Neurons Chapter 3. Axon The part of the neuron that takes information AWAY from the cell body

Neurons

Chapter 3Chapter 3

Axon

The part of the neuron that takes information AWAY from the cell body.

The part of the neuron that takes information AWAY from the cell body.

Cell Body

Also called the soma; the part of the cell that contains the

nucleus.

Also called the soma; the part of the cell that contains the

nucleus.

Nucleus

Part of the neuron that contains chromosomes

(genetic material)

Part of the neuron that contains chromosomes

(genetic material)

Dendrites

Extensions from the neuron cell body that take information TO

the cell body.

Extensions from the neuron cell body that take information TO

the cell body.

Myelin

Fatty substance that surrounds some axons. Speeds up conduction

velocity of action potentials.

Fatty substance that surrounds some axons. Speeds up conduction

velocity of action potentials.

Node of Ranvier

Gaps in the myelination of

axons.

Gaps in the myelination of

axons.

Synaptic Terminal

The end of the axon containing vesicles

with neurotransmitters.

The end of the axon containing vesicles

with neurotransmitters.

The Nervous System

Nervous System

System of nerves involved in thought processes, heartbeat, visual-motor coordination, etc…

Central and Peripheral systems

System of nerves involved in thought processes, heartbeat, visual-motor coordination, etc…

Central and Peripheral systems

Central Nervous System

Consists of the brain and spinal cord

Consists of the brain and spinal cord

Spinal Cord

A column of nerves within the spine that transmits messages from sensory receptors to the brain and from the brain to muscles and glands throughout the body.

A column of nerves within the spine that transmits messages from sensory receptors to the brain and from the brain to muscles and glands throughout the body.

Spinal Cord

Spinal Reflexes: an unlearned response to a stimulus that may involve only two neuronsa) Sensory (afferent) neuron-to cortexb) Motor (efferent) neuron-away

S A M EYou are *affected* by a situation, you

*effect* change on someone else. Blink, swallow,knee-jerk, sexual

responses, urinating, etc…

Spinal Reflexes: an unlearned response to a stimulus that may involve only two neuronsa) Sensory (afferent) neuron-to cortexb) Motor (efferent) neuron-away

S A M EYou are *affected* by a situation, you

*effect* change on someone else. Blink, swallow,knee-jerk, sexual

responses, urinating, etc…

Brain

Hindbrain(lower part of brain): Medulla-heart rate, blood

pressure, respiration Pons-respiration, attention,

sleep, dreaming Cerebellum-muscle

coordination and balance

Hindbrain(lower part of brain): Medulla-heart rate, blood

pressure, respiration Pons-respiration, attention,

sleep, dreaming Cerebellum-muscle

coordination and balance

Brain

Reticular Activating System (RAS):

Vital in the functions of attention, sleep, and arousal

Injury to RAS can cause comatose

Filtering (awakened by infant)

Reticular Activating System (RAS):

Vital in the functions of attention, sleep, and arousal

Injury to RAS can cause comatose

Filtering (awakened by infant)

Brain

Forebrain (front most part):1). Thalamus-center of brain Relay station for sensory stimulation Relays sensory input from the eyes to

the visual areas of the cerebral cortex Functions of sleep and attention

Forebrain (front most part):1). Thalamus-center of brain Relay station for sensory stimulation Relays sensory input from the eyes to

the visual areas of the cerebral cortex Functions of sleep and attention

Brain

Forebrain (front most part):2). Hypothalamus-beneath thalamus and

above pituitary gland Body temperature, motivation, emotion Involved in hunger, thirst, sexual

behavior, caring for offspring, aggression

Forebrain (front most part):2). Hypothalamus-beneath thalamus and

above pituitary gland Body temperature, motivation, emotion Involved in hunger, thirst, sexual

behavior, caring for offspring, aggression

Brain

Forebrain (front most part):3). Limbic system-inner edge of

cerebrum and in mammals only Memory, emotion, drives of hunger, sex,

aggression Amygdala-facilitates aggressive

responses

Forebrain (front most part):3). Limbic system-inner edge of

cerebrum and in mammals only Memory, emotion, drives of hunger, sex,

aggression Amygdala-facilitates aggressive

responses

Brain

Forebrain (front most part):4). Basil ganglia-between thalamus and

cerebrum Control of movements and coordination Dopamine produced-degeneration can

cause Parkinson’s disease

Forebrain (front most part):4). Basil ganglia-between thalamus and

cerebrum Control of movements and coordination Dopamine produced-degeneration can

cause Parkinson’s disease

Brain

Forebrain (front most part):5). Cerebrum-crowning glory of brain Cerebral cortex-the wrinkled and

convoluted surface Consists of two hemispheres Corpus Callosum-connects the two

hemispheres

Forebrain (front most part):5). Cerebrum-crowning glory of brain Cerebral cortex-the wrinkled and

convoluted surface Consists of two hemispheres Corpus Callosum-connects the two

hemispheres

Peripheral Nervous System

Consists of sensory and motor neurons that transmit messages to and from the central nervous system

Without the PNS, our brains would be isolated from the world

Somatic and Autonomic NS

Consists of sensory and motor neurons that transmit messages to and from the central nervous system

