You do not want to capitalize guide as it is not a specific type of guide or his name. It is a general noun. The rest of the words you only capitalize if they are at the beginning of a sentence. They is at the beginning of the sentence so capitalize they.
Explanation: A proper noun is the name of a specific person, place, or thing. Proper nouns always begin with a capital letter. Examples: boy, state, month.
Explanation: This is because the hippocampus is located in the forebrain section called the telencephalon and the hippocampus is responsible for the formation of long-term and spatial memories.
