Ma'anar ƙamus na "abu mai launin toka" yana nufin ƙwayar jijiyoyi a cikin kwakwalwa da kashin baya wanda ya ƙunshi jikin tantanin halitta, dendrites, da synapses, waɗanda ke da alhakin sarrafawa da haɗakar da bayanan hankali da motsi. An kuma san shi da launin toka kuma an bambanta shi da fararen fata, wanda ya ƙunshi axon myelinated. Abun launin toka yana da mahimmanci don fahimta, fahimta, da motsi na son rai.