Still outside. It's our thoughts about them, models, and concepts that are in the brain.
Plus, even if it was true, this wasn't the parent's point (that things exist in the brain while we're reasoning about them). His point (also wrong) was that different architectures must exist as structures in the brain (not as concepts we think and memories etc., but as parts of brains matter organization and wiring) for us to be able to reason about it.
