the brain
DESCRIPTION
The Brain. AP Psychology Chapter 2. Techniques to Study the Brain. Brain lesions experimentally destroy brain tissue to study animal behaviors after such destruction Usually done for scientific and medicinal purposes Not done on humans – unethical. Techniques to Study the Brain. - PowerPoint PPT PresentationTRANSCRIPT
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The BrainAP Psychology Chapter 2
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Techniques to Study the Brain
Brain lesions experimentally destroy brain tissue to study animal behaviors after such destructionUsually done for scientific and medicinal purposes
Not done on humans – unethical
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Techniques to Study the Brain
Naturalistic Observation
Alterations in brain morthpology are now being study and catalogued
EEG (Electroencephalography)Electroencephalography (EEG) is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain.[1] In clinical contexts,
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Techniques to Study the Brain
MRIMagnetic resonance imagingUses magnetic fields and radio waves to create computer generated images of brain tissue
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Techniques to Study the Brain
PET Positron emission tomographyVisual display of activity that detects radio active form of glucose while brain performs a specific task
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Phineas Gage
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Phineas GagePhineas Gage is often referred to as one of the most famous patients in neuroscience. He suffered a traumatic brain injury when an iron rod was driven through his entire skull, destroying much of his frontal lobe. Gage miraculously survived the accident, but was so changed as a result that many of his friends described him as an almost different man entirely.
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Phineas Gagehttp://www.youtube.com/watch?v=oPAqTP7058Q
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Older Brain StructuresThe Brainstemisthe oldest part of the brain,
beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival
functions.
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Brain StemThe Medulla [muh-DUL-uh] is the base of the brainstem
It controls autonomic functions and relays nerve signals between the brain and spinal cord.
respiration
blood pressure
heart rate
reflex arcs
vomiting
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Brain StemThe Medulla [muh-DUL-uh] is the base
of the brainstem that controls heartbeat
and breathing.
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Brain Stem
The Thalamus [THAL-uh-muss]is
the brain’s sensory switchboard,
located on top of the brainstem. It
directs messages to the sensory areas in
the cortex and transmits replies to the cerebellum and
medulla.
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PonsThe Pons plays a role in muscle coordination.
Pons
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Reticular Formation
• Reticular Formationisa nerve network in the brainstem that plays an important role in controlling arousal.
• Damage to this causes a disorder called narcolepsy in which a person falls asleep suddenly during the daytime and cannot resist the sleep.
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The “little brain” attached to the rear of the brainstem. It
helps coordinate voluntary
movements and balance.
Cerebellum
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The Limbic Systemisa doughnut-shaped system of neural structures at the
border of the brainstem and
cerebrum, associated with emotions such as fear, aggression and drives for food and sex. It includes the
hippocampus, amygdala, and hypothalamus.
The Limbic System
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The Limbic System
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Amygdala [ah-MIG-dah-la] two almond-shaped neural clusters that are
components of the limbic system and are linked to emotion (fear and aggression)
http://www.youtube.com/watch?v=cu7A8LIzL1o
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HippocampusMemory – Involved in processing new memories. Everything you learn filters through hippocampus first. Clive Wearing http://www.youtube.com/watch?v=c62C_yTUyVg
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Hypothalamus neural structure / below
(hypo) the thalamus; Basic Drives: hunger thirst body temperature Sex drive (libido)
helps govern the endocrine system via the pituitary gland
is linked to emotion Sometimes referred to as
the pleasure center
Two Parts to HypothalamusVentromedial – “Vomit” Tells you when to stop eatingLateral – “ Lets Eat” Tells you when you are hungry
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Rats cross an electrified grid for
self-stimulation when electrodes are placed
in the reward (hypothalamus)
center (top picture). When the limbic
system is manipulated, a rat
will navigate fields or climb up a tree
(bottom picture).
