Transcript Neuro Slides - Northside College Prep High School

Neural
Communication
 Biological Psychology
 branch of psychology concerned with the links
between biology and behavior
 some biological psychologists call themselves behavioral
neuroscientists, neuropsychologists, behavior geneticists,
physiological psychologists, or biopsychologists
 Phrenology (Franz Gall)
 Study of the bumps on your head
 Bumps reveal a person’s abilities and traits
Phrenology
Neural Communication
Resting Potential
• At rest, the inside of the cell is at -70 microvolts
• With inputs to dendrites inside becomes more positive
• If resting potential rises above threshold, an action
potential starts to travel from cell body down the axon
• Figure shows resting axon being approached by an AP
Depolarization Ahead of AP
• AP opens cell membrane to allow sodium (Na+) in
• Inside of cell rapidly becomes more positive than outside
• This depolarization travels down the axon as leading edge
of the AP
Repolarization follows
• After depolarization potassium (K+) moves out restoring
the inside to a negative voltage
• This is called repolarization
• The rapid depolarization and repolarization produce a
pattern called a spike discharge
Finally, Hyperpolarization
• Repolarization leads to a voltage below the resting
potential, called hyperpolarization
• Now neuron cannot produce a new action potential
• This is the refractory period
Neural Communication
Locks and Keys
• Neurotransmitter
molecules have
specific shapes
Receptor molecules have
binding sites
When NT binds to
receptor, ions enter
Some Drugs Work on
Receptors
• Some drugs are
shaped like
neurotransmitters
• Antagonists: fit the
receptor but poorly
and block the NT
– e.g., beta blockers
Agonists:
fit receptor
well and act like the
NT
e.g.,
nicotine
Neural Communication
Neurotransmitter
molecule
Receptor site on
receiving neuron
Receiving cell
membrane
Agonist mimics
neurotransmitter
Antagonist
blocks
neurotransmitter
12
Excitatory and Inhibitory Messages
• Excitatory message— increases the
likelihood that the postsynaptic neuron will
activate
• Inhibitory message— decreases the
likelihood that the postsynaptic neuron will
activate.
Neural Communication
Serotonin Pathways
Dopamine Pathways
Neurons and Synapses
Types of Neurons
Sensory
Motor
Interneurons
Sensory Neurons
• INPUT From sensory organs to the
brain and spinal cord
Drawing shows a
somatic neuron
Also called
AFFERENT
NEURONS
Sensory
Neuron
Brain
Spinal
Cord
Motor Neurons
• OUTPUT From the brain and spinal
cord, to the muscles and glands
Also called
EFFERENT
NEURONS
Sensory
Neuron
Brain
Spinal
Cord
Motor
Neuron
Interneurons
• Interneurons
carry
information
between other
neurons only
found in the
brain and
spinal cord
Sensory
Neuron
Brain
Spinal
Cord
Motor
Neuron
The Nervous System
 Nervous System
 the body’s speedy, electrochemical
communication system
 consists of all the nerve cells of the peripheral
and central nervous systems
 Peripheral Nervous System (PNS)
 the sensory and motor neurons that connect
the central nervous system (CNS) to the rest
of the body
The Nervous System
Nervous
system
Central
(brain and
spinal cord)
Peripheral
Autonomic (controls
self-regulated action of
internal organs and glands)
Somatic (controls
voluntary movements of
skeletal muscles)
Sympathetic
(arousing)
Parasympathetic
(calming)
The Nervous System
 Somatic Nervous System
 the division of the peripheral nervous system
that controls the body’s skeletal muscles
 Autonomic Nervous System
 the part of the peripheral nervous system that
controls the glands and the muscles of the
internal organs (such as the heart)
The Nervous System
 Sympathetic Nervous System
 division of the autonomic nervous system that
arouses the body, mobilizing its energy in
stressful situations
 Parasympathetic Nervous System
 division of the autonomic nervous system that
calms the body, conserving its energy
The Nervous System
AROUSAL
Fight or Flight
The Nervous System
Restores
Homeostasis
Brain and Spinal Cord
 Central Nervous System (CNS)
 the brain and spinal cord
 Brain
 part of the CNS that plays important roles in
sensation, movement, and information processing.
 Spinal Cord
 plays a role in body reflexes and in communication
between the brain and the peripheral nervous
system.
The Nervous System
 Reflex
 a simple, automatic, inborn response to a sensory stimulus
Brain
Sensory neuron
(incoming information)
Muscle
Skin
receptors
Motor neuron
(outgoing
information)
Interneuron
Spinal cord
The Brain
 Lesion
 tissue
destruction
 a brain lesion
is a naturally
or
experimentall
y caused
destruction of
brain tissue
Electroencephalogram
(EEG)
 an amplified
recording of the
waves of electrical
activity that sweep
across the brain’s
surface
 these waves are
measured by
electrodes placed
on the scalp
The Brain
 CT (computed tomography) Scan
 a series of x-ray photographs taken from different
