I agree with memory-based. Has the concept of memory-based been developed into any kind of explanation? The qualia connecting everything?
Non-consciousness (as in being dead) is the absence of all modes of manifestation: visual, auditory, olfactory, tactile, gustatory, interoception, etc. Which accordingly also means lack of the world presenting itself as representations, or no evidence of existence.
Flip that meaning of non-consciousness around, and you then have a basic definition of elemental experience: The presentation or manifestation of anything, the feeling of anything.
But minus identification and understanding of what is there, which is dependent upon information storage and retrieval systems (the memory that cognition requires, whether made possible by a biological or a technological substrate).
Qualia are just an attempt to contend that our broad manifestations/feelings are composed of distinct properties which "show" themselves. Crudely similar to a television image being composed of pixels or writing being composed of letters, or a building constituted of bricks.
For instance, if an image of either perception or thought was constituted of colors (including the grayscale spectrum between black and white), then those would be the qualia arguably making the visual manifestations possible. (When restricted solely to appearances rather than underlying neural or physical causes.)
Traditionally, the term "consciousness" implied both experience and knowing (intellectual activity). But today philosophers seem to toss "consciousness" around as narrowly focusing on what the
hard problem of consciousness deals with (i.e., experience, the qualitative presentations). Which can create confusion, because the hard problem doesn't concern understanding and identifying what is exhibited.
Over-simplistically, the hard problem concerns how presentations arise from "stuff" (neural tissue, particles, fields, etc) that is dogmatically taken to lack the ability to manifest as anything.
That mystery is why a theory like
Russellian monsim can contend that manifestation is how matter exists internally to itself -- how it exists independent of technical description (physics nomenclature). Those internal states are the case prior to matter's organization as a mind (the brain), and thus Russellian monism doesn't actually concern psychological attributes existing everywhere (mental affairs).
As a result, in the context of Russellian monism rather than conventional physicalism, death or non-consciousness would not be the absence of everything. Primitive, rudimentary events might arguably still be presenting themselves. But there is no intelligence available to verify that they are there and to cognitively apprehend them (know and learn).