Attack repertoires in outbred male CD1-mice are associated with nucleus accumbens neuroligin-2

Aggressive behavior presents for different reasons, and two important clinical presentations include appetitive (sought after) and reactive (fight or flight) aggression. Understanding how these phenotypes differ in their behavioral and neural signatures is essential for identifying mechanisms at the intersection of neuropsychiatric disease and maladaptive aggression. Using an operant model in outbred male CD-1 mice, we combined explainable machine learning and forebrain Fos mapping to compare contingent (appetitive) and non-contingent (reactive) aggression. We find that, although behavioral repertoires are notably similar across contingency contexts, neural activity and nucleus accumbens neuroligin-2 expression distinguish aggression severity and phenotype. These findings reveal that molecular features can diverge from behavior, providing new insight into the neurobiology of contingent and non-contingent aggression.