As per JIRA documentation http://www.atlassian.com/software/jira/docs/latest
The following filter will show the issues opned by me (Current User).
repor
if you know the name of the user (lets assume the name is Tom you can do:
Tom
issueFunction in commented("by Tom")
you can also filter it by date of the comment like:
issueFunction in commented("after -1d by Tom")
UPDATE: this requires ScriptRunner being installed in JIRA server (as JBert pointed out)