The Human Nervous System
The Human Nervous System
Reminders
Peer Evaluation - submit on Google Classroom
Holiday Homework Booklet - submit to Ms S
Brain Disorders Brochure - submit to Compass Learning Task
Brain Warmer
Q.3. Label the basic parts of a neuron.
Q.4. The axon is a long extension of the neuron that carries impulses away from the cell body to other neurons and muscles.
Q.5. Synapse is the small gap exists between the axon of one neuron and the dendrite of another neuron.
Parts of the Nervous System Success Criteria
Describe the difference between the central and peripheral nervous systems
Explain the difference between the somatic and autonomic nervous systems
Differentiate between the sympathetic and parasympathetic divisions of the autonomic nervous system
Divisions of the Nervous System
The nervous system is divided into two major subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS comprises the brain and spinal cord.
The PNS connects the CNS to the rest of the body.
Questions to Consider
Identify the part of the nervous system that coordinates the activity of the entire nervous system.
Explain why injury to the spinal cord can result in loss of brain-body control.
Subdivisions of the Nervous System
Nervous System
Central Nervous System (CNS)
Brain: Receives and processes sensory information, initiates responses, stores memories, generates thoughts and emotions.
Spinal Cord: Conducts signals to and from the brain, controls reflex activities.
Peripheral Nervous System (PNS)
Sensory Neurons: Sensory organs to CNS.
Motor Neurons: CNS to muscles and glands.
Somatic Nervous System: Controls voluntary movements.
Autonomic Nervous System: Controls involuntary responses.
Sympathetic Division: "Fight or Flight".
Parasympathetic Division: "Rest or Digest".
The Peripheral Nervous System: Somatic & Autonomic Nervous Systems
The Peripheral Nervous System
Composed of thick bundles of axons, called nerves, carrying messages back and forth between the CNS and the muscles, organs, and senses in the periphery of the body (i.e., everything outside the CNS).
Has two major subdivisions: the somatic nervous system and the autonomic nervous system.
The Somatic Nervous System
Associated with activities thought of as conscious or voluntary.
Involved in relay of sensory and motor information to and from the CNS.
Motor neurons, carrying instructions from the CNS to the muscles, are efferent (means “moving away from”).
Sensory neurons, carrying sensory information to the CNS, are afferent (means “moving toward”).
Questions to Consider
Describe a scenario where the sensory neural pathway would be activated in an individual. State where the information would travel to?
Describe a scenario where the motor neural pathway would be activated in an individual. State where the information would travel to?
The Autonomic Nervous System
Controls internal organs and glands.
Subdivided into the sympathetic and parasympathetic divisions.
Considered to be automatic or not in our voluntary control.
Examples: heart rate, breathing, pupils contracting and dilating, sweating, digestion.
Questions to Consider
What vital processes do you think are governed by the ANS?
What purpose does the autonomic nature of this system serve?
The Sympathetic & Parasympathetic Nervous Systems
The sympathetic nervous system prepares the body for stress-related activities; the parasympathetic nervous system returns the body to routine, day-to-day operations.
The two systems have complementary functions, operating in tandem to maintain the body’s homeostasis.
Homeostasis: A state of equilibrium, in which biological conditions (such as body temperature) are maintained at optimal levels.
Sympathetic Nervous System
Excites the body when we experience an extreme emotion or feel threatened.
Example: A vicious rabid dog running towards you with gnashing teeth activates the sympathetic nervous system to elicit an increase in production of adrenaline, increased heart rate, and increased respiration rate.
Parasympathetic Nervous System
Calms or restores the body to its normal state of functioning after an extreme emotion subsides or threat has passed.
Example: The owner of the dog restrained it to stop it from attacking you. You notice your heart rate and respiration rate dropping to a normal pace and you feel calmer.
Questions to Consider
What are some instances where your Sympathetic NS would be more dominant?
What are some instances where your Parasympathetic NS would be more dominant?
Questions to Consider
In what main way is the functioning of the ANS different from other divisions of the nervous system?
