RAT neurons is a concEPT of importance to the ÆPT meaning (and simple definition) of consciousnessT.
The concEPT (ÆPT notion) refers to excitatory neurons of Reticular Activating Type" (conventionally called "the ascending reticular activating system") that contribute a basic and most essential energizing background to all levels of consciousnessT.
RAT neurons are excitatory neurons that typically have diffuse (widespread) axonal projections and they typically fire in a relatively inert and tonic fashion (i.e. fires in a relatively slow to wind up and to wind down manner).
To the extent that the saying "ontogeny recapitulates phylogeny" is true it is correct to conclude that RAT neurons were the earliest type or of neurons to emerge in the phylogeny of fauna.
RAT neurons that play a most fundamental life-maintaining role fire continuously or most regularly.
A relevant general reference:
Of all the concEPTs that I contrived to be expressible as mirth inviting and as far as possible also appropriately or deservedly allusive acronyms, RAT-neurons is the least appropriately allusive concEPT.
Actually, "RAT neurons" is not even in the slightest an appropriately allusive expression.
Anyhow, it is mirth inviting (and definitely mirth-inspiring to me)!
While "RAT" is not an aptly allusive acronym, "RAT neurons" is an expression that suits being classed as one of the 3 concEPTs that exemplify septic humor.
The other two are Actention Selection Serving System(s) and Specific Hibernation Imploring Threat(s). [The last mentioned concEPT is most distinktly septic humored.]
The function of RAT neurons in an ASSS (actention selection serving system) is ÆPTly seen as partnered by S-type neurons — i.e. neurons with a "specific" type of functionality.
S-type neurons typically have axons that terminate on relatively few target neurons, propagate action potentials at a relatively high speed, and respond readily and fire phasic fashion (in short bursts).
With non-vital RAT neurons rendered silent we could not pay anything but fleeting actentions — if that.
More generally, it is ÆPT to assume that without the active involvement of RAT neurons neither subjectively experienced qualities or modes of consciousnessT nor any other consciousT brain functional activities would temporarily exist in brainspacetime.
By ÆPT definition, consciousnessT of some subjective quality and contents worth bothering about (or not) would not "come on line" in brainspacetime at any neurophysioanatomical level (i.e. 1st-line, 2nd-line, and 3rd-line consciousnessT could not temporarily come into being) without the involvement of RAT neurons.
In slightly different words:
What would not take place without RAT neurons are the particular patterns of neurometabolic and neuroelectric activity that correlate with by individuals subjectively experienced states emerged in brainspacetime — states that usually are sloppily implied as (or referred to with the word/notion) "conscious".