Illusions and manipulating the brain

Understanding that the brain constructs the ‘reality’ in which we live has been a vital step forward in neuroscience. One of the best studied illusions is the rubber hand illusion (RHI) (see a video here) in which the brain takes ownership of a false hand. In fact, the brain can take ownership of any number of inanimate objects. The prop is taken on as part of ‘self’ and feels like it is part of the individual subject to the illusion. A more common example of ownership is wearing a pair glasses and when removed they continue to feel as if they are in situ. All that we see and all that we feel is created by our brains, meaning that our experiences, albeit very real, are unique to us and hence an illusion.

As an example, a recent study by Banakou created an illusion whereby the subjects were placed in the virtual body of a 4 year old. They viewed the environment from a first person perspective (as you looking out as opposed to looking from the outside). The outcome was fascinating:

An illusory sensation of ownership over a surrogate limb or whole body can be induced through specific forms of multisensory stimulation, such as synchronous visuotactile tapping on the hidden real and visible rubber hand in the rubber hand illusion. Such methods have been used to induce ownership over a manikin and a virtual body that substitute the real body, as seen from first- person perspective, through a head-mounted display. However, the perceptual and behavioral consequences of such transformed body ownership have hardly been explored. In Exp. 1, immersive virtual reality was used to embody 30 adults as a 4-year-old child (condition C), and as an adult body scaled to the same height as the child (condition A), experienced from the first-person perspective, and with virtual and real body movements synchronized. The result was a strong body-ownership illusion equally for C and A. Moreover there was an overestimation of the sizes of objects compared with a nonembodied baseline, which was significantly greater for C compared with A. An implicit association test showed that C resulted in significantly faster reaction times for the classification of self with child-like compared with adult-like attributes. Exp. 2 with an additional 16 participants extinguished the ownership illusion by using visuomotor asynchrony, with all else equal. The size-estimation and implicit association test differ- ences between C and A were also extinguished. We conclude that there are perceptual and probably behavioral correlates of body-ownership illusions that occur as a function of the type of body in which embodiment occurs. Read the full paper here

Illusionists have created amazing tricks for hundreds of years. Without necessarily understanding the neuroscience, these impressive individuals have been able to manipulate the brains of audiences, using methods of distraction and attentional blindness.

When it comes to pain, we can use certain illusions to trick the brain into perceiving that the body is in a different state. The RHI we have already described and is well studies as is mirror therapy whereby the affected body part is concealed whilst the individual looks at a mirror reflection of the healthy side. This tricks the brain into seeing normal tissue and movement in many cases but not all. Mirror therapy is part of the graded motor imagery programme (see here), an approach grounded in neuroscience that targets the brain. In part, GMI evolved from witnessing that mirror therapy can in fact make some people experience more pain despite the fact that they are moving their unaffected side. The pain is due to the brain perceiving activity and threat in the affected side because of the reflective image. The pain is very real but created by an illusion. Actually it is an illusion of an illusion because as already stated, what we see is an illusion created by the brain.

Although this science may come as a surprise, the fact that our brains can be manipulated is very useful in rehabilitation. We can apply these methods to develop normal, healthy movement in many cases as part of a comprehensive treatment and training programme.

For further information or to book an appointment, please visit our clinic site: Specialist Pain Physio Clinics
t. 07932 689081

Keith Barry: Brain Magic

The way in which ‘magic’ works is now intriguing neuroscientists as the art of illusion describes certain aspects of brain function.

What we see is created by the brain, using the basic information via the eye and optic nerve, then creating our reality with pre-existing knowledge of the world, expectation and fills in the gaps. Arguably, all that we see and feel are illusions as they are created by our unique brains.

With pain being a brain experience, some argue that pain is an illusion. Do not misunderstand this to mean that you cannot feel it, but rather that the brain allocates pain to a body location using the body schema – see the next video. Understanding this process allows for Keith Barry and others to deceive us and entertain with the seemingly impossible.

Creating therapeutic illusions can change pain perception. For example, altering the perceived size of the painful area and mirror box therapy are two examples. We use these techniques commonly, often with great effect that allows for a period of healthy movement and ‘good’ feedback to the brain, hence helping with the desensitising process - see here.

If you suffer symptoms as a result of a car accident, you may like to fast forward through the driving trick.

CRPS & pain – some things you may not have realised

Pain is multidimensional. Pain is 100% produced by the brain in response to a perceived threat. The brain allocates a location using the cortical maps, hence why we feel pain in our backs or knees. The brain tries to make sense of the situation, scrutinising what is going on on the basis of past experience (learning) and comparing to the information being received from ALL body systems. This is the reason for the term ‘multisystem output’ as a way of describing what is happening when we are in pain.

The most obvious reason why the pain worsens is that we move, exercise or sit for too long. All of these activities are ‘physical’, asking the tissues to take the strain either rapidly or gradually. On reaching a certain level of strain, lower than normal in cases of sensitivity, nerves start sending danger signals to the spinal cord. From the spinal cord messages are relayed to the brain, still on the subject of danger. Theses are not pain signals. It is only when the brain interprets the information as threatening that the experience of pain is produced – an output from the brain. This is typical in acute situations when the injury or problem is new. The pain is vital, useful and motivates action.

A key point to understand is that the brain does not actually need the tissues to produce pain. Think about phantom limb pain. There is no limb. There are no tissues. But it hurts. It seriously hurts in may cases. So, there are other ‘triggers’ for pain besides actually moving or asking the tissues (muscles, tendons, ligaments, bones etc) to take the strain. Common ‘non-tissue’ circumstances that can amplify pain include stress, circadian rhythms, menstrual cycle, fatigue and thoughts. I think that to take this on board is an enlightening experience. To understand that your pain can be as a result of other reasons besides what you are doing physically can help to explain why it hurts at times when you have not done anything differently and you really cannot comprehend why the pain has increased.

A further influential player in our experiences is vision. I’m really interested in this as the process of ‘seeing’ is much aligned to the way pain is experienced. Information is received by the brain via the optic nerve. The brain must make sense of this data and create a credible outcome, again very much using past experience to judge the present. We still see a bird in his cage despite slender lines dividing his body (the struts of the cage). We don’t see ‘slices’ of a bird. Also consider optical illusions. A great deal of work has been done looking at the use of vision for therapeutic effect, i.e. the graded motor imagery programme. Clearly the mirror box is creating the illusion that the affected side is moving and appearing to be normal. Imagined movements requires us to ‘see’ and feel movement although we are keeping very still. The premotor cortex is very active during these imagined movements, and this part of the brain is involved in the production of pain.

From the book 'Explain Pain' by D Butler & L Moseley

What we are seeing is deemed to be an illusion in some quarters. We all have different experiences and backgrounds. Our beliefs about life and ourselves vary. This will influence what we ‘see’. If you have just watched a scary movie and then go outside into the dark to put the rubbish out, a shadow could be ‘seen’ as something more dangerous than if you have just laughed at a comedy show. Also consider when we see someone injure themselves, again on TV or watching sport. We often wince, grab our corresponding body part or take some other defensive action. Our brains are interpreting someone else’s danger and imprinting this onto our experience, perhaps as a way of helping us to learn that it is dangerous to be in their situation. This is likely due to the mirror neuron network and that when we watch someone else move or position themselves, our virtual body that exists in the brain mimics that position. There are also aspects of empathy in sharing someone’s pain. But, if that position is ‘threatening’ to our brain, we will hurt.

What do we do about that? We use strategies to desensitise and habituate, similar to dealing with any fear. The modern way of tackling pain states, especially those that persist, is using a biobehavioral approach. This means that as well as addressing tissue health with movement and treatment, we must concurrently target the brain and other systems that are involved in the pain experience, e.g. immune, endocrine. It is called ‘top-down’ – ‘bottom-up’. Top-down referring to the brain and our beliefs, understanding, thoughts, how the brain is controlling movement and protecting us; bottom-up signifying the need to nourish the tissues with movement. These exist on a spectrum and both are addressed in a contemporary biopsychosocial treatment programme – see http://www.specialistpainphysio.com/treatment

Below are some interesting abstracts in relation to this blog:

Pain. 2010 Feb;148(2):268-74. Epub 2009 Dec 11.

Pain sensation evoked by observing injury in others.

Source

School of Psychology, University of Birmingham, Edgbaston, UK.

Abstract

Observing someone else in pain produces a shared emotional experience that predominantly activates brain areas processing the emotional component of pain. Occasionally, however, sensory areas are also activated and there are anecdotal reports of people sharing both the somatic and emotional components of someone else’s pain. Here we presented a series of images or short clips depicting noxious events to a large group of normal controls. Approximately one-third of this sample reported an actual noxious somatic experience in response to one or more of the images or clips. Ten of these pain responders were subsequently recruited and matched with 10 non-responders to take part in an fMRI study. The subjects were scanned while observing static images of noxious events. In contrast with emotional images not containing noxious events the responders activated emotional and sensory brain regions associated with pain while the non-responders activated very little. These findings provide convincing evidence that some people can readily experience both the emotional and sensory components of pain during observation of other’s pain resulting in a shared physical pain experience.

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J Cogn Neurosci. 2007 Jan;19(1):42-58.

The neural substrate of human empathy: effects of perspective-taking and cognitive appraisal.

Source

INSERM Unit 280, France.

Abstract

Whether observation of distress in others leads to empathic concern and altruistic motivation, or to personal distress and egoistic motivation, seems to depend upon the capacity for self-other differentiation and cognitive appraisal. In this experiment, behavioral measures and event-related functional magnetic resonance imaging were used to investigate the effects of perspective-taking and cognitive appraisal while participants observed the facial expression of pain resulting from medical treatment. Video clips showing the faces of patients were presented either with the instruction to imagine the feelings of the patient (“imagine other”) or to imagine oneself to be in the patient’s situation (“imagine self”). Cognitive appraisal was manipulated by providing information that the medical treatment had or had not been successful. Behavioral measures demonstrated that perspective-taking and treatment effectiveness instructions affected participants’ affective responses to the observed pain. Hemodynamic changes were detected in the insular cortices, anterior medial cingulate cortex (aMCC), amygdala, and in visual areas including the fusiform gyrus. Graded responses related to the perspective-taking instructions were observed in middle insula, aMCC, medial and lateral premotor areas, and selectively in left and right parietal cortices. Treatment effectiveness resulted in signal changes in the perigenual anterior cingulate cortex, in the ventromedial orbito-frontal cortex, in the right lateral middle frontal gyrus, and in the cerebellum. These findings support the view that humans’ responses to the pain of others can be modulated by cognitive and motivational processes, which influence whether observing a conspecific in need of help will result in empathic concern, an important instigator for helping behavior.

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Hum Brain Mapp. 2009 Oct;30(10):3227-37.

Empathic neural responses to others’ pain are modulated by emotional contexts.

Source

Department of Psychology, Peking University, Beijing 100871, People’s Republic of China. shan@pku.edu.cn

Abstract

Recent brain imaging studies indicate that empathy for pain relies upon both the affective and/or the sensorimotor nodes of the pain matrix, and empathic neural responses are modulated by stimulus reality, personal experience, and affective link with others. The current work investigated whether and how empathic neural responses are modulated by emotional contexts in which painful stimulations are perceived. Using functional magnetic resonance imaging (fMRI), we first showed that perceiving a painful stimulation (needle penetration) applied to a face with neutral expression induced activation in the anterior cingulate cortex (ACC) relative to nonpainful stimulation (Q-tip touch). However, when observation of the painful stimuli delivered to a neutral face was intermixed with observation of painful or happy faces, the ACC activity decreased while the activity in the face area of the secondary somatosensory cortex increased to the painful stimulation. Moreover, the secondary somatosensory activity associated with the painful stimulation decreased when the painful stimulation was applied to faces with happy and painful expressions. The findings suggest that observing painful stimuli in an emotional context weakens affective responses but increases sensory responses to perceived pain and implies possible interactions between the affective and sensory components of the pain matrix during empathy for pain.

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Neuron. 2007 Aug 2;55(3):377-91.

The cerebral signature for pain perception and its modulation.

Source

Centre for Functional Magnetic Resonance Imaging of the Brain, Clinical Neurology and Nuffield Department of Anaesthetics, Oxford University, OX3 9DU Oxford, England, UK. irene@fmrib.ox.ac.uk

Abstract

Our understanding of the neural correlates of pain perception in humans has increased significantly since the advent of neuroimaging. Relating neural activity changes to the varied pain experiences has led to an increased awareness of how factors (e.g., cognition, emotion, context, injury) can separately influence pain perception. Tying this body of knowledge in humans to work in animal models of pain provides an opportunity to determine common features that reliably contribute to pain perception and its modulation. One key system that underpins the ability to change pain intensity is the brainstem’s descending modulatory network with its pro- and antinociceptive components. We discuss not only the latest data describing the cerebral signature of pain and its modulation in humans, but also suggest that the brainstem plays a pivotal role in gating the degree of nociceptive transmission so that the resultant pain experienced is appropriate for the particular situation of the individual.

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Neuroimage. 2009 Sep;47(3):987-94. Epub 2009 May 28.

The influence of negative emotions on pain: behavioral effects and neural mechanisms.

Source

Nuffield Department of Anaesthetics, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK. kwiech@fmrib.ox.ac.uk

Abstract

The idea that pain can lead to feelings of frustration, worry, anxiety and depression seems obvious, particularly if it is of a chronic nature. However, there is also evidence for the reverse causal relationship in which negative mood and emotion can lead to pain or exacerbate it. Here, we review findings from studies on the modulation of pain by experimentally induced mood changes and clinical mood disorders. We discuss possible neural mechanisms underlying this modulatory influence focusing on the periaqueductal grey (PAG), amygdala, anterior cingulate cortex (ACC) and anterior insula as key players in both, pain and affective processing.

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Disclaimer: this blog is for informational purposes only. If you are concerned or unsure about your pain or condition, you must consult with your GP or a health professional.

Imagery & mirrors

Many readers will know about mirror box therapy for CRPS and other painful conditions. The Graded Motor Imagery Programme that we use at Specialist Pain Physio is sequential training that starts with laterality, progressing to imagined movements and then to mirror therapy. There is some really good data for the programme and CRPS but it can also be effective with other chronic pains. Interestingly we are now seeing components of GMI being used and written about in the popular press, most recently for Parkinson’s disease and arthritis.

Brain training for pain

A brief article in New Scientist describes the Parkinson’s research by David Linden at Cardiff University. 10 subjects were asked to think about movement for 45 minutes whilst they were having brain scans. Five of the subjects were given feedback that showed them how they were activating the brain and all were asked to practice the imagery at home. Two months later rigidity and tremor had reduced some 37% in the feedback group. The thinking is that there is cortical change underpinning this improved function that is feasible.

Mirror therapy for pain

At The Society for Neuroscience annual meeting 2011 a small study was performed with arthritis (OA & RA) patients used mirror therapy. Subjects observed the moving reflection of the researcher’s hand in the mirror whilst producing the same movement themselves with their hidden hand. After 1 minute it was noted that the subjects pain improved. This was reported in The Guardian today.

For details on our treatment programmes including imagery, mirror therapy, graded motor imagery and other neuroscience-based techniques, come and see our website at http://www.specialistpainphysio.com or call 07518 445491. Our clinics are based in London and Surrey http://www.specialistpainphysio.com/clinics

The illusion of vision

What we look at and what we see can be completely different. Our perception is filtered by what we think we know, past experience and expectation. Indeed this is what the brain does before creating a plausible image. When we are looking at an animal in a cage we do not think ‘there is a series of segments of a lion’ when the bars are positioned in front of the animal. No, the brain creates an experience of a lion. Equally, if we have just watched a spooky film and on taking the rubbish out into the alley we see a moving shadow we are more likely to believe that it could be an intruder rather than a cast of a branch.

In the world of neuroscience, all conscious experiences are created by the brain including vision and pain. The world that we see in front of us is no exception, however it is entirely possible that we can miss something right befroe our very ‘eyes’ if the brain does not perceive it to be there or happening. Christopher Chabris and Daniel Simons explain this brilliantly in their book that discusses the illusions of vision, memory and knwledge amongst other functions that we take for granted. Daniel Simons is known for a famous experiment that you can do here:

Have a go and see how you get on. Then ask friends and family! It helps to explain how we can be falsely secure in what we see, know and experience.

The illusion of vision is relevant to daily practice with patients in pain for several reasons. Firstly it demonstrates how we must be targeting the brain and the processing of information to change someone’s experience of their pain and secondly how we can use vision and illusion to ‘train the brain’. In simple terms, the brain is operating in a particular mode or state that is giving the current experience of the body and mind that could include pain.

To alter this experience we need to give the brain something else to do that has meaning and purpose. Of course, the meaning will need to be personal and contextual to that person but could include a position change, an exercise, a change of thought, writing a poem or drawing a picture. Treatment-wise we think about the types of intervention that could either change the flow of informatioin into the brain or to stimulate descending pathways that runs from brain to spinal cord and dampen the activity here in the dorsal horn.

In brain training we are focusing upon particular changes that we know take place in the brain termed cortical plasticity (click here, here and here). This includes the Graded Motor Imagery programme (and click HERE) that we use as part of the treatment programme and training for CRPS and other conditions.

If we are living in an illusion, which many of the leading lights in the field of neuroscience are saying, then this is still our experience and our ‘illusion’. Modern rehabilitation is not only about developing health and function in the tissues, but also changing the brain so that the sense of self is normal in terms of ‘feeling’ the body and in controlling movement. Both of these are developed through redefining the sensory and motor maps that change when we are in pain and not moving properly. Only in achieving this will nomal service be restored in function, confidence and longevity.