Within the depth-psychology corpus, ‘defensive responses’ names a cluster of psychobiological action patterns — ranging from fight, flight, and freeze to feigned death and social engagement — that are understood as evolutionarily conserved survival mechanisms activated in the face of threat. The term operates across at least three registers: the neurobiological, the sensorimotor-clinical, and the psychodynamic. Ogden and the sensorimotor tradition provide the most sustained treatment, arguing that defensive responses are not pathological in themselves but become so when trauma arrests their completion, leaving habitual, inflexible somatic residues that persist long after the original danger has passed. LeDoux’s neuroscientific perspective grounds these responses in defensive survival circuits — particularly amygdala-PAG pathways — emphasizing their subcortical, pre-conscious architecture and the imminence-gradient sequencing of freezing, fleeing, and fighting. Nijenhuis extends the framework into dissociation theory, reading somatoform dissociative symptoms as homologues of animal defensive and recuperative response-sets. The central clinical tension across these positions concerns restoration: whether maladaptive defensive responses require extinction and new learning (LeDoux) or somatic completion and reinstatement of adaptive flexibility (Ogden, Levine). The stakes are high, for it is the persistence of altered defensive responses — not merely cognitive distortions — that sensorimotor approaches identify as the primary engine maintaining post-traumatic symptomatology.