Reward CenterSanjiv Talw
ar, SUN
Y D
ownstate
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Hemispheres of the BrainLeft:
Language and logicRight:
Spatial, creative
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Why do most strokes affect the right side of the body?Most strokes occur in the left hemisphere
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Cerebral Features:
• Sulci – Small grooves dividing the gyri– Central Sulcus – Divides the Frontal Lobe from the Parietal Lobe
• Fissures – Deep grooves, generally dividing large regions/lobes of the brain
– Longitudinal Fissure – Divides the two Cerebral Hemispheres
– Transverse Fissure – Separates the Cerebrum from the Cerebellum
– Sylvian/Lateral Fissure – Divides the Temporal Lobe from the Frontal and Parietal Lobes
• Gyri – Elevated ridges “winding” around the brain.
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Gyri (ridge)
Fissure (deep groove)
Sulci (groove)
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
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Cerebral Cortex
Cerebral Cortex
Cerebral Cortex - The outermost layer of gray matter making up the superficial aspect of the cerebrum.
http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg
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The Cerebral Cortex(Thin layer of densely packed neurons: .0039-inch)
Cerebral Cortex intricate fabric of interconnected neural
cells that covers the cerebral hemispheres (20 billion nerve cells!)
body’s ultimate control and information processing center
The larger the cortex, more adaptability, capacity for learning
Wrinkles = fissures (3 sq ft w/o them!) *Perceiving, thinking, speaking*
Glial Cells cells in the nervous system that support,
nourish, and protect neurons Aka neuron nannies or glue cells
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The Cerebral Cortex
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Lobes of the Brain (4)FrontalParietalOccipitalTemporal
* Note: Occasionally, the Insula is considered the fifth lobe. It is located deep to the Temporal Lobe.
http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
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Lobes of the Brain - FrontalThe Frontal Lobe of the brain is located deep to the Frontal Bone of the skull.
(Investigation: Phineas Gage)
• It plays an integral role in the following functions/actions:- Memory Formation
- Emotions
- Decision Making/Reasoning
- Personality
Investigation (Phineas Gage)
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
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Lobes of the Brain - Parietal LobeThe Parietal Lobe of the brain is located deep to the Parietal Bone of the skull.
• It plays a major role in the following functions/actions:
- Senses and integrates sensation(s)
- Spatial awareness and perception(Proprioception - Awareness of body/ body parts in space and in relation to each other)
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
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Lobes of the Brain – Occipital Lobe
The Occipital Lobe of the Brain is located deep to the Occipital Bone of the Skull.
• Its primary function is the processing, integration, interpretation, etc. of VISION and visual stimuli.
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
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Lobes of the Brain – Temporal LobeThe Temporal Lobes are located on the
sides of the brain, deep to the Temporal Bones of the skull.
• They play an integral role in the following functions:- Hearing
- Organization/Comprehension of language
- Information Retrieval (Memory and Memory Formation)
Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
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The Cerebral Cortex Motor Cortex at the rear of the frontal lobes / controls voluntary
movements What parts of body occupy most cortical
space? Fingers and mouth (require most precise control)
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Cerebral Cortex Sensory Cortex
at the front of the parietal lobes / registers and processes body sensations
The more sensitive the body region, the more area occupied in the sensory cortex
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The Cerebral Cortex
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Q: What do you notice about the proportions depicted in the aforementioned homunculus?
Q: What is meant by depicting these body parts in such outrageous proportions?
A: They are not depicted in the same scale representative of the human body.
A: These outrageous proportions depict the cortical area devoted to each structure. - Ex: Your hands require many intricate movements and sensations to function properly. This requires a great deal of cortical surface area to control these detailed actions. Your back is quite the opposite, requiring limited cortical area to carry out its actions and functions, or detect sensation.
Back-Hom.
* Note: Homunculus literally means “little person,” and may refer to one whose body shape is governed by the cortical area devoted to that body region.
