An oddity

I’ve come across a note I made when reading Eimear McBride’s Strange hotel (2021). At one point the drifting unnamed woman who is the central character is described as having a specific recollection “screwed into the vegetal bolts of her brain”. Please, how can anything be screwed into bolts? If the author overlooked this in haste, perhaps excusable, we’ve all done that: but what are editors for?