Even if you’re not a scientist or a psychology student, the name Ivan Pavlov probably rings a bell. Remember, Pavlov’s dogs? Pavlov was a Russian physiologist (and Nobel Laureate) who made his mark on history for his work in classical conditioning. Having contributed to the fields of physiology and neurological science, Pavlov developed a body of work centered on involuntary reflex actions and conditioning.
Many of Pavlov’s experiments investigated how we could manipulate events or environmental stimuli to influence behavior. Pavlov's passion led him to conduct his most famous study in which he was able to elicit a response from dogs in which they would salivate whenever he would ring a bell.
Pavlov’s dogs began to associate the ringing bell with getting fed (a conditioned response), hence why they would salivate. Pavlov's work would go on to influence a variety of fields, from education to psychology. Classical conditioning is the foundation of modern behavioral modification practices.
Here's how conditioning works. Humans (and other animals) learn to associate environmental stimuli that initially lacks significance with a reflexive response. After they become conditioned, anytime they are exposed to the stimuli again they present an automatic response (without even thinking about it).
Another scientist -- Dr. John B. Watson -- followed Pavlov's lead and demonstrated how Pavlovian conditioning produces phobias and fear responses. One of his most controversial studies was called the "Little Albert" experiment. Watson ran the test on rabbits (raising ethical questions). By exposing the rabbits to loud sounds with otherwise pleasant stimuli, the rabbits developed a phobia around these stimuli.
Firstly, Pavlov’s work has helped us unravel how fear conditioning can be used outside the lab. In hopes of developing new treatments, more and more scientists have used the Pavlov model to further our understanding of various psychiatric disorders such as PTSD.
Similar to the rabbits, patients who suffer from PTSD have developed a fear response to a traumatic event (or events). Later, when they are exposed to seemingly neutral stimuli in otherwise safe and ordinary situations, they can experience severe physiological and behavioral responses.
Moreover, consistent with animal studies, researchers have found that PTSD alters the human brain - particularly the amygdala, hippocampus, and prefrontal cortex. Further research has demonstrated that malfunctioning synaptic plasticity (the brain's ability to adapt - or rewire) likely plays a significant role in what causes PTSD.
There are two concepts here: fear conditioning and memory extinction.
Fear Conditioning: During fear conditioning, the brain rewires itself creating a new association between the stimuli they were exposed to and their automatic fear response.
Memory Extinction: During memory extinction, the brain rewires itself so that it no longer associates that stimuli with a fear response.
Many researchers believe that patients with PTSD have a malfunctioning synaptic ability that prevents them from being able to replace the fear response. Predictably, when patients are later exposed to the stimuli, they experience the undesirable fear response.
By attempting to understand the synaptic basis for post-traumatic stress, scientists hope to be able to develop more effective medications that influence synaptic chemical actions. Our hope is that scientists will be able to develop new medications (including cannabinoid and non-pharmacological treatments) to alleviate many of the symptoms patients experience so they can more efficiently improve their outcomes.