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The Cerebral Cortex
Functional MRI scan shows the visual cortex activated as the subject looks at faces
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Visual and Auditory Cortex
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Association Areas More intelligent animals have increased “uncommitted” or association areas
of the cortex Association areas = 75% of cortex Interprets, integrates and acts on info processed by sensory areas Associates sensory input with stored memories (complex mystery)
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Language and the Brain Broca’s Area
Location: lower left frontal lobe Major Function
directs muscle movements making speech Speech Production Involved in the analyzing the grammatical
structures of sentences Composition
Contains the motor neurons involved in the control of speech
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Broca’s AphasiaAphasia refers to the speech impairment caused by brain damagePatients know what they want to say but have a hard time getting it out.Spoken sentences lack prepositions and conjunctionsThey are typically able to comprehend words and produce sentences however they must be simple grammatical sentences.Reading and writing are not as affected however, it can be in some caseshttp://www.youtube.com/watch?v=f2IiMEbMnPM
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Wernickes AreaLocations
Left temporal lobeMajor Function
Involved in the interpretation of speechKnown as the language comprehension centerVital for locating appropriate words from memory to express meaning
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Wernickes AphaciaTrouble with speech comprehensionCan’t produce meaningful sentences. Can string together words but what they say is nonsensical Leave out key words and substitute random or invented wordsTalk excessively http://www.youtube.com/watch?v=dKTdMV6cOZw
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Specialization and Integration
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Specialization and Integration
Brain activity when hearing, seeing, and speaking words
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Brain Reorganization Plasticity
brain’s capacity to modify itself brain reorganizes / compensates
after damage, injury children have the most plasticity Example: blind and braille- one
finger used: sense of touch invades visual cortex
http://www.youtube.com/watch?v=2MKNsI5CWoU
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Review Question1. When stroking the face of someone who’s
hand has been amputated, why did the subject feel the sensation not only on his face, but also on his amputated (“phantom”) fingers?
Answer: Hand area of the sensory cortex is no longer used, thus fibers from other sensory areas invade the space. (Note that the hand area is between the face and arm regions of the sensory cortex.)
In other words…. Plasticity!
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Plasticity
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Our Divided BrainSevered Corpus Callosumhttp://www.youtube.com/watch?v=lfGwsAdS9Dc
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Our Divided Brain Corpus
Callosum large band of
neural fibers: 200,000,000!
connects the two brain hemispheres
carries messages between the hemispheres (billion pieces of info / second!)
Corpus callosum
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Our Divided Brain The information
highway from the eye to the brain
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Split Brain Isolate the 2
hemispheres by cutting the connecting fibers between them (corpus callosum)
To remedy uncontrollable epileptic seizures
Testing the “split brain” proves specific functions of each hemisphere
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The Split Brain ExperimentDr. Gazzaniga- 1967
Stare at the Dot…..
he.art1. Which word would the split-
brain patient verbalize seeing? Why?
2. Which word, when asked to point with his left hand, would he report seeing? Why?
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Split BrainExplain the following…
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The Split brain1. If this visual was shown to the right
hemisphere of a split brain patient, how might the patient identify the object?
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The Split BrainInteresting facts about the split brain:
Subjects can simultaneously draw different figures with the left and right hand.
When the 2 hemispheres are at odds, the left will rationalize reactions it doesn’t understand.
The hemispheres are an “odd couple”, each with “a mind of its own.”
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The Split BrainWhich hemisphere is more active
with…Simple requests
Perceiving objects
Decision making (deliberative)
Quick intuitive responses
Recognizing faces
Perceiving , expressing emotion
Right brain
Right brain
Left brain
Right brain
Right brain
Right brain
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Hemispheric Differences in the Intact Brain
Hemispheric specialization = lateralizationBlood flow, glucose, brain waves detected between hemispheres for perceptual tasks and speaking, calculating tasks (EEG, PET, FMRI)
Sedative to artery to specific hemisphere: alters specific functions of the body
If left hemisphere is sedated, what functions would be lost?Language, right side of body limp
If sedative to right hemisphere?Difficulty identifying themselves in altered photo, left side limp
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Questions to consider….1. If a word is flashed to your right hemisphere
(through your left visual field), why does it take you slightly longer to state what you see than it would if flashed to your left hemisphere?
Process time through the corpus callosum
2. Which hemisphere would a deaf person use for sign language?right (visual / spatial) or left (language)?
• Left: to the brain, language is language
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HandednessWhat percentage of humans are right handed?
