Stability is one of the most important factors – if not the most important factor – in selecting the head fixation for two-photon imaging and electrophysiological recordings in awake mice. This is why the clamp and head plate design are so important. This is also the reason why we continuously innovate the clamp design and expand the variety of clamp options.
Comparison between two main clamp options
The Mobile HomeCage® devices come with a choice of two clamps that must be specified at order: the standard clamp (top picture, left) and the Levelt clamp (top picture, right). While both clamps provide the same level of stability, they differ in several respects. The table below provides a quick reference guide to choosing between the two options:
*) Beware of possible magnetic field interaction between the clamp and the cage magnets (this is relevant for the Mobile HomeCage with locomotion tracking capabilities only). Tests have shown that this interaction does not affect mouse behavior. Nevertheless, avoid leaving mice with magnetic head plates in the cage with tracking mats without first head-fixing them in the clamp.
The standard clamp is secured with two thumb screws. It is compatible with a wide range of head plates designed for different research needs. In addition to the straight clamp (0 degree tilt), the clamp can be manufactured with a 10, 20, 30 and 35 degree tilt (inclination in the nodding direction). The clamp rotates up to 40 degrees in both directions (left and right inclination) either as a continuum or in 10 degree steps. Besides that, the clamp has attachment holes for mounting liquid reward, miniature cameras and other auxiliary devices.
The tilted clamp is a variant of the standard clamp. It allows adjusting the mouse’s head position in the nodding direction. Beware that the tilted clamps cannot be used for imaging without a tilting objective. Please remember to specify the degree of tilt at order. The straight clamp (0 degree tilt) is a default option. Other options include 10, 20, 30 and 35 degree tilt. The degree of tilt cannot be adjusted.
The Levelt clamp was developed by Christiaan Levelt’s lab at the Netherlands Institute for Neuroscience. The clamp is magnetic. It allows head-fixing a mouse quickly and effortlessly. This clamp must be used with a dedicated magnetic head plate (currently only one model # 13 is available). There is currently no tilted version for this clamp. The clamp rotates up to 40 degrees in both directions (left and right inclination) either as a continuum in 10 degree steps. Besides that, the clamp has attachment holes for mounting liquid reward, miniature cameras and other auxiliary devices.
The Levelt clamp is suitable for imaging/recording in the somatosensory cortex of adult mice (age > 2 month; weight > 20g).
Please note that the smallest unit that we sell is the clamp kit (standard or Levelt), which includes a clamp, a neck, a rotation block and 10 head plates.
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