Figure 2. Time scales of pain-related behaviors in rodents.

(a) Spontaneous behavior in preclinical models of acute and chronic pain reflective of the sensory-discriminative and affective-motivational dimensions, and pain affect, arise at different timescales. Application of noxious stimuli immediately trigger reflexive behaviors (red), including withdrawal and vocalization, followed by a series of affective-motivational behaviors (blue) aimed at reducing ongoing pain. The ongoing negative affect associated with pain can lead to the emergence of enduring behaviors associated with pain affect (purple), either directly initiated by motivational processes to avoid further pain, such as contextual avoidance and gait alteration; or that arise as a consequence of ongoing negative affect, including anxiety- and depression-like behaviors, that disrupt normal behavior. (b) Our group categorizes pain-related behavior across a number of identifiable and distinct categories following application of an acutely-painful stimulus: paw withdrawal, orienting, licking, acceleration, rearing, and jumping.