A Subset of Serotonergic Neurons Evokes Hunger in Adult Drosophila.
Hunger is a complex motivational state that drives multiple behaviors. The sensation of hunger is caused by an imbalance between energy intake and expenditure. One immediate response to hunger is increased food consumption. Hunger also modulates behaviors related to food seeking such as increased locomotion and enhanced sensory sensitivity in both insects and vertebrates. In addition, hunger can promote the expression of food-associated memory. Although progress is being made, how hunger is represented in the brain and how it coordinates these behavioral responses is not fully understood in any system. Here, we use Drosophila melanogaster to identify neurons encoding hunger. We found a small group of neurons that, when activated, induced a fed fly to eat as though it were starved, suggesting that these neurons are downstream of the metabolic regulation of hunger. Artificially activating these neurons also promotes appetitive memory performance in sated flies, indicating that these neurons are not simply feeding command neurons but likely play a more general role in encoding hunger. We determined that the neurons relevant for the feeding effect are serotonergic and project broadly within the brain, suggesting a possible mechanism for how various responses to hunger are coordinated. These findings extend our understanding of the neural circuitry that drives feeding and enable future exploration of how state influences neural activity within this circuit.
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA. Electronic address: stephanie.d.albin@gmail.com.
Stephanie D
SD
Albin
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
Karla R
KR
Kaun
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
Jon-Michael
JM
Knapp
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
Phuong
P
Chung
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
Ulrike
U
Heberlein
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA. Electronic address: jhsimpson@lifesci.ucsb.edu.
Julie H
JH
Simpson
D000818:Animals; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000502:physiology*; D005247:Feeding Behavior; D005260:Female; D005508:Food Deprivation; D006815:Hunger; D007473:Ion Channels; D008297:Male; D008568:Memory; D009042:Motivation; D059326:Serotonergic Neurons / Q000502:physiology; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels / Q000378:metabolism
D029721:Drosophila Proteins; D007473:Ion Channels; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels; C475684:TrpA1 protein, Drosophila