You need a few leeches for that. https://phys.org/news/2011-05-serotonin-role-leeches-abilities.html https://phys.org/news/2011-05-serotonin-role-leeches-abili

You need a few leeches for that. https://phys.org/news/2011-05-serotonin-role-leeches-abilities.html https://phys.org/news/2011-05-serotonin-role-leeches-abiliti... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3210650/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3210650/