angles and combined by computer into a composite
representation of a slice through the body; also called
CAT scan
 PET (positron emission tomography) Scan
 a visual display of brain activity that detects where a
radioactive form of glucose goes while the brain
performs a given task
PET Scan
PET Scan
Pet Scan of a Normal Brain
The Brain
 MRI (magnetic resonance imaging)
 a technique that uses magnetic fields and radio
waves to produce computer-generated images that
distinguish among different types of soft tissue;
allows us to see structures within the brain
 Stimulation
 Electrical stimulation of the brain involves sending a
weak electric current into a brain structure to
stimulate it. (It is not painful because the brain has no
pain receptors
MRI Scan
The Cerebral Cortex
 Functional MRI
scan shows the
visual cortex
activated as the
subject looks at
faces
Association Areas
– Association Areasof the cerebral cortex that
are not involved in primary motor or sensory
functions. They are involved in higher mental
functions such as learning, remembering,
thinking and speaking.
– Phineas Gage
– AreAeas of the cerebral cortex that are not
involved in primary motor or sensory
functions. They are involved in higher mental
functions such as learning, remembering,
The Brain
 Brainstem
 the oldest part and central core of the brain,
beginning where the spinal cord swells as it
enters the skull
 responsible for automatic survival functions
Developing Brain
•Neural tube—beginning of
nervous system develops at 2
weeks after conception
•Neurogenesis—development of
new neurons
Hindbrain Structures
• Cerebellum
• Brainstem
y medulla
y reticular
formation
y pons
Medulla
•
•
•
•
Breathing
Heart rate
Digestion
Other vital
reflexes
y
y
y
y
swallowing
coughing
vomiting
sneezing
Pons
• Helps coordinate
movements on left
and right sides of
the body
y e.g., postural
reflexes which
help you
maintain
balance while
standing or
moving
Reticular Formation
• Network of
neurons in the
brainstem (and
thalamus)
• Sleep and
arousal
• Attention
Cerebellum
• Coordinated, rapid
voluntary
movements
y e.g., playing the
piano, kicking,
throwing, etc.
• Lesions to
cerebellum
y jerky, exaggerated
movements
y difficulty walking
y loss of balance
y shaking hands
The Brain
 Cerebellum [sehruh-BELL-um]
 the “little brain”
attached to the
rear of the
brainstem
 it helps coordinate
voluntary
movement and
balance
Forebrain Structures
• Thalamus
• Limbic
System
• Cortex
Thalamus
• Relay station
in brain
• Processes
most
information to
and from
higher brain
centers
The Limbic System
The Limbic System
• Hypothalamus
• Amygdala
• Hippocampus
The Limbic System
 Electrode
implanted in
reward
center
Amygdala and Emotion
• Identify emotion from
facial expressions
Amygdala damage
makes this task
difficult
The Cerebral Cortex
Sensory
Homunculus
Specialization and Integration
The Cerebral Cortex
 Aphasia
 impairment of language, usually caused by left
hemisphere damage either to Broca’s area
(impairing speaking) or to Wernicke’s area
(impairing understanding)
 Broca’s Area (Disrupts speaking)
 an area of the left frontal lobe that directs the
muscle movements involved in speech
 Wernicke’s Area (Disrupts understanding)
 an area of the left temporal lobe involved in
language comprehension and expression
Visual and Auditory
Cortex
Specialization and
Integration
and InInteIntegration
 Brain activity when hearing, seeing, and speaking
words
Brain Reorganization
 Plasticity
 the brain’s capacity for
modification, as evident in brain
reorganization following damage
(especially in children) and in
experiments on the effects of
experience on brain development
Brain Reorganization
• Hemispherectomy
– The surgical removal of an entire cerebral
hemisphere
Our Divided Brain
Corpus callosum
 Corpus
Callosum
 large band of
neural fibers
 connects the
two brain
hemispheres
 carries
messages
between the
hemispheres
Split Brain
 a condition in which
the two hemispheres
of the brain are
isolated by cutting
the connecting fibers
(mainly those of the
corpus callosum)
between them
Our Divided Brain
 The
information
highway from
the eye to the
brain
Split Brain
“What word
did you see?”
or
“Look at the dot.”
Two words separated
by a dot are
momentarily projected.
“Point with
your left
hand to the
word you
saw.”
Hemispheric
Specialization
The Endocrine System
 Endocrine System
 the body’s “slow”
chemical
communication
system
 a set of glands
that secrete
hormones into the
bloodstream
Neural and Hormonal Systems
 Hormones
 chemical messengers, mostly those
manufactured by the endocrine glands, that are
produced in one tissue and affect another
 Pituitary Gland
 under the influence of the hypothalamus, the
pituitary regulates growth and controls other
endocrine glands
The effects of the pituitary are clearly shown here.
Entertainer David Frost stands between the
world’s tallest and smallest man.
