Final answer:
Visual, auditory, and touch sensory signals are routed through the thalamus and directed to their respective cortical areas, but olfactory signals directly reach the olfactory bulb, bypassing the thalamus.
Step-by-step explanation:
Visual, auditory, and touch signals in humans are processed through the midbrain and the thalamus before being directed to their specific cortical regions for further processing. However, this statement is partly false with respect to olfactory signals. The olfactory signals bypass the thalamus and go directly to the olfactory bulb and further to parts of the olfactory system for processing. The thalamus acts as a crucial relay station where it receives sensory signals from the nervous system and then redirects them to the designated areas of the cortex.
For visual signals, after processing in the thalamus, they continue to the primary visual cortex at the back of the brain and later split into streams that project either to the parietal lobe or the temporal lobe carrying information concerning "where" and "what" about the visual input. In contrast, the olfactory signals have a direct route to the olfactory bulb and are not relayed through the thalamus.