Today, we are going to look deeper at pain association and the opposite, pain disassociation with movements. First, let us take a look at the most famous conditioned response case, Pavlov’s Dog. Ivan Pavlov was a Russian physiologist that studied the salivation response of dogs during feeding. In seeing food, dogs begin to salivate in anticipation of eating. Prior to feeding his dogs, Pavlov began ringing a bell and then would immediately introduce food to the dogs. After a period of time the dogs began to salivate with only the bell being rung, prior to the animals seeing their food. The bell ringing became associated with the anticipation of food, and thus elicited a physical salivary response.
Why is this important to PT and Pain? It is important to our discussion because the brain remembers different inputs and movements (output). Muscle, ligament, joint movements all provide a stimulus or input to our brain. If those inputs to our brain are consistently danger signals (i.e. pain), then the brain remembers those patterns as negative or threatening.
Let’s look at an example. If Ben injures his shoulder, some motions may be normal and some motions may elicit a pain response. During the non-painful movements, the brain recognizes that these movements are non-threatening. Normal movement without pain ensues and everything functions correctly.
Contrary, the brain remembers every time Ben reaches up into the cabinet and pain is perceived. When Ben feels pain with movement, the brain creates an associated memory that elicits fear anxiety, tonal changes, and even pain prior to the (pain inducing) activity. If these physical and emotional responses occur prior to the movement, how does the body ever have a chance to perform the activity without pain?
Let’s look back at our Pavlov’s dog scenario. Through repetition the bell becomes associated with food in Pavlov’s dog scenario- in out example above movement and pain become associated with one another. The key is disassociation. Overtime Pavlov began to present the food to the dogs without the bell. He later rang the bell, and no salivatory response was obtained. Overtime after the bell and food were separated, the dog no longer associated the bell with the food and thus simply ringing the bell did not elicit pain.
In regards to Ben and our shoulder example, if we can modulate pain or perform an alternate but similar movements that do not increase his pain, the pain and movement pattern can be disassociated. The key is modulating pain, and providing new input to the brain that does not obtain a pain response from the brain. This dissociation is crucial to allowing the patient to return to normal function. In some cases, this is extremely simple, for others, it’s much more difficult.
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