Introduction

In the lab, we try to understand the role of sleep in many physiological functions, one of them being memory consolidation, using Drosophila (the fruit fly). Sleep is required for memory consolidation in some contexts but not others. To understand the necessity of sleep, we deprive flies of sleep in the post-learning consolidation window (6 hrs. in the case of flies in most of our paradigms). Flies are most readily deprived of sleep by mechanical means. They are put on a vortexer and pulsed at regular intervals(for 2 secs randomly within every 20 secs). 

One way of controlling the vortexer is using proprietary hardware from Trikinetics Inc. which manufactures other sleep/activity recording instruments for Drosophila. The problems of the proprietary system are:

  • Cost: It requires two components( a LC4 light controller  ~$800 and a power supply ~$400) : For the astute, it is recommended to have a separate power supply(PSU) for the vortexer and the monitors as the pulses can only be as short as the reading interval, which is 1min for sleep/activity recording. So you cannot have pulses every 20s with a 1 min reading interval. You can have a single PSU reading every 20s but this leads to bulky files and if many monitors are connected(>10) then the upload delay becomes an issue.
  • Requires a dedicated computer connected to the setup.

The Arduino based system described here costs much much less and does not need to be connected to the computer once the initial user inputs are given over serial. 

The device connects to the wall outlet and the vortexer connects to the device through the other socket. The relay inside switches the live(hot wire). The Arduino switches the relay for 2s placed randomly within every 20s for a user defined duration of time. Once the user input is given, the connection to the computer can be disconnected.

The sockets can be customized based on requirements in different geographical locations.

Circuit

Operation:

  1. Connect the device to the wall socket through the socket 1 in the figure. 
  2. Connect the vortexer to the device through socket two.
  3. Power the Arduino inside through the barrel jack (9V-12V)
  4. Connect the Arduino to a laptop/PC 
  5. Open Arduino IDE and then Tools>Serial Monitor (make sure the correct COM port is selected)
  6. Input the duration.
  7. Disconnect from the PC but keep the Arduino powered on through the barrel jack
  8. Default Mode: If the device is not connected to a  computer, it will wait for a time after switching on (2mins) and then go the default mode which is what we use in the lab most regularly(a duration of 6hrs)

References:

Beckwith EJ, French AS. Sleep in Drosophila and its context. Frontiers in physiology. 2019 Sep 11;10:1167.

Chouhan NS, Griffith LC, Haynes P, Sehgal A. Availability of food determines the need for sleep in memory consolidation. Nature. 2021 Jan 28;589(7843):582-5. https://doi.org/10.1038/s41586-020-2997-y