A distinct neural ensemble to integrate contradictory information and form long-term memory in <i>Drosophila</i>

Interpreting contradictory information to favor survival is a crucial challenge for the brain. Although the parallel competing mode and memory convergence mode are proposed to resolve how contradictory information is processed in the brain, no detailed regulatory mechanism is proposed, and the formation of a memory trace to support either one is also lacking. The current study demonstrated that competition and integration existed after contradictory training, i.e., aversive/appetitive, followed by appetitive/aversive conditioning. Although information from aversive and appetitive training competes within 3 hours after conditioning, approach behavior gradually prevails, and avoidance behavior decays. The training type-dependent neural network consolidating and storing contradictory memory differs from the circuit for sole aversive and reward memory. A contradictory memory trace formation in the brain, indicating aversive and reward memories, is integrated into one approach memory. Our study reconciles the current two modes and proposes a competition-integration mode for contradictory memory expression.