Head injury rules Ireland prop O'Toole out of upcoming Argentina Test
He suffered the knock moments after coming on to replace Finlay Bealham in Friday's match in Dublin.
Tighthead prop Tadhg Furlong trained on Monday after missing his side's first November international with a hamstring strain.
Ireland's head of athletic performance Aled Walters is confident there will be a positive response following the end of the team's 19-game winning run at home.
"I think it's natural that there's a bit of hurt but there's no anger," Walters, who recently left England to join Andy Farrell's staff, told reporters on Monday.
"It's a group that doesn't seem to be used to losing.
"It's probably an environment that's been immediately down in the changing room (post-match) but as I understand, Faz (Farrell) is pretty good at getting things back on track pretty quickly, and the coaches and leaders the same. They were pretty good today.
"It's such a good group to reflect and be honest. Home truths were definitely the case and no one has shied away from it."
