What does TCA stand for?

[confused]

In a lecture on the reticular formation, my notes say

AROUSAL (Ascending Reticular Activating System is a physiological concept based on neuronal networks producing arousal effects on the brain. Pontine acetylcholine cells stimulate TCAs.

Any idea?

Thanks

[Steffen]

In case you also talked about antidepressants, TCA might mean "tricyclic antidepressants". Does that make sense? Otherwise you'll just have to ask some of your class mates...