Distinguish between the sympathetic and parasympathetic nervous systems with reference to someone bungee jumping for the first time.
Review + Extend
In table groups, collaborate to create a mind map using the words in the table.
Start by discussing the prompts below.
a. Which words do you know? Which words are you unsure of?
b. Do any of the words relate to each other?
c. Could you add any information to the words?
Then, see if you can organise the words onto a sheet of A3 paper.
Draw links between the words, add definitions and examples to make your mind-map stand out.
Cells of the Nervous System Success Criteria
Identify the basic parts of a neuron
Describe how neurons communicate with each other
Explain the functional relationship between the three types of neurons
The Nervous System
Composed of two basic cell types: glial cells (also known as glia) and neurons.
Glial cells play a supportive role to neurons, both physically and metabolically.
Provide scaffolding on which the nervous system is built.
Help neurons line up closely with each other to allow neuronal communication.
Provide insulation to neurons.
Transport nutrients and waste products.
Mediate immune responses.
Neurons serve as interconnected information processors essential for all of the tasks of the nervous system.
Focus on the structure and function of neurons.
What do Neurons Actually Look Like?
Anatomy of a Neuron
The nucleus of the neuron is located in the soma, or cell body.
The soma has branching extensions known as dendrites.
Anatomy of a Neuron
The neuron is a small information processor.
Dendrites serve as input sites where signals are received from other neurons.
Anatomy of a Neuron
These signals are transmitted electrically across the soma and down a major extension from the soma known as the axon, which ends at multiple terminal buttons.
Anatomy of a Neuron
The axon terminal buttons contain synaptic vesicles that house neurotransmitters, the chemical messengers of the nervous system.
Anatomy of a Neuron
Some axons have glial cells that form a fatty substance known as the myelin sheath, which coats the axon and acts as an insulator, increasing the speed at which the signal travels.
The myelin sheath is crucial for the normal operation of the neurons within the nervous system: the loss of the insulation it provides can be detrimental to normal function.
Anatomy of a Neuron
The neuronal signal moves rapidly down the axon to the terminal buttons, where synaptic vesicles release neurotransmitters into the synapse.
The synapse is a very small space between two neurons where communication between neurons occurs.
The Synapse
Once neurotransmitters are released into the synapse, they travel across the small space and bind with corresponding receptors on the dendrite of an adjacent neuron.
Neurotransmission & Reuptake
Neurotransmitters travel across the synapse and bind to receptors on the dendrites of the postsynaptic neuron.
Once the signal is delivered, excess neurotransmitters in the synapse drift away, are broken down, or are reabsorbed in a process known as reuptake.
Reuptake involves the neurotransmitter being pumped back into the neuron that released it, in order to clear the synapse.
Types of Neurons
Need to know how all the neurons work together.
However, you will only need to draw/label a motor neuron.
Neurons Work Together
If you pick up a hot pan, sensory neurons will carry the sensory information from the PNS to the CNS where interneurons will receive and process the information, before relaying it through to the motor neurons to move your hand so that the pan drops.
Review Questions
Fill in the blanks: Motor neurons are efferent, whereas sensory neurons are afferent.
Compare and contrast the effects of the parasympathetic and sympathetic nervous system, using specific examples.
List the main structural components of a neuron
Describe the function of dendrites and how they relate to neuron communication.
Explain the role of the cell body (soma) in a neuron.
Explain the function of the axon in a neuron, and how it transmit signals.
Define neurotransmitters and explain their significance in neuronal communication.
Describe the process of synaptic transmission, including the release, reception, and reuptake of neurotransmitters.
Zaineb is going for a walk in the park, when a huge gust of wind picks up. Without having to think about it, her eyes squeeze shut. Compare the 3 types of neurons by describing their functions in Zaineb’s reflex action.
Brain Development Success Criteria
explain synaptogenesis and myelination
describe the purpose of synaptic pruning
outline the timeline of events involved in brain development
Synaptogenesis & Synaptic Pruning
Synaptogenesis
In order for a synapse to form between two neurons, the axon terminal of one neuron and the dendrites of another neuron must grow and connect with each other.
