Izquierdo-neural-2017

This is a fairly comprehensive review of reversal learning. I'm going to skim it just for the bits relevant to serotonin. Maybe I'll come back to it later.

When it comes to the role of serotonin, Izquierdo is more cautious than I expected. Serotonin depletion seems to affect multiple learning modalities (see lapiz-bluhm et al. 2009). They describe the role of serotonin in reversal learning as being specific to the OFC, and cite a huge litany of papers investigating the role of serotonin here, most of which I hadn't found yet. They do state a consistent theme: reduction in cortical serotonin impairs reversal learning, and increasing serotonin facilitates reversal learning.

Izquierdo cautions against drawing a straightforward conclusion however. It seems to depend partly on the stimulated receptors. as shown by boulougouris-dissociable-2008 It also seems to be highly sensitive to details like the timing of the manipulation relative to the training and testing, and the location of the depletion in the brain.

Different roles have been suggested for serotonin in reversal learning.

• affecting punishment and absence-of-reward processing subcortially (how?)
• regulating outcome-tracking cortically (how?)

Personally, I found this paragraph to be a little messy.