The human brain is full of wonder, mystery, perhaps even spirit. But it’s also a machine. And so even though it might sound far-fetched to suggest that a device can beam happiness into someone’s head, for some people living with depression that is the truth.

Transcranial magnetic stimulation, the subject of the latest installment of Clever Apes, works by sending an intense, focused magnetic field about an inch deep into someone’s forehead. The field comes in pulses – about 3,000 per session. The pulses activate a neural network on the surface of the brain, which in turn sends signals deep inside that stimulate brain structures in charge of your mood. The result, for about half the people who use it, is real relief from major depression. And these are generally people for whom medication hasn’t worked.

TMS is sort of the younger, gentler cousin of electro-convulsive therapy, or shock treatment. It seems to affect the same brain circuit as ECT (which is still considered the gold standard for treatment-resistant depression). In fact, almost all the medical approaches to depression, including surgical techniques like deep brain or vagus nerve stimulation, antidepressant drugs and even some kinds of talk therapy, all go to work on that same neural network.

The actual mechanism by which they make someone feel better is still a mystery to science. It may have to do with increasing the production of brain chemicals that affect mood. Or it may overwhelm certain neurological ruts that our brains get into and help them reboot. Whatever the case, it means thinking about the brain less as the center of some mystical life force, and more like an engine that a smart mechanic can recalibrate. Indeed, the real happiness machine is the one inside our heads.

Also in today’s episode, we revisit our occasional series Ask an Ape, where we answer a listener’s question about science. This was a succinct one: “Magnets?” We chose to take this simple question and needlessly complicate it, by delving into nuclear magnetic resonance. Atoms in a strong magnetic field will align with (or against) that field, like little compasses. If you then feed them some radio waves, they’ll broadcast them right back to you. Who cares? Well, this allows you to identify mysterious atoms and molecules … and it also plays music, sort of.

Josh Kurutz, senior scientist for NMR at Northwestern University, gives us a little primer. He has made art from the resonant signals of molecules, as well as lots of other great nerdy stuff. His website is well worth a visit.

You can suggest your own question for Ask an Ape in the comments below. You can also tweet it to us, post it to our Facebook wall, or even call our Clever Apes hotline at 312- 893-2935. While you’re at it, subscribe to our podcast and, if you like it, feel free to give it a little review in iTunes.