The Brain AP Psychology Chapter 2. Techniques to Study the Brain Brain lesions experimentally...

The BrainAP 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

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,

Techniques to Study the Brain

MRI

Magnetic resonance imaging

Uses magnetic fields and radio waves to create computer generated images of brain tissue

Techniques to Study the Brain

PET Positron emission tomography

Visual display of activity that detects radio active form of glucose while brain performs a specific task

Phineas Gage

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.

Phineas Gagehttp://www.youtube.com/watch?v=oPAqTP7058Q

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Older Brain Structures

The 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 Stem

The 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 Stem

The 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.

Pons

The Pons plays a role in muscle coordination.

Pons

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

The Limbic System

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

HippocampusMemory – Involved in processing new memories.

Everything you learn filters through hippocampus first.

Clive Wearing

http://www.youtube.com/watch?v=c62C_yTUyVg

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 eating

Lateral – “ Lets Eat” Tells you when you are hungry

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 Center

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Hemispheres of the BrainLeft:

Language and logic

Right:Spatial, creative

Why do most strokes affect the right side of the body?Most strokes occur in the left hemisphere

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.

Gyri (ridge)

Fissure

(deep groove)

Sulci (groove)

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

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

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

The Cerebral Cortex

Lobes of the Brain (4)

Frontal

Parietal

Occipital

Temporal

* 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

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

Lobes of the Brain - Parietal Lobe

The 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

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

Lobes of the Brain – Temporal Lobe

The 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

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)

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

The Cerebral Cortex

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.

The Cerebral Cortex

Functional MRI scan shows the visual cortex activated as the subject looks at faces

Visual and Auditory Cortex

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)

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

Broca’s AphasiaAphasia refers to the speech impairment caused by brain damage

Patients know what they want to say but have a hard time getting it out.

Spoken sentences lack prepositions and conjunctions

They 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 cases

http://www.youtube.com/watch?v=f2IiMEbMnPM

Wernickes AreaLocations

Left temporal lobe

Major FunctionInvolved in the interpretation of speechKnown as the language comprehension centerVital for locating appropriate words from memory to express meaning

Wernickes Aphacia

Trouble with speech comprehension

Can’t produce meaningful sentences. Can string together words but what they say is nonsensical

Leave out key words and substitute random or invented words

Talk excessively

http://www.youtube.com/watch?v=dKTdMV6cOZw

Specialization and Integration

Specialization and Integration

Brain activity when hearing, seeing, and speaking words

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

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!

Plasticity

Our Divided Brain

Severed Corpus Callosum

http://www.youtube.com/watch?v=lfGwsAdS9Dc

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

Our Divided Brain The information

highway from the eye to the brain

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

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?

Split BrainExplain the following…

The Split brain

1. If this visual was shown to the right hemisphere of a split brain patient, how might the patient identify the object?

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.”

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

Hemispheric Differences in the Intact Brain

Hemispheric specialization = lateralization

Blood 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

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

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

Lefties tend to be…..

Musicians

Mathematicians

Professional baseball / cricket players

Architects

artists

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

Brain Structures and their Functions

Neuroscience, Genetics and Behavior

True or False?

“Basic biological processes underlie all human behavior.”

Various branches of psychology rest on this foundation.

Biological Psychology(or Psychobiology)

The most significant transformation in modern psychology

AKA Biopsychologists, behavioral neuroscientists, behavior geneticists, physiological psychologists, neuropsychologists…

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.”

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.

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!

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

Neural Structure

So 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..)

Neural Structure

Neural Communication “an electrochemical

process…”“Neural communication is a conversation between cells that generates our thoughts, actions, moods and memory.”

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

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)

Neural Communication…

Neurons generate electricity from chemical events (like batteries)

The chemistry to electricity process involves the exchange of ions

Ions: electrically charged atoms

Ions…

Resting PotentialFluid 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..)

Reaching a Neuron’s Threshold…

When the neuron fires…

Axon opens gates (selectively permeable) and +charged sodium ions flood the membrane

+sodium ions cause depolarization

Depolarization causes reaction as axons pass the impulse down the chain (like dominoes)

Opens and closes 100-1000 times /second!

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)

Neural Communication

Cell body end of axon

Direction of neural impulse: toward axon terminals

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..

Neural Communication

ReuptakeExcess neurotransmitters are reabsorbed by the sending neuron

Neural Communication

Neurotransmitters

About 75 have been discovered

We will study 7-8

Neurotransmitters(Take notes on last 2 listed)

NeurotransmittersGABA

Inhibitory neurotransmitter

Undersupply = seizures, tremors, insomnia

Glutamate

Excitatoryneurotrasmitter

Invovled in memory

Too much = migraines, seizures

Excitotoxicity: “excite a neuron to death” (glial cells help prevent…)

Chinese food- MSG (glutamate) = headaches

Neurotransmitters

Acetylcholine [ah-seat-el-KO-leen] ACh triggers muscle contraction

(movement, learning, memory) Undersupply = Alzheirmer’s

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”

Neurotransmitters…

NorepinephrineMood

Too much = mania / too little = depression

Imbalance = bipolar disorder

Neurotransmitters

SerotoninSleep, eating, mood

Related to depression

Prozac (anti-depressant drug) raises serotonin levels

Neurotransmitters

DopaminePerceptual awareness, muscle control

Too much = Schizophrania (up to 6x more dopemine)

A Beautiful Mind / The Soloist

Too little = Parkinson’s Disease (tremors: Muhammad Ali)

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

Neural Communication

Serotonin Pathways Dopamine Pathways

Remember…

Communication within the neuron is…….Electrical

Communication between neurons is….chemical

Glial cells (Glia)

Make up 90% of brain’s cells

Protect, nourish neurons

Current research suggests possible action potentials, debate as to role…

See p. 45: Alchemy of Mind

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.”

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

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

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.

The Nervous System

The Nervous System

The Peripheral Nervous System

Links CNS to body’s sense receptorsFor 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

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

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)

The Central Nervous System

“The motherboard of our humanity…”

10’s of billions of neurons

Brain and spinal cord

Spinal cord: Information highway connecting PNS to the brain

ReflexesSpinal Reflex: Autonomic response to stimuli (Single sensory neuron, single motor neuron, interneuron:…..Brain’s not involved!)

Pain Reflex Sensory neuron, interneuron, motor neuron

a simple, automatic, inborn response to a sensory stimulus

The BrainCenter for all sensory information and voluntary movement (receives, interprets, decides…)

Without the brain…no pain or pleasure, no voluntary movement

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

In other words…

“Neurons that fire together... wire together.”

The Endocrine SystemThe body’s 2nd communication system

Interconnected with nervous system

Endocrine System

ES glands produce hormones

Hormones travel through bloodstream to affect body

Influences 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…

Important Glands…

Pituitary Gland (the master gland..)Pea sized, in middle of brain

Influences growth

Influences other Endocrine glands’ release of hormones

Controlled by hypothalamus (brain)

Brain – pituitary – other glands – hormones – brain (complex system: blend of Endocrine system and nervous systems)

Pituitary Gland

Adrenal Glands

Located on top of kidneys

Release epinephrine and norepinephrine (adrenaline and noradrenaline)

Heart rate, blood sugar, blood pressure etc.

Adrenal Glands

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.

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.

The typical human brain…

o contains about 100 billion neurons

o consumes about ¼ of the body’s oxygen

o spends most of the bodies calories

o Is 70% water!!!

o weighs about 3 pounds