Synaptogenesis is the formation of synapses between neurons in the nervous system.
Synapse: To fasten together.
Genesis: To create.
Synapses in the brain begin to form long before birth.
After birth, synaptogenesis occurs so rapidly within the first 15 months that the total number of synapses increases tenfold.
Synaptogenesis is important for brain development.
Synaptic Pruning
The infant brain forms far more neural connections through synaptogenesis than it will ever use.
Weak or unused connections are 'pruned'.
Synaptic pruning is the process of eliminating synaptic connections; the means by which the brain 'fine tunes' its neural connections.
There is a burst of synaptic pruning during early adolescence, with almost half the synaptic connections eliminated at this time.
Myelination
Myelination
Myelination is the process by which brain oligodendrocytes (a type of specialised cell) produce layers of myelin that wrap around the neuronal axons and act as a layer of insulation for the transmission of electric action potentials down the neuronal axon.
The thicker the myelin sheath, the faster the transmission of action potentials.
Myelination
Myelination starts before birth during fetal development and continues through childhood, adolescence and into adulthood.
The most intense period of myelination occurs shortly after birth.
By this stage, axons have also grown in size; they are longer, with denser branching at their ends because there are more axon terminals.
There is also a burst of myelination in adolescence.
Myelination
Myelination typically emerges in the hindbrain then spreads over time into the midbrain and forebrain.
Within the cerebral cortex, sensory areas are myelinated before motor areas.
This progression of myelination through the brain is consistent with the overall course of brain growth and development.
Myelination does not occur in a uniform way across the cortex.
Sensory and motor areas are myelinated by age 3 or 4, whereas association areas in the frontal and temporal lobes responsible for more complex functions are myelinated last.
Review questions
What is a neuron?
Explain the meaning of the statement 'Neurons are the primary functional units of the entire nervous system'.
In what way are the structure and functions of a dendrite different from those of axon terminals?
Draw and label a diagram of a neuron, identifying and briefly summarising the main function of each of its key structures.
(a) Explain what sensory neurons, motor neurons and interneurons are in terms of their specific functions.
(b) Describe the interactive nature of these three types of neurons, with reference to an example not used in the text.
(c) Suggest two possible consequences of damage to significant numbers of each of these three types of neurons.
Chemicals in the Brain Success Criteria
Compare excitatory and inhibitory neurotransmitters, using examples
Contrast neurotransmitters and neurohormones
Discuss the role of neurohormones in the brain and body
Neurotransmitters
There are 1000 neurotransmitters in your nervous system, each with a distinct function
Your neurons can each produce two or more different types of neurotransmitters
Neurotransmitters can be either excitatory or inhibitory
Excitatory vs. Inhibitory
EXCITATORY neurotransmitters increase the activity of the neuron when it is received. E.g., glutamate, aspartate, acetylcholine
INHIBITORY neurotransmitters decrease the activity of the neuron when it is received. E.g., GABA
Excitatory Neurotransmitters
Glutamate plays a role in memory and learning. It is the most common neurotransmitter in your nervous system.
Aspartate is important for keeping the mind focused, promoting metabolism, and can be used to help treat depression and chronic fatigue.
Acetylcholine is what causes your muscles to contract and is released by motor neurons. It is important for attention, learning, and memory.
Inhibitory Neurotransmitters
Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in your nervous system.
It plays a role in regulating stress/anxiety, and acts by reducing neuron activity and thereby calming your nervous system.
Neurohormones
Some neurotransmitters can also act like hormones.
They are called neurohormones.
Some examples include - serotonin, endorphins, and dopamine (your happy hormones)
Neurotransmitters vs. Neurohormones
NEUROTRANSMITTERS
Travel between synapses
Do not travel through the blood
Produced by neurons
NEUROHORMONES
Travel between synapses and the blood
Produced by glands and neurons
Neurohormone Examples
Serotonin produced by neurons and intestinal glands.
