Zwetlana Rajesh
Age 18 | Pembroke, Ontario
Canada-Wide Science Fair 2016 Excellence Award: Intermediate Gold Medal | Western University $4,000 Entrance Scholarship | Renfrew County Regional Science Fair Award: First Place
The brain is truly a magical organ and it has always fascinated me. My interest in neuroscience has led me to consider complex concepts and issues about the nervous system. The idea for this experiment came from a scenario that I experienced during my volunteering days in a long-term care home. A resident in the home asked me to adjust his shoe on his left foot, as it was hurting him, and he felt the shoe was an ill fit. As I bent down to help him, I was astounded to find that this resident did not have a left foot at all! My research started there. From that point on, I tried to study and understand the neurophysiology behind this phenomenon.
INTRODUCTION
The cerebrum, the largest part of the human brain, contains the cerebral cortex, which also contains nerve cell bodies. The cerebrum is responsible for the integration of complex sensory and motor functions (“Brain,” n.d.). The human brain has an assigned area for each part of our body. Every body part is connected to specific neurons in the brain (neurons are the basic units of nervous system, having specialized cells that carry messages between the brain and other parts of body). All sensory information received from each area of our body is conveyed to the brain for interpretation via neuronal connections and are then relayed back to the muscle, tissue or organ for motor action (British Neuroscience Association & European Dana Alliance for the Brain,” n.d.). For example: when we detect a stimulus, like a touch (sensation) on our hand, the neurons in our hand send signals to the corresponding neurons in the brain, and when this is interpreted by our brains, we feel the touch. If it is a painful stimulus, we withdraw our hands (motor action) (“Pain and how you sense it,” n.d.). If a neuron is inactive for long time, the active regions in the brain take over inactive regions. A reorganization of the brain’s neurons happens, because of brain malleability. The area representation for the hand is close to the area for the face in the cerebral cortex. When this hand area in the brain stays inactive for longer duration, the neighboring representing area takes over (Scott, 2011). This is called ‘Neuroplasticity’; and it allows the neurons in the brain to compensate for injury and disease. This also enables people to adjust their activities in response to new situations or to changes in their environment. It is a process of re-learning and highlights certain recuperative abilities of the brain.
When a part of our body, such as an arm, is amputated, the limb is no longer physically present, but the area of representation for the arm in the brain’s cerebral cortex still exists and slowly gets reorganized. This gives the amputee a realistic sensation that the amputated limb is still there. The experiencing of body parts that are not present on your body is called a ‘Phantom Limb’(Cruz, Nunes, Reis, & Pereira, 2003). Often, this can be a painful experience for patients and may require rehabilitation and physiotherapy to overcome the pain.
When your body is in a normal state, all systems remain calm. At a time of stress, our body releases hormones, creating chemical changes that cause increased heart rate, perspiration and low oxygen saturation through shallow increased breath rate (“The Science of Stress, Heart Rate and Breathing,” 2013).
Research was done to prove that it is possible to trick the brain and create an illusion to make a person assume a rubber hand as one’s own body part in a rubber glove experiment (Ehrsson, Holmes, & Passingham, 2005). Knowing this, I wondered whether it was possible for the brain to accept a phantom limb as part of one’s body without the cue of an artificial limb. The experiment was designed based on this query. With the background knowledge, I also thought of numerous novel applications and future implications the experiment could have if successful. The experimental conditions were then decided to involve using human subjects of different age groups and the non-dominant hand chosen to be removed from sight. Cotton ball is selected to provide minimal tactile cuing. A screwdriver was used to create a threat and stress levels were recorded using a pulse oximeter, as it rapidly records the change of the dependent variables: heart rate and oxygen saturation. Other dependent variables were facial expressions and reaction to stimuli. The controlled variables were the environment of experiment and moods of the subjects.
PURPOSE
The purpose of this experiment is to assess if the brain of a non-amputee accepts a simulated phantom limb as part of their body. If there is an increase in subjects’ heart rate and decrease in Oxygen Saturation level after the sudden introduction of screwdriver, then it can be concluded that the brain of the non-amputee has accepted the simulated phantom limb as part of their body.
MATERIALS
1. Chair
2. Cotton balls
3. Desk
4. Non-transparent screen
5. Pulse oximeter
6. Screwdriver
7. Towel
PROCEDURE
1. The subject and the researcher sit on opposite sides of a desk
2. Record the resting heart rate and oxygen saturation of the subject using a pulse oximeter
3. Have the subject place their dominant hand on a desk and cover their non-dominant hand using a towel
4. Place an opaque screen between the dominant and non-dominant hand
5. Using a cotton ball, simultaneously stroke the subject’s dominant hand and do a similar motion in air on the non-dominant side. Instruct to focus on non-dominant side where the air is being stroked. Stroke for about 20-30 seconds
6. After 20-30 seconds, suddenly introduce the blunt screwdriver, performing a rapid stabbing motion aimed towards the empty space ‘occupied’ by the invisible hand
7. Notice the changes, if any, in subject’s reaction and facial expression. Immediately record their heart rate and oxygen saturation using the pulse oximeter. Also note what the subject said with regards to the experiment
8. Compare the results with the prerecorded heart rate and oxygen saturation (step 2)
RESULTS
The experiment was performed with 10 different subjects. After the experiment was performed, 90% of the subjects’ heart rates increased and oxygen saturation decreased (Table 1). This is visually represented in Figure 1 and Figure 2. This change in heart rate and oxygen saturation indicates that a stress reaction was created in the subjects with regard to accepting the limb as part of their body and protecting the limb from getting hurt.
