This 2015 Czech research studied individual neurons in an area of the limbic system of Parkinson’s disease patients. The findings corroborated several findings of previous research, such as:
“We confirm the importance of the subthalamic nucleus as a hub within the limbic circuitry involved in both emotional valence and arousal processing as in two functionally and spatially segregated systems.”
This statement summed up the study for me:
“Several factors could affect our results and reduce the inferences that can be drawn with regards to the physiology of emotional processing and the role of the subthalamic nucleus in the limbic circuits.
One such factor is that the study was conducted with Parkinson’s disease patients, who are known to have a widespread central nervous system pathology and to experience problems in emotional processing.”
The current study referenced The amygdala is where we integrate our perception of human facial emotion study, which similarly used the opportunity of patients with electrodes implanted for deep-brain stimulation to study individual neurons in the amygdala. However, a design difference was that the amygdala study had healthy control subjects in addition to patients, which led to fewer potential limitations on their findings.
Also referenced was a summary study entitled Exploring emotions using invasive methods: review of 60 years of human intracranial electrophysiology. Despite excluding studies of decision making, reward processing, learning, mood disorders, and pain experiences, it didn’t demonstrate, in my opinion, that 60 years of experiments using implanted electrodes in the brains of people with epilepsy had substantially advanced science, other than confirming what fMRI and animal research had shown.
I’m not sure how I would feel if I had a disease where the physicians treated my symptoms in such a way that I became a lab rat for research that wasn’t groundbreaking. Do people with epilepsy and Parkinson’s disease have treatments available that factually resolve the underlying causes?
http://www.pnas.org/content/112/10/3116.full “Distinct populations of neurons respond to emotional valence and arousal in the human subthalamic nucleus”