In the brain, serotonin regulates mood, sleep and is linked to happiness.
In the intestines, serotonin regulates bowel movements to help get rid of toxic waste.
Endorphins are produced by the pituitary gland and are our body’s natural pain killers, released when we experience pain/stress.
Dopamine is referred to as our reward hormone.
Gets released by specialised neurons in the substantia nigra in the centre of the brain when we do something that makes us feel good.
It is involved in memory, learning, smooth motor movements and coordination.
Review
Describe how neurohormones differ from neurotransmitters.
Discuss where serotonin can be released to impact the brain and body.
Explain why dopamine is referred to as a reward hormone.
Your brain on drugs Success Criteria
Describe addiction on a neural level
Discuss the role of serotonin and endorphins in addiction
Explain how drugs act as agonists or antagonists for a given neurotransmitter system
True or False?
All drugs are illegal (False)
Alcohol is a stimulant (False)
Marijuana can be both a hallucinogenic and a depressant (True)
Polydrug use means taking more than one type of drug at a time (True)
All people who take ecstasy react the same way (False)
A drug overdose means you took so many drugs you died (False)
Legal drugs come with information such as ingredients and recommended dosage (True)
It’s safe to take drugs if you ask another person what type of drug it is first (False)
Legal VS Illegal
What are drugs?
Drugs affect the way your body and mind function; they can change how you feel, think and behave, your understanding and your senses.
Brainstorm
In pairs list as many answers as you can to the question “Why do people take drugs”
Think about reasons young people vs. old(er) people might have…
Some Other Reasons
To relax
For enjoyment
To be part of a group
Sometimes to avoid physical and/or psychological pain
Experiment out of a sense of curiosity
Excitement
Rebellion
Types of Drugs
Stimulant
Drugs that stimulate the brain and central nervous system speeding up communication between the two. They usually increase alertness and physical activity.
Similar category of drugs: Empathogens
Examples - ecstasy, cocaine, caffeine, ice, speed
Depressant
Slow down the activity of the brain and nervous system, slowing down the communication between the two. For medical purposes they can calm nerves, relax muscles and useful for sleeping disorders such as insomnia
Similar category of drugs- Cannabinoids, opioids
Examples – Alcohol, cannabis, GHB, inhalants, benzodiazepines
Hallucinogen (psychedelics)
Interfere with the central nervous system and results in radical distortions of a user’s perception of reality. Profound images, sounds and sensations will be experienced, but they will not actually exist.
Similar category of drugs: Psychedelics, dissociatives
Examples – LSD and magic mushrooms
So Why Do We Become Addicted To These Drugs?
It’s All About Learning
When we learn, a memory is formed.
Dendrites sprout on neurons, synaptogenesis increases, and axon terminals grow.
When we learn something, we feel good because serotonin, endorphins, and dopamine are released.
Glutamate is also released to make the memory more permanent.
Sometimes, We Learn Harmful Behaviour
If we learn a harmful behaviour, like using an addictive substance, it can hijack this reward system.
Drugs can cause neurohormones like dopamine to flood the brain at levels 10 times higher than a natural reward (e.g., learning).
How an Addicted Brain Works
Reward Pathway:
Natural Reward
Addiction Reward
Tolerance, Addiction, Dependence
Drug tolerance occurs when someone abuses a substance over a long period.
When someone continuously abuses a substance, their body becomes used to it, meaning the drug will stop having as much of an effect.
Drug addiction affects someone’s mind and behavior.
Addiction refers to the inability to control the use of drugs or alcohol.
Drug dependance refers to someone feeling like they cannot function normally without the use of the substance, OR medically cannot function without the drug.
E.g. High blood pressure or diabetes medication (not addicted to it but body has physical dependence on it)
Quick Check
Using the scenarios below, explain the difference between drug tolerance, dependance, and addiction.
