Mobile HomeCage Large® with tracking capability

New product! The Mobile HomeCage-Large® with tracking capability (MHC-L-T V3) allows combining live imaging and physiological recordings with complex behavioral readouts such as maze navigation. The motion tracker collects actionable data about the mouse’s movement trajectory and speed. The tracking software controls external devices in closed-loop experiments and synchronizes with external imaging and recording software in real time.

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Curious to know which part of the floating cage the mouse goes to during the recording session and how long it stays there? How fast does it move, and what is its trajectory? What is the locomotive response to a sensory stimulus? The new motion tracking device recently added to the Mobile HomeCage® Large (MHC-L) records data about mouse’ position, trajectory and speed of movement during neurophysiological experiments combined with complex behavioral paradigms such as maze navigation.

New tracking capability is a significant milestone on the road to integrating neurophysiological experiments in awake mice with behavioral research.

Mobile HomeCage® Large basics

Mobile HomeCage® Large is a flat-floored air lifted platform used for high precision tests in non-anesthetized, head-restrained but otherwise freely moving mice. It is large enough to accommodate floating mazes and to create conditions for place cell recordings (in a donut-maze). To recapitulate core benefits and functionalities of the Mobile HomeCage® Large click here.

Enters the tracker!

Tracker monitors and records the mouse’s movement inside the floating cage. The software tracks the trajectory, acceleration and speed, displays the data in real time and saves them for offline analysis. Through TTL ports, the tracker integrates (in real time) with external imaging and recording software. In addition, it controls external stimulation devices (such as a liquid reward system) during closed-loop experiments.

How the tracker works

The tracking apparatus consists of a sensor board (located inside the air dispenser), a specially designed carbon fiber cage or foam maze with magnets built into the bottom, a control unit and an open source software. Sensors detect the movement of magnets, a processor in the control unit calculates the cage coordinates in real time and streams the data to the computer software, which extrapolates the cage movements into the animal’s trajectory relative to the cage.

Why magnetic tracking?

The magnetic tracker’s speed (100 fps) and resolution (1 mm) would be hard to match for camera-based tracking devices. Unlike video tracking, magnetic tracking is unaffected by lighting conditions. Besides that: the sensor board is hidden inside the air dispenser and does not require extra space in experimental set-up.

Bigger and better

If you are familiar with our tracking solution for the regular size Mobile HomeCage®, you might be curious to learn how we improved on it. We upgraded both the hardware and the software. As a result we…

  • increased temporal resolution from 80 fps to 100 fps;
  • made TTL ports reconfigurable for input and output;
  • implemented real-time synchronization with external software
    • There are two synchronization options: short TTL pulse (225 us) at the beginning of each frame and/or TTL long pulse during every second frame;
  • created a new (very colorful) software interface;
  • lowered CPU and memory footprint;
  • dramatically increased the speed of data saving and loading, and made data saving more reliable during long recording sessions;
  • taught the software to save the parameters of each recording session;
  • incorporated magnets into the bottom of carbon cages and foam cages/mazes, which had a remarkable “side effect” of reducing the effects of rotational inertia!

Integrating behavior

Locomotion tracking capabilities are key to integrating high precision tests with behavioral research. Mobile HomeCage user labs monitor locomotion patterns during learning and memory tasks in various types of mazes. They study fleeing and freezing behavior as well as social interactions between mice.

Neurotar team has recently validated a social approach task modified for the experiment in the Mobile HomeCage Large. We have head-fixed a mouse, build a small enclosure for another mouse, and observed their interaction over the course of 20 minutes. The diagram below shows head-fixed mouse’s locomotion patterns while it is alone in the cage (left), while it is in the cage with an empty enclosure (center) and with an enclosure occupied by the second mouse (right).

Social behavior in Mobile HomeCage Large

The beauty of this set-up is that it allows studying social behavior and correlating it with changes in the brain activity during the same experiment! The experimental design was suggested by Rebecca Piskorowski’s lab at the Institute of Psychiatry and Neuroscience, Paris.

What would you do in the Mobile HomeCage, if you let your imagination run wild?

Benefits

Let’s bring it all together. The key benefits of the Mobile HomeCage® Large remain unchanged:

  • Ability to perform high precision imaging, electrophysiological recordings, optogenetic stimulation and functional ultrasound tests (that require head restraint for supreme stability) in the brain of awake behaving mice;
  • Ability to combine these neurophysiological tests with complex behavioral paradigms such as maze navigation and social interactions;
  • Abandoning anesthetics during experiments and training;
  • Fast ramp-up to experiments and high stability of recordings due to efficient stress reduction;
  • Access to lateral parts of the brain enabled by clamp rotation (requires tilting objective for imaging);
  • Ability to study place cells (in a donut-maze with circumference of approx. 1 meter).

