Midfielder Alex Gilbey concluded business for MK Dons on deadline day, joining from Wigan Athletic on a three-year deal.
The 22-year-old joins for an undisclosed fee from the DW Stadium having made just 17 appearances for the Latics since joining from Colchester last summer, but spent a lot of the season sidelined with a knee injury.
Neilson told mkdons.com: "He's been a player we've admired for a long time. We've worked hard to get the deal done - he is exactly the type of player we are after.
"He's got great hunger and he'll be top addition for us."
Gilbey joins Aidan Nesbitt and Scott Golbourne as deadline day signings, while Paul Downing departed for Blackburn Rovers on loan.