Dreams are some nerve impulses released by the brain when processing information and consolidating long-term memory (such as dust raised during cleaning or information flow being processed), which are interpreted by the conscious brain as bizarre vision and hearing. In order to understand the formation and generation of dreams, we must understand the working mode of the brain. From the perspective of brain structure, primary functions are realized by specific brain regions. To explain the sensory problems in dreams, we must start from the perspective of cooperation between brain regions.
There are direct fiber bundles related to vision, hearing, somatosensory movement and face processing in hippocampus. However, the olfactory bulb is connected with the hippocampus fiber, and the heel is active and small, and the area is independent, which is doubtful. Therefore, in our sleep, we will have visual, auditory, tactile and facial information from memory, as well as limb/muscle movements, but there is no direct olfactory information. You may say that something is fragrant/smelly in your dream, but this is no longer the category of direct olfactory information.
Pain does not directly correspond to the region, but is more like advanced cognition such as emotion, which needs to be processed by the cerebral cortex, so people's perception of pain is very slow (relative to hearing and vision), so our pain feeling in dreams is more like thinking than feeling.