Without the PNS, our brains would be isolated from the world

Somatic and Autonomic NS

Somatic Nervous System

Connects the central nervous system with sensory receptors, skeletal muscles, and the surface of the body

Ex:raising hand, winking, running, posture, balance

Connects the central nervous system with sensory receptors, skeletal muscles, and the surface of the body

Ex:raising hand, winking, running, posture, balance

Autonomic Nervous System

Regulates the glands and the muscles of internal organs

Heartbeat, respiration, digestion, dilation of the pupils of the eyes

Can occur automatically Sympathetic & Parasympathetic

Regulates the glands and the muscles of internal organs

Heartbeat, respiration, digestion, dilation of the pupils of the eyes

Can occur automatically Sympathetic & Parasympathetic

Autonomic Nervous System

Sympathetic- most active during processes that involve the spending of body energy from stored reserves

“Fight-or-Flight”

Sympathetic- most active during processes that involve the spending of body energy from stored reserves

“Fight-or-Flight”

Autonomic Nervous System

Parasympathetic- most active during processes that replenish reserves of energy (eating)

Parasympathetic- most active during processes that replenish reserves of energy (eating)

Autonomic Nervous System

Sympathetic--accelerates the heart rate-inhibits digestion Parasympathetic-

-decelerates the heart rate-stimulates digestive processes

Sympathetic--accelerates the heart rate-inhibits digestion Parasympathetic-

-decelerates the heart rate-stimulates digestive processes

Lobes of the Brain

Frontal Lobe

Located in front of the central sulcus

Concerned with reasoning, planning, parts of speech, movement (motor cortex), emotions, and problem-solving

Located in front of the central sulcus

Concerned with reasoning, planning, parts of speech, movement (motor cortex), emotions, and problem-solving

Parietal Lobe

Located behind the central sulcus

Concerned with perception of stimuli related to touch, pressure, temperature, pain

Located behind the central sulcus

Concerned with perception of stimuli related to touch, pressure, temperature, pain

Temporal Lobe

Located below the lateral fissure

Concerned with perception and recognition of auditory stimuli (hearing) and memory (hippocampus)

Located below the lateral fissure

Concerned with perception and recognition of auditory stimuli (hearing) and memory (hippocampus)

Occipital Lobe

Located at the back of the brain, behind the parietal lobe and temporal lobe

Concerned with many aspects of vision

Located at the back of the brain, behind the parietal lobe and temporal lobe

Concerned with many aspects of vision

Brain Structures

Cerebral Cortex

Thought Voluntary movement

Language Reasoning Perception

Thought Voluntary movement

Language Reasoning Perception

Cerebellum

Movement

Balance

Posture

Movement

Balance

Posture

Brain Stem

Breathing

Heart Rate

Blood Pressure

Breathing

Heart Rate

Blood Pressure

Hypothalamus

Body temperature Emotions Hunger Thirst

Circadian rhythms

Body temperature Emotions Hunger Thirst

Circadian rhythms

Thalamus

Sensory processing

Movement

Sensory processing

Movement

Limbic System

Emotions

Memory

Emotions

Memory

Hippocampus

Learning

Memory

Learning

Memory

Basal Ganglia

Movement Movement

Midbrain

Vision Audition

Eye movement Body Movement

Vision Audition

Eye movement Body Movement

The BrainTechniques to Study the Brain

A brain lesion experimentally destroys brain tissue to study

animal behaviors after

such destruction.

A brain lesion experimentally destroys brain tissue to study

animal behaviors after

such destruction. Hubel (1990)

Clinical Observation

Clinical observations have shed light on a number of brain disorders. Alterations in brain morphology due to neurological and psychiatric

diseases are now being catalogued.

Clinical 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

Electroencephalogram (EEG)

An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp.

An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp.

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

MRI Scan

MRI (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

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.

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.

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.

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.

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.

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.

The “little brain”

attached to the rear of the

brainstem. It helps

coordinate voluntary

movements and balance.

The “little brain”

attached to the rear of the

brainstem. It helps

coordinate voluntary

movements and balance.

Cerebellum

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 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

AmygdalaThe Amygdala [ah-MIG-dah-la] consists of two almond-

shaped neural clusters linked to the emotions

of fear and anger.

The Amygdala [ah-MIG-dah-la] consists of two almond-

shaped neural clusters linked to the emotions

of fear and anger.

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.

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.

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).

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

Sanjiv T

alwar, S

UN

Y D

ownstate

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.

The intricate fabric of interconnected neural cells that covers the cerebral hemispheres.

It is the body’s ultimate control and information processing center.

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).

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).

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.

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.

Visual Function

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

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

Auditory Function

The functional MRI scan shows the

auditory cortex is active in patients who

hallucinate.

The functional MRI scan shows the

auditory cortex is active in patients who

hallucinate.

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

cortex.

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

cortex.

Association Areas

Language

Aphasia 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).

Specialization & Integration

Brain activity when hearing, seeing, and speaking words

Brain activity when hearing, seeing, and speaking words

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 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

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.

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.

Splitting the Brain

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

(mainly those of the corpus callosum) between them.