Table 1. Observations Summary.
Figure 1. Heart rate (bpm) comparison.
Figure 2. Oxygen saturation (SpO2%) comparison
9/10 of the subjects felt the presence of an invisible hand as part of their body before the screwdriver was introduced and wanted to guard their hand as the screw driver approached. This demonstrates that the brain accepted the invisible hand as the subjects’ own hand. The subjects were startled, and surprised, while some reported of being mildly scared and feeling defensive as the screwdriver approached the invisible limb. Some subjects even stated that they felt as if their own hand was going to be stabbed and that they felt “hypnotized” into believing a hand was present. On the contrary, one of the subjects described that they did not feel an invisible hand, nor did they express a significant change in their facial expression.
DISCUSSION
Some intriguing results were observed during this experiment. This experiment utilizes the phantom sensation to help with proper and faster reorganization of altered sensory and motor maps in the brain, which could enable patients such as stroke patients to regain lost functions. It is possible that if this process is reversed, that we could perform surgery without anesthesia and avoids anesthesia complications! This technique can reduce phantom limb pain by recreating phantom limb sensation and thus encouraging a better sense of motor control and pain control. By creating phantom limb sensation in the area of lost limb, we could train an artificial limb effectively as it would be able to send signals to cerebral cortex and a new mapping would be created which can enhance the functioning of the artificial limb, with more coordination.
CONCLUSION AND FUTURE WORK
By analyzing the results from the experiment, the phantom limb sensation created in a non-amputee could be accepted by the brain as part of their body. The recorded variation in a majority of the subjects’ oxygen saturation, heart rate, facial expressions and reactions to the stimuli further proves the theory. I hypothesized that I would be able to see a change in subject’s heart rate and oxygen saturation reading after the stabbing of the screwdriver on the phantom limb, and this proved to be true.
In the future, the experiment can be tested with more participants. I also want to analyze the times at which the subject starts to feel the phantom limb and how long it lasts if uninterrupted. Moreover, the dependent variables could be analyzed using more advanced technologies such as fMRI and EKG. In addition, the effect of the experimental environment the subject can be looked into. I would also like to research and find an experimental method that could prospectively create a sensation that a body part is not present, which will aid with one of my applications: performing a surgery without anesthesia.
ACKNOWLEDGEMENTS
I am thankful to the local long-term care facility from where I was inspired to perform this experiment, and all of the staff there for volunteering to take part in this experiment and providing the space and equipment needed.
REFERENCES
Brain. (n.d.). Retrieved from http://www.scienceclarified.com/Bi- Ca/Brain.html
British Neuroscience Association, & European Dana Alliance for the Brain. (n.d.). Science of the Brain - An Introduction to Young Students. Retrieved from http://www.uni-heidelberg.de/md/izn/teaching/neuroscience/img/neuroscience-of-the-brain-english.pdf
Choi, C. Q. (2013, April 12). Even Non-Amputees Can Feel a Phantom Limb. Retrieved from http://www.livescience.com/28694-non-amputees-feel-phantom-limb.html
Cruz, V. T., Nunes, B., Reis, A. M., & Pereira, J. R. (2003). Cortical remapping in amputees and dysmelic patients: a functional MRI study. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/14757926
Ehrsson, H. H., Holmes, N. P., & Passingham, R. E. (2005, November 9). Touching a rubber hand: feeling of body ownership is associated with activity in multisensory brain areas. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1395356/
Pain and how you sense it. (2012). Retrieved from http://www.mydr.com.au/pain/pain-and-how-you-sense-it
Scott, H. (2011, April 27). Brain Plasticity Influencing Phantom Limb and Prosthetics. Retrieved from https://scholarcommons.usf.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=1047&context=honors_et
The Science of Stress, Heart Rate and Breathing. (2013, October 28). Retrieved from http://www.mybasis.com/en-CA/blog/2013/10/the-science-of-stress-heart-rate-and-breathing/
BIBLIOGRAPHY
Doidge, N. (2016). The brain’s way of healing: Remarkable discoveries and recoveries from the Frontiers of neuroplasticity. NY, NY: Penguin Books.
Cajal Santiago Ramon y, Pasik, P., & Pasik, T. (1999). Texture of the nervous system of man and the vertebrates. Wien: Springer.
Crawford, C. S. (2014). Phantom limb: Amputation, embodiment, and prosthetic technology. New York: New York University Press.
Zwetlana Rajesh is currently an undergraduate student at Queen’s University, from Pembroke, ON. She was selected to represent Renfrew County at the Canada Wide Science Fair consecutively in 2016 and 2017, receiving silver and gold medals. Zwetlana enjoys poetry, badminton, yoga, public speaking and is involved in volunteering and numerous extracurricular projects in the areas of mental health, youth advocacy, healthcare, and sustainable farming