Misty Mayer, works as the receptionist in a

private hospital. She is known to be a friendly, well-balanced and optimistic

person with diverse hobbies and good interpersonal relations. However, since a

month ago Misty has succumbed to severe depression, without any change in her

work and life circumstances. The psychiatrist prescribes an antidepressant to

better regulate her mood and her sleeping patterns. A deficit in which

neurotransmitter may be the cause of Misty’s depression?