The NFL is not the only sport figuring out how to deal with head injuries. Major League Baseball might create a seven-day disabled list just for players with concussions as soon as next season, a person familiar with the proposal told The Associated Press.

The new DL would be in addition to the 15- and 60-day lists that already exist for injuries of all sorts, the person told the AP, speaking on condition of anonymity because the proposal is in the preliminary stages.

It's the latest example of the ways in which various leagues are addressing concussions, an injury that has drawn the most attention lately in football -- and an injury that medical experts say they are still in the process of understanding, particularly when it comes to prevention and treatment.

After a series of illegal hits last weekend, the NFL imposed fines of at least $50,000 US on three players and warned that, starting with this week's games, violent conduct will be cause for suspension. Commissioner Roger Goodell sent teams a memo "to emphasize the importance of teaching safe and controlled techniques" related to "contact to the head and neck."

Make no mistake: Concussions can happen on all fields of play, and officials at Major League Baseball, the NHL and NBA are following the developments in the NFL.

There was a two-day summit on hockey concussions at the Mayo Clinic this week, for example. And now comes word that a seven-day DL will be considered this off-season by a new concussion subcommittee that is being formed under baseball's medical advisory committee, according to the person who described the proposal to the AP.

If the subcommittee OKs the idea, it would need to be approved by Commissioner Bud Selig, then the players' union. A change to the disabled list rules would be subject to collective bargaining with the union.

All four of the major U.S. sports have moved closer to each other on concussion policies in recent years.