chapter 2 lecture powerpoint myers ed. 10
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PowerPointPresentation
by Jim Foley
2013 Worth Publishers
Chapter 2The Biology
of Mind
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Surveying the Chapter: OverviewWhat We Have in Mind
Building blocks of the mind: neuronsand how they communicate(neurotransmitters)
Systems that build the mind: functionsof the parts of the nervous system
Supporting player: the slower-communicating endocrine system(hormones)
Star of the show: the brain and itsstructures
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Searching for the self by studying the body
Phrenology
Phrenology yielded one big idea--that the brain might havedifferent areas that do differentthings (localization of function).
Phrenology(developed by Franz Gall in
the early 1800s):
the study of bumps on the
skull and their relationshipto mental abilities andcharacter traits
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Biological psychologyincludes neuroscience,behavior genetics,neuropsychology, andevolutionary psychology.
All of thesesubspecialties exploredifferent aspects of:how the nature of mindand behavior is rooted in
our biological heritage. Our study of the biology
of the mind begins withthe atoms of the mind:neurons.
Todays search for the biology of the self:
biological psychology
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Neurons and Neuronal Communication:The Structure of a Neuron
There are billions of neurons
(nerve cells) throughout the body.
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Action potential:a neural impulse that travels down an
axon like a waveJust as the wave can flow tothe right in a stadium eventhough the people only moveup and down, a wave movesdown an axon although it is
only made up of ion exchangesmoving in and out.
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The neuronreceives
signals fromother
neurons;
some aretelling it tofire and someare telling itnot to fire.
When thethreshold isreached, theaction potentialstarts moving.
Like a gun, iteither fires or itdoesnt; morestimulation doesnothing.
This is known asthe all-or-
none response.
The actionpotential
travels downthe axon
from the cellbody to theterminal
branches.
The signal istransmittedto another
cell.However, the
messagemust find away to cross
a gapbetweencells. Thisgap is also
called thesynapse.
How neurons communicate
(with each other):
When does the cell sendthe action potential?...
when it reaches athreshold
The threshold is reached whenexcitatory (Fire!) signalsoutweigh the inhibitory (Dontfire!) signals by a certain amount.
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The synapse isalso known as thesynapticjunction orsynaptic gap.
The SynapseThe synapse is ajunction between theaxon tip of thesending neuron andthe dendrite or cellbody of the receivingneuron.
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Neurotransmitters
Neurotransmittersare chemicalsused to send asignal across thesynaptic gap.
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Reuptake:
Recycling Neurotransmitters [NTs]
Reuptake:After the neurotransmittersstimulate the receptors on
the receiving neuron, thechemicals are taken back upinto the sending neuron tobe used again.
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Seeing all the Steps TogetherNeural Communication:
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Some Neurotransmitters and Their Functions
Neurotransmitter Function Problems Caused by Imbalances
Roles of Different Neurotransmitters
Serotonin Affects mood, hunger,sleep, and arousal
Undersupply linked to depression;some antidepressant drugs raiseserotonin levels
Dopamine Influences movement,
learning, attention, andemotion
Oversupply linked to schizophrenia;
undersupply linked to tremors anddecreased mobility in Parkinsonsdisease and ADHD
Acetylcholine(ACh)
Enables muscle action,learning, and memory
ACh-producing neurons deteriorate asAlzheimers disease progresses
Norepinephrine Helps control alertness
and arousal
Undersupply can depress mood and
cause ADHD-like attention problems
GABA (gamma-aminobutyric acid
A major inhibitoryneurotransmitter
Undersupply linked to seizures,tremors, and insomnia
Glutamate A major excitatoryneurotransmitter;involved in memory
Oversupply can overstimulate the brain,producing migraines or seizures; this iswhy some people avoid MSG(monosodium glutamate) in food
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Serotoninpathways
Networks of neurons thatcommunicate with serotoninhelp regulate mood.
Networks of neurons that
communicate with dopamine areinvolved in focusing attentionand controlling movement.
Dopaminepathways
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Hearing the message
How Neurotransmitters ActivateReceptors
When thekey fits,the site is
opened.
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Keys that almost fit:Agonist and AntagonistMolecules
An antagonist moleculefills the lock so that theneurotransmitter cannotget in and activate thereceptor site.
An agonistmolecule fillsthe receptor site andactivates it, acting like theneurotransmitter.
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The Inner and Outer Parts of theNervous System
The centralnervoussystem[CNS]consists ofthe brainand spinalcord.