The tallest man in history was 8 feet 11
inches tall. He died at the age of 22,
partly as a result of this defect. The
shortest known person was 23 inches
tall when she died at the age of 19.
Today’s medicines can handle most of
these problems if caught earlier
enough, but these cases show what
happen if the pituitary gland goes awry.
Neural and Hormonal Systems
• Oxytocin– stimulates contractions of the
uterus during labor and secretion of milk
during nursing.
• Growth Hormone– stimulates the physical
development of bones and muscles.
Neural and Hormonal Systems
 Adrenal [ah-DREEN-el] Glands
 a pair of endocrine glands just above the kidneys
 secrete the hormones epinephrine (adrenaline) and
norepinephrine (noradrenaline), which help to arouse
the body in times of stress
 Cortisol– regulates metabolism and response to
stress.
Neural and Hormonal Systems
• Pancreas Hormones
– Insulin– decreases blood sugar
– Glucagon– Increases blood sugar
Neural and Hormonal Systems
• Thyroid Hormone
– Thyroxin– regulates metabolism and growth
Neural and Hormonal Systems
• Sex Glands (Gonads)
– Female Sex Hormone– Estrogen (Ovary)
– Male Sex Hormone– Androgen (Testis)
Association Areas
• Association Areas
– Areas of the cerebral cortex that are not
involved in primary motor or sensory
functions. They are involved in higher mental
functions such as learning, remembering,
thinking and speaking.
– Phineas Gage
Association Areas
 More intelligent animals have increased
“uncommitted” or association areas of the cortex
The Cerebral Cortex
 Aphasia
 impairment of language, usually caused by left
hemisphere damage either to Broca’s area
(impairing speaking) or to Wernicke’s area
(impairing understanding)
 Broca’s Area (Disrupts speaking)
 an area of the left frontal lobe that directs the
muscle movements involved in speech
 Wernicke’s Area (Disrupts understanding)
 an area of the left temporal lobe involved in
language comprehension and expression
Hypothalamus
(The Four F’s)
• Contains nuclei involved in a variety
of behaviors
–
–
–
–
–
–
–
sexual behavior
hunger, thirst
sleep
water and salt balance
body temperature regulation
circadian rhythms
role in hormone secretion
Hypothalamus and Hormones
Hypothalamus
releases
hormones or
releasing factors
which in turn
cause pituitary
gland to release
its hormones
Hippocampus
• Hippocampus– structure that contributes
to the formation of memories.
• Damage to the hippocampus has been
implicated in the memory loss associated
with Alzheimer’s.
Specialization and Integration
Disappearing Southpaws
 The percentage of left-handers decreases sharply in
samples of older people (adapted from Coren, 1993).
Percentage of14%
left-handedness
12
The percentage of
lefties sharply
declines with age
10
8
6
4
2
0
10
20
30
40
50
Age in years
60
70
80
90
Brain Structures and their
Functions
The Nervous System
Neurons in the brain
connect with one
another to form networks
Inputs
The brain learns by modifying
certain connections in
response to feedback
 Neural Networks
 interconnected neural
cells
 with experience,
networks can learn, as
feedback strengthens
Outputs or inhibits connections
that produce certain
results
 computer simulations
of neural networks
show analogous
learning
Neural Communication
 Neuron
 a nerve cell
 the basic building
block of the nervous system
 Soma
 cell body; serves as neuron’s control
center
Neural
Communication
 Dendrite
 the bushy, branching extensions of a neuron that
receive messages and conduct impulses toward the
cell body
 Axon
 the extension of a neuron, ending in branching
terminal fibers, through which messages are sent to
other neurons or to muscles or glands
 Myelin [MY-uh-lin] Sheath
 a layer of fatty cells segmentally encasing the fibers
of many neurons
 enables vastly greater transmission speed of neutral
impulses
Neural
Communication
 Action Potential
 a neural impulse; a brief electrical charge
that travels down an axon
 generated by the movement of positively
charged atoms in and out of channels in the
axon’s membrane
 Threshold
 the level of stimulation required to trigger a
neural impulse
Neural
Communication
Cell body end
of axon
Direction of neural impulse: toward axon
terminals
Action Potential Within a Neuron
How Neurons Communicate
Neurons communicate by means of an
electrical signal called the Action Potential
Action Potentials are based on
movements of ions between the outside
and inside of the cell
When an Action Potential occurs, a
molecular message is sent to neighboring
neurons
Neural
Communication
 Synapse [SIN-aps]
 junction 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
 Neurotransmitters
 chemical messengers that traverse the synaptic gaps
between neurons
 when released by the sending neuron, neurotransmitters travel across the synapse and bind to
receptor sites on the receiving neuron, thereby
influencing whether it will generate a neural impulse
Neurotransmitter Release

