The Human Nervous System Organ system composed of specialized cells o Neurons- transmit signals through body to control actions and reactions Central Nervous System Comprised of brain, spinal cord & retina (eyes) o Integrates information received through the five senses o Coordinates activity in response to stimulation Peripheral Nervous System Consists of sensory neurons, groupings of neurons (ganglia tissue) & nerves o Primary duty is to link the central nervous system to the body limbs and organs
*The Central Nervous System, specifically the brain, will be the focus of this study* Retina Brain/ Upper Spinal Cord Lower Spinal Cord
Mapping the Human Brain The brain can be broken into four interconnected structures o Cerebrum: identifies with higher brain function (thought/ action) Frontal Lobe: controls reasoning, speech & emotions Parietal Lobe: responsible for movement/ orientation & processing of stimulation Occipital Lobe: controls visual perception Temporal Lobe: processes memory and auditory stimulation o Cerebellum: two hemispheres that regulate coordination, posture & balance o Brain Stem: largely responsible for innate/ subconscious bodily functions Midbrain: controls eye and body movement & hearing Pons: responsible for sensory analysis and motor function Medulla: maintains vital life functions (breathing, heartbeat etc.)
Mapping the Human Brain o The Limbic System: controls memory, behaviour, emotion & olfactory senses Thalamus: regulates consciousness (sleep/ alertness) Hypothalamus: links the endocrine system to the brain through the pituitary gland Ex. In reaction to stimuli, the release of chemicals from the endocrine system induces an “emotional” reaction Amygdala: processes and compartmentalizes emotional reactions Memorizes specific chemical (emotional) reactions to certain outside stimuli Hippocampus: stores long term memory and controls spatial coordination
Rational Thought Subconscious Thought Coordination Emotions
Transmitting Messages The brain= intricate communications system o Consists of billions of neurons and neural tissue (ganglia) Every action/ reaction, sensation, memory & emotion is invoked through a system of electrical signals sent through the body o Sent across Neurons Electrically stimulated (non- duplicating) somatic cells that process and transmit info via electrical/ chemical signals
Transmitting Messages Neurons can be categorized into specialized roles o Sensory neurons respond to stimuli affecting our sensory organs o Motor neurons receive signals from the brain & spinal cord, thereby causing muscle contractions and affecting glands (endocrine system) o Interneurons connect neurons within the same region of the brain/ spinal cord
Transmitting Messages Anatomy of a Neuron Soma: central part of the neuron (contains the nucleus) o Where most protein synthesis occurs Dendrite: cellular branches/ extensions to the neuron that facilitate information input Axon: fine, cable- like projection that carries nerve signals to & from the soma o Axon is relatively long compared to soma (tens of thousands of times longer) o Often has several branches which enable communication with numerous target cells Axon Terminal: contain synapses (structures wherein neurotransmitter chemicals are release) that communicate with adjacent neurons
Neural Communication 1) Dendrite receives input from outside stimulation. 2) Neuron reads this information and sends an electrical impulse through the neuron. 3) Electrical signal travels down the axon until it branches toward next target neuron. 4) Electrical signal travels down axon terminal where it approaches a synapse ; there, neurotransmitter chemicals (each specified to invoke a certain response from neurons) carry the signal across the synaptic cleft (area between two neurons’ synapses) to an adjacent neuron. Once a neurotransmitter’s function is fulfilled, it is sent back to the neuron via transporters, shutting off the signal between the neurons.
Damaging the Brain- Drugs Drugs are essentially unfamiliar chemicals introduced to the body o These chemicals (when taken in excessive amounts) interfere with the process of neural information transfer Drugs (ie. Heroine) fool the chemical receptors found on the synapses, lock onto them and activate the neurons o Cause neurons to send abnormal messages to through brain Results in disorientation and altered perception (“high” feeling) Other drugs (ie. Cocaine) cause neurons to release excessive levels of the naturally produced neurotransmitters o Inhibits the recycling of these brain chemicals- ultimately destroys these communication channels
Damaging the Brain- Injury There exist three main processes that cause injury to the brain o Bruising/ Bleeding: When soft brain tissue collides against the cranium, it “squishes” Blood vessels that had once provided oxygen and nutrients for the brain are damaged and pool blood into areas surrounding the brain Causes pressure against neurons= neural death o Tearing: Sudden jolt can either tear glial cells from cranium or tear the established connections between neurons Faulty connection prevents the transference of electrical signals In extreme circumstances, movement, memory and speech are restricted
Damaging the Brain- Injury o Swelling: When injured, location of injury often characterized by bruising and swelling This phenomena is a result of body recognizing injury and attempting to heal it Similarly with the brain: The body recognizes an injury in the cranial area and sends agents to the specified area This causes swelling- putting pressure on the brain, ultimately killing/ damaging neurons
Tearing Vessels torn from inside of cranium, damaging the blood vessels and the surrounding neurons alike.
