Figure 4.

Amygdala microdialysis (in vivo extracellular serotonin levels). (a) Coronal section through the amygdala illustrating the positioning of the microdialysis probe. (b) Extracellular levels of amygdala serotonin in high-anxious marmosets expressed as % of the mean low-anxious levels, at baseline (white bars, samples 1–3, no citalopram) and following citalopram challenge (shaded bars, samples 4–6 and samples 7–9). *P<0.05, **P<0.01 compared with low-anxious mean. Although three out of five high-anxious animals also showed substantially reduced serotonin levels at baseline (39–52% of low-anxious mean), this did not reach statistical significance for the group (samples 1–3, t₍₄₎=−1.53, P=0.49).