Yogic dhyana originates in back brain, based on past experience.
japa
Pranayama — Vehicle of Prana Shakti
When body, mind, & breath benefit, we benefit from pranayama.
Dhyana Serves Embodiment
Classical Yoga serves the three “spiritual” dimensions of embodiment—adhibhautika (five elements within), adhidaivika (inner celestial forces), and adhyatmika (Self).
Japa Benefits Subtle Body
Japa nourishes and purifies the subtle body just as food and medicine nourish the gross body. Nama japa includes chanting OM, and requires no prerequisite.
Five Types of Dhyana
Dhyana pacifies the causes of suffering, purifies chitta, & normalizes a disorganized mind. Sages used meditation & dhyana to attain jnana (spiritual knowledge).