The CNS
makesdecisionsfor thebody.
Theperipheralnervoussystem [PNS]consists of
the rest ofthe nervoussystem.
The PNSgathers and
sendsinformationto and fromthe rest ofthe body.
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Types of Neurons
Sensory
neurons carrymessages INfrom the
bodys tissuesand sensory
receptors tothe CNS forprocessing.
Motorneurons carryinstructions
OUT from theCNS out to thebodys tissues.
Interneurons(in the brainand spinal
cord) processinformationbetween thesensory input
and motor
output.
Th N
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The Nervesare not the same as neurons.
Nerves consist ofneural cablescontaining manyaxons.
Nerves are part ofthe peripheralnervous system andconnect muscles,
glands, and senseorgans to thecentral nervoussystem.
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More Parts of the Nervous System
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The Peripheral Nervous System
Th
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TheAutonomic
NervousSystem:
The sympathetic
NS arouses(fight-or-flight)
Theparasympathetic
NS calms(rest and digest)
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The Central Nervous System
The brain is a web ofneural networks.
The spinal cord is full ofinterneurons thatsometimes have a mindof their own.
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Neural Networks
These complex webs of interconnected
neurons form with experience.Remember:
Neurons that fire together, wire together.
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Interneurons in the SpineYour spines
interneurons triggeryour hand to pullaway from a firebefore you can sayOUCH!
This is an exampleof a reflex action.
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The Endocrine System
The endocrine systemrefers to a set of glands that
produce chemicalmessengers calledhormones.
Th B d Sl b t S
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The Bodys Slow but SureEndocrine Message System The endocrine
system sendsmolecules asmessages,just likethe nervous system,but it sends them
through thebloodstream insteadof across synapses.
These molecules,called hormones,
are produced invarious glandsaround the body.
The messages go tothe brain and other
tissues.
d h h
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1. The sympatheticfight or flightnervous systemresponds to stressby sending amessage toadrenal glands torelease thehormones listedabove.
2. Effect: increasedheart rate, bloodpressure, andblood sugar. Theseprovide ENERGYfor the fight orflight!
Adrenal Glandsproduce hormones such asadrenaline/epinephrine,noradrenaline/norepinephrine, andcortisol.
Pancreas
Adrenal Glands
h l d
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The Pituitary Gland
The pituitary gland is the
master gland of theendocrine system. It is controlled through
the nervous system by thenearby brain area--the
hypothalamus. The pituitary gland
produces hormones thatregulate other glandssuch as the thyroid.
It also produces growthhormone (especiallyduring sleep) andoxytocin, the bondinghormone.
Pituitary gland
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The Brain
What well discuss: how we learn about the brain the life-sustaining inner parts of the
brain: the brainstem and limbic system the outer, wrinkled bark: the cortex left, right, and split brains
Questions about parts of the brain: Do you think that the brain is the
sum of its parts, or is the brainactually about the way they areconnected?
What do you think might happenif a particular area of the brainwas stimulated?
What do you think might happenif a particular area of the brainwas damaged or not working
well?
Is it possible tounderstand the brain?
If the human brain wereso simple that we couldunderstand it, we would
be so simple that wecouldnt.
Emerson M. Pugh
but we can try.
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Investigating theBrain and Mind:How did we move beyondphrenology?How did we get inside theskull and under thebumps?
by finding what happenswhen part of the brain isdamaged or otherwiseunable to work properly
by looking at thestructure and activity ofthe brain: CAT, MRI,fMRI, and PET scans
Strategies for finding outwhat is different about themind when part of the
brainisnt workingnormally:
case studies ofaccidents(e.g. Phineas Gage)
case studies of split-brain
patients (corpus callosumcut to stop seizures) lesioning brain parts in
animals to find out whathappens
chemically numbing,magnetically deactivating,or electrically stimulatingparts of the brain
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Studying cases of brain damage
When a stroke or injury damages part of the brain, wehave a chance to see the impact on the mind.
I t ti l b i d
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Intentional brain damage:
performed on animals
has yielded someinsights, especiallyabout less complexbrain structures
no longer necessary, as
we now can chemicallyor magneticallydeactivate brain areasto get similarinformation
Lesions (surgical
destruction of braintissue)
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Split-Brain Patients
Split = surgery inwhich theconnection betweenthe brainhemispheres is cut
in order to endsevere full-brainseizures
Study of split-brainpatients has yielded
insights discussed atthe end of thechapter
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Monitoring activity in the brain
Tools to read electrical, metabolic, and magneticactivity in the brain:
EEG:electroencephalogram
MRI: magneticresonance imaging
fMRI: functional MRI
PET: positron emissiontomography
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An EEG (electroencephalogram)is a recording of the electricalwaves sweeping across the
brains surface.An EEG is useful in studyingseizures and sleep.
