Dr. Jack Feldman

And she gets relief in their anxiety.

So CO2 levels, which are not going to affect brain function on a breath-by-breath level,

although it does fluctuate breath by breath, but sort of as a continuous background, can change.

And if it's changed chronically, we know that highly elevated levels of CO2 can produce panic attacks.

Your body is so sensitive, the control of breathing, like how much you breathe per minute, is determined in a very sensitive way by the CO2 level.

So even a small change in your CO2 will have a significant effect on your ventilation.

So this is another thing that not only changes your ventilation, but affects your brain state.

Now, another thing that could affect how breathing practice can affect your emotional state is simply the descending command.

Because breathing practice involves volitional control of your breathing, and therefore there's a signal that's originating somewhere in your motor cortex.

That is not—of course, that's going to go down to pre-Butzinger—

but it's also going to send off collaterals to other places.

Those collaterals could obviously influence your emotional state.

So we have quite a few different potential sources.

None of them are exclusive.

Almost everything.

So we have, for example, on the autonomic side, we have respiratory sinus arrhythmia.

That is, during expiration, the heart slows down.

Your pupils oscillate with the respiratory cycle.

Your fear response.

Let's take something like depression.