Cortisol negatively influences retrieval of memories. And where does this hormone come from? Stress. A study out of Ruhr University, Germany looked at participants’ tactile sensation and how it changed once a dose of Cortisol was administered. The results showed that memories formed within the hippocampus were disrupted and that new learning was suppressed. More studies are needed to look into Corticosteriods as they are often prescribed during the rehab process and may actually inhibit plasticity.