The portion of the diencephalon that acts as a relay station for sensory impulses traveling upward to the sensory cortex is the thalamus. The thalamus is a small symmetrical structure within the vertebrate brain, located between the cerebral cortex and the midbrain. The primary function of the thalamus is to relay motor and sensory impulses to the cerebral cortex and it also work by regulating sleep, alertness and consciousness.