There is a difference between cause and effect relationships and actually being about something. This is not about the imagination, or mental images, or perception. When you see a cat, or the word cat, or hear the word cat, and a sequence of neural activity occurs in your brain, is the meaning of the concept of cat objectively in those neurons and in that pattern sequence? If I were to rip that particular neuron sequence out of your brain, or if I were to rip out your entire brain and freeze it at the moment of firing of that neuron sequence, does that material actually quantify the meaning “cat,” in itself. Is the concept “cat” in the material? Is there a cat in your brain? I would say it’s in your mind, but is it in the material? Substitute “cat” with chiliagon, triangularity, love. Is the material quantifiably carrying those meanings?
Consider language. The written word “cat”, the paper and ink that goes into making that word when handwritten, carries no such meaning in itself. That same pattern could be a pointer to any number of concepts, depending upon the language. It’s meaning is derived by an external mind reading it. The meaning is not quantifiably existing as an imbued part of the paper and ink. Are you saying the neuron sequence that fires does have such meaning intrinsic to it?