Mind Over...Mind? How Attention Modulates Pain

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Biology 202

2006 First Web Paper

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Mind Over...Mind? How Attention Modulates Pain

Gray Vargas

Several years ago, at the Biofeedback Research Institute in California, researchers and friends watched as Joo Bang Lee drove a bicycle spoke through the fleshy part of his forearm (1). While this scene is already strange enough, the most remarkable part about it is that this man did not feel any pain. If you were only looking at the recordings of his brain waves researchers were making, you would not be able to tell that anything significant had happened to him (the expected spike of activity was not present). How was this man able to ignore his screaming sensory neurons? Or were his neurons even screaming in the first place? He explained that he was concentrating on his "ki," a small area at the bottom of his stomach, and once he applied his mind in that way he no longer existed in this world and felt no pain (1). He was focusing his attention on something besides the painful stimulus, and this redirection of focus let him turn off his conscious sensation of pain. In this paper I will discuss how this might be possible, and the implications that follow.

When subjected to the same painful stimulus, different individuals may experience differing levels of intensity and unpleasantness. In addition, one individual may feel different levels of pain depending on the situation. Thus, the nervous system and the brain are not a purely reactive stimulus/response machine when it comes to pain. There are steps in between the sensation and perception (a cognitive interpretation of the sensations) that determine how the pain is experienced (2). Some researchers claim that in order to feel pain, one needs to attend to and process the stimulus in an emotional way. If pain is not attended to or processed in a certain way then it might not reach the level of conscious awareness. Thus, how much attention one gives to pain determines how intense and unpleasant the sensation will be.

There are many situations in which an individual might not attend to their pain as much as they normally would—such as a stressful situation like war or in competitive situations like a sports event. There are countless stories of athletes and soldiers being terribly injured and only realizing after the event that something was wrong (3). Normally, pain serves to notify us of a problem and point our attention towards it. This way we can alter our behavior in such a way that we can treat the injury and somehow reduce the pain. But there were times when we have bigger problems than pain—such as survival, when attending to an injury could be costly or even fatal. (For instance, in our evolutionary past, if we were injured and being chased by a tiger.) Hence, in the classic evolutionary crisis, we could fight or flee without being bothered by an injury. Thus, it is adaptive to prioritize what we attend to and in some cases, to be able to ignore pain. Therefore, if one could fool their brain into thinking that there was something more important than the upcoming pain, they could theoretically feel the pain less—or none at all.

There is scientific evidence that individuals in much less stressful settings can be distracted in various ways so that they do not feel as much pain (4)(5)(6). And likewise, paying attention to a painful stimulus increases its intensity ratings (5). Studies have shown that being hypnotized, either by a hypnotist/experimenter or through self-hypnosis, diminishes pain sensation (6)(7). Since 1998, in a Seattle Hospital, burn patients experience a virtual reality environment called "Snowworld" while they are being subjected to a painful procedure to care for their wounds (4). Patients report feeling less pain during these virtual reality sessions, and the effect is not diminished with multiple treatments (4)(8). It has been found that during the more difficult trials of a cognitive task, subjects report lower pain intensity from a painful stimulus (9). Even during childbirth, part of the popular Lamaze strategy is finding a focal point to focus on to distract the mother from the pains of childbirth (2). Listening to music has been found to reduce postoperative pain (11). However, one study found that using mental imagery and music during suturing procedures did not reduce pain or distress ratings relative to other patients who did not experience the imagery and music. Regardless, almost all of the patients reported that the treatment was beneficial, that they would use it again, and that they would recommend it to others (9). This is consistent with many other studies that find no positive effect of distraction while the subjects are still confident in the treatment. The reason for these inconsistencies is unclear, besides differing intensities of pain and individual differences in response to distraction. Interestingly enough, though, it has been found that individuals that were high or low self-controllers, and with different cognitive styles, did not differ consistently on how well distraction helped their pain (2). In general, though, when this distraction method is found to be useful, it is in alleviating low intensity pain.

All of these findings support the idea that we all have a finite pool of attention that we must divide between different tasks or stimuli. Thus, if a good amount of attention is devoted to an activity, there is less attention available to devote to the processing of the pain (2). The catch, according to some researchers, and the reason we cannot all completely will away our pain, is that focused attention is not perfect. It has been shown in many studies that when people are told to attend to specific stimuli they can still detect certain "outside" stimuli (2). There are individual differences in this variable, too. Therefore, perhaps Joo Bang Lee is so talented at focused attention that he really does not have any attention left to devote to his pain. It would be interesting to run Lee on selective attention tests to see how his results are different from others, if at all. If this theory is true, then we should all practice our focused attention. But how can we perfect this ability, and is everyone capable of doing so with enough practice?

