I found my ancestor listed in a probate index for McLeod County, Minnesota, USA around the year 1882. His record is in the format "Last Name, First Name, Insanity of", instead of "Last Name, First Name, Estate of", like many of the others. What's the difference between "estate of" and "insanity of"?
It means a case was brought before the court to declare that person insane. Apparently Minnesota probate courts handled insanity cases in addition to estate cases. From the Minnesota Historical Society:
Case Files are the major records created by the probate courts. Case files contain copies of each document filed in a probate action. ...
In an insanity action the case file may contain a petition asking the court to declare an individual insane, medical testimony bearing on the individual’s mental capacity, a determination by the court of the individual’s mental state, the possible commitment to a state hospital or other facility, and the appointment of a guardian for the individual.
Here's an example from Indiana.
Also based on Justin's link from the Minnesota Historical Society:
"Insanity Record Books. Frequently, probate courts kept separate “insanity” books. These books recorded a summary of the mental competency cases that came before the court and frequently included a detailed medical evaluation of the individual whose competency was being questioned. If declared to be not competent to conduct one’s own affairs, an individual may have been committed to a state hospital. These insanity records may assist the researcher in searching further in other records. Insanity records, frequently dated before 1920, are available for a substantial number of counties. Access to certain information may be restricted."
The record for your ancestor, and the record below his, do not have minute book notations as the records for probate cases do. In the remarks field the phrase "No record" is recorded. This most likely means that if you were to obtain file 354 for your ancestor, the information in the file will lead you to one of the "insanity books".