every object that you've seen is encoded by a neuronal ensemble associated with it

If you try to imagine a pineapple later,the whole ensemble will light up,assembling a complete mental image.Dolphins are encoded by a different neuronal ensemble.In fact, every object that you've seen is encoded by a neuronal ensemble associated with it,
the neurons wired together by that synchronized firing.But this principle doesn't explain the infinite number of objects that we can conjure up in our imaginations without ever seeing them.
The neuronal ensemble for a dolphin balancing a pineapple doesn't exist.So how come you can imagine it anyway?