Peterborough United central defender Brisley and Queens Park Rangers right-back Furlong will now stay at Sixfields until at least November 14.
It is great news for Cobblers boss Chris Wilder as the pair have been excellent since joining the club ahead of the Oxford United match on September 12.
Town have enjoyed a five-match unbeaten run in the league with Brisley and Furlong in the team, and Wilder and Town fans will be hoping that form continues.
“You always hope your loan signings are successful and, touch wood, they have been so far,” said Wilder. “Hopefully they’ll continue to be.”
The pair are set to line up in the Cobblers defence in Saturday’s Sky Bet League Two clash with Harlepool United at Sixfields (3pm).
They will also be available for league two games against Cambridge United, Carlisle United, Stevenage, Newport County and Mansfield Town.