Best sources I have found for asylum records,the local newspaper, and the county probate office, during this time the local newspaper used to print articles about people being committed and why. Check with the county probate office first, to get a date.
Wisconsin has a "Restriction" forever, on these records. I am going through this to find more detail on the Oshkosh Northern Hospital, and the UWSP archivist, check with the state of Wisconsin, NO ACCESS. But they do have the records. there is a book written called "Annies Ghost" written by Steve Luxumberg, who went through the asylum process to gain access to his Aunts records, in 2006. Good background for Wisconsin search as well.