An operational definition is___

the articulation of operationalization used in defining the terms of a process needed to determine the existence of an item or phenomenon and its properties such as duration, quantity, extension in space, chemical composition, etc

Explanation:

there are treatment options for depression (mdd) that may work for you. one way of treating depression may be to affect the levels of certain chemicals that brain cells use to communicate, called neurotransmitters. scientists believe that certain neurotransmitters may be out of balance in depression.

although the exact way depression medications shown to ease overall depression symptoms in some people work is unknown, scientists think that some medications work by affecting the levels of a neurotransmitter called serotonin in the brain. other treatments work by affecting the levels of other neurotransmitters like norepinephrine or dopamine.