Sayyam: Tolerance
Luella: Dependence
Anahita & Aanoushka: Addiction
Addiction Dependence Tolerance
Addiction: When you continue to use drugs despite the negative health consequences.
Dependence: When the body physically relies on a drug and cannot perform biological functions without it.
Tolerance: When your body adapts to the drug and a higher dose is required to feel its effects
Drugs Can Act as Agonists or Antagonists
Agonist drugs bind to a neural receptor, activate it, and mimic the effects of a natural neurotransmitter (e.g., alcohol mimics actions of GABA)
Antagonist drugs bind to a receptor and block it’s activity (e.g., caffeine binds to receptors to block the action of adenosine, a neurotransmitter which plays a role in promoting sleep.
Alcohol (depressant)
In the short term…
Amplifies the effect of GABA, which makes us feel relaxed and slows down neuronal activity
It releases endorphins, serotonin and dopamine - making us feel happy
In the long term…
Alcoholism can cause liver cirrhosis, brain damage, heart disease, cancer, stroke, and alcoholism (addiction)
Methamphetamines (stimulant)
In the short term…
makes people feel euphoric
Increases speed of neural transmissions, triggers release of glutamate, dopamine, and serotonin
Transporter cells (responsible for reuptake) are damaged to increase concentrations of dopamine, and serotonin in the synaptic cleft
Increases talkativeness, heart rate, body temperature, and breathing rate
In the long term…
Brain damage, memory loss, mental health problems
Heart attack, stroke, psychosis (paranoia + hallucinations)
Weight loss
Drugs & Addiction in the Media
Much of our understanding of drug addiction comes from the media.
For instance, in Euphoria, the main character Rue struggles with an opioid addiction.
Your Task
Read the script of the diner scene in Euphoria. Answer the following questions.
State the reasons Rue gives for relapsing.
Identify the type of drug(s) Rue is addicted to. Use evidence from the script to justify your answer.
“When you tried drugs for the first time, it, uh, set something off in your brain that's beyond your control. ” Explain what this quote conveys about the reasons behind addiction.
Your Task
Your brain on drugs: case study
Key Science Skills Check Success Criteria
Collect and represent data
Describe the impact of limitations on your data
Construct a conclusion
Activity- ‘You Robot’
Rule a data table in your exercise book with 4 columns to record each condition.
Work with a partner.
With untied shoes, Partner A should sit on a chair in front of Partner B.
Time how long Partner B takes to tie Partner A’s shoelaces. Record the data.
Activity- ‘You Robot’
Repeat step 3 with Partner B whilst closing your eyes. Record the data under condition 2.
Repeat step 3 with Partner B whilst closing your eyes and listening to music with headphones. Record the data under condition 3.
Pre Prac Questions: You Robot
On the paper slip you’ve been give, draw a data table and answer the following questions:
Identify the IV and DV in this experiment.
Write an aim, and hypothesis, Make sure to include the IV and DV.
Post Prac Questions: You Robot
Using the data collected, identify an appropriate representation to display your findings.
Create a data display in your books. Summarise 2 major trends below your data display.
Post Prac Questions: You Robot
Identify the types of neurons that were active during each trial in the experiment.
Using an example from the experiment, describe how your sensory neurons function in your nervous system.
Post Prac Questions: You Robot
Identify any errors/limitations you and your partner encountered during the experiment.
Describe how the errors impacted your results.
Write a conclusion, based on your findings. Make sure to refer back to your aim and hypothesis.
Central Nervous System Success Criteria
recall the components of the CNS
identify the 4 lobes of the brain and their functions
predict the impact of damage to specific lobes
compare the structures of the hindbrain, midbrain, and forebrain
The Spinal Cord
It can be said that the spinal cord is what connects the brain to the outside world.
Because of it, the brain can act.
The spinal cord is like a relay station, but a very smart one.
It not only routes messages to and from the brain, but it also has its own system of automatic processes, called reflexes.
The Brain
The brain is a remarkably complex organ composed of billions of interconnected neurons and glia.
It is bilateral, or two-sided, structure that can be separated into distinct lobes.