90%
What ultimately makes you right or left handed?
Genetics? Pre-natal? Social-Cultural?
What expressions can you think of that discriminate against “lefties?”
Right on / right hand man / righteous / right mind -- out in left field / left-handed compliment
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Lefties tend to be…..MusiciansMathematiciansProfessional baseball / cricket playersArchitectsartists
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Disappearing Southpaws
The percentage of left-handers decreases sharply in samples of older people (adapted from Coren, 1993).
The percentage of lefties sharplydeclines with age
10 20 30 40 50 60 70 80 90Age in years
14%
12
10
8
6
4
2
0
Percentage ofleft-handedness
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Brain Structures and their Functions
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Neuroscience, Genetics and Behavior
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True or False?“Basic biological processes underlie all human behavior.”
Various branches of psychology rest on this foundation.
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Biological Psychology(or Psychobiology)
The most significant transformation in modern psychologyAKA Biopsychologists, behavioral neuroscientists, behavior geneticists, physiological psychologists, neuropsychologists…
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An intro to neuroscience…Explain the following…
1. “Modern psychology views each individual as a biopsychosocial system.”
2. “Everything psychological is simultaneously biological.”
3. “The mind is what the brain does..”4. “A brain simple enough to be understood
is too simple to produce a mind able to understand it.”
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Introducing the neuron…
Simple definition: a nerve cell
The incredible neuron…. basic unit of information processing and the
building block of the brain. (and nervous system) Working together with other neurons and cells
throughout the body, it allows us to think, feel, move and breathe.
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A vastly complex system…
Facts about neurons: 100 billion neurons in the human brain and
CNS! (and 400 trillion synapses!)
A grain of sand-size part of the human brain holds 100,000 neurons!
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Neural Structure Dendrite (receives impulse)
Branching extensions of a neuron / receive messages / conduct impulses toward the cell body
Axon (transmits impulse) extension of a neuron, ending in branching
terminal fibers, through which messages are sent to other neurons or to muscles or glands
Remember: “Axons speak, dendrites listen…”
Myelin Sheath(speeds impulse) a layer of fatty cells segmentally encasing the
fibers of many neurons Speeds transmission of neutral impulses
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Neural StructureSo what happens when the myelin sheath begins to wear out?
Alzheimer's (impedes transmissions affecting thought process)Multiple sclerosis: interferes with muscle control (as message to muscles is impeded..)
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Neural Structure
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Neural Communication “an electrochemical
process…”“Neural communication is a conversation between cells that generates our thoughts, actions, moods and memory.”
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Neural Communication Action Potential
a neural impulse; a brief electrical charge that travels down an axon
Stimulated when neuron receives signals from sense receptors stimulated by heat, pressure or light
generated by the movement of positively charged atoms in and out of channels in the axon’s membrane
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Neural Communication“What one neuron tells another neuron is simply
how much it is excited.”
Each neuron has a threshold… the level of stimulation required to
trigger an action potential (or neural impulse)
Threshold is determined by excitatory (accelerator) and inhibitory (brakes) triggers that determine the action potential (neural impulse)
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Neural Communication…
Neurons generate electricity from chemical events (like batteries)The chemistry to electricity process involves the exchange of ions
Ions: electrically charged atoms
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Ions…Resting Potential
Fluid inside a resting axon has negatively charged atomsFluid outside the axon membrane has positively charge atomsNatural state of inside / outside ions = resting potential
Axon’s surface is selectively permeable (it decides what it allows in..)
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Reaching a Neuron’s Threshold…
When the neuron fires…Axon opens gates (selectively permeable) and +charged sodium ions flood the membrane+sodium ions cause depolarizationDepolarization causes reaction as axons pass the impulse down the chain (like dominoes)Opens and closes 100-1000 times /second!
