Animal Location Tracker


Overview

In addition to recording telemetry signals, our Animal Location Trackers (ALTs) measure the activity and proximity of animals living in a cage by monitoring the movements of the Subcutaneous Transmitters (SCTs) implanted in their bodies. We place the cage on the ALT platform, and the array of detector coils within the platform measure the power received from each SCT separately. The distribution of received power across the coil array allows us to estimate the position of each SCT above the platform. This position estimate gives us a distorted and inaccurate view of the locations of the animals, rather like viewing a room full of people through a distorted piece of glass. As an animal moves steadily across the platform, it's apparant position will surge forward, veer to either side, and pause. Distorted and innacturate as it may be, the location estimate does provide us with a robust measurement of animal activity and proximity. By activity we mean the distance moved by the animal in a given time, perhaps per second or per minute. By proximity we mean the average separation of each pair of animals in the cage. We can tell when an animal is asleep, when it is active, and whether or not it socializes with the other animals or remains on its own. Furthermore, we can detect circulation in the clockwise or anti-clockwise direction, and measure which animals spend more time towards the edges of the cage as compared to the center of the cage.


Figure: Animal Location Tracker, Version A3038C. A 48 cm × 24 cm array of coils provides telemetry reception and animal location tracking. Two mouse toys show scale. White lights on left edge show reception from two data channels.

An ALT makes it possible to watch and identify co-habiting and socializing animals, while the implanted SCTs provide simultaneous EEG recording from the watched animals. Fully-automated analysis of animal activity and social interaction may now be performed along with fully-automated event detection in EEG, such as automated association of spike-waves with decision making or seizure spikes with convulsions.


Figure: ALT System with Four Faraday Enclosures (FE3A). A data acquisition computer (1) runs the Neurotracker software and records telemetry and position to disk. A power over ethernet switch (2) provides communication between eight ALTs and the computer, as well as providing power to the ALTs. Unshielded ethernet cables (4) connect the switch to a feedthrough (8) in the back wall of each Faraday enclosure (5). A shielded ethernet cable (3) completes the connection to the ALT (6) inside the enclosure. Each ALT will provide tracking for half a dozen animals with implanted SCTs (7).

Another use of the ALT location measurement is to permit us to identify which animal is which in synchronous video recordings. Our Video Blob Tracking (VBT) software applies blob-tracking analysis to the video to obtain the coordinates of each animal or animal-like object in the field of view. But it cannot tell us which animal is which, and it quickly loses track of the animals when they come together or move through enrichment features present in their cages. But the ALT provides us with a movement vector for each animal in each second, and by correlating these movement vectors with those provided by the blob-tracking, we are able to identify which blob corresponds to which SCT. We call this ALT function video disambiguation

Further Reading

Real-Time System Setup: Watch us put together an ALT recording system with Animal Cage Cameras (ACC) in five minutes.

Animal Location Tracker (A3038): Operational description of the A3038 animal location tracker. The A3038 requires only one cable connection for power and communication: 100 MBPS Power over Ethernet (PoE). It requires no external antennas, but provides one auxilliary antenna input for extending telemetry reception.

Animal Location Tracker (A3032): Description of the original, prototype animal location tracker. The A3032 is also an array of fifteen coils, but did not perform telemetry reception itself. The manual contains presentation of feasability studies.

Neurotracker: The component of the Neuroarchiver that displays and controls ALT measurements.

Neuroarchiver: The component of the LWDAQ Software that provides recording, playback, control, and export of ALT measurements.

LWDAQ Software: Our data acquisition software, download and use is free and open-source.

Animal Cage Camera (A3034): A camera with variable white and infra-red illumination for recording video of animals in cages.

Videoarchiver Tool: Manual for the Videoarchiver, a LWDAQ Tool, which records video from an Animal Cage Camera in such a way that it may be played back synchronously with EEG and ALT recordings.

Videoarchiver Libraries: Archive of libraries for MacOS, Linux, and Windows necessary to run the Videoarchiver in LWDAQ. Download, decompress, and place the Videoarchiver folder in LWDAQ.app/Contents/ to make LWDAQ.app/Contents/Videoarchiver.

Video Blob Tracking (VBT): A description of how we analyze video frames to obtain the coordinates of animal-like objects. This link leads to our GitHub repository, where we keep the developing software files.

Feasibility Studies: Initial work showing feasibility of the animal location tracker using a pick-up coil and our radio-frequency spectrometer.

Platform Development: Design and testing of the original fifteen-coil array platform.

Animal Location Tracker (A3032): An array of coils to detect power from subcutaneous transmitters and so measure the movement of these transmitters.

Parts and Prices: A list of devices and their prices in various quantities.