Here's some information about AHR:
Supplemental Active Head Restraints (AHR)
These head restraints are passive, deployable components,
and vehicles with this equipment cannot be readily
identified by any markings, only through visual inspection
of the head restraint. The head restraint will be split
in two halves, with the front half being soft foam and
trim, the back half being decorative plastic.
How The Active Head Restraints (AHR) Work
The Occupant Restraint Controller (ORC) determines
whether the severity, or type of rear impact will require
the Active Head Restraints (AHR) to deploy. If a rear
impact requires deployment, both the driver and front
passenger seat AHRs will be deployed.
When AHRs deploy during a rear impact, the front half
of the head restraint extends forward to minimize the gap
between the back of the occupant’s head and the AHR.
This system is designed to help prevent or reduce the
extent of injuries to the driver and front passenger in
certain types of rear impacts.
NOTE: The Active Head Restraints (AHR) may or may
not deploy in the event of a front or side impact.
However if during a front impact, a secondary rear
impact occurs, the AHR may deploy based on the severity
and type of the impact.
Additional information can be found in the Owner Manual available here