Meaning
Supreme God Krishna spoke
With all the bodily gates firmly closed {shutting out incursion of all sensory and other influences}, the mind centered within the heart, life force fixed in the cerebrum deep in Yogic concentration, (8:12)
With Me in mind and well established in Aum {the audible icon of} Brahm (God-the-Supreme), the one who departs from his mortal frame ascends to the Highest Station of Divine Existence. (8:13)
Sanskrit
श्रीभगवान् उवाच
ओमित्येकाक्षरं ब्रह्म व्याहरन्मामनुस्मरन् ।
यः प्रयाति त्यजन्देहं स याति परमां गतिम् ॥
Word-by-word
'ओम्' इति एक-अक्षरम् ब्रह्म व्याहरन्, माम् अनु-स्मरन्,
यः प्रयाति त्यजन् देहम्— सः याति परमाम् गतिम्।
Commentary
Please refer to verse 5:13 for additional insight.
This practice pertains to the science of Meditative Yoga, where the mind is consciously withdrawn from the three lower spinal centers and directed toward the heart center. This heart center serves as an intermediate stop on the journey toward accessing the highest spiritual centers located in the brain.