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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