"it's hardly likely that physicians can recommend that human patients reduce their brain activity to keep their gliomas from growing,"

I have to admit my imagination flashed to an image of somebody wearing a portable biofeedback rig that buzzed (or perhaps zapped) them every time they used the target portion of their brain, in an attempt to starve the tumor.

It would make a really fascinating experiment to hook someone up to such a device, then see whether the brain considers that enough of an aversive stimulus to move the targeted functionality to another part of the brain, as if that part of the brain was damaged. No way to get that past the ethics committees, I'm sure, but interesting.

There's probably an interesting sci-fi story in the crazy home DIY tinker diagnosed with inoperable brain cancer who just puts together such a rig anyways with no medical approval... if we don't already have the off-the-shelf tech to do that today we're pretty darned close. (But I've never really worked out how to move from "high concept" to "actual plot", despite a few attempts.)