Chimera Table enables impacts on an unrestrained head. Impact angle, usually skull-flat, is set with a lock knob and hinge. The angle is shown on a digital display inclinometer.
PURPOSE
The Neuropactor™ mounted on a stereotaxic instrument is designed to optimize reproducibility. Impacts can be placed with stereotaxic precision at the same location on each head and at the same velocity, dwell time, and approach angle. In contrast, since the CHIMERA* does not restrain the head, impacts cannot be as precisely placed. Instead, it is designed to model naturally occurring head impacts where the head is usually free to move. The experimental question being asked guides selection of which instrument to use.
The Neuropactor™ and the CHIMERA have in common that a metal tip
impacts an anesthetized animal on the dorsal surface of the head at a selected
velocity to create TBI. The important difference is not the tip driver, but the
stand. Neuropactor™ was designed to mount on a stereotaxic instrument, while
the CHIMERA Table allows impacts from below on the head of an animal
lying on its back, strapped to the table at the chest, with room for the
head to bounce away from the impact.
Depth of penetration and dwell time are not relevant for CHIMERA.
Neuroscience Tools™ manufactures a CHIMERA type table as an accessory to the Neuropactor™. The actuator may be interchangeably mounted on a stereotaxic instrument, or on the underside of the table, impacting through a hole.
Features of the CHIMERA
- Surgery-free (closed head, can also be done with Neuropactor™)
- Non-surgical is useful for repeated impacts, as rTBI, a model of sports injury
- Head free to rotate, whip lash damage. (Neuropactor is locked head)
- Human accidents usually involve unrestrained head movement
- Brain tissue not impacted or cut, but concussed internally
- Assessment shortly after impact, no time for healing needed
- Faster throughput without surgery. (~10 min./animal)
The CHIMERA table manufactured by Neuroscience Tools™ features a precise digital readout of the head angle, which the user is to adjust until the head appears flat over the hole the probe will come through. Straps for mice and for rats are both provided. One knob loosens or locks the angle. No electric air pump is required to fill a tank before an impact. No condensation from compressed air in the system. Since the identical impact driver and tip can be used, a study comparing fixed head CHI and CHIMERA type impacts is convenient. Which parts of the after effects are due to head movement should be discernable.
* Namjoshi, D.R., Cheng, W.H., McInnes, K.A. et al. Merging pathology with biomechanics using CHIMERA (Closed-Head Impact Model of Engineered Rotational Acceleration): a novel, surgery-free model of traumatic brain injury. Mol Neurodegeneration 9, 55 (2014). https://doi.org/10.1186/1750-1326-9-55
Neuroscience Tools, 401 Church St. #1635, O’Fallon MO 63366
Ph: 630 964-0501
email: Charles.Scouten@NeuroscienceTools.com