Figure 4.

Frames of reference in animal models of concussion, traumatic brain injury, and chronic traumatic encephalopathy. Different frames of reference, illustrated here by head injury context (“input”) and head injury consequences (“output”), establish different criteria for evaluating model biofidelity, validity, and utility. Frames of reference and model validity, biofidelity, and utility are defined by reference to experimental purpose. See text for details. Brain pathology images adapted from Ref. (106).