A creature with blindsight can perceive its surroundings without relying on sight, within a specific radius. Creatures without eyes, such as oozes, and creatures with echolocation or heightened senses, such as bats and true dragons, have this sense.
Without other knowledge of the intellect devourer's anatomy, it would seem this ability is psychic. This is augmented by a second trait:
Detect Sentience. The intellect devourer can sense the presence and location of any creature within 300 feet of it that has an Intelligence of 3 or higher, regardless of interposing barriers, unless the creature is protected by a mind blank spell. (MM 191)
The ‘Devour Intellect’ ability states:
The intellect devourer targets one creature it can see within 10 feet of it that has a brain.
Is it safe to assume that the ‘it can see’ line specifically requires line of sight, or would the two initially quoted traits work in conjunction within ten feet to allow the ‘Devour Intellect’ ability to work through barriers?