In addition, the tracking device gives you these advantages:

  • Tracking animal’s locomotion with high spatial and temporal resolution;
  • Independence from lighting conditions during experiment;
  • Fast data saving and loading;
  • Real-time synchronization with external imaging and recording software;
  • Controlling external hardware such as a reward system (during closed-loop experiments) via TTL ports;
  • Tracking software is provided as an open source.

Compatibility

Fitting a large sensor board inside the air dispenser required making modifications to the original air dispenser design. As a result, earlier Mobile HomeCage® Large models (MHC-L V1 and V2) cannot be upgraded with tracking capabilities. All new Mobile HomeCage® Large devices (MHC-L V3) are compatible with tracking. If you want to upgrade an earlier version of the Mobile HomeCage® Large with tracking capabilities, please contact support for a solution.

The Mobile HomeCage® Large is compatible with some two-photon microscope models manufactured by Femtonics, La Vision Biotech, NeuroLabware, Scientifica, Sutter, and ThorLabs. Some of these manufacturers offer extendable objective arms and tiltable objectives. There may be restrictions on the size of the magnetic cage, which is why we have both 325 mm and 290 mm diameter options. For more information about compatibility requirements, please contact our support. If we have missed a two-photon manufacturer, that would accommodate the Mobile HomeCage® Large, let us know and we shall happily add them to the list.

Disclaimer (no legal gibberish)

Although Mobile HomeCage® devices greatly facilitate neurophysiological experiments in awake head-fixed mice, the quality of the cranial surgery and training remain crucially important to success. Knowing this, we offer help setting up surgery and training protocols. Interested? Send us a message to support.

Air flow and noise

The Mobile HomeCage® can operate from a standard laboratory air source or any air source capable of supplying an air flow of at least 120 L/min. We include a noise reduction unit with every Mobile HomeCage® Large device. Although it does not look grand, it helps to further reduce the acoustic noise generated by air streaming through the air dispenser lid. If your air source does not satisfy the air flow requirements, contact us for a portable air blower recommendation.

Technical characteristics

  • Dimensions, MHC-L V3 with sensor board: 720 X 570 X 210 mm
  • Dimensions, electronic control unit (ECU): 92 X 100 X 40 mm
  • Magnetic cage cage dimensions: Ø325 X 70 mm, Ø325 X 40 mm, Ø290 X 70 mm or Ø290 X 40 mm
  • Data transfer interface: USB 3.0
  • Direct data transfer to external hardware over RS 232 interface: ASCII or binary (time stamp, x, y, angular coordinate, TTL status
  • Four TTL O/I ports
  • Net weight: 16,3 kg

Mobile HomeCage® Large (with tracking) kit composition

A standard Mobile HomeCage® Large with tracking capabilities has everything you need to start using the device. It includes:

  • Air dispenser with built-in sensor board
  • Bridge and towers
  • Head fixation block: narrow clamp with rotating neck
  • Ultralight weight carbon fiber cage (choice of 2 sizes and 2 wall heights, see below under accessories) with built-in magnets
  • Ten head plates of your choice (default: model 1 head plates, 4,2 mm opening)
  • A 12 mm diameter hose (length: 3 meters) for connecting to air source
  • Noise reduction  unit
  • Electronic control unit (ECU)
  • RS 232 cable
  • USB connector cable
  • Open source software

Accessories

  • Ultralight weight magnetic carbon cages, Ø325 X 70 mm, Ø325 X 40 mm, Ø290 X 70 mm and Ø290 X 40 mm are designed to optimize weight for effortless movement;
  • Wall-less carbon discs (diameter 325 or 290 mm) allow for easier visual stimulation and unobstructed access with micromanipulators and other research equipment – the air stream at the edges of the disc discourages mice from leaving the disc;
  • Floating foam cages and mazes enable more complex behavioral tests such as maze navigation;
  • Head plates (selection of 12 models for various research purposes);
  • Angled clamp (10, 20, 30 or 35 degrees tilt in the nodding direction, not adjustable) is designed to provide for a more natural head position (must be used with tilting microscope objective);
  • Elongated clamp is a 20 mm longer “lower lip” than the standard clamp. It is designed to ensure compatibility with wide-diameter objectives. Any standard clamp can be modified by replacing the lower lip;
  • Short neck (45 mm vs. standard 75 mm) is designed to ensure compatibility with short objectives or piezo z-drives;
  • MultiCage Training Arena enhances the work flow by making it possible to train three mice simultaneously;
  • MultiCage Upgrade Kit allows converting the Mobile HomeCage® Large into a training arena for three mice and vice a versa.

If unsure which spare parts and accessories you need or whether the Mobile HomeCage® Large will fit into your experimental set-up, please contact mhc-support@neurotar.com.