Studies have connected deficient cerebellar LTD with impaired motor learning. In one study, metabotropic glutamate receptor 1 mutant mice maintained a normal cerebellar anatomy but had weak LTD and consequently impaired motor learning. However the relationship between cerebellar LTD and motor learning has been seriously challenged. A study on rats and mice proved that normal motor learning occurs while LTD of Purkinje cells is prevented by (1R-1-benzo thiophen-5-yl-2[2-diethylamino)-ethoxy] ethanol hydrochloride (T-588). Likewise, LTD in mice was disrupted using several experimental techniques with no observable deficits in motor learning or performance. These taken together suggest that the correlation between cerebellar LTD and motor learning may have been illusory.