Each lobe is associated with certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviors.
The Lobes of the Brain
Each side of your brain contains four lobes.
The frontal lobe is important for cognitive functions and control of voluntary movement or activity.
The parietal lobe processes information about temperature, taste, touch and movement, while the occipital lobe is primarily responsible for vision.
The temporal lobe processes memories, integrating them with sensations of taste, sound, sight and touch.
The Frontal Lobe
The frontal lobe is the part of the brain that controls important cognitive skills in humans, such as emotional expression, problem solving, memory, language, judgment, and sexual behaviors.
It is, in essence, the “control panel” of our personality and our ability to communicate.
DAMAGE TO THE FRONTAL LOBE: Damage to the neurons or tissue of the frontal lobe can lead to personality changes, difficulty concentrating or planning, and impulsivity.
The Parietal Lobe
The parietal lobe is one of the major lobes in the brain, roughly located at the upper back area in the skull.
It processes sensory information it receives from the outside world, mainly relating to touch, taste, and temperature.
DAMAGE TO THE PARIETAL LOBE: Damage to the parietal lobe may lead to dysfunction in the senses.
The Temporal Lobe
It is the lower lobe of the cortex, sitting close to ear level within the skull.
The temporal lobe is largely responsible for creating and preserving both conscious and long-term memory.
DAMAGE TO THE TEMPORAL LOBE: Difficulty placing words or pictures into categories. Language can be affected. Left temporal lesions disturb recognition of words. Right temporal damage can cause a loss of inhibition of talking.
The Occipital Lobe
It processes and interprets everything we see.
The occipital lobe is also responsible for analyzing shapes, colors, and movement, and also for interpreting and drawing conclusions about the images we see.
DAMAGE TO THE OCCIPITAL LOBE: lead to visual field cuts, difficulty seeing objects or colors, hallucinations, blindness, inability to recognize written words, reading or writing, inability to see objects moving
Brain Structures
The Midbrain:
Associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation.
The Hindbrain:
Coordinates functions that are fundamental to survival, including respiratory rhythm, motor activity, sleep, and wakefulness.
The Hindbrain - Structures
Cerebellum: Associated with regulation and coordination of movement, posture, and balance.
Medulla: Responsible for maintaining vital body functions, such as swallowing, breathing, heart rate, blood pressure
Pons: Involved in motor control and sensory analysis
The Midbrain - Reticular Formation
In the middle of the brain and extending up to the front is the reticular formation, made of a network of neurons about the size of your middle finger.
The reticular formation sifts through incoming information to prevent overwhelming the brain, notifies higher brain areas of important details, sustains awareness, and manages alertness and muscle tension.
Forbrain - Two Cortices
The MOTOR CORTEX is located in the Frontal lobe. More of the cortex is devoted to body parts involved in finely tuned movements compared to other parts.
The SOMATOSENSORY CORTEX is located in the Parietal lobe. More of the cortex is devoted to the more sensitive parts of the body, compared to other parts.
Your Task
Read the case studies and determine which area of the brain has been damaged. Use the case notes and theory from class to justify your decision. Be prepared to discuss your reasoning with classmates.
Review Questions
Compare the functions of the parietal and temporal lobes.
Explain the impacts of damage to the occipital lobe.
Identify the area of the brain that you would least prefer to be damaged. Justify your response using your class notes.
Hemispheric Specialisation
contrast the specialisations of the two brain hemispheres
explain the role of the corpus callosum
Are You Left Brain or Right Brain?
Left Brain
Logical
Focused on facts
Realism predominates
Planned and orderly
Math-and-science-minded
Prefers nonfiction
Right Brain
Emotional
Focused on art and creativity
Imagination predominates
Occasionally absentminded
Prefers fiction
Enjoys creative storytelling
Hemispheric Specialisation
Left hemisphere specialisations
specialises in verbal and analytical functions.
Verbal functions involve the use or recognition of words such as in reading, writing, speaking and understanding speech, all of which are important in language.
