From publisher blurb:
The history of the Grat’tals (as they are known) is not a kind one. The horrors known as Brain Gorgers, the ruthlessly amoral and deeply feared denizens of the deep dark, are well known and loathed for their unrelenting desire to feed on the psychic energy and brains of other sentient beings. These creatures who live collectively in hive-like fashion at the direction of the Great Brain decided that they needed a new type of servant. This is where the history of the Grat’tals begins. Unlike other mixed-race humanoids that result from sexual reproduction, the Grat’tals are humans that as fetuses were subject to Brain Gorger magical and psionical manipulation, forever changing them. The result was a new race, the Grat’tals – of human ancestry but that share some characteristics and powers of the Brain Gorgers.
Within this PDF:
The complete playable race of the Grat'tal, or "Brain-Gorger Spawn"
A Grat'tal advancement feat
Brain-Gorger Spawn background tables