1

Neuroscience and Behavior

Chapter 2

Bell Ringer - Fact or Falsehood?1. A small amount of brain tissue from a person

cannot be distinguished from that of a monkey. 2. The human brain produces its own natural

opiates that elevate mood and ease pain.3. Electrically stimulating a cat’s brain at a certain

point can cause the animal to cower in terror in the presence of a small mouse.

4. Both animals and humans seem to have reward centers located in the brain.

5. We ordinarily use only 10 percent of our brains.6. Some people can write but are unable to read.7. If a blind person uses one finger to read Braille,

the brain area dedicated to that finger expands.8. Adult humans cannot generate new brain cells.9. Some people have had the hemispheres of their

brains split with no apparent ill effect.10. Identical twin pairs are necessarily both left-

handed or both right-handed.

Answers1. T

2. T

3. T

4. T

5. F6. T7. T

8. F9. T

10. F

Answers

• 1.T 6. T

• 2. T 7. T

• 3. T 8. F

• 4. T 9. T

• 5. F 10. F

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Neuroscience and Behavior

Neural Communication Neurons

How Neurons Communicate

How Neurotransmitters Influence Us

The Nervous System The Peripheral Nervous System

The Central Nervous System

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Neuroscience and Behavior

The Endocrine System

The Brain The Tools of Discovery

Older Brain Structures

The Cerebral Cortex

Our Divided Brain

Left Brain-Right Brain

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History of Mind

Plato correctly placed the mind in the brain. However, his

student Aristotle believed that the mind was in the heart.

Ancient Conceptions About Mind

Today we believe mind and brain are faces of the same coin.

On one side of the coin is the brain (biological) and the other

is the mind (psychological).

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History of Mind

In 1800, Franz Gall suggested that bumps of

the skull represented mental abilities. His

theory, though incorrect, nevertheless proposed that different mental

abilities were modular.

Phrenology – belief that the bumps of the skull can predict mental ability and character traits

Bettm

an/ Corbis

How does the brain communicate with the body?

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The body consist of the brain and neurons that connect the brain and

all other parts of the bodyBrain Neurons Body

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When the brain wants to send a message to your foot, it does it through a network of neurons

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Neural Communication Network

The body’s information system is built from billions of interconnected cells

called neurons.

Need to know

Central nervous system is:

There are 3 types of neurons

1. Sensory neurons – carry information from the body’s tissues and organs to the central nervous system

There are 3 types of neurons

2. Motor neurons – carry instructions from the central nervous system to muscles and glands

Interneuron (Relay Neurons)

3. Interneurons in the spinal cord link the motor neurons with the sensory neurons. They also process the additional information present to make sense of what is happening in their body and outside their body

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Neural Communication – How humans and animals compare?

Note the similarities in the above brain regions, which are all engaged in information processing.

Neurobiologists and other investigators understand that humans and animals operate similarly when

processing information.

Bell ringer – making a Neuron

All students need to get the following

1. One Styrofoam ball

2. Five wood sticks

3. One plastic tie (black)

4. Three pipe cleaner

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Neuron A nerve cell, or a neuron,

consists of many different parts.

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Parts of a Neuron Cell Body: Life support center of the neuron.Dendrites: Branching extensions at the cell body. Receive messages from other neurons.Axon: Long single extension of a neuron, covered with myelin [MY-uh-lin] sheath to insulate and speed up messages through neurons.Terminal Branches of axon: Branched endings of an axon that transmit messages to other neurons.

Bell ringer

Complete the quiz – 10 minutes –

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Action PotentialA neural impulse. A brief electrical charge that travels down an axon

and is generated by the movement of positively charged atoms in and out

of channels in the axon’s membrane.

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Depolarization & Hyperpolarization

Depolarization: Depolarization occurs when positive ions enter the neuron,

making it more prone to firing an action potential. Hyperpolarization occurs when negative ions enter the neuron, making it

less prone to firing an action potential.

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Threshold Threshold: Each neuron receives depolarizing and hyperpolarizing

currents from many neurons. When the depolarizing current

(positive ions) minus the hyperpolarizing current (negative ions) exceed minimum intensity (threshold) the neuron fires an

action potential.

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Refractory Period & Pumps Refractory Period: After a neuron

fires an action potential it pauses for a short period to recharge itself to

fire again.

Sodium-Potassium Pumps: Sodium-potassium pumps pump positive ions

out from the inside of the neuron, making them ready for another action

potential.

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Action Potential Properties

All-or-None Response: When the depolarizing current exceeds the

threshold, a neuron will fire. If the depolarizing current fails to exceed the threshold, a neuron will not fire.

