Thornton (undisclosed) was spotted heading to the conditioning field during Wednesday's practice, Zack Cox of NESN.com reports.
The Patriots haven't revealed what prompted Thornton's visit to the tent, but Cox notes that "it's been a quiet camp" thus far for the second-year wideout, who hasn't yet logged any catches from quarterback Mac Jones in full-team drills. Thornton still has time to pick up the pace, which is what he'll need to do in order to carve out a steady role in a New England wideout corps that also includes JuJu Smith-Schuster, DeVante Parker and Kendrick Bourne.