Which sensory functions are not affected by the brain stem?

The sensory functions that are not affected by the brain stem are vision and smell. This is because these particular sensory modalities primarily involve different pathways and brain structures.

Vision is primarily processed in the occipital lobe of the brain, where the visual cortex is located, rather than in the brain stem. The occipital lobe is responsible for interpreting visual information received from the eyes, thus making it largely independent of the functions of the brain stem.

Smell, or olfaction, is processed through the olfactory bulbs and the olfactory cortex. The olfactory pathway bypasses the brain stem and goes directly to the limbic system and other regions of the cerebral cortex, meaning it doesn't rely on the brain stem for processing like some other senses do.

In contrast, the other options relate to functions that are indeed influenced by the brain stem. For instance, taste and touch are processed through cranial nerves and pathways that involve the brain stem. Similarly, hearing and balance are governed by the vestibulocochlear nerve and other structures that have pathways through the brain stem. Pain and temperature sensations are also processed through the spinal cord and brain stem pathways before being relayed to the thalamus and cortex.