A good source to answer your question is the book by B. Kolb and I.Q. Whishaw (5th  ed. 2009): Fundamentals of Human Neuropsychology. Briefly, all sensory information from all sensory systems is encoded by action potentials, hence every bundle carries the same kind of signal. Your question: How do action potentials encode the different kinds of sensations, represents a fundamental challenge to neuroscience. Partly this can be explained (1) because different sensations are processed in distinct regions of the cortex; (2) further we learn through experience to distinguish them; (3) and also that each sensory system has a preferential link with a repertoire of actions, reflexes; (e.g. pain will produce withdrawal responses, and fine touch will produce approach responses). However, there is sometimes also a mix of senses called synesthesia which makes neuroscience so attractive for studying.

Dear Kartik, you can find some clues (incomplete of course, nobody currently knows) here: 

https://www.researchgate.net/publication/273452923_Information_processing_in_the_CNS_a_supramolecular_chemistry

Article Information processing in the CNS: a supramolecular chemistry?

Thanks Arturo. I found the Mancuso study referenced in your paper to be intriguing (injecting into the retina of dichromatic squirrel monkeys genes that produced L cones, and observing trichromacy several months later). I wonder if it might be possible to compare spike traffic along the optic nerve for "red" stimuli pre- and post-treatment in such experiments, to see if there are any clear differences in patterns. I also wonder what's happening during those several months before the treatment seems to take effect. Are the genes having an effect further into the brain, beyond the retina? Are the new impulse patterns from the optic nerve influencing plasticity in the LGN, V1 and possibly even V4 and other places?

I'm wondering if an analogous experiment might be possible to take grayscale monochromatic vision and upgrade it to dichromatic vision, and whether that might reveal more insights into the qualia of color.

dear Kartik, I think that the two experiments of Jacobs and Mancuso are truly astonishing and demonstrate that the qualia depend on the receptors. It is difficult to answer to your questions, but there is another interesting data: It has been demonstrated, during the fetal development, that the nerves find their sterotypic pattern from the olfactive receptor to the corresponding sensory cortex. It further corroborates the idea that the receptors are wired together with the nervous pathways and the cortex, in a genetic-constrained way.

For further details, you may look at my synopsis entitled: Brain theories together.

...not to mention the role of multisensory integration... According to some scientists, all the senses are melted together from the very first passage in the primary sensitive cortex... Indeed, the senses do not exist in isolation one each other...

further details once again in "brain theories together", the last chapter...

Your brain theories paper is over my head :-)

It's difficult for me to see how "qualia depend on the receptors" as a strongly worded statement. How can that explain qualia during dreams, where qualia is present in the absence of corresponding signals from the receptors, or phantom limb pain, where the corresponding receptors themselves are absent?

two basic states of the brain, with low and high energy...

see my " spontaneous and evoked activity", wich puts together a lot of paper about our sensations/perceptions...

of course, it's just a thory... To say the truth, despite my 500 references, we DID NOT UNDERSTAND ANYTHING ABOUT BRAIN FUNCTION!