SAN FRANCISCO (Reuters) -Andrej Karpathy, senior director of artificial intelligence at Tesla Inc who has been on a four-month sabbatical, said on Wednesday he is leaving the company, without giving reasons for his departure.

“It’s been a great pleasure to help Tesla towards its goals over the last 5 years and a difficult decision to part ways,” Karpathy tweeted, adding he does not have concrete plans for what is next.

Tesla CEO Elon Musk responded in a tweet: “Thanks for everything you have done for Tesla! It has been an honor working with you.”

In late March, Karpathy said he was on a four-month sabbatical to “re-sharpen my technical edge.” The sabbatical came at a critical time for the company, as Musk seeks to achieve full self-driving capability and roll out a humanoid robot prototype this year.

Musk said in a podcast interview in January that Karpathy played an important role, but added: “People will give me too much credit and they’ll give Andrej too much credit.”

Kaparthy led the computer vision team of Tesla Autopilot, which is Tesla’s advanced driver assistant technology.

(Reporting by Hyunjoo Jin in San FranciscoEditing by Leslie Adler and Matthew Lewis)