Analytical functions essentially involve breaking a task down into its key parts and approaching it in a sequential step-by-step way.
Right hemisphere specialisations
specialises in non-verbal functions that do not depend on language skills.
spatial and visual thinking, such as completing a jigsaw puzzle, reading a map or visualising the location of objects or places
recognising faces, patterns and tunes
appreciating music and artworks (but not necessarily producing them)
creative thinking
daydreaming.
more involved in recognising emotions from facial cues (signals), such as a raised eyebrow or trembling lips, and in non-verbal emotional expression.
The Corpus Callosum
A deep furrow divides the cerebrum into two halves, known as the left and right hemispheres.
The two hemispheres look mostly symmetrical yet it has been shown that each side functions slightly different than the other.
The CORPUS CALLOSUM is a bundle of axons which connects these two hemispheres.
What Happens if the Corpus Callosum is CUT?
Sperry and Gazzaniga (1967) were the first to investigate hemispheric lateralisation with the use of split-brain patients.
Sperry and Gazzaniga conducted many different experiments, including:
describe what you see tasks
tactile tests
drawing tasks.
What Happens if the Corpus Callosum is CUT?
Researchers, Sperry and Gazzaniga, investigated patients who had their corpus callosum severed as a way to treat their epilepsy.
At first, it seemed the patients had NO symptoms…
Findings from Sperry & Gazzaniga (1967)
Describe What You See
Picture presented to the right visual field (processed by left hemisphere)
The patient could describe what they saw, demonstrating the superiority of the left hemisphere when it comes to language production.
Picture presented to the left visual field (processed by right hemisphere)
The patient could not describe what was shown and often reported that there was nothing present.
Tactile Tests
Objects placed in the right hand (processed by the left hemisphere)
The patient could describe verbally what they felt. Or they could identify the test object presented in the right hand (left hemisphere), by selecting a similar appropriate object, from a series of alternate objects.
Objects placed in the left hand (processed by the right hemisphere)
The patient could not describe what they felt and could only make wild guesses.
However, the left hand could identify a test object presented in the left hand (right hemisphere), by selecting a similar appropriate object, from a series of alternate objects.
Drawing Tasks
Pictured presented to the right visual field (processed by left hemisphere)
While the right-hand would attempt to draw a picture, the picture was never as clear as the left hand, again demonstrating the superiority of the right hemisphere for visual motor tasks.
Picture presented to the left visual field (processed by right hemisphere)
The left-hand (controlled by the right hemisphere) would consistently draw clearer and better pictures than the right-hand (even though all the participants were right-handed).
This demonstrates the superiority of the right hemisphere when it comes to visual motor tasks.
What Do You Remember About the Video?
Write down absolutely everything you remember about that video we just watched. No talking and no discussions.
Results of Split Brain Surgery
Split-brain patients have undergone surgery to cut the corpus callosum, the main bundle of neuronal fibres connecting the two sides of the brain.
A word is flashed briefly to the right field of view, and the patient is asked what he saw.
Because the left hemisphere is dominant for verbal processing, the patient's answer matches the word.
Now a word is flashed to the left field of view, and the patient is asked what he saw.
The right hemisphere cannot share information with the left, so the patient is unable to say what he saw, but he can draw it.
Review Questions
What is a 'split-brain' experiment?
What medical procedure is used to achieve a 'split-brain'?
Why was a control group used in the Sperry experiments?
What are two key findings about brain function from the split-brain experiments?
(a) If a doctor injected a sedative drug into an artery leading to your left hemisphere just before a friend visits you in hospital, in what way(s) would you be able to greet your friend?
(b) What abilities normally used to greet someone would you be unable to use?Would split-brain experiments be ethically permissible today according to National Statement guidelines? Explain your answer.
Draw a flowchart to briefly summarise the Sperry and Gazzaniga experimental design for their split-brain studies. Your flowchart should refer to a research hypothesis, IV and DVs, experimental design, key results and a possible limitation of the