Subjects having elevated signaling of a mammalian target of rapamycin (mTOR) are treated with compositions that include at least one compound that activates a Group 1 mGluR. In an embodiment, the subject has tuberous sclerosis complex (TSC). In an embodiment, the compound is a Group 1 mGluR agonist. In another embodiment, the compound is a Group 1 mGluR positive allosteric modulator.