EEG:electroencephalogram
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The PET scan allows us to see whatpart of the brain is active bytracing where a radioactive form
of glucose goes while the brainperforms a given task.
PET: positron emissiontomography
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MRI (magnetic resonance imaging)makes images from signals produced bybrain tissue after magnets align the spinof atoms.
The arrows below show ventricularenlargement in a schizophrenic patient(right).
MRI: magneticresonance imaging
Functional MRI revealsbrain activity andfunction rather thanstructures.
Functional MRIcompares successiveMRI images taken asplit second apart, andshows changes in the
level of oxygen inbloodflow in the brain.
fMRI: functional MRI
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Areas of the brain and their functions
The brainstemand cerebellum:
coordinatesthe body
The limbic(border) system:
managesemotions, andconnectsthought to
body
The cortex (theouter covering):
integratesinformation
Th B i
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The Brain:Less Complex Brain Structures
Our tour of the brain begins with parts of the human
brain found also in simpler animals; these partsgenerally deal with less complex functions:
Brainstem (Pons and Medulla)
Thalamus
Reticular Formation
Cerebellum
Limbic System
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The Brainstem:
Pons and Medulla
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The Base of theBrainstem:
The Medulla
The medulla controls the most basic functionssuch as heartbeat and breathing.
Someone with total brain damage above themedulla could still breathe independently, butsomeone with damage in this area could not.
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TheBrainstem:
The Pons
The pons helpscoordinate automaticand unconsciousmovements.
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The Thalamus (Inner Chamber)
The thalamus is thesensory switchboard orrouter.
All sensory messages,except smell, are routedthrough the thalamus onthe way to the cortex(higher, outer brain).
The thalamus also sendsmessages from the cortexto the medulla andcerebellum.
R i l (N lik ) F i
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Reticular (Netlike) Formation
The reticular formation is anerve network in thebrainstem.
It enables alertness,(arousal) from coma towide awake (asdemonstrated in the catexperiments).
It also filters incomingsensory information.
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The cerebellumhelps coordinatevoluntarymovement such as
playing a sport.
Cerebellum(little brain)
The cerebellum has many otherfunctions, including enablingnonverbal learning and memory.
The Limbic (Border) System
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emotions such as fear andaggression.
basic drives such as hungerand sex.
the formation of episodicmemories.
The hippocampus
(seahorse) processes conscious,
episodic memories. works with the amygdala
to form emotionallycharged memories.
The Amygdala (almond) consists of two lima bean-
sized neural clusters. helps process emotions,
especially fear and
aggression.
The Limbic ( Border ) SystemThe limbic system coordinates:
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The Amygdala
Electricalstimulation of acats amygdalaprovokes aggressive
reactions. If you move the
electrode veryslightly and cage
the cat with amouse, the cat willcower in terror.
The Hypothalamus:
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lies below (hypo) thethalamus.
regulates body temperature andensures adequate food andwater intake (homeostasis), andis involved in sex drive.
directs the endocrine system viamessages to the pituitary gland.
The Hypothalamus:Thalamus
Riddle: Why did the ratcross the grid?
Why did the rat want toget to the other side?
The Hypothalamus as a Reward Center
Pushing the pedal thatstimulated the electrodeplaced in thehypothalamus was muchmore rewarding than food
pellets.
R i f B i St t
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Review of Brain Structures
The Cerebral Cortex
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The Cerebral CortexThe lobes consist of:
300 billion synaptic
connections
The brain hasleft and right
hemispheres
outer grey bark structure that is wrinkled in order tocreate more surface area for 20+ billion neurons.
inner white stuffaxonslinking parts of the brain. 180+ billion glial cells, which feed and protect neurons
and assist neural transmission.
The Lobes of the Cerebral Cortex:
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The Lobes of the Cerebral Cortex:Preview
Frontal Lobes
Parietal Lobes
Occipital Lobes
Temporal Lobes
involved in speaking andmuscle movements and inmaking plans and judgments
include the sensory cortex
include the visual areas;they receive visualinformation from theopposite visual field
include the auditoryprocessing areas
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Input: Sensorycortex (Lefthemispheresection receivesinput from thebodys right side)
Output: Motorcortex (Lefthemispheresectioncontrols thebodys rightside)
Functions of the Brain:
The Motor and Sensory Strips
Axonsreceiving motorsignals FROMthe cortex
Axonssendingsensory
information
TO the cortex
Using our knowledge of functions:
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Using our knowledge of functions:
Brain-computer interfaces
and neural prosthetics Here, a robotic arm is
operated through
controls embedded inthe motor strip of thecortex.
