dentons

Hello everyone, I'm a student of a Master's degree in Neuroscience and I'm preparing a journal club presentation on an article called "Differential extrageniculostriate and amygdala responses to presentation of emotional faces in a cortically blind field". I'm struggling to understand some of the results, in particular what a negative effect size means in fMRI. Is there someone that can explain that to me? I'm referring in particular to this picture of the paper (the one attached).

What can I say about the "unseen CS-"? Why is it so negative? Does it mean that the amygdala has a very low degree of activation?

Thanks to anyone that can help me