14 DAY TRIAL // It's common knowledge that the human brain features billions of neurons, all connected with each other via synapses and other channels. These connections are all related to everyday feelings, including one of the most powerful, fear. Studies on neural fear have usually focused on fear-conditioning experiments, but advancements in science have now made it possible to look deeper into the underlying mechanisms that dictate the feeling. For example, a new study focuses on using computational models of the brain to pinpoint how it reacts to fear, experts from the University of Missouri-Columbia report.
Their report implies that the new type of investigation could be of great use for people suffering from the post-traumatic stress disorder (PTSD), as well as other similar conditions. In charge of the UMC team was electrical and computer engineering doctoral student Guoshi Li. Before this approach was taken, the expert argued that computer models were far more effective at studying brain connections than any other method.
“Computational models make it much easier to study the brain because they can effectively integrate different types of information related to a problem into a computational framework and analyze possible neural mechanisms from a systems perspective. We simulate activity and test a variety of 'what if' scenarios without having to use human subjects in a rapid and inexpensive way,” Li explains. In their experiments, the UMC researchers confirmed that fear extinction memory played an important part in subsidizing fear, but also that it did not make the emotion go away completely.
“Fear extinction memory is not well understood, and our computational model can capture the neuron response well in rat during auditory fear conditioning with a mixture of mathematics and biophysical data. Our main contribution is that our model predicts that fear memory is only partially erased by extinction, and inhibition is necessary for a complete extinction, which is a reconciliation of the erasure and inhibition theories. Furthermore, our model shows that the inhibitory connection from interneurons to pyramidal cells serve as an important site for the storage of extinction memory,” the expert adds.
Li notes that, in patients suffering from PTSD, the fear circuit inside the cortex is severely disrupted, which means that the patients cannot retrieve the fear extinction memory. This memory is essential to allowing them to have a normal life, and to returning the brain to the state it had before the incident that triggered the PTSD. In the absence of this circuit, every time a fear cue is triggered, the victim experiences the full effects of fear memory. This negatively affects their quality of life. But, Li adds, it may be that this mechanism could become a target for future drug therapies against PTSD.
“Treatment for PTSD patients depends on which connection stores the fear extinction memory and which circuit misfires. With our model, we can figure out what specific connections store fear/extinction memory and how such connections are disrupted in the pathology of PTSD, which may lead to the suggestions of new drugs to treat the disease,” the scientist adds. Details of the new research appear in the latest issue of the respected scientific Journal of Neurophysiology and Psychiatric Annals.