We may soon be able to
use computers totranslate neural inputsinto more commandsand words than simplygrabbing food.
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Sensory Functions of the Cortex
Thesensory stripdealswith information fromtouch stimuli.
The occipital lobe dealswith visualinformation.
Auditoryinformation is
sent to thetemporallobe.
The Visual Cortex
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The Visual Cortex
This fMRI scanshowsincreasedactivity in thevisual cortexwhen a personlooks at aphotograph.
A i ti f ti f th t
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Association function of the cortex
More complex animals have more cortical spacedevoted to integrating/associating information
Association Areas
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Association Areas:
Frontal Lobes
The frontal lobes areactive in executivefunctions such asjudgment, planning, and
inhibition of impulses. The frontal lobes are also
active in the use ofworking memory and the
processing of newmemories.
Phineas Gage (1823 1860)
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Phineas Gage (1823-1860)
Case study: In a work accident, ametal rod shot up through PhineasGages skull, destroying his eye andpart of his frontal lobes.After healing, he was able to functionin many ways, but his personalitychanged; he was rude, odd, irritable,and unpredictable.
Possible explanation:
Damage to the frontal lobes couldresult in loss of the ability to suppressimpulses and to modulate emotions.
Parietal Lobe Association Areas
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Parietal Lobe Association Areas
This part of the brain has many functions in the
association areas behind the sensory strip: managing input from multiple senses
performing spatial and mathematical reasoning
monitoring the sensation of movement
Temporal Lobe Association Areas
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Temporal Lobe Association Areas
Some abilities managed by association areas in this bythe temples lobe:
recognizing specific faces
managing sensory input related to sound, which helps
the understanding of spoken words
Whole brain Association Activity
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Whole-brain Association Activity
Whole-brain associationactivity involves complexactivities which requirecommunication amongassociation areas across thebrain such as:
memory
language
attention
meditation and spirituality
consciousness
Specialization and Integration
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Specialization and IntegrationFive steps in reading a word aloud:
Plasticity: The Brain is Flexible
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This 6-year-old had ahemispherectomy to end life-threatening seizures; herremaining hemispherecompensated for the damage.
Plasticity: The Brain is Flexible
If the brain is damaged,especially in the generalassociation areas of thecortex: the brain does not
repair damagedneurons, BUT it canrestore some functions
it can form newconnections, reassign
existing networks, andinsert new neurons,some grown from stemcells
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Our Two
Hemispheres
Lateralization (going to one side)The two hemispheres serve some different functions.How do we know about these differences? Brain damage studies revealed many functions of
the left hemisphere. Brain scans and split brain studies show more aboutthe functions of the two hemispheres, and how theycoordinate with each other.
The intact but lateralized brain
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Thoughts and logic
Details such as trees
Language: words and
definitions
Linear and literal
Calculation
Pieces and details
Feelings and intuition
Big picture such as forest
Language: tone, inflection,
context
Inferences and associations
Perception
Wholes, including the self
Right-Left Hemisphere Differences
Left Hemisphere Right Hemisphere
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Brain Studies
Researchers have studied theimpact of this surgery onpatients functioning.
Split-
To end severe
whole-brainseizures, somepeople have hadsurgery to cut thecorpus callosum,
a band of axonsconnecting thehemispheres.
Separating the Hemispheres:
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p g pFactors to Keep in Mind
Each hemisphere controls the opposite side ofthe body AND is aware of the visual field on
that opposite side.
Without the corpus callosum, the halves ofthe body and the halves of the visual field do
not work together.
Only the left half of the brain has enoughverbal ability to express its thoughts out loud.
S lit i l fi ld
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Split visual field
Each hemisphere doesnot perceive what eachEYE sees. Instead, itperceives the half of the
view in front of you thatgoes with the half of thebody that is controlledby that hemisphere.
Divided Awareness in the Split Brain
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Divided Awareness in the Split Brain
Try to explain the following result:
The divided brain in action
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The divided brain in action
Talent: peopleare able tofollow twoinstructions anddraw two
different shapessimultaneously Drawback:
people can befrustrated that
the right and leftsides dodifferent things
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