A picture was posted on the 29-year-old's Instagram account on Thursday morning, showing Mr Prime awake in a hospital bed with tubes attached to his head and most of his hair shaved off.

A spokeswoman for the hospital said Mr Prime remained in a serious but stable condition on Thursday afternoon.

The positive signs come more than two weeks after police warned the results of a brain activity scan "may not be positive" and grievous bodily harm charges could be upgraded.

It is alleged Mr Prime was bashed on the side of the M1 at Yatala on February 24, leaving him fighting for life in hospital after suffering a suspected fractured skull and broken leg.

Detective Inspector Mark Thompson said the incident began when the van and Mr Prime's car came close to colliding on the M1 around Coomera.

A "cat and mouse game" then began, with the two vehicles ducking and weaving through traffic in wet conditions on the motorway before they both finally pulled over and the alleged assault took place.

Ryan Hallifax, Jonathan Lawrence and Jordan Baklas have since faced court charged with grievous bodily harm. Lawrence remains in custody while Hallifax and Baklas were released on bail.

All three men were scheduled to have their matters mentioned in the Beenleigh Magistrates Court on May 2.

During the month prior to the alleged attack, Mr Prime had stepped up to fill his late step-father's shoes as one of the main breadwinners in his family to support his mother, brother and sister.