We do not yet completely understand why some people are more vulnerable to contracting stress-related illnesses such as depression and post-traumatic stress disorder (PTSD), and why some do not respond well to medications and psychotherapy. We have recently developed an experimental procedure that makes rodents display behaviors mimicking some aspects of depression/PTSD. We found that these depressive-like rodents show changes in the functioning of a type of ion channel called calcium-activated small-conductance potassium channel (SKC) that controls the activity of neurons in brain regions affected by chronic stress. Because different types of these channels have different functions, we will use different experimental approaches to determine exactly which subtype is affected in stress disorders. We will investigate how this channel influences behaviour and brain processes, including the activity and connectivity of neurons. On this basis, we will test whether drugs that will selectively act on this subtype will have beneficial effects in reversing depressive/hyperanxious-like abnormalities. Through this endeavor, we anticipate to better understand the causes of stress-related illnesses and their effects on the brain, and to be able to develop a novel class of medication that can safely correct these effects and treat depression and PTSD.