Prelude: A reading from the Gospel of Matthew (1 Corinthians 2 12-16):
And he said: Truly I tell you, unless you change and become like little children, you will never enter the kingdom of heaven.

Effects of Zazen

Neuroplasticity and Brain Function:

Zazen, a form of seated meditation emphasizing stillness and present awareness, influences the brain in several measurable ways: Structural Changes (Neuroanatomy):

1. Increased gray matter in regions like the prefrontal cortex (decision-making, self-regulation) and anterior cingulate cortex (attention and emotion regulation).
2. Thickening of the hippocampus, which supports memory and learning.
3. Reduction in amygdala size/activity, a key region for fear and emotional reactivity.
4. Functional Changes:
   1. Enhanced functional connectivity between the prefrontal cortex and limbic system, improving emotional regulation.
   2. Reduced default mode network (DMN) activity. The DMN is linked to self-referential thinking, rumination, and worry. Zazen quiets this mental chatter.
5. Neurotransmitter Shifts:
   1. Increased dopamine, serotonin, and GABA activity during and after practice, all of which are linked to feelings of contentment, calm, and reduced anxiety.
   2. Lower cortisol levels, reflecting reduced stress.
   3. These changes are key markers of neuroplasticity­the brain's ability to reorganize and form new neural connections in response to experience and practice.

Health and Well-Being

Zazen supports overall health through interconnected mind-body mechanisms:

1. Reduced Chronic Stress:
   1. Activates the parasympathetic nervous system, promoting relaxation and recovery (rest-and-digest mode).=
   2. Improves heart rate variability (HRV), a marker of adaptability and resilience.
2. Immune Function:
   1. Mindfulness practices like zazen have been shown to enhance immune response by modulating stress-related suppression.
   2. Lower systemic inflammation (via reduced pro-inflammatory cytokines).
3. Sleep Quality:
   1. Zazen supports deeper, more restorative sleep, likely due to lowered anxiety and improved nervous system balance.
4. Pain Perception:
   1. Regular practice can modulate pain signals in the brain, reducing both the emotional and physical experience of pain (linked to changes in the insula and somatosensory cortex).
5. From Reactivity to Responsiveness: This is a central transformation offered by zazen practice
   1. Zazen develops meta-awareness­the ability to observe thoughts, feelings, and sensations without identifying with them.
   2. This de-centering allows for a pause between stimulus and response­opening the space for intentional action instead of knee-jerk reactions.
6. Improved Emotion Regulation:
   1. The prefrontal cortex helps downregulate the amygdala, letting practitioners remain calm in challenging situations.
   2. This fosters equanimity­a key Zen virtue and natural outgrowth of consistent zazen.
7. Embodied Presence:
   1. Zazen shifts awareness into the felt sense of the body, grounding the practitioner in the present moment rather than lost in future/past narratives.

Summary: Zazen as an Integrative Practice

1. Domain Effect
   1. Brain Structural and functional neuroplasticity; emotion regulation; quieting of mental noise.
   2. Body Improved stress response, immune function, sleep, and pain perception.
2. Behavior Shifts from habitual reactivity to mindful responsiveness.
3. Spirit Cultivation

Closing

1. Zen Quotes:
   1. When you sit, just sit. When you walk, just walk. Above all, don't wobble.
      —Yunmen
   2. Just sitting, with no gaining idea, is the most subtle form of practice.
      — Shunryu Suzuki
   3. The practice of Zen is forgetting the self in the act of uniting with something.
      — Dogen Zenji
   4. Not thinking about anything is Zen. Once you know this, walking, sitting, or lying down—everything you do is Zen.
      — Bodhidharma
   5. When the mind is at peace, the world too is at peace. Nothing real, nothing absent.
      — Layman Pang
   6. To study the Way is to study the self. To study the self is to forget the self.
      — Dogen
   7. Before enlightenment: chop wood, carry water. After enlightenment: chop wood, carry water.
      — Zen proverb
2. Neuroscience Insights
   1. What wires together, fires together—and what you observe non-reactively, begins to change.
      — Hebbian learning + mindfulness
   2. Neuroplasticity is the capacity of the nervous system to be shaped by experience. Zazen is the ultimate shaping experience: quiet, sustained, and embodied.
      
   3. Neuroscientific interpretation of Zen practice:
      1. The brain is shaped by what it repeatedly does. When we practice stillness and awareness, the brain learns to become still and aware.
         — Mindfulness-based neurobiology

Zazen and Christianity
Zen Practice
Zazen: Scenery of Life
Zazen Practice: Ceremony
Monastics' Reflections on Zazen