Advanced technologies for rewiring the brain
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Advanced technologies for rewiring the brain
"Scientists were unable to find out much about the workings of the brain until relatively recently . . . "
"The freedom to observe the brain that imaging techniques have afforded has allowed for an explosion of knowledge within neuroscience, and has deepened our understanding of the brain and how it works."
Rita Carter in The Human Brain Book, 2009
Frontiers in neuroscience
Advances in science and technology, including an understanding of electricity, have revolutionized neuroscience.
Pioneers like Paul Bach-y-Rita have been on the frontiers of science, using their knowledge and imagination to develop new theories and innovative technologies that pushed the boundaries of science beyond the limitations of established ideas.
The arrival of brain imaging machines in very recent decades gave scientists the technology to observe both the structures and the functions of the living brain.
Evidence thus produced not only changed established mindsets, but also enabled the development of advanced technologies for rewiring the brain.
These technologies include sensory substitution, transcranial magnetic stimulation, deep brain stimulation, and neuroimaging for pain management. We will learn about some of these technologies in the following pages of this module.
Some of the technologies and procedures are at the frontiers of neuroscience. Even though some may have produced impressive results, they may be unavailable beyond laboratories and a very few facilities. The radical nature of a procedure or the very high cost of equipment may restrict it's availability until more studies or more affordable technology can be produced.
First, a word about gene functions
We often think of genes as permanent and unchangeable.
Each cell in our body contains all our genes, stored in its nucleus. However, not all those genes are "turned on."
There are two gene functions.
The template function, which is beyond our control, allows our genes to copy themselves and pass from generation to generation.
However, the transcription function is plastic, and influenced by what we think and do.
A "turned on" gene makes a protein that enables the growth of new connections between neurons. Information about how to make these proteins is "transcribed" from the individual gene.
Intervention strategies and therapies aimed at turning our genes on and off are based on this aspect of brain plasticity.
Enabling sensory substitution
Paul Pach-y-Rita introduced the term sensory substitution to explain that brain plasticity allows us to use one sense, e.g., touch, to gain information that will be used by another sense, e.g., vision. Our sensory areas are able to process signals from more than one sense, so if one sense is damaged, another can sometimes take over or substitute.
He invented an artificial vestibular to help Cheryl Schiltz, a wobbler at the time, who had lost her sense of balance after taking the antibiotic gentamicin to cure a postoperative infection. The antibiotic damaged her vestibular apparatus. The artificial vestibular consisted of: a hat equipped with a sensor to detect movement; connected to the sensor, a tongue display equipped with electrodes that was placed on the tongue; and a computer monitor that translated movement onto a map. Following regular practice over time, and ever-extending periods of a residual effect after practice sessions, the machine enabled the brain to recruit new pathways to take over the function of the vestibular apparatus.
An article from the National Eye Institute reports that Erik Weihenmayer, visually impaired at birth and completely blind by age 13, mountain climbs, skydives, runs marathons and ski, independently - i.e., without guides. He "sees" using a device known as BrainPort, which consists of a video camera and a tongue sensor. When a person becomes blind , they are unable to transmit sensory signals from their retina to their brain. However, we "see" with our brain, and not with our eyes, so sensory substitution is possible. Erik's brain interprets the electrical signals it receives from the video camera and his tongue.
TMS (transcranial magnetic stimulation)
TMS, transcranial magnetic stimulation, is used as a noninvasive method of studying the brain as well as therapeutically - for example, to treat severe depression. TMS provides a way to inhibit or excite neurons, and may be used to turn on an area of the brain, or block it from functioning. It may influence or bring about changes in the behaviour of the individual experiencing brain-related problems. A coil of copper wire inside a paddle-shaped machine encased in plastic produces a changing magnetic field which surges painlessly and harmlessly through the cranium into the specified area of a person's brain. It induces an electric current to cause particular neurons to fire or not to fire.
Deep brain stimulation
Deep brain stimulation involves a surgical procedure. A device often called a brain pacemaker, which is inserted in the brain, sends electrical impulses to selected areas of the brain. This invasive therapy is used to treat chronic pain, Parkinson's disease, and other treatment-resistent disorders, including severe depression.
Neuroimaging for pain management
The term neuroimaging refers to various techniques that either directly or indirectly create images of the structure, function, or chemistry of the brain. They include MRI, fMRI, and PET scans.
Scientists studying pain tell us that there are two pain systems: pain perception and pain modulation.
Neuroimaging therapy measures the brain's activity - live action, in real time, second by second - when it is projecting pain information to patients. When brain activity projecting pain information is repeated over and over, it strengthens pathways and produces changes that may be experienced as chronic pain.
With neuroimaging therapy, patients see the physical process in their brain that causes them to feel pain. The goal is for patients to learn how to understand their pain, how to control their brain activity, and how to modulate the intensity of their pain. Learning to modulate their pain means they practice how to increase and reduce the intensity of their pain.
Chronic pain is different from acute pain. This source, for example, explains that acute pain may begin suddenly to signal disease or result from surgery, broken bones, dental work, burns, cuts, etc. Acute pain may be mild or severe, fleeting, or severe and long lasting. But it stops when the body has healed. Without relief or cure, acute pain may become chronic.
Chronic pain persists even after the body has healed. Chronic pain includes headache, lower back pain, arthritis, etc. The cause of chronic pain is often unknown, but the pain is persistent and severe, and resistant to treatment.
According to the gate control theory of pain, the brain does not passively receive input about pain, but rather, controls the pain signals we experience along a series of "gates." Pain messages travel from the site of injury to the spinal cord, where the brain may "open a gate" to let them through, allowing certain neurons to turn on and transmit their signals. Or the brain may "close a gate" and release endorphins to block the pain signal.
Neuroimaging therapy teaches people to take control of pain signals by learning to control their brain. Patients attempt to reduce and eventually eliminate pain by reversing the process in their brain that causes them to feel pain.
Melanie Thernstrom's article, "My Pain, My Brain," published in The New York Times, presents a personal and informative perspective on neuroimaging and pain management.
Light therapy for neuromodulation
Neuromodulators, sometimes referred to as modulatory neurotransmitters, are chemicals in the brain that affect how neurons respond to messages received from other neurons.
For the most part, it is unnecessary to distinguish between neuromodulators and neurotransmitters. However, distinguishing them may help us better understand chemical transmission between neurons and what neuromodulation therapies attempt to achieve.
Neurotransmitters directly excite or inhibit partner receptors on the dendrites of receiving neurons. Neuromodulators, or modulatory neurotransmitters, enhance the excitatory or inhibitory responses of the receptors.
In other words, neuromodulators increase or decrease the overall effectiveness of the synaptic connections. Examples of neuromodulators include dopamine, serotonin, and acetylcholine. See neurotransmitter.Neuromodulation light therapy - optogenetics - refers to a combination of techniques that use light in the brain to turn cells on and off. It allows the activity of specific brain areas to be precisely altered, revealing how specific neurons contribute to brain functions.
Sharon Begley in Time Magazine - "How the Brain Rewires Itself"
CBC Documentary - Changing Your Mind
Norman Doidge - The Brain That Changes Itself
Jeffrey Schwartz - You are not your brain
The Globe and Mail - Can a controversial learning program transform brains?
Article on Alain Brunet's treatment for PTSD - The Spotless Mind