i am trying to to do short-term memory assessment in C.elegans for my study. I follow the protocol from this paper
http://www.jove.com/video/2490/c-elegans-positive-butanone-learning-short-term-long-term-associative.
But unfortunately the naive chemotaxis for my wild type worms is very high (~0.65) instead of the reported (0.23). I mailed the author of the paper and she says it is due to stress to the worms. I am making sure i handle the worms very carefully. But it is not helping me. Has anyone here worked on this before? it will be helpful if someone can guide me through this protocol.