Ovid is a platform with a number of databases and with subject strengths in health and medicine, nursing, psychology, and earth sciences. It includes MEDLINE, a number of EBM Reviews databases, PsycINFO, and CAB Abstracts.
In Ovid, you can change the database(s) you are searching by clicking on Change in the Search panel.
Ovid databases should default to the Advanced Search screen. Here, the default is to a phrase search. If you wish to search for the specific phrase brain injury, you can type in brain injury (without quotation marks). If you wish to search for the keyword brain and the keyword injury, you should type in brain AND injury.
In Basic Search you can enter your topic in pretty much whatever words you like, and your results will be tagged and sorted by relevance.
Ovid always displays your previous searches in a table above the search box. If you can't see all of your previous searches, click on the Expand link at the top right of this table.