Blindsight by Peter watts.

Now some half-derelict space probe, sparking fitfully past Neptune’s orbit, hears a whisper from the edge of the solar system: a faint signal sweeping the cosmos like a lighthouse beam. Whatever’s out there isn’t talking to us. It’s talking to some distant star, perhaps. Or perhaps to something closer, something en route.

So who do you send to force introductions on an intelligence with motives unknown, maybe unknowable? Who do you send to meet the alien when the alien doesn’t want to meet?

You send a linguist with multiple personalities, her brain surgically partitioned into separate, sentient processing cores. You send a biologist so radically interfaced with machinery that he sees X-rays and tastes ultrasound, so compromised by grafts and splices he no longer feels his own flesh. You send a pacifist warrior in the faint hope she won’t be needed, and a fainter hope she’ll do any good if she is needed. You send a monster to command them all, an extinct hominid predator once called “vampire,” recalled from the grave with the voodoo of recombinant genetics and the blood of sociopaths. And you send a synthesist – an informational topologist with half his mind gone – as an interface between here and there, a conduit through which the Dead Center might hope to understand the Bleeding Edge.

Blindsight is the ability of people who are cortically blind to respond to visual stimuli that they do not consciously see due to lesions in the primary visual cortex, also known as the striate cortex or Brodmann Area 17. --Wikipedia