The potential effects of micromotion have been recently investigated by researchers at the University of Utah and Michigan. Standard Michigan silicon probes were implanted into rats and either tethered to the skull (using a common surgical technique) or left floating in the parenchyma. These researchers showed that cranial tethering forces in neural probes produce a quantifiable, significant increase in glia activation at 2 and 4 weeks post-implant (Biran, R. in press). While not direct evidence of micromotion, this is a very strong indication and the most plausible cause for the increase in glial encapsulation. These results advocate addressing the tissue-electrode mechanical interface in probe design.