Intensity of an action potential remains the same throughout the

length of the axon.

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Synapse Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or

cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft.

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NeurotransmittersNeurotransmitters

(chemicals) released from the sending

neuron travel across the synapse and bind to receptor

sites on the receiving neuron,

thereby influencing it to generate an action potential.

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ReuptakeNeurotransmitters in the synapse are

reabsorbed into the sending neurons

through the process of reuptake. This

process applies the brakes on

neurotransmitter action.

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Neurotransmitters

Neurotransmitters:• are endogenous chemicals which allow

the transmission of signals from one neuron to the next across synapses.

• They are also found at the axon endings of motor neurons, where they stimulate the muscle fibers.

• They are produced by some glands such as the pituitary and the adrenal glands.

 

How neurotransmitters work

• Neuron fires – neurotransmitters go from one neuron to the next

• They are received by receptors

• Some neurotransmitters block receptors (inhibitory), others excite receptors (excitatory)

1. Acetylcholine (uh-set-le-co-len)• Acetylcholine (ACh) was the first

neurotransmitter to be discovered.  It was isolated in 1921 by a German biologist named Otto Loewi, who would later win the Nobel Prize for his work. 

• Acetylcholine has many functions:  It is responsible for much of the stimulation of muscles, including the muscles of the gastro-intestinal system. 

• It is also found in sensory neurons and in the autonomic nervous system, and has a part in scheduling REM (dream) sleep.

Examples for Ach:• When the ACh receptors are blocked

by poisons, paralysis occurs

• Botox – patients use this to eliminate wrinkles – inject directly into muscle to paralyze the area so wrinkles can’t form

• 90% loss of ACh in the brains of people suffering from Alzheimer's

Dopamine:• discovered to be a neurotransmitter in the

1950s by Arvid Carlsson (Nobel Prize in 2000)

• It is an inhibitory neurotransmitter, meaning that when it finds its way to its receptor sites, it blocks the tendency of that neuron to fire. 

• Dopamine is strongly associated with reward mechanisms in the brain. 

• If it feels good, dopamine neurons are probably involved!

Examples for Dopamine:• Drugs like cocaine, opium, heroin, and

alcohol increase the levels of dopamine, as does nicotine

• schizophrenia has been shown to involve excessive amounts of dopamine in the frontal lobes, and drugs that block dopamine are used to help schizophrenics

• too little dopamine in the motor areas of the brain are responsible for Parkinson's disease, which involves uncontrollable muscle tremors

Serotonin:• Vittorio Erspamer first discovered

what we now call seratonin in the 1930s 

• It was found in blood serum in 1948 by Irvine Page, who named it serotonin (from “serum-tonic”)

• an inhibitory neurotransmitter that has been found to be intimately involved in emotion and mood

Examples for Serotonin:• Too little serotonin has been shown to lead to

depression, problems with anger control, obsessive-compulsive disorder, and suicide. Also eating disorders and trouble sleeping

• It has also been tied to migraines, irritable bowel syndrome, and fibromyalgia.

• Prozac – drug used to keep serotonin levels up• Impact on perception: Hallucinogens such as

LSD and ecstasy work by attaching to serotonin receptor sites and thereby blocking transmissions

Norepinephrine- (nor·epi·neph·rine )• In 1946, a Swedish biologist by the name of Ulf

von Euler discovered norepinephrine He also won a Nobel Prize.

• Norepinephrine is strongly associated with bringing our nervous systems into "high alert." 

• It is prevalent in the sympathetic nervous system, and it increases our heart rate and our blood pressure.  Our adrenal glands release it into the blood stream, along with its close relative epinephrine (aka adrenalin). 

• It is also important for forming memories

Examples for Norepinephrine• Stress tends to deplete our store of

adrenalin

• Exercise tends to increase it 

• Amphetamines ("speed") work by causing the release of norepinephrine, as well as other neurotransmitters called dopamine and seratonin

Gamma Amino Butyric Acid)- GABA • In 1950, Eugene Roberts and J.

Awapara discovered GABA, which is also usually an inhibitory neurotransmitter. 

• GABA acts like a brake to the excitatory neurotransmitters that lead to anxiety

Examples for GABA• People with too little GABA tend to suffer from

anxiety disorders, and drugs like Valium work by enhancing the effects of GABA 

• Lots of other drugs influence GABA receptors, including alcohol and barbituates 

• If GABA is lacking in certain parts of the brain, epilepsy results.

