The thalamus the thalamus is a "bridge" that relays nerve impulses between the cerebrum and cerebellum via the middle cerebellar peduncles is a bundle of about twelve nuclei in which every sense except smell has a synapse; it is the "gateway" to the cerebral cortex is the region in which complex visual stimuli are distinguished and interpreted contains the nuclei of cranial nerves v-vii is the structure that connects the right and left cerebral hemispheres

I think the thalamus is the gateway to the cerebral cortex. Thalamus is a small structure within the brain located just above the brain stem between the cerebral cortex and the mid brain and has extensive nerve connections to both. Its main function is to relay motor and sensory signals to the cerebral cortex. A sensory impulse travels from the body surface towards the thalamus, which receives it as a sensation, which is then passed onto the cerebral cortex for interpretation as touch, pain or temperature.

The direction a chemical reaction occurs is represented by an arrow