The "Brain" in question houses the FM tuner, the changer controls, and a video switching matrix. Maybe some DSP electronics. It's a similar unit to my Alpine IVA-C800 I'm trying to sell. You can connect a carputer though it, but it will be NTSC video. What that means is that it will look much akin to a computer being run to a TV. Text will be hard to read and sharper resolutions than 640-480 will be impractical. However you do have the convience of having a hidden monitor.
It's your call.