Glutamate:• Glutamate was discovered by Kikunae

Ikeda of Tokay Imperial Univ. in 1907, while looking for the flavor common to things like cheese, meat, and mushrooms

• He was able to extract an acid from seaweed – glutamate

• He went on to invent the well known seasoning MSG - monosodium glutamate

• It took decades for Peter Usherwood to identify glutamate as a neurotransmitter (in locusts) in 1994.

Glutamate – con’t• Glutamate is an excitatory relative of

GABA 

• It is the most common neurotransmitter in the central nervous system - as much as half of all neurons in the brain - and is especially important in regards to memory 

• Curiously, glutamate is actually toxic to neurons, and an excess will kill them

Examples for Glutamate:• Sometimes brain damage or a stroke will

lead to an excess and end with many more brain cells dying than from the original trauma

• ALS, more commonly known as Lou Gehrig's disease, results from excessive glutamate production 

• Many believe it may also be responsible for quite a variety of diseases of the nervous system

Homework• Read Pg 61 -67 (objectives7-10)

• Know the difference between the following in the Nervous System:

–Central Nervous System (CNS)

–Peripheral Nervous System (PNS)

You also need to know what consist of each system and the different functions

• You also need to know parts of the endocrine system and their Functions

Endorphin

• In 1973, Solomon Snyder and Candace Pert of Johns Hopkins discovered endorphin

• Endorphin = "endogenous morphine"  • It is structurally very similar to opium,

morphine, and heroin• Inhibitory, it is involved in pain reduction and

pleasure, and the opioid drugs work by attaching to endorphin's receptor sites

• It is also the neurotransmitter that allows bears and other animals to hibernate

• Consider:  Heroin slows heart-rate, respiration, and metabolism in general - exactly what you would need to hibernate.  Of course, sometimes heroin slows it all down to nothing:  Permanent hibernation.

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How Neurotransmitters Influence Us?

Serotonin pathways are involved with

mood regulation.

From Mapping the Mind, Rita Carter, © 1989 University of California Press

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Dopamine Pathways

Dopamine pathways are involved with diseases such

as schizophrenia

and Parkinson’s disease.

From Mapping the Mind, Rita Carter, © 1989 University of California Press

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Lock & Key MechanismNeurotransmitters bind to the

receptors of the receiving neuron in a key-lock mechanism.

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Agonists

50

Antagonists

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Nervous System

CentralNervousSystem(CNS)

PeripheralNervousSystem(PNS)

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The Nervous System

Nervous System: Consists of all the nerve cells. It is the body’s speedy, electrochemical communication system.

Central Nervous System (CNS): the brain and spinal cord.

Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

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The Nervous System

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Kinds of NeuronsSensory Neurons carry incoming information from

the sense receptors to the CNS. Motor Neurons carry outgoing information from the CNS to muscles and glands. Interneurons connect the two neurons.

Sensory Neuron(Bipolar)

Interneuron Neuron (Unipolar)

Motor Neuron(Multipolar)

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Kinds of Glial Cells

Astrocytes provide nutrition to neurons.

Oligodendrocytes and Schwann cells insulate neurons as

myelin.

Astrocytes

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Peripheral Nervous System

Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles.

Autonomic Nervous System: Part of the PNS that controls the glands and other muscles.

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The Nerves

Nerves consist of neural “cables” containing many axons. They are part of the peripheral

nervous system and connect muscles, glands, and sense organs to the central nervous

system.

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Autonomic Nervous System (ANS)

Sympathetic Nervous System: Division of the ANS that arouses the body, mobilizing its energy in stressful situations.

Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy.

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Autonomic Nervous System (ANS)

Sympathetic NS “Arouses”

(fight-or-flight)

Parasympathetic NS “Calms”

(rest and digest)

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Central Nervous System

The Spinal Cord and Reflexes

Simple Reflex

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Central Nervous System

The Brain and Neural Networks

Complex Neural Network

Interconnected neurons form networks in the brain. Theses networks are complex and modify with growth and experience.

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The Endocrine System

The Endocrine System is the body’s “slow”

chemical communication

system. Communication is

carried out by hormones

synthesized by a set of glands.

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Hormones

Hormones are chemicals synthesized by the endocrine glands that are secreted in the

bloodstream. Hormones affect the brain and many other tissues of the body.

For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood

sugar and feelings of excitement during emergency situations.

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Pituitary Gland

Is called the “master gland.” The anterior pituitary lobe releases hormones that

regulate other glands. The posterior lobe regulates water and salt balance.

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Thyroid & Parathyroid Glands

Regulate metabolic and calcium rate.

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Adrenal GlandsAdrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones (epinephrine and norepinephrine) during stressful and

emotional situations, while the adrenal cortex regulates salt and carbohydrate

metabolism.

