Yogic dhyana originates in back brain, based on past experience.
Prashant S. Iyengar
Pranayama — Source of Dhyana (Meditation)
Yogic dhyana commences with pranayama. Pranayama to samadhi is a single continuous process.
Prana kriya touches 350 nadis (channels) within.
Pranayama—Desha Kala Samkhya Regulation
Pranayama regulates breath by desha (region), kala (duration), samkhya (cycles).
Pranayama Is Driven, Not Done
Breath driven to touch pranic manas (mind), loosen grip of mental vasanas (tendencies).