Swelling Dangerous swelling to the brain; pressure is put on the brain tissue.
Damaging the Brain- Stroke Strokes are one of the leading cause of neural debilitation in the United States o Strokes are results of clogged arteries or a coagulated clump of blood travelling through the arteries, preventing blood from arriving to areas of the body If such clump of blood inhibits the flow of blood to the brain (thereby, inhibiting oxygen) the neurons do not receive the required nutrients and oxygen Depending on the period of time this deprivation is in effect, neurons can either die or suffer extreme damage This results (depending on area of damage)in the temporary or permanent paralysis of certain limbs/ a speech impediment
Result of a Damaged Brain Damage to the brain, although not uncommon, can be very debilitating o The damaging or death of large areas of neurons can result in the following: Memory Loss: certain connections of neurons store specific memories; if these connections are destroyed, the memory is as well Speech Impediment: either as a result of memory loss or inability for neurons to transmit the will to speak to the vocal chords Coma: Injury to the thalamus Inability to Coordinate Movement: Interrupted neural network cannot transmit the act of movement It is said that adult neurons cannot divide, although not strictly true (as interneurons can divide as the adult brain develops), once a neuron is damaged or dead, it is irreplaceable, thus the debility it brings is thought to be permanent
Indication of Rewiring Neuroscience is a fairly new field of study as only recently have scientists been able to take proper imaging of the brain and explored its continual development o Until recently it was assumed that once a specific area of the brain was damaged, it was irredeemable o This view has been tested on several occasion due to the rehabilitation of those who were thought to have permanently damaged their brain
Natural Rewiring Discovery by researchers as the Brain & Mind Institute of the EPFL o Brain naturally rewires itself after an experience Research indicates that the process of creation, testing & configuration of brain circuits occurs over span of a few hours- brain evolves exponentially over course of a day Scientists know the strength of neural connections shape memory & that youth allows for greater brain plasticity (the ability to form neural connections) o New study indicates that these connections switch rapidly o Adaptive natural rewiring= continuous changing and strengthening of neural circuitry
Natural Rewiring Study included observation of neuron clusters of neonatal rats o Instead of observing preferential growth patters, study concluded that neurons have no particular such affinity Neurons perpetually ready to configure new circuits o Over the course of several hours, neural connections formed/ reformed several times This continual rewiring of the micro circuitry of the brain is likened to Darwinian evolution o New experiences trigger connections- only the fittest survive Implies that the natural plasticity can be used to artificially rewire the brain
Mouse Brain Naturally Rewires Research group led by Professor Junichi Nabekura of the National Institute for Physiological Sciences o Observed that mouse brain rewires its neural circuits to recuperate from damaged neural function after stroke Researchers induced cerebral store to right side of mouse brain o Investigated the rearrangement of neural circuitry using two-photon laser microscopy in vivo (fluorescence imaging technique that allows imaging of living tissue at depth
Inducing stroke to the right side (observer’s left side) of a mouse’s brain.
