In terms of, or in relation to, the subcortex.(adverb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "subcortically" in a sentence
"Parallel to visual processing, auditory processing is also done subcortically and cortically replace 'visual cortex' with 'auditory cortex', replace 'superiour colliculus' with 'inferior colliculus'."