Ch 3 – Biological Basis of Behavior: The Brain.
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Transcript of Ch 3 – Biological Basis of Behavior: The Brain.
Ch 3 – Biological Basis of
Behavior: The Brain
Human Brain (coronal section)
(1) cerebrum(2) thalamus (3) midbrain(4) pons(5) medulla
(6) top of the spinal cord
Ways we Study the Brain
• Accidents• Lesions• EEG• CAT Scan• PET Scan• MRI• fMRI
Accidents
Phineas Gage story• Personality
changed after the accident.
What does this tell us?
• That different parts of the brain control different aspects of who we are.
Lesions
• Purposeful removal or destruction of some part of the brain/brain tissue.
• e.g., Frontal Lobotomy
EEG
• Electroencephalogram
• Detects brain waves through their electrical output.
• Used mainly in sleep research.
CAT or CT Scan• Computerized
Axial Tomography • 3D X-Ray of brain• Good for tumor
locating, but tells us nothing about function.
MRI
• Magnetic Resonance Imaging
• More detailed picture of brain using magnetic field
• Takes many still pictures and turns images into a movie like production.
• Does not study function!
PET Scan• Positron Emission Tomography• Measures how much of a chemical the brain is using
(usually glucose consumption).
• Good for studying function.
fMRI
• Functional MRI
• PET + MRI• Good for
studying function (hence the f).
f MRI example
The Superbowl Brain• 2006 UCLA experiment using (fMRI) to measure brain responses in a group of subjects while they were watching the Super Bowl ads.
• Amygdala activation
Cerebrum
• 85% of the brain’s weight• Divided into two hemispheres,
each with four lobes• Densely packed neurons we
call “gray matter”• Cerebral Cortex - exterior
surface of cerebrum– Bulges are called gyri. – Small grooves are called sulci. – Large grooves are called
fissures.• Adult Cerebral Cortex ~16’2”• CC ~ 1/16” – 3/16” thick
Two Hemispheres
Generally,
Left Hemisphere = logic & sequential tasks. Language!
Right Hemisphere = spatial & creative tasks. Understanding emotions.
Four Lobes of the Cerebral Cortex
Frontal Lobes
• Contains Motor Cortex
• Contains Broca’s area (left hemisphere only)
• Abstract thought, emotional control & planning.
• Lobotomies are performed on this area.
Four Lobes of the Cerebral Cortex
Parietal Lobes
• Contains Sensory Cortex
• Contains Wernicke’s Area (left hemisphere only)
Where would this girl sense the pain from her sunburn?
Four Lobes of the Cerebral Cortex
What are Motor and Sensory Cortexes?
The wires are “switched”…right controls left.
Sensory Homunculus
A visual representation of how much brainpower is required to operate parts of your body.
Broca's Area– makes words (L
frontal lobe)– Broca’s Aphasia:
disrupts organization of speech
Wernike's Area:– comprehends words
(L temporal lobe)– Wernike's
Aphasia: unable to understand language
Which side of brain are we seeing?
LanguageAreas
Brain Activity when Hearing, Seeing, & Speaking Words
Which side of the brain are we seeing?
Specialization and Integration in Language
Occipital Lobes
• Think “optical”.• Contains Visual
Cortex: • interprets
messages from our eyes into images we can understand.
Four Lobes of the Cerebral Cortex
Temporal Lobes
• Contains Auditory Cortex
• Interprets sound sensed by our ears.
Four Lobes of the Cerebral Cortex
Notice how close the auditory cortex is to the ear.
Functions associated with the Four Lobes of the Cerebrum
Brain Plasticity• The idea that,
when damaged, the brain will attempt to find news ways to reroute messages.
• Children’s brains are more plastic than adults.
Divides the cerebrum into hemispheres.Connects the left & right sides of the brain.
The Brain: Lateralization
• The left and right hemispheres of the brain specialize in particular operations.
