I’m currently attending the Winter Conference on Neural Plasticity in lovely St. Kitts & Nevis and I’ll be tweeting when I can from #wcnp12 when the Internet access in the room decides to cooperate.

Today’s opening session at the meeting was a historical perspective on selected topics in neural plasticity. I thought I’d share an interesting piece of history about one topic that has exploded in terms of research output over the last 20 years: conditioned fear. Michael Fanselow gave the lecture on the history of fear research and focused on the era prior to the exponential growth of the literature, sticking to 1920-1980. Here’s a graph from a very recent review simply noting the number of “fear extinction” papers in the literature (one small sub-field in this topic,) just to give you a sense of how rapidly this field has grown:

Found on Google Images, not sure why it's in front of the paywall!!

I’ll do may best to channel Dr. Fanselow with the next few paragraphs:

John Watson, considered the psychologist who started the American school of behaviorism, published his “Behaviorist Manifesto” in 1913. Here is an excerpt considered as the central thesis of this approach:

Psychology as the behaviorist views it is a purely objective experimental branch of natural science. Its theoretical goal is the prediction and control of behavior. Introspection forms no essential part of its methods, nor is the scientific value of its data dependent upon the readiness with which they lend themselves to interpretation in terms of consciousness. The behaviorist, in his efforts to get a unitary scheme of animal response, recognizes no dividing line between man and brute. The behavior of man, with all of its refinement and complexity, forms only a part of the behaviorist’s total scheme of investigation. [Watson, 1913]

In this “behaviorist’s approach,” Watson placed Pavlov’s classical conditioning experiments as the central tenant to discovery. There was one major problem, though — Pavlov was a notoriously meticulous scientist who relied upon exact experiential design and detailed methods, methods that were all spelled out in his papers, papers written in his native Russian. But nobody in Dr. Watson’s lab spoke Russian. So a number of exact terms and strategies were lost in the (lack of) translation. In turn, Watson’s lab could not reproduce any of the salivation results published by Pavlov, not because the original experiments were wrong, but rather, because potentially because Watson’s lab couldn’t properly conduct the assays. So here’s Dr. Watson, chairman of the department at Johns Hopkins, just having published a manifesto outlining how conditioning was the future of his discipline, leading us all to a better understanding of human behavior, yet he couldn’t get critical experiments to work in his own lab.

Lucky for Watson and colleagues, another Russian scientist, Vladimir Bekhterev, was also working on conditioning, but instead of hunger and salivation, the task involved paired tones and shocks. One of Bekhterev’s main assays involved placing a dog’s paw on a shock-emitting grid and pairing the delivery of shock with a tone. In this experiment, the measurement was the motor reflex (withdrawal) in response to the shock, and after a short learning phase, to the tone alone. Watson learned of these methods because Bekhterev was translated into French, a more accessible language for the lab. And best of all, these shock-tone pairing experiments also worked on humans. Ironically though, because of his lack of access to Russian publications, Watson was unaware of the countless criticisms Pavlov had of Bekhterev’s work, not least of which involved the sloppiness of the laboratory’s conduct, including a lack of proper controls. But the behaviorists would not be denied and psychology marched forward with conditioned fear!! In fact, one of the more famous historical conditioned fear experiments (and also one of the more controversial) was conducted shortly after, the “Little Albert Experiment.” This was initially some of the first evidence that classical conditioning could be done in humans.

Fast-forward a few decades, after a number of “advances” in conditioned fear learning by B.F. Skinner and others, an American psychologist by the name of Robert Bolles (FULL DISCLOSURE: Bolles was Fanselow’s graduate advisor) came along and declared that the study of fear and the learning of a fear response was all hogwash. Bolles’ analysis of the literature led him to conclude that 90% of the variance in learning from all of these studies depended on the type of assay being used and the animal being studied. These “big picture” issues regarding the fear operant learning literature and more were manifested in this publication, cited 727 times to date (according to Google Scholar.) Basically, as Fanselow and Bolles explored more specifically here in 1980, many of the fear responses being studied for the previous 60 years were manifestations of species-specific defensive mechanisms and reactions, elicited avoidance behaviors rather than operant behaviors. One could say that there is technically no “response learning” when an individual is afraid. Instead, instinct kicks in and instincts are not necessarily rational and amenable to learning, having been honed by evolution over thousands of years. This is why so many anxiety disorders in humans are so debilitating; response learning is difficult, even in the face of rational training. This warning from Fanselow near the end of the lecture stuck with me: “One cannot use scientific intuition to understand fear from a rational perspective.”

With the rise of this better understanding of animal behavior/defense mechanisms and improvements in methodology and technology, we are now taking a more careful approach to the science of fear, including the study of many other aspects of the fear response that can be studied from a learning perspective, including extinction and context, just to name a couple. So as it turns out, although “conditioned fear” has emerged as terms of choice for this research (dating back to its roots,) the term Pavlov would have preferred was “conditional fear,” the precise terminology of classical conditioning. Of course, Watson wouldn’t have known this when these terms were coined in the 1920s. He didn’t speak Russian.