Action Potential causes vesicle to open
Neurotransmitter
Locks
released into synapse
onto receptor molecule in
postsynaptic membrane
Locks and Keys
Neurotransmitter
molecules have specific
shapes
Receptor molecules have
binding sites
When NT binds to
receptor, ions enter

Some Drugs Work on Receptors


Some drugs are
shaped like
neurotransmitters
Antagonists: fit the
receptor but poorly
and block the NT

e.g., beta blockers
Agonists:
fit receptor
well and act like the
NT
e.g.,
nicotine
Dopamine
Involved in movement, attention
and learning
Dopamine imbalance also
involved in schizophrenia
Loss of dopamine-producing
neurons is cause of Parkinson’s
disease
Parkinson’s Disease


Results from loss of dopamine-producing neurons
Symptoms include





difficulty starting and stopping voluntary movements
tremors at rest
stooped posture
rigidity
poor balance
Parkinson’s Disease

Treatments
L-dopa
 transplants of fetal dopamine-producing substantia
nigra cells
 adrenal gland transplants
 electrical stimulation of the thalamus has
been used to stop tremors

Serotonin
 Involved
in sleep
 Involved in depression
Prozac
works by keeping serotonin in
the synapse longer, giving it more time
to exert an effect
Excitatory and Inhibitory Messages
Excitatory message— increases the
likelihood that the postsynaptic neuron will
activate
 Inhibitory message— decreases the
likelihood that the postsynaptic neuron will
activate.

Neural Communication
Neurotransmitter
molecule
Receptor site on
receiving neuron
Receiving cell
membrane
Agonist mimics
neurotransmitter
Antagonist
blocks
neurotransmitter
Acetylcholine




First neurotransmitter discovered
Ach is found in all motor neurons
It stimulates muscles to contract,
including the heart and stomach
muscles
Primary Roles: learning, memory, muscle
contractions
Disruption of
Acetylcholine Functioning
 Curare—blocks
 paralysis results
 Nerve
ACh receptors
gases and Black Widow
spider venom; too much ACh
leads to severe muscle spasms
and possible death
Disruptions in ACh Functioning
 Cigarettes—nicotine
works on
ACh receptors
can
artificially stimulate skeletal
muscles, leading to slight trembling
movements
Alzheimer’s Disease
 Deterioration
of memory, reasoning,
and language skills
 Symptoms
may be due to loss of
ACh neurons
Endorphins
Control pain and pleasure
 Released in response to pain
 Morphine and codeine work on
endorphin receptors; involved in
healing effects of acupuncture
 Runner’s high— feeling of pleasure
after a long run is due to heavy
endorphin release

Norepinephrine
 Arousal
 “Fight
or flight” response
 Primary Roles: physical
arousal, learning, memory
 Disorders: depression
GABA
 Inhibition
of brain activity
 Huntington’s disease involves loss
of neurons in striatum that utilize
GABA
Symptoms:
jerky involuntary movements
 mental deterioration

Glutamate
 Major
excitatