Presentation on theme: "Your Amazing Brain Phantom Limb Pain How can we help amputees to get rid of the pain they feel from their absent limb?"— Presentation transcript:
Your Amazing Brain Phantom Limb Pain How can we help amputees to get rid of the pain they feel from their absent limb?
An experiment to demonstrate how the brain computes an illusion. Explain the illusion and the experience. Show how this can be used therapeutically, to help amputees with pain from the absent limb. Today’s Taster Session in Psychology.
The Phantom Limb Experiment I can make you ‘own’ a rubber hand!
I need a willing volunteer to try out the Rubber Hand Experiment! Or, go to the next slide.
Video clip 1 (Horizon version of the Rubber Hand Experiment.)
It is estimated there are 100 Billion neurons in the human brain. If we count every possible connection potential, it has been computed that there are more neuronal connections possible in one brain, than there are elementary particles in the entire universe! We are only just beginning to unravel the structure and function of this amazing organ, which makes us human.
Proprioception the ability to sense the position and location and orientation and movement of the body and its parts
Proprioception...the ability to sense the position, location, orientation and movement of the body and its parts... The Somato-sensory Cortex is responsible for constantly seeking bio- feedback from the senses, to ensure we are in the optimum position. a positive bio-feedback loop
The brain is constantly integrating sensory information from TOUCH, SOUND & VISION, to form a meaningful proprioception (understanding of where one’s body is in time/space). If the input from these 3 modalities is incongruent (appearing to disagree), the brain is pre-determined to favour the VISUAL information. So, the brain interprets the sensation happening to the rubber hand as actually happening to it’s own hidden hand, and reacts accordingly. The visual cortex Even though we know it is a rubber hand
Here, the brain registers the sensation on the rubber hand is actually happening to them, and react to the hammer as if they were about to be injured. This is entirely involuntary
In one version of the rubber hand experiment, after a few minutes of stroking the rubber hand and their own left hand simultaneously, the person was asked to point to their LEFT hand. They usually pointed to the rubber hand!
Proprioception is the collection of sensory registrations we use to know where our body is in time/space. The somato-sensory cortex is responsible for collating these sensory inputs and is very hungry for input at all times, to keep us safe, upright etc. That bio- feedback loop is constantly being updated
The brain has re-organised its perception of what it is feeling and seeing and tells us we should be feeling this sensation. Although this is a brief, temporary effect in this experiment, in reality it can become a permanent re- organisation of the neural pathways in the brain, e.g. after amputation. The brain keeps sending out messages requesting sensation from the absent limb. It becomes hungry for the sensory feedback it usually gets from that limb. No feedback? Send out stronger neural messages! Eventually, the amputee can register entirely false sensations of pain and contractures of the affected limb. For proprioception to happen, the somato-sensory cortex is hungry for stimulation, all of the time. So, in this experiment...
Contractures Contractures often follow damage to the CNS ability to provide adequate positive bio- feedback from a limb, e.g. after trauma, arthritis or even cerebral palsy. After a while, failing to get good bio-feedback from the hand – the CNS will keep sending out stronger and stronger messages seeking the sensory feedback and will often clench the hand into a fist, (desperately seeking the feedback it is used to getting), the tendons shorten through lack of use and the limb becomes locked in this position. Contractures are painful and even with physiotherapy, that pain is hardly eased. Many amputees experience a virtual contracture, from their phantom limb!
Many amputees experience debilitating pain and distress for years after their limb has been removed. We have only had pain killers to offer them, until now. Most say these don’t help. Amputees are at a high risk of PTSD, depression and suicide, if they suffer from PLP
Feeling the sensation associated with a limb which is no longer present. E.g. Amputees often retain a strong sensation from their amputated arm/leg, (twitching, itching, cramping, contractures etc). It’s as if the limb is still there. Phantom Limb Syndrome (PLS) The subjective sensation of pain in a limb which is no longer there. Originates in the brain, which is still functioning as if the limb is present. Probably caused by an excessive positive feedback loop. Brain tries to clench fist in missing hand – doesn’t get the usual motor feedback – so, brain strengthens the sensation, and so on, until pain level is high and virtual contractures occur. Phantom Limb Pain (PLP)
Some amputees experience something even more strange. A while after their amputation, they begin to get sensation from their absent limb on their FACE! Dr V Ramachandran investigated this and suggested the brain had actually re-wired the nerves to get feedback via the facial muscles instead of the absent limb. Can a brain RE-WIRE it’s neural pathways, after birth???
It’s called NEURAL PLASTICITY. Brain cells (neurons) have an amazing capacity to move/re-locate and transform their function, in response to environmental demand. In the case of brain damage, other neurons can (sometimes) take on the function of the damaged/missing neurons and thus restore the function, at least partially. YES!
An Oxford University study of 7 amputees with PLP, & 7 amputees without PLP & 7 healthy controls. fMRI scans show clearly that the nearby sensory registration area for the FACE has been activated only in the amputees with PLP. This is called MALADAPTIVE NEURAL PLASTICITY PLP is worse in those who had greater pain, pre-amputation. The neurons are setting off others nearby.
Ramachandran is a very clever Psychologist, who suggested that if the brain can re-wire itself to receive feedback from the absent limb on the FACE it should therefore, be possible to use this neural plasticity in therapy, to treat the pain felt from a phantom limb. It is, after all, phantom pain! The brain is registering a FALSE pain, due to lack of positive bio-feedback. Can we give the brain some kind of bio-feedback and cause it to register that the phantom limb is actually there, and fine??? Can I create adaptive neural plasticity to provide false positive bio- feedback? Could this re-wire the CNS to switch off the sensation of pain from the phantom limb?
Mirror Box Therapy This incredibly simple therapy came directly from Ramachandran’s thinking! Use a mirror to create the illusory bio-feedback, showing the image of an apparently ‘healthy’ missing limb. Gradually, flex and move the healthy (existing) limb, e.g. The LEFT leg shown here..... and create the apparent image that the absent (amputated RIGHT) leg is fine and working. Fool the brain! Switch off the pain! Research shows improvement in PLP within an hour! Regular sessions – PLP usually GOES altogether!
Thanks to Dr V Ramachandran! A cheap and effective therapy for PLP, which almost always works. Using the plasticity of the brain! Suitable for: PLP contractures of limbs stroke damage to limbs CRPS
wnQ Video clip of Mirror Box Therapy to treat PLP
But: Not all doctors know about this yet! And, even if they do, their patients may not believe them when they tell them the pain they feel is phantom, and originates IN THEIR BRAIN. Check this out!
Mark Goddard, suffered nerve damage to his arm, after a serious motorbike crash in The incurable CNS pain he has suffered since, eventually led him to lose patience with the doctors treating him. In March 2014 he cut off his own hand at the wrist, with a home-made guillotine.
Mark had tried to cut his hand off with a knife before, but surgeons re-attached it. This time, he burnt the amputated hand, in a bucket, so they couldn’t do that again. Mr Goddard seems convinced this was the only way to rid himself of the pain he felt. Doctors had refused to amputate, because they felt the problem was not in the hand itself, but in the brain. Who was right?
Doctors have said they will now have to amputate his arm above the elbow, due to the nerve damage he inflicted upon himself, as a result of his botched self- amputation. “Father builds guillotine and chops off his own hand in bid to end years of agony after accident left him in pain but doctors did not help...and it still hurts” Mark Goddard, 44, used an axe, some springs and a gate post to cut it off Father-of-one from Devon says NHS has ignored his pleas for amputation Ten days ago sliced off hand and burnt it in bucket to stop reattachment But pain he suffered remains and he has issued deadline for NHS surgery 'I've told them that if nothing is done, I will take the arm off,' he said! 28 March 2014 Of course his pain remains! And, cutting off his arm will not solve the problem!
And the moral of this tale is Always listen to Psychologists! We ROCK!
Get ready for September and more exciting episodes of: The AS Level Psychology Show! Using your excellent research skills, rearrange the information in the boxes on the sheet, to create a TIMELINE for Psychology, as an academic discipline. Early 1900s Present day Bring to your first lesson and we’ll see how correct you were.
See you in September! Come prepared! To be dazzled by Psychology!