Revealed: Why scientists want the brains of All Blacks when they die

As a junior All Black in the 1970s and '80s, JJ Williams was knocked out again and again.

On Friday, New Zealand's Brain Bank announced it wanted donations from rugby players, boxers and other contact sports people to see how knocks to the head affected their health.

Williams has agreed to donate his brain and urges others to jump on board to help future generations.

Shedding light on the matter was Sir Richard Hall from the Neurological Foundation, who spoke to The Project.

Watch the video.