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Gonads

Sex glands are located in different places in men and women. They regulate bodily

development and maintain reproductive organs in adults.

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The Brain

Techniques to Study the Brain

A brain lesion experimentally

destroys brain tissue to study animal behaviors after such destruction.

Hubel (1990)

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Clinical ObservationClinical observations have shed light on a

number of brain disorders. Alterations in brain morphology due to neurological and

psychiatric diseases are now being catalogued.

Tom

Landers/ B

oston Globe

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Electroencephalogram (EEG)An amplified recording of the electrical waves

sweeping across the brain’s surface, measured by electrodes placed on the scalp.

AJ P

hoto/ Photo R

esearchers, Inc.

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PET Scan

PET (positron emission tomography)

Scan is a visual display of brain

activity that detects a radioactive form of glucose while the

brain performs a given task.

Courtesy of N

ational Brookhaven N

ational Laboratories

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MRI ScanMRI (magnetic

resonance imaging) uses magnetic fields and radio waves to produce computer-

generated images that distinguish among

different types of brain tissue. Top images show ventricular enlargement in a

schizophrenic patient. Bottom image shows brain regions when a

participants lies.

Both photos from Daniel Weinberger, M.D., CBDB, NIMH

James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations

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Older Brain Structures

The Brainstem is the 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 that controls heartbeat

and breathing.

Reticular Formation is a nerve network in the brainstem that plays an important role in controlling

arousal.

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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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The “little brain” attached to the rear of the brainstem. It

helps coordinate voluntary movements

and balance.

Cerebellum

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The Limbic System is a 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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Amygdala

The Amygdala [ah-MIG-dah-la] consists of two almond-shaped neural clusters linked to the emotions of fear and

anger.

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Hypothalamus

The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating,

drinking, body temperature, and

control of emotions. It helps govern the

endocrine system via the pituitary gland.

80

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 CenterS

anjiv Talw

ar, SU

NY

Dow

nstate

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The Cerebral Cortex

The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the body’s ultimate control and information processing center.

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Structure of the Cortex

Each brain hemisphere is divided into four

lobes that are separated by

prominent fissures. These lobes are the

frontal lobe (forehead), parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of

head).

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Functions of the Cortex

The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements. The Sensory Cortex (parietal cortex) receives

information from skin surface and sense organs.

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Visual Function

The functional MRI scan shows the visual cortex is active as the subject looks at faces.

Courtesy of V

.P. Clark, K

. Keill, J. M

a. M

aisog, S. Courtney, L

.G.

Ungerleider, and J.V

. Haxby,

National Institute of M

ental Health

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Auditory Function

The functional MRI scan shows the

auditory cortex is active in patients who

hallucinate.

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More intelligent animals have increased “uncommitted” or association areas of the

cortex.

Association Areas

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LanguageAphasia is an impairment of language,

usually caused by left hemisphere damage either to Broca’s area (impaired speaking)

or to Wernicke’s area (impaired understanding).

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Specialization & Integration

Brain activity when hearing, seeing, and speaking words

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The brain is sculpted by our genes but also by our experiences.

Plasticity refers to the brain’s ability to modify itself after some type of injury or illness.

The Brain’s Plasticity

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Our Divided Brain

Our brain is divided into two hemispheres. The left hemisphere processes reading,

writing, speaking, mathematics, and comprehension skills. In the 1960s, it was

termed as the dominant brain.

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Splitting the BrainA procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers

(mainly those of the corpus callosum) between them.

Corpus Callosum

Ma

rtin M

. Ro

the

r

Courtesy of T

erence William

s, University of Iow

a

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Split Brain Patients

With the corpus callosum severed, objects (apple) presented in the right visual field can be named.

Objects (pencil) in the left visual field cannot.

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Divided Consciousness

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Try This!

Try drawing one shape with your left hand and one with your right hand,

simultaneously.B

BC

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Non-Split Brains

People with intact brains also show left-right hemispheric differences in mental

abilities.

A number of brain scan studies show normal individuals engage their right

brain when completing a perceptual task and their left brain when carrying out a

linguistic task.

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Brain Organization & Handedness

Is handedness inherited? Yes. Archival and historic studies, as well as modern

medical studies, show that the right hand is preferred. This suggests genes and/or prenatal factors influence handedness.

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Is it Alright to be Left Handed?

Being left handed is difficult in a right-handed world.

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Is it Alright to be Left Handed?

The percentage of left-handed individuals decreases sharply in samples of older

people (Coren, 1993).