Animal Cage Camera


Summary

The Animal Cage Camera (ACC) operates with our Videoarchiver software to provide video that is synchronous with the data acquisition computer clock to within ±50 ms. The ACC is a Power-over-Ethernet (PoE) device that requires only one ethernet cable connection to a PoE switch for power and communication. We place the ACC in a Faraday enclosure, connect it with a shielded ethernet cable to to an ethernet feedthrough at the wall of the enclosure, and then with an unshielded ethernet cable to a PoE switch. We connect this switch to our data acquisition computer, and so allow the data acquisition computer to download video from the camera.


Figure: Animal Cage Camera (A3034C).

The Neuroarchiver software, meanwhile, makes sure that its telemetry recordings are synchronized to ±50 ms the data acquisition computer clock. Assuming we have both the Videoarchiver and Neuroarchiver running on the same computer, the result is synchronization of telemetry and video to within ±100 ms.

Our ACCs are expensive: roughly US$1000 each. If you can tolerate ±10 s synchronization between telemetry and video, we suggest you try our Telemetry-Compatible Webcams (TCW). These webcams are also power-over-ethernet (PoE) webcams we buy on the consumer market. We test them with our telemetry system to make sure they do not disturb signal reception, and we equip with the correct cables for integration into a recording system. We sell our TCWs for a fraction of the cost of our ACCs.

Links

Animal Cage Camera (A3034): A high-resolution, power-over-ethernet camera with remote-controlled white and infrared illumination.

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

Neuroarchiver Tool: Manual for the Neuroarchiver, a LWDAQ Tool that plays simultaneous video recorded from ACCs, biometric signals recorded from subcutaneous transmitters (SCTs), and activity monitoring recorded by animal location trackers (ALTs).

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.

Animal Location Tracker (ALT): A platform of radio-frequency pick-up coils that measures the movement of individual subcutaneous transmitters in a cage above.

Test_21AUG20.zip: Fifty-five 20-s videos with accompanying telemetry from two transmitters mounted on mouse toys.

Test_13JUN19.zip: Four 600-s videos with accompanying telemetry from an animal with an Implantable Sensor with Lamp (ISL). We see the light flashing, and unwanted lamp artifact in the recorded EEG signal, which is perfect for checking synchronization of video.

Test_05JUN18.zip: Ten 60-s videos with accompanying telemetry from four transmitters being handled in a Faraday enclosure.

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

Description

The ACC provides video that is synchronous with our subcutaneous transmitter recordings to within a twentieth of a second over any recording duration. The camera streams its video as separate frames at a fixed rate. These are received by the Videoarchiver process on the video recording computer, where they are assembled and compressed into a video that is synchronous with the local computer clock. Given that the EEG recorded by our subcutaneous transmitters is also synchronized to the local computer clock, the result is EEG and video synchronized to the same clock within a twentieth of a second. In the Neuroarchiver Tool, we specify a directory containing the video files, as well as a directory containing the EEG recording files, we can navigate through the EEG recordings and see the synchronous video displayed automatically.

The image quality we obtain from the ACC is far superior to that of low-cost CCTV systems. The ACC lens's depth of field and sharpness of focus, and the superb exposure compensation of the ACC's image sensor, provide clear, sharp images of laboratory animals in poorly-lit cages, even when the camera is only ten centimeters from the cage wall or ceiling. The ACC provides remote-control white and infrared illumination that we can use to enhance image contrast, take pictures at night, or to generate twenty-four hour illumination cycles.


Figure: Images of Brightly-Colored Object in White LED Light (Left), Infrared LED Light (Center), and White Plus Infrared Light (Right).

One use of video recordings is to track the movements of individual animals. Given that animals tend to remain in one piece as they move around, and rodents tend to remain the same color, we can treat animals as blobs in image analysis, and track them with video blob tracking algorithms. But when we have more than one animal in a cage, and the animals are near-identical in appearance, and keep vanishing underneath obstacles, and grouping together into larger blobs, video blob tracking cannot distinguish between the animals. But if we have subcutaneous transmitters implanted in our animals, we can use an Animal Location Tracker (ALT) to measure the approximate movements of each animal, compare these movements to those of the blobs produced by blob tracking, and so determine which blob corresponds to which transmitter, which results in unique identification of each blob. We call this disambiguation of the blob tracking by the ALT data. This disambiguation is possible only because the ACC videos are so well-synchronized with the subcutaneous transmitter system, and in particular the ALT's recordings of pick-up coil power reception.

Motivation

When commercial CCTV camera systems record continuous video, they produce a sequence of files on our data acquisition computer, each of which is supposed to span a specified length of time. When we view these files, we find that the length of time spanned by each file is a few seconds longer or shorter than specified. Each file has a name that gives its time of creation, and the difference in creation time from one file to the next differs by a few seconds from length of the video contained in each file. When we start viewing a new file recorded by a CCTV system, we must wait a few seconds before the picture establishes itself. As a result of these problems, we cannot rely upon synchronization between video produced by such systems and recordings obtained form our subcutaneous transmitter system. In practice the two chronologies disagree by tens of seconds, and in a manner that we cannot predict or correct for. Our Animal Cage Camera (ACC) is designed to solve these synchronization and viewing problems, and provide superb image quality in both light and darkness. Our ACC is, however, more expensive than low-cost CCTV cameras. The wide-angle lens of the ACC alone costs us $100, and the image sensor and readout electronics another $100. For experiments in which synchronization between video and telemetry can be as poor as ±10 s, we recommend our far less expensive line of Telemetry-Compatible Webcams.