How are these modulating effects of attention on pain manifested in the brain? One candidate region is the prefrontal cortex, a region in the frontal lobe responsible for many higher order brain functions. Studies have shown that activity in a region of this cortex (the dorsolateral prefrontal cortex) is related to attending to pain (10). Another region of the prefrontal cortex (the orbitofrontal cortex) was shown to be more active when individuals are being distracted from pain, and in this study, also experiencing less pain (5). Interestingly, activation of the prefrontal cortex has also been shown to lower the midbrain response to painful stimulus in rats and cats (10). Researchers have postulated that there is a pain modulation pathway, at least in rats, that includes the midbrain, medial thalamus, and prefrontal cortex (10). It is known that the prefrontal cortex is active during selective attention, and these findings point towards an inhibitory role of this region on activity in the "lower," midbrain areas that are responsible for the sensation of pain. Therefore, it appears that "willing away pain" is a function of the prefrontal cortex.

All of this research has left me with several questions. For one, the two scenarios discussed here where attention is directed away from pain—when someone is in either a very stressed, excited state or a very relaxed, calm one—are very different in their levels of arousal and in general mental state. And in the former, adrenaline plays a large role in causing analgesia. It would be interesting to research how adrenaline interacts with the prefrontal cortex, and whether levels of adrenaline are consciously controllable. I also wonder what it means in terms of the brain to have a finite pool of attention. Can only so many neurons fire at once? Or is it that only certain numbers of signals can be simultaneously and consciously processed by the frontal lobe and prefrontal cortex? (A function of our limited short term memory capacity.) I also wonder if alpha waves are associated with analgesic effects—since these are the types of brain waves that tend to be present during meditation, hypnosis, and relaxed states.

When Professor Grobstein asked in class whether anyone was able to "will away pain" a large portion of the class raised their hands. This along with our discussion of pain made me very interested in the topic. One of the most interesting issues this topic raised for me was the idea of a hierarchy in the brain—the ability of some regions to inhibit or diminish activity in other areas of the brain/nervous system. We are not always ruled by our more basic, instinctive brain regions and functions. And this, I think, is a key part of what makes us human. Before starting this research, I assumed that pain responses/perceptions were much more automatic than I found them to be. The idea of individual differences in pain also fascinates me—that in some individuals the ruling regions in the brain's hierarchy have more or less power. I wonder how neurons in the peripheral nervous system fit into the hierarchy, and how levels of activity in these neurons change with different attention and different levels of prefrontal cortex activity.

This area of research could lead to pain relief for millions of patients—and a simple, cheap one at that. However, all of these treatment strategies have a high level of variability between individuals—e.g. some people are more or less susceptible to being hypnotized or able to focus selectively. This means that even if these strategies are found to have analgesic effects, not every patient will be able to benefit to the same extent. But regardless, if we can find a way of emulating Joo Bang Lee and his attentional state, it is possible that we too can have conscious control over our pain.

1)Turn Off Your Mind to Turn Off Pain, an interesting article about Joo Bang Lee

2) McCaul, K.D. & Malott, J.M. (1984). Distaction and Coping With Pain. Pschological Bulletin, 95(3): 516-533.

3)Iverson Puts Heart Online, Ignores Injuries, a fun article about Allen Iverson

4)VR Devices Trick the Brain into Ignoring Pain , an interesting article about virtual reality pain treatment

5) Bantick, S.J., Wisel, R.G., Ploghaus, A., Clare, S., Smith, S.M., and Tracey, I. (2002). Imaging how attention modulates pain in humans using functional MRI. Brain, 125(2): 310-319.

6) Syrjala, K.L., Cummings, C., Donaldson, G.W. (1992). Hypnosis or cognitive behavioral training for the reduction of pain and nausea during cancer treatment: a controlled clinical trial. Pain. 48(2):137-46.

7) Spiegel, D., & Bloom, J.R. (1983). Group therapy and hypnosis reduce metastatic breast carcinoma pain. Psychosomatic Medicine, 45(4): 333-339.

8) Hoffman, H.G., Patterson,D.R., Carrougher, G.J., Sharar, S.R. (2001). Effectiveness of virtual reality-based pain control with multiple treatments. Clinical Journal of Pain, 17(3): 229-235.

9) Albert, R.E. (2002). The effect of guided imagery and music on pain and anxiety during laceration repair. Dissertation Abstracts International: Section B: The Sciences and Engineering, 62(11-B):5030.

10) Lorenz, J., Minoshima, S., and Casey, K.L. (2003). Keeping pain out of mind: the role of the dorsolateral prefrontal cortex in pain modulation. Brain, 126:1079-1091.

11) Good et al, 1999, cited in (9)

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