title: Feeding Experimentation Device (FED): A flexible open-source device for measuring feeding behavior.
abstract: Measuring food intake in rodents is a conceptually simple yet labor-intensive and temporally-imprecise task. Most commonly, food is weighed manually, with an interval of hours or days between measurements. Commercial feeding monitors are excellent, but are costly and require specialized caging and equipment.
  
  
  
  We have developed the Feeding Experimentation Device (FED): a low-cost, open-source, home cage-compatible feeding system. FED utilizes an Arduino microcontroller and open-source software and hardware. FED dispenses a single food pellet into a food well where it is monitored by an infrared beam. When the mouse removes the pellet, FED logs the timestamp to a secure digital (SD) card and dispenses a new pellet into the well. Post-hoc analyses of pellet retrieval timestamps reveal high-resolution details about feeding behavior.
  
  
  
  FED is capable of accurately measuring food intake, identifying discrete trends during light and dark-cycle feeding. Additionally, we show the utility of FED for measuring increases in feeding resulting from optogenetic stimulation of agouti-related peptide neurons in the arcuate nucleus of the hypothalamus.
  
  
  
  With a cost of ∼$350 per device, FED is >10× cheaper than commercially available feeding systems. FED is also self-contained, battery powered, and designed to be placed in standard colony rack cages, allowing for monitoring of true home cage feeding behavior. Moreover, FED is highly adaptable and can be synchronized with emerging techniques in neuroscience, such as optogenetics, as we demonstrate here.
  
  
  
  FED allows for accurate, precise monitoring of feeding behavior in a home cage setting.
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 10-CRC, Room 5-5932, Bethesda, MD 20892, USA. Electronic address: katrina.nguyen@nih.gov.
authors.forename: Katrina P
authors.initials: KP
authors.lastname: Nguyen
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 10-CRC, Room 5-5932, Bethesda, MD 20892, USA. Electronic address: timothy.oneal@nih.gov.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: O'Neal
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 10-CRC, Room 5-5932, Bethesda, MD 20892, USA. Electronic address: obolonduro@gmail.com.
authors.forename: Olurotimi A
authors.initials: OA
authors.lastname: Bolonduro
authors.affiliation: Logical Elegance, San Jose, CA 95130, USA. Electronic address: elecia@logicalelegance.com.
authors.forename: Elecia
authors.initials: E
authors.lastname: White
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 10-CRC, Room 5-5932, Bethesda, MD 20892, USA. Electronic address: alexxai.kravitz@nih.gov.
authors.forename: Alexxai V
authors.initials: AV
authors.lastname: Kravitz
mesh_terms: D000821:Animal Feed; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology; D057205:Automation, Laboratory / Q000191:economics / Q000295:instrumentation* / Q000379:methods*; D017076:Computer-Aided Design; D004435:Eating / Q000502:physiology; D011211:Electric Power Supplies; D004867:Equipment Design; D005247:Feeding Behavior / Q000502:physiology; D006799:Housing, Animal; D008297:Male; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009474:Neurons / Q000502:physiology; D062308:Optogenetics; D017440:Photoperiod; D066330:Printing, Three-Dimensional; D012984:Software; D013997:Time Factors
keywords: Arduino; Feeding behavior; Food intake; Open-source