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Reaching a Neuron’s Threshold…
Refractory PeriodOnce impulse has been passed, the axon pumps +ions back out of membrane, and thus recharges
All or none responseIncreased stimulus does not increase the action potential’s intensity (a gun either fires or doesn’t)
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Neural Communication
Cell body end of axon
Direction of neural impulse: toward axon terminals
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Neural Communication Synapse (Where the action is…)
gap between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
tiny gap at this junction is called the synaptic gap or cleft (less than a millionth of an inch!)
Neurotransmitters chemical messengers that cross the synaptic
gaps between neurons neurotransmitters bind to receptor
sites(“lock and key”) on the receiving neuron, thereby influencing whether it will generate a neural impulse
Thus ions passed on to new neuron: exciting or inhibiting its readiness to fire..
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Neural CommunicationReuptake
Excess neurotransmitters are reabsorbed by the sending neuron
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Neural Communication
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NeurotransmittersAbout 75 have been discoveredWe will study 7-8
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Neurotransmitters(Take notes on last 2 listed)
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NeurotransmittersGABA
Inhibitory neurotransmitterUndersupply = seizures, tremors, insomnia
GlutamateExcitatoryneurotrasmitterInvovled in memoryToo much = migraines, seizuresExcitotoxicity: “excite a neuron to death” (glial cells help prevent…)
Chinese food- MSG (glutamate) = headaches
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Neurotransmitters
Acetylcholine [ah-seat-el-KO-leen] ACh triggers muscle contraction
(movement, learning, memory) Undersupply = Alzheirmer’s
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Neurotransmitters Endorphins [en-DOR-fins]
“morphine within” natural, opiate-like
neurotransmitters linked to pain control and to
pleasure “Runners high” Opium, heroine addicts: brain
stops producing natural opiates, thus “withdraws”
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Neurotransmitters…Norepinephrine
MoodToo much = mania / too little = depressionImbalance = bipolar disorder
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NeurotransmittersSerotonin
Sleep, eating, moodRelated to depressionProzac (anti-depressant drug) raises serotonin levels
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NeurotransmittersDopamine
Perceptual awareness, muscle controlToo much = Schizophrania (up to 6x more dopemine)A Beautiful Mind / The SoloistToo little = Parkinson’s Disease (tremors: Muhammad Ali)
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Drugs Affect Neurotransmission
Drugs can be used to affect communication at the synapse
Agonists excite, or mimic the neurotransmittors / or block reuptake (drug addicts and withdraw)Antagonists block, or inhibit neurotransmitters signal (examples=Botox/ botulism blocks Ach)
A complicated process: Brain has blood-brainbarrier that blocks out unwanted chemicals
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Neural Communication
Serotonin Pathways Dopamine Pathways
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Remember…Communication within the neuron is…….
Electrical
Communication between neurons is….chemical
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Glial cells (Glia)Make up 90% of brain’s cellsProtect, nourish neurons Current research suggests possible action potentials, debate as to role…See p. 45: Alchemy of Mind
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An Alchemy of MindExplain fully each of the following quotes from your
reading. “Neurons speak an elite pidgin neither chemical nor
electrical but a lively buzz that joins the two, an electrochemical lingo all their own.”
“It is important to realize that what one neuron tells another neuron is simply how much it is excited.”
It is a small liquid space, as is the air between two whispering lovers, yet so much life happens there. Each junction is a bazaar full of commerce, intrigue and possibility. In the brain, everything depends on almost nothing, a lively space….”
“Coexisting as they must, both neurons and glia are dependable, dependent… central to the brain’s social fabric and perpetual hum.”
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The Nervous System Nervous System
the body’s speedy, electrochemical communication system
consists of all the nerve cells of the PNS and CNS Central Nervous System (CNS)
the brain and spinal cord (encased in bone) Peripheral Nervous System (PNS)
connect the central CNS to the rest of the body’s sense receptors
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The Nervous System
Central(brain and
spinal cord)
Nervoussystem
Autonomic (controlsautomatic action of
internal organs and glands)
Somatic (Skeletal) (controlsvoluntary movements of
skeletal muscles)
Sympathetic (arousing: flight or fight)
Parasympathetic (calming)
Peripheral
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The Autonomic Nervous System Autonomic Nervous System
part of the PNS: controls the glands and the muscles of the internal organs (involuntary)
A Dual System Sympathetic Nervous System
arouses the body, mobilizing its energy in stressful situations (“Fight or flight”, or “sympathy in crisis”)
Parasympathetic Nervous System calms the body, conserving its energy “paramedics to calm down”- lowers heartbeat etc.
