A phobia is a strong, irrational fear, often triggered by something that poses little to no actual threat. Phobias are considered an anxiety disorder and cripple the livelihood of many people, sometimes preventing them from performing a normal task without extreme discomfort. In 1999, neuroscientist Karim Nader tested a theory on the process of memory reconsolidation process in which a series of neurochemical events retrace over a memory's route, established by synapses firing and communicating with each other as something is learned. Recollection of memories further strengthen this pathway, and proteins, eventually, are deployed in order to formalize the pathway, signaling the transition between short term and long term memory.
theÂ Mice were conditioned for fear
Nader tested the pathway of memory reconsolidation by experimenting on mice. The mice in the study were conditioned to associate a high-pitched beep with an electrical shock. After ensuring the mice had completely associated the beeping with the pain, freezing in fear from the sound, Nader provided a dose of anisomycin. The antibiotic inhibits the protein synthesis that strengthens the neural pathways in the brain.
ANISOMYCIN interrupts fear consolidation
The rats began to ignore the tone and no longer displayed signs of fear, leading to a conclusion published by Nader in the journal Nature that memories must be reconsolidated every time they are recalled. The permanent neural pathways associated with long term memory formation must be strengthened by the neurochemistry of reconsolidation every time they are used thus being susceptible to interruption by drugs during this time. This interruption can lead to rearrangement of the memory's pathway, making the mice less fearful of the supposedly impending electrical shock.
Merel Kindt and Marieke Soeter, inspired by Nader's study, gathered 15 patients with arachnophobia in a 2009 study and treated them with a beta-blocker propranolol, a drug sometimes administered for treatment of anxiety disorders. The participants of the study were instructed to touch a tarantula as they were treated with propranolol. All 15 of the participants were able to overcome their fear better than the control group, some even requesting to hold the tarantula or touch it again. The follow up study a year and three months later had similar results, with most of the treatment group reporting being even less fearful some time after the day of the study, displaying that the effects of the drug had stuck. Interrupting memory reconsolidation with drugs, she concluded, can be utilized in psychotherapy for those suffering with post traumatic stress disorder and anxiety as a cheaper and more effective option than more traditional methods such as extinction training or exposure therapy.
Sights for the Future
Although the results from Kindt and Soeter were positive, there are still challenges present in utilizing reconsolidation treatments on human patients. Because drugs, in general, are nonspecific in their targets, the usage of drugs to block protein synthesis in animals can be toxic. Propranolol is safer but is also less effective. Human fears are also more complex than the clinical study portrayed, as fear is a multi-faceted emotion of which can be caused by trauma or an underlying anxiety of death. Human reconsolidation-based treatments have yet to reach a consensus of effectiveness by the psychological community; results in these treatments are difficult to reproduce as well as being inconsistent in terms of the measurements of fear. More research into the exact mechanisms of memory reconsolidation and how to interfere with this process in a safer way must be undergone before it can be used to treat human patients routinely.
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