Interpretation of electroantennogram (EAG)

[Austinys]

Hello,

 

I was doing EAG of Culex pipiens with odours of Thymus pulegioides essential oils. I know I can do quantified comparison of response to different compounds and it gives me information about presence of receptors in C. pipiens anntenae and it's sensitivity.

 

But I also noticed that the shapes of EAG curves are different depending on compound. For example, curve of carvacrol are going up, while all others - down (see attached file). So my question is - how should I explain this phenomenon?

 

Thanks!

 

Austinys.