Resonance of human brain under head acceleration

Area of Science:

• Biomechanics
• Neuroscience
• Medical Imaging

Background:

• Severe head trauma is addressed by safety standards.
• Mild head trauma from repetitive impacts poses risks for chronic brain changes.
• Understanding the brain's physical response to mild impacts is crucial.

Purpose of the Study:

• To develop the first dynamic skull-brain model using in vivo MRI data.
• To investigate the brain's physical sensitivities to mild head impacts.
• To explore the mechanisms behind repetitive mild traumatic brain injury.

Main Methods:

• Developed a dynamic skull-brain model based on in vivo MRI data.
• Characterized brain motion as a rigid-body with constrained kinematics.
• Approximated skull-brain dynamics as an under-damped system with resonance.

Main Results:

• Skull-brain dynamics exhibit a low-frequency resonance around 15 Hz.
• Head motions in various activities, including sports, primarily occur below 20 Hz.
• Typical head impacts may approach the brain's mechanical resonance, amplifying skull-brain motion.

Conclusions:

• Repetitive head exposures may drive the brain near its resonance frequency.
• Amplified relative motion between the brain and skull could cause mild traumatic brain injury.
• This mechanism may explain chronic brain changes from activities with repetitive head oscillations.