I'm not sure what's behind the Brain Training DS boom. I don't believe it's the Wii interation that did it though. I'm going to take a guess than the DS spent another week over 200k, and that the Wii slipped just under 100k.
Just under 100k sounds a lot knowing that Paper Mario outsold Wii Sport. I mean Wii sport usually have an attachment ratio around 60%
Buy it and pray to the gods of Sigs: Naznatips!