Reduction is a relationship between theories.
Microreduction is a specific subset of reduction that focuses on explaining the macro using the micro (emergent behaviour)
This is the opposite of downward causation
A successful neuroscience would show how to reduce statements about mental properties (qualia) to statements about neural properties (actual neural activity).
An alternate to this is functionalism, wherein a successful neuroscience would show how to reduce statements about mental properties to statements about functional properties (an abstraction to apply this to other potentially non-human conscious minds — e.g. AI)