Once stroke had been induced, researchers monitored neural activity o In the two weeks after the stroke, the left side of the mouse brain began to actively rearrange its neural circuitry o By the fourth week, the left side of the brain started to receive sensory information from the left leg Usually this information is delivered to the right side of the brain Scientists monitored the above rearrangement by stimulating the left and right limbs of the mouse and tracking the electrical signals sent to the brain- this data was then compared to normal mouse data (control group) This data reveals that the small mammals’ (and perhaps human) bodies are able to naturally invoke the recuperation process of rewiring the brain Mouse Brain Naturally Rewires
Behavioural Rewiring Scientists from Carnegie Mellon University have uncovered evidence of behavioural rewiring of the brain o Found that intensive instruction to improve reading skills in young children causes brain to physically rewire itself New white matter is created- improves communication within the brain Brain imaging of children between ages of 8-10 showed that quality of white matter (brain tissue that carries signals between areas of grey matter where information is processed) improved significantly after children received 100 hours of remedial training Discovering the possibility of rewiring the brain's white matter has important implications o Aids in the treatment of reading disabilities and other developmental disorders, i.e. autism
Artificial Electrical Impulses Scientists at the Case Western Reserve University have developed method to t ransmit electrical impulses to muscles that are no longer connected to neurotransmitters o Coined FES: Functional Electrical Stimulation Taking the body’s pre-existing electrical signals to control muscles that have been cut off from the neurotransmitters and the nervous system Implants a sensor that reads electrical signals into one of the muscles that is in functioning order o Signals are transmitted through thin implants to the muscle that can’t move This muscle can then be used my moving the muscle with the implant However, implanting too many sensors is not practical o Can begin to affect the fully functioning muscles’ mobility
Microchip Technology Researchers in the Midwest (Case Western Reserve University & Kansas University Medical Center) are electronically rewiring the brain o Developing micro electric circuitry to guide the growth of axons in a damaged brain o Goal is to rewire the brain to bypass region injured from trauma Will connect uninjured neurons to other areas of the brain & restore normal behaviour/ movement
Microchip Technology Researchers believe that repeated communications between distant neurons via simulated electrical impulses in the weeks after an injury may spark long- reaching axons to form & connect o Found that the month following an injury, brain is most susceptible to redeveloping Fibres naturally connect different parts of the brain, performing extensive rewiring so as to recuperate This is the window of opportunity for scientists to develop their treatment
Microchip Technology Scientists have built a multichannel micro electronic device to facilitate this rewiring o A brain- machine- brain interface composed of a microchip & a circuit board Microchip amplifies signals called neural action potentials, produced by one part of the brain, and uses an algorithm to separate this from ambient noise Once this brain spike is isolated, the microchip sends a current pulse to stimulate neurons in the other area of the brain This allows the artificial connection of the two parts of the brain This experiment is still in its early stages- current testing is done on rats, and will graduate to non- human primates
Social Impact Behavioural Rewiring: o Developmental Disability Rehabilitation Currently implemented as a treatment method for children with learning disabilities Enables them to be integrated into society and mentally mature with their cohorts Microchip Technology: o Can Revolutionize Teaching Methods Instead of memorizing information, students can use electrical impulses to store specific data and information o Potential Rehabilitation for Stroke & Brain Trauma Patients Enables the restoration of normal behaviour and movement of patients
Ethical Impact Behavioural Rewiring: o The fairness and mental stresses of implementing strenuous treatment on youth and children Microchip Technology: o Memory/ knowledge is recalled through repeated connection of neurons- can artificially connect these neurons Can implant a specific belief or thought in a mind if the carefully control of these microchips are not monitored How can we be certain that the development of our personality and character is all our own?
Economic Impact Studies in both the natural and artificial rewiring of the brain are fairly new o Still in elementary and experimental stages Large values of grant and research money are required for the continuation and better understanding of this branch of neuroscience Money could either come from universities, private donors, or the Government Becomes an ethical issue if the Government or a private corporation become proprietor of microchip technology- what will they do with it?
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"J. Neurosci. -- Search Result."The Journal of Neuroscience Online. N.p., n.d. Web. 9 Dec. 2010.. "Mouse Brain Rewires Its Neural Circuits To Recuperate From Damaged Neural Function After Stroke." Science Daily: News & Articles in Science, Health, Environment & Technology. N.p., n.d. Web. 27 Nov. 2010.. "Rewiring The Mammalian Brain: Neurons Make Fickle Friends." Science Daily: News & Articles in Science, Health, Environment & Technology. N.p., n.d. Web. 17 Dec. 2010.. "Rewiring a damaged brain."Science Daily: News & Articles in Science, Health, Environment & Technology. N.p., n.d. Web. 17 Dec. 2010.. "Rewiring the Brain: Inside the New Science of Neuroengineering." Wired.com. N.p., n.d. Web. 9 Dec. 2010.
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"description": "N.p., n.d. Web. 9 Dec. 2010.. Mouse Brain Rewires Its Neural Circuits To Recuperate From Damaged Neural Function After Stroke. Science Daily: News & Articles in Science, Health, Environment & Technology. N.p., n.d. Web. 27 Nov. 2010.. Rewiring The Mammalian Brain: Neurons Make Fickle Friends. Science Daily: News & Articles in Science, Health, Environment & Technology. N.p., n.d. Web. 17 Dec. 2010.. Rewiring a damaged brain. Science Daily: News & Articles in Science, Health, Environment & Technology. N.p., n.d. Web. 17 Dec. 2010.. Rewiring the Brain: Inside the New Science of Neuroengineering. Wired.com. N.p., n.d. Web. 9 Dec. 2010.