to modulate physiological equilibrium – what scientists call homeostasis. Homeostasis is a basic survival need and crucial for an organism’s physical integrity.

For example, when someone is exposed to cold, certain brain centers initiate changes in how the body responds. These include decreasing the blood flow to the extremities and activating deep-layer muscle groups to produce heat. These changes let the body hold onto more of its heat and occur automatically without conscious control.

Messages go back and forth from brain to body, working to keep systems in homeostatic equilibrium. Diwadkar and Muzik, CC BY-ND
Homeostasis is maintained when peripheral organs (“the body”) collect sensory data and forward it to the processing center (“the brain”), which organizes and prioritizes this data, generating action plans. These directives are then conveyed to the body, which executes them.

It’s the balance between bottom-up physiological mechanisms and top-down psychological mechanisms that mediates homeostasis and guides actions. Our idea is that this balance between physiology and psychology can be “hacked” by training the brain to deal with exposure to cold. This is a very interesting trick – and we believe the brain changes that occur extend beyond just cold tolerance.

Brain systems for maintaining homeostasis form a complex hierarchy. Anatomical regions in the primitive brainstem (midbrain, pons) and the hypothalamus form a homeostatic network. This network creates a representation of the body’s current physiologic state.

Based on what this representation describes about the body’s conditions right now, regulatory processes trigger physiological changes in the periphery via the nervous system. The representation also generates basic emotional responses to physiologic changes – “cold is unpleasant” – that trigger actions – “I need to get indoors.”

The midbrain, colored red in this illustration, is tucked deep inside the human brain. Life Science Databases(LSDB)/Wikimedia, CC BY-SA
In human beings, an area in the back of the midbrain called the periaqueductal gray is the control center that sends messages about pain and cold to the body. This area releases opioids and cannabinoids, brain chemicals also associated with mood and anxiety. The periaqueductal gray sends these chemical signals both to the body, via the descending pathway that suppresses the experience of pain and cold, and via other neurotransmitters to the brain.