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The Nervous System
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The Nervous System
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The Peripheral Nervous SystemLinks CNS to body’s sense receptors
For each of the following, identify it as a function of the Somatic or Autonomic Nervous System.
SneezingTurning the pageScratching your headBreathingKissing your dateDigesting your food
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Communication in the Nervous System
Nerves neural “cables” containing millions of axons part of the PNS (carry PNS info) connect the CNS with muscles, glands, and sense
organs Extend through the body
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Communication in the Nervous System
3 neurons that carry info in the nervous system Sensory Neurons (afferent: millions!)
neurons that carry incoming information from the sense receptors to the central nervous system
Motor Neurons (efferent: millions) carry outgoing information from the CNS to muscles
and glands Interneurons (billions!)
CNS neurons that internally communicate / process sensory and motor neurons (most complex)
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The Central Nervous System
“The motherboard of our humanity…”10’s of billions of neuronsBrain and spinal cordSpinal cord: Information highway connecting PNS to the brain
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ReflexesSpinal Reflex: Autonomic response to stimuli (Single sensory neuron, single motor neuron, interneuron:…..Brain’s not involved!)
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Pain Reflex Sensory neuron, interneuron, motor neuron
a simple, automatic, inborn response to a sensory stimulus
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The BrainCenter for all sensory information and voluntary movement (receives, interprets, decides…)Without the brain…no pain or pleasure, no voluntary movement
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Neural NetworksA Complex Mystery…
Neural Networks interconnected
neural cells with experience,
networks can learn, as feedback strengthens or inhibits connections that produce certain results
computer simulations of neural networks show analogous learning
Inputs Outputs
Neurons in the brain connect with one
another to form networks
The brain learns by modifyingcertain connections in response to feedback
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In other words…“Neurons that fire together... wire together.”
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The Endocrine SystemThe body’s 2nd communication systemInterconnected with nervous system
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Endocrine SystemES glands produce hormonesHormones travel through bloodstream to affect bodyInfluences growth, mood, metabolism, reproduction etc.Thus ES works to keep body in balance in response to stress, exertion, thoughts etc.“Snail mail”- Much slower to process, several seconds, but lasts longer…
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Important Glands…Pituitary Gland (the master gland..)
Pea sized, in middle of brainInfluences growthInfluences other Endocrine glands’ release of hormonesControlled by hypothalamus (brain) Brain – pituitary – other glands – hormones – brain (complex system: blend of Endocrine system and nervous systems)
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Pituitary Gland
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Adrenal GlandsLocated on top of kidneysRelease epinephrine and norepinephrine (adrenaline and noradrenaline)Heart rate, blood sugar, blood pressure etc.
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Adrenal Glands
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What do you know about the human brain?
Answer the following as true or false.1. The larger the brain, the smarter the animal.2. The brain’s structure is a better indicator of
intelligence than it’s size.3. The right side of the brain controls the right side
of the body, and so on with the left.4. You fall in love with your heart, not your brain.5. Your brain uses 20% of your body’s energy, but
makes up only 2% of your body’s weight.
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What do you know about the human brain?
True-False continued…6. Your brain is about the size of a cantaloupe and is
wrinkled like a walnut.7. Your brain feels like a ripe avocado and looks pink
because of the blood running through it.8. The baby’s brain grows 3x in size during its first
year.9. At birth, the human brain weighs 4/5 of a pound,
while an adult’s weighs about 3 pounds.10. Your brain generates about 25 watts of power while
awake- or enough to illuminate a light bulb.
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The typical human brain…
o contains about 100 billion neuronso consumes about ¼ of the body’s oxygeno spends most of the bodies calories o Is 70% water!!!o weighs about 3 pounds