What term describes a brief record of facts or topics used as an aid to memory?

The term that describes a brief record of facts or topics used as an aid to memory is "note." Notes are typically concise and focus on capturing essential information in a way that helps the individual recall details later. They are often used in educational settings to summarize key points from lectures, readings, or discussions, making it easier to study and remember the material.

In contrast, a comment refers to an expression of opinion or reaction, which does not necessarily function as a memory aid. An index is a systematic list of topics included in a book or document, generally organized in alphabetical order but is broader than a brief record. A list is simply a series of items written down but does not carry the same connotation of being tailored to help with memory retention as notes do. Thus, "note" is the most fitting term among the choices for describing a tool specifically designed to aid memory.