Watford have announced the signing of Italy international Marco Motta, subject to international clearance.
Mark Noble has signed a new deal with West Ham which will keep him at the club until the summer of 2020.
The 22-year-old, a former France Under-21 international, was given the all clear to switch to the French club following an approach before the transfer deadline.
Gueye, who moved to Goodison Park from Strasbourg in June 2010, has made just six appearances for the Toffees this season.
Brest are currently only four points above the Ligue 1 relegation zone.