Mobile HomeCage® (MHC V5)

Mobile HomeCage allows using precise optical and electrophysiological techniques such as two-photon imaging, patch clamp recordings, and single-cell optogenetics in the brain of non-anesthetized, head-fixed and naturally behaving mice.

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How it came to be

Anesthetics affect the brain functions. They limit the number and frequency of recording sessions. Therefore, imaging and electrophysiological data obtained in non-anesthetized animals are more relevant.  This is a no-brainer. But how do you head-fix an awake mouse without causing enormous stress to the animal? We pondered this question in 2012 when we struggled to implement a method for two-photon imaging in awake head-fixed mice. Immobilization would only aggravate the stress, and the air-lifted Styrofoam ball would not fit into our 2-photon set-up. We also could not invest into a virtual reality (VR) system needed to compensate for the lack of the sensory input on the ball.

Instead, we have developed a Mobile HomeCage, a flat-floored air lifted platform for high precision neurophysiological tests in head-fixed awake mice.

How it works

The Mobile HomeCage® is a combination of a head-fixation system and an air table. After a cranial surgery, recovery and short training, we place the mouse into the light but durable carbon fiber cage. We secure the mouse’s head in the clamping mechanism and connect the device to an air source. (Scroll to the bottom for the video of head fixation in the Mobile HomeCage®).

Once the carbon fiber cage starts to float, the animal can easily move it with its paws. Since there is very little friction, the mouse has an illusion of freely walking around the cage. Besides that: the mouse does not experience the disconnect (typical for the ball systems) between the visual projections and the (lack of) somatosensory stimuli. It can whisker-touch the walls while walking effortlessly on a perfectly flat surface. This reduces the stress and keeps the mouse calm for the duration of the experiment. The carbon cage also serves as a platform for behavioral tests.

What you can do with the Mobile HomeCage®

  • Firmly immobilize the head of an otherwise freely moving awake animal;
  • Perform high-precision neurophysiological tests (e.g., patch clamp, two-photon microscopy, optogenetic stimulation) in non-anesthetized mice;
  • Combine these high-precision tests with simple behavioral readouts;
  • Greatly reduce the stress experienced by awake animals under standard head-fixation conditions;
  • Begin experiments after only 4 days of mouse training/habituation;
  • Use natural sensory stimuli (including tactile, visual, auditory or olfactory) during recording/imaging;
  • Provide mice with food and drink during experiment;
  • Monitor the animals as they socialize, groom or sleep while head-fixed in the Mobile HomeCage®;
  • Access lateral regions of the brain (using the rotating clamp);
  • Avoid making major modifications to your microscopy set-up (the Mobile HomeCage® is compatible with most commercial microscopes and standard xy-stages);
  • Ensure higher yield and superior reproducibility of results;
  • Engage in new areas of research.

Technical specifications

  • Dimensions: 430 X 300 X 159 mm
  • Floating cage dimensions: 180 X 70 mm or 180 X 40 mm
  • Weight: 6,2 kg
  • Materials: aluminum, carbon fiber

Mobile HomeCage kit composition

A standard Mobile HomeCage® V5 kit has all you need to start using the device. It includes:

  • air dispenser
  • bridge and towers
  • standard rotating clamp and neck
  • 180 X 70 mm carbon fiber cage (can be substituted with 180 X 40 mm cage)
  • ten model 1 head plates (4,2 mm opening); head plates can be substituted with other models on request
  • 12 mm diameter hose (length: 3 meters) for connecting to air source
  • noise reduction unit (a shorter hose with connectors)
  • hex screws

We can substitute some of these items with optional parts. (See below for parts and accessories).  We recommend that you contact us prior to making the purchase to share information about your experimental set-up. This would help us configure the system for your needs.

Features

  • Fast and firm head fixation with micrometer precision;
  • Clamp rotates up to 40 degrees in each direction  in 10 degree increments (fixed rotational angle positions ensure reproducibility of position between experiments);
  • Floating carbon cages are designed to roughly match the weight of the animal thus making the movement practically effortless;
  • Transparent cage ensures compatibility with virtual reality systems and makes it possible to video-record the animal from a side;
  • Device operates from a standard laboratory air source (required airflow is 100 L/min) or a portable air blower;
  • Large selection of precise-engineered head plates accommodates different research needs.

Parts and accessories

  • Carbon cage, 180 X 70 mm, designed to roughly match the weight of the test animal for effortless movement;
  • Carbon cage, 180 X 40 mm, designed to allow better access with micromanipulators at non-vertical angles;
  • Transparent cage, 180 X 70 mm, designed to ensure compatibility with virtual reality systems and to enable video recording from the side;
  • Head plates (selection of 12 models for various research purposes);
  • Noise reduction unit consists of a 30 mm hose with connectors and an air filter; it helps to further decrease the noise level of the Mobile HomeCage;
  • Tilted clamp (10, 20, 30, 35 degrees tilt in the nodding direction, pre-set) designed to provide for a more natural head position (must be used with tilting microscope objective);
  • Elongated lower lip designed to ensure compatibility with wide-diameter objectives;
  • Short neck (45 mm vs. standard 75 mm) designed to ensure compatibility with short objectives;
  • MultiCage Training Arena for training up to three (3) mice simultaneously;
  • Motion tracking device (and open source software) designed to record the speed and the trajectory of movement and to control external devices.

If unsure which spare parts and accessories you need or whether the Mobile HomeCage® will fit into your experimental set-up, contact us in the online chat, send us an email to mhc-support@neurotar.com or call, +358 9 428 344 56.

Mobile HomeCage patents: US8485133B1, EP2712500B1.