Distinct Traces for Appetitive versus Aversive Olfactory Memories in DPM Neurons of Drosophila

• Published in: Current biology 2012-07, Vol.22 (13), p.1247-1252
• Main Authors: Cervantes-Sandoval, Isaac, Davis, Ronald L.
• Format: Article
• Language: English
• Subjects: Animals; Animals, Genetically Modified; Appetite Regulation; brain; Brain - cytology; Brain - physiology; Calcium - metabolism; Conditioning (Psychology); Cyclic AMP - metabolism; Drosophila; Drosophila melanogaster - physiology; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; memory; Memory - physiology; neurons; Neurons - physiology; Neuropeptides - genetics; Neuropeptides - metabolism; Odorants; odors; Olfactory Pathways - physiology; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Sucrose; Synaptic Transmission
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2012.05.009

The global logic used by the brain for differentially encoding positive and negative experiences remains unknown along with how such experiences are represented by collections of memory traces [1] at the cellular level. Here we contrast the cellular memory traces that form in the dorsal paired medial (DPM) neurons of Drosophila [2] after conditioning flies with odors associated with aversive or appetitive unconditioned stimuli (US) [3, 4]. Our results show that the appetitive DPM neuron trace is distinguished from the aversive in three fundamental ways: (1) The DPM neurons do not respond to an appetitive US of sucrose by itself, in contrast to their robust response to an aversive US. (2) The appetitive trace persists for twice as long as the aversive trace. (3) The appetitive trace is expressed in both neurite branches of the neuron, rather than being confined to a single branch like the aversive trace. In addition, we demonstrate that training flies with nonnutritive sugars that elicit a behavioral memory that decays within 24 hr [5, 6] generates, like aversive conditioning, a short-lived and branch-restricted memory trace. These results indicate that the persistence and breadth of the DPM neuron memory trace influences the duration of behavioral memory. ► A memory trace forms in both branches of DPM neurons after appetitive conditioning ► A memory trace forms in only one branch of DPM neurons after aversive conditioning ► The appetitive memory trace persists twice as long as the aversive trace ► More persistent appetitive trace is critical for nondecaying behavioral memory