Also, I have no evidence to back any of this up. But I always perceived that the heightened senses that a channeler experienced was similar to an adrenaline-like effect. I thought of it as though channeling brought out those natural chemicals in the human body that heightened and enhanced its function. Like how Rand is able to endure exhaustion when he is holding the source, but collapses with exhaustion when he releases it. His body is actually tired, but when he is holding the source, he doesn't notice it. Similar behavior and effects have been reported with soldiers and victims who endure or survive high stress situations. They are able to do outstanding feats while their bodies are pumping out these chemicals, but as soon as the stress passes, they are bone-tired.

I always thought of Perrin's heightened senses as an actual change in physiology. Just as the pigments in his eyes actually changed in color, I assumed that his telepathy and heightened senses were actual, tangible changes in his body anatomy.

This is all purely speculation on my part though. I study biology, and I can tell that a lot of my biological biases come out when it comes to stuff like this .

In summary, my view is that channeling takes advantage of natural body chemicals, while being a wolfbrother actually enhances those sense.