Anhedonia: Understanding the Lack of Feeling
The inability to feel pleasure from any kind of activity that is normally enjoyed by the individual is present in many psychiatric illnesses, such as schizophrenia and depression. The Greeks named this symptom ‘anhedonia.’ From music, eating, playing and even sex, anhedonia can cause those who have it to feel no pleasure from those activities.
The specific causes to anhedonia are unknown, but there has been a lot of ongoing research to diminish this symptom in most people with depression. According to Stanford scientist and doctor, Robert Malenka, MD, PhD, the feelings of anhedonia and depression are typically associated with being in a stress-inducing environment, and the hormone melanocortin is also associated with depression-related syndromes. Another Stanford scientist, Emily Ferenczi, links anhedonia and depression with the malfunction of the medial prefrontal cortex (mPFC), which is a part of the brain that mediates decision making, supports memory consolidation, and is now speculated to have a part in conducting part of the brain’s reward system.
While the final consensus to what causes anhedonia is disputed, there have been recent peripheral studies on various types of anhedonia – like musical anhedonia, that can help us in the understanding of our brain. According to the University of McGill in Montreal, about 3-5% of the healthy population do not experience any pleasure from listening to music. This is only characterized by lack of sensitivity to music and not to any other pleasurable stimulus, like money. This percentage of the population understands and perceives the melodies and rhythms of music but does not enjoy musical stimulus. By observing various groups through an fMRI, scientists were able to observe that musical stimuli is related to “a reduction in the activity of the nucleus accumbens, a key subcortical structure of the reward system,” while other pleasurable stimuli like money had the normal effect of the nucleus accumbens like that in a normal healthy person. Studies like these have given us a lot of insight on how the mystery that is our brain truly works and allowed mental illnesses to be better understood.
~ Cindy Wu
Sources:
http://neurosciencenews.com/music-sensitivity-neuroscience-5543/
http://neurosciencenews.com/melanocortin-anhedonia-depression-symptom-pleasure-loss-treatment/
Image Source:
http://skepchick.org/wp-content/uploads/2013/12/mr-sunshine-2.jpg