A 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

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.

With the corpus callosum severed, objects (apple) presented in the right

visual field can be named. Objects (pencil) in the left visual field cannot.

Divided Consciousness

Try This!

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

simultaneously.

BB

C

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.

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.

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.

Is it Alright to be Left Handed?

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

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

Is it Alright to be Left Handed?

The percentage of left-handed individuals decreases sharply in samples

of older people (Coren, 1993).

The percentage of left-handed individuals decreases sharply in samples

of older people (Coren, 1993).

Language Functions

Aphasia

Damage to the left part of the brain in the cerebral cortex

Definition:impaired ability to comprehend or express oneself through language

Damage to the left part of the brain in the cerebral cortex

Definition:impaired ability to comprehend or express oneself through language

Broca’s Area

Prevents a person from producing speech

Person can understand language

Words are not properly formed Speech is slow and slurred

Prevents a person from producing speech

Person can understand language

Words are not properly formed Speech is slow and slurred

Wernicke’s Area

Loss of ability to understand language

Person can speak clearly, but the words that are put together make no sense.

“Word salad” because it appears that the words are all mixed up like the vegetables in a salad

Loss of ability to understand language

Person can speak clearly, but the words that are put together make no sense.

“Word salad” because it appears that the words are all mixed up like the vegetables in a salad

Journal

Would you rather have Broca’s aphasia or

Wernicke’s aphasia? Why?

Would you rather have Broca’s aphasia or

Wernicke’s aphasia? Why?

Alzheimer’s Disease

Alzheimer’s Disease

A progressive form of mental deterioration that may affect as many as 4 million Americans

Connected with aging but it is a disease and NOT part of a normal aging process

A progressive form of mental deterioration that may affect as many as 4 million Americans

Connected with aging but it is a disease and NOT part of a normal aging process

Alzheimer’s Disease

Characterized by progressive deterioration in mental processes such as memory, language, and problem solving

Seriously impairs vocational and social functioning

Characterized by progressive deterioration in mental processes such as memory, language, and problem solving

Seriously impairs vocational and social functioning

Alzheimer’s Disease

Memory loss: difficult to recall basic info (zip codes,

telephone #s, names of grandchildren, addresses)

Large gaps in memory for recent events May fail to recognize familiar people or

forget their names

Memory loss: difficult to recall basic info (zip codes,

telephone #s, names of grandchildren, addresses)

Large gaps in memory for recent events May fail to recognize familiar people or

forget their names

Alzheimer’s Disease

Continue.. May not recognize themselves in the

mirror Unable to recall names of their school,

birthplace, parents No longer able to speak in full

sentences and limit their verbal responses to a few words

Continue.. May not recognize themselves in the

mirror Unable to recall names of their school,

birthplace, parents No longer able to speak in full

sentences and limit their verbal responses to a few words

Alzheimer’s Disease

Subtle personality changes: signs of withdrawal or irritability

May need assistance to manage everyday tasks (selecting clothes to wear)

Difficulties in personal functioning (using bathroom and washing themselves)

Subtle personality changes: signs of withdrawal or irritability

May need assistance to manage everyday tasks (selecting clothes to wear)

Difficulties in personal functioning (using bathroom and washing themselves)

Alzheimer’s Disease

May pace or fidget or display aggressive behavior (yelling, hitting, throwing)

May wander off and not be able to find their way back

1 in 3 show signs of hallucinations or delusions

May pace or fidget or display aggressive behavior (yelling, hitting, throwing)

May wander off and not be able to find their way back

1 in 3 show signs of hallucinations or delusions

Alzheimer’s Disease

Severe cases:People become helpless-unable to communicate or walk and require help in toileting and feeding.

Severe cases:People become helpless-unable to communicate or walk and require help in toileting and feeding.

Alzheimer’s Disease

Discovered by German physician Alois Alzheimer

Found brain abnormalities in a 56-year old woman with dementia

Discovered by German physician Alois Alzheimer

Found brain abnormalities in a 56-year old woman with dementia

Brain Abnormalities

1) Plaques: destroy brain tissues which leads to loss of memory function, confusion, and other symptoms

2) Tangles: twisted bundles of nerve cells

1) Plaques: destroy brain tissues which leads to loss of memory function, confusion, and other symptoms

2) Tangles: twisted bundles of nerve cells

Biochemical

Reduced levels of acetylcholine (ACh): reflect loss of brain cells and can lead to brain trauma, aluminum poisoning

Reduced metabolic rates Negative correlation between

cognitive performance and metabolic rate

Reduced levels of acetylcholine (ACh): reflect loss of brain cells and can lead to brain trauma, aluminum poisoning

Reduced metabolic rates Negative correlation between

cognitive performance and metabolic rate

Genetic Transmission

90% of people who inherit a key gene from both parents contract Alzheimer’s disease by the age of 75

Chemotherapy is used to heighten ACh levels

Researchers are hopeful that genetic studies may lead to effective medications

90% of people who inherit a key gene from both parents contract Alzheimer’s disease by the age of 75

Chemotherapy is used to heighten ACh levels

Researchers are hopeful that genetic studies may lead to effective medications