Shea describes 'vehicles' as 'individuable physical particulars that bear contents and whose causal interactions explain behaviour'. In this context, I assume this means groups of neurons or a region of cortex, eg the fusiform face area (FFA) representing faces or MT representing motion.
Given how strict Shea is in defining representation elsewhere, it is surprising how lax he seems to be in ascribing the term 'representation' to areas like the FFA.
Two of the examples covered in these pages are relevant to thinking about how a group of neurons contribute (or not) to perception. Hence (I not sure about this...), Shea's argument would that these are (or are not) vehicles with representational content.