Split Brain Patients
Those who, due to epilepsy, have their corpus callosum cut or removed.
The corpus callosum is lesioned to prevent seizures from spreading from one hemisphere to the other.
Split-Brain Research
• Severing the corpus callosum provides data regarding the functions of the brain’s two hemispheres.
Experiment #1 Split-brain patients
• Researcher shows fork to left hemisphere (presents to right side)
• Participant is asked what he saw• Response “fork”• Researcher shows spoon to right hemisphere (presents to left side)
• Participant is asked what he saw• Response: “I don’t know”• Participant is asked to reach in a bag with left hand (right hemisphere) to retrieve what he saw
• He pulls out a spoon…explain?
Testing the Divided Brain
• "The great pleasure and feeling in my right brain is more than my left brain can find the words to tell you."
Roger Sperry (Nobel Prize Winner, 1981)
Dear Left Brain…
• KIA Optima commercial 2012
On the next slide, say the
COLOR of the word without
reading the word that is
written.
Your right brain tries to identify the color, but
your left brain wants to read the word.
Brain Structures
1.Hindbrain2.Midbrain3.Forebrain
(Cerebral Cortex
is part of forebrain)
(R hemisphere, medial view)
The brain was builtlike a house, bottomto top.The hindbrain controlsbasic functions like breathing.The forebrain is themost complex and is responsible for functions like decision making.
Structure & Function
Hindbrain• Structures at the top of the spinal cord.
• Controls basic biological functions.• All animals have hindbrains!
HINDBRAIN
Hindbrain:Cerebellum
• Bottom rear of the brain
• means “little brain”
• Responsible for balance & muscle coordination
Hindbrain: Medulla Oblongata
• Located just above the spinal cord.
Involved in control of basic functions:
•blood pressure•heart rate•breathing
Hindbrain:Pons • Located above
the medulla.• Bridge between
the cerebral cortex & the medulla oblongata
• Involved in facial expressions. (Pons = yawns)
•Connects cerebrum to spinal cord• consists of •Midbrain •Medulla•Pons
parts of hindbrain
The Brainstem
Midbrain• Smallest, innermost region of the brain
• A relay station for auditory & visual information
• Involved in controlling body movement
Midbrain:Reticular Formation
• Coordinates simple movements with sensory information
• Most important structure in Midbrain
• controls arousal & ability to focus our attention. damaged
stimulated
MidbrainReticular Activating
System• RAS or ARAS• Top of reticular formation - responsible for regulating arousal & sleep-wake transitions
• Affects consciousness • Sleep meds affect this part of the brain.
• Damage leads to a coma.
Forebrain• What makes us human (homo sapien not homo
erectus)
• Most recently developed part of brain• Largest part of the brain
• Thalamus, limbic system & cerebral cortex
All gray = forebrain.
Cerebral cortex
Forebrain:Limbic System
Thalamus
• Directly connects lower & higher brain functions
• Influences emotions & visceral responses to emotions, motivation, mood & sensations of pain & pleasure
• Involved with memory
Forebrain:Thalamus
• Switchboard “relay station” of the brain.
• Receives sensory signals from the spinal cord & sends them to other parts of the forebrain.
• Every sense except smell.
Forebrain:Hypothalamu
s • Controls & regulates the Four F’s
FightingFleeingFeeding
“Fornicating”(mating)
• Controls the endocrine system
Maybe most important structure in the brain.
The ventromedial nuclei gives a signal when
to stop eating.
Forebrain:Hypothalamus
The lateral hypothalamus tell your body you’re
full.
Forebrain: Hippocampus
• Involved in the processing and storage of memories.
• Proximity to emotional centers helps explain why memories & emotions are so linked!
Forebrain:Amygdala
• Involved in telling your body to produce norepinephrine (adrenaline)
• More involved in volatile emotions like fear or anger
The emotions of fear & anger have not changed much throughout evolution.