Dolphin brain is a metaphor for the mental connections/ train of thought made by a ND person in between conversation. It can be used to describe the thought process made mentally by a ND person in-between verbal conversation.
Imagine a dolphin jumping out of the water; that's the voiced thoughts/conversation. The dolphin then disappears in the water which is when the unvoiced thoughts happen, and the mental connections between a to z is made.
NT's only see the breach of the water which is just a faction of what is happening beneath the surface which is why confusion happen when a ND goes from talking about mango to orchids.
(Inspired from tweet by @3TrackMind79 on twitter)
Neurodiverse (ND): I love mangoes
Neurotypical (NT): Yeah, me too
ND: I want more orchids
NT: ???
With dolphin brain
ND out loud: I love mangoes
ND in their head: Pineapple is an amazing fruit too
ND in their head: Sponge-Bob lives in a pineapple
ND in their head: He's probably from Hawaii
ND in their head: Uh, there's so many pretty flowers in Hawaii
NT: Yeah, me too
ND out loud: I want more orchids