Movement monitoring system assembly:
* Start by arranging the 6 piezo-electric disks to fit into the shape of the Plexiglas plate. Then, solder the outer rings of the piezo-electric disks to each other as shown in Figure 2.
* Place copper foil strips, cut into pieces, to connect between the inner parts of the piezo-electric disks (the silver color inner part if the disks). Place the strips with the isolated part facing down (to prevent shortcuts between the inner and outer parts of the piezo-electric disks). Solder all edges of the strips to the inner part of the piezo-electric disks. Solder two more wires to one of the piezo-electric disks aimed to be closer to the 90 degrees' corner (Figure 3). Those will be used for connecting the piezo-electric disks to the wire leading the signal to the DAQ system.
* Position the soldered piezo-electric array in between the laminating films (Figure 4) and blow it gently with hot air (~100-150℃) using the hot air gun in order to laminate them together. Then, using the scalpel, cut the laminated film around the piezo-electric array in a triangulated shape (Figure 5).
* Tape the edges of the assembled array to the edges of the Plexiglas plate using the packaging tape. Leave the hole in the plate uncovered (Figure 6).
* Insert the main leading wire into the pipette tube (Figure 7). Then, expose the leading ends using a wire striper. Place shrink tubes on the wires. Solder the leads on the back end of the pipette to the piezo-electric array leads. Solder the leads on the other side to two pins of the USB female connector (Figure 7). Heat the shrink tubes to create electrical isolation.
* Cut a slit of about 2 mm wide and 5 mm height at the flat end of the pipette to enable the leading wires from the piezo-electric array to fit into the slit. Then insert the flat end of the pipette to the hole in the Plexiglas plate. Tape the pipette to the Plexiglas plate to protect the wires (Figure 8).
* Solder a two leads wire (as long as needed) to the corresponding pins on the USB male connector. The leads on the other side should be connected to the recording system.
* The assembly is done!!! Take a break :)
We have used a Flea3 - USB3 video camera (Catalog number FL3-U3-13Y3M-C, FLIR (formerly PointGrey)) for recording the subjects' activity. Video recordings were done using FlyCapture Ver. 22.214.171.124 (FLIR Systems, Wilsonville, OR, USA) with the trigger mode enabled. In addition, the camera was configured to send TTL pulses for every frame acquired. A PGIO cable from the camera was connected to one of the digital inputs of Intan RHD data acquisition board.
The movement monitoring device was connected to one of the analog inputs of Intan RHD data acquisition board through the electrical circuit described in Figure 9 (important for protecting the board from high voltages that may be generated by the piezo-electric disks).
We first started the recordings of the data acquisition system and then triggered the camera. Therefore, when recording, we recorded both the timestamps of each frame acquired (TTL pulses from the camera), as well as the piezo-electric signals.
* Comments: for more information about the camera configuration, please refer to the user manual supplied by Flir.
For recordings, we have used an Intan RHD data acquisition board (sampling rate of 20 kHz) and extracted the data using codes supplied by Intan Technologies (See Intan Technologies website for more details). All extracted signals were than analyzed using a custom-made codes written in MATLAB (2017a-2020a).
See example of a single recording in Figure 9.
Supplementary code files
The purpose of the codes supplied with the current protocol is to help extracting large movement time points from down sampled signals (2000Hz) and to synchronize it with the video recordings analyzed using the "TrackRodent" software. The codes cannot run as is and requires modifications that includes data importation and sampling rate adjustments.
The attached files are:
* A single .m file (matlab) with code for extracting large movement time points – AnalyzePiezoData_LargeMovements_10_5_2021.m.
* A folder containing three .m files (matlab) with codes for analyzing the synchronized subject investigation towards the stimulus while large movements occurs. The main file is AnalyzePiezo_SubjectActivityRelativeToLargeMovements_10_5_2021.m , which uses two additional files (Analyze_Grooved_Video_Results_14_6_2017.m and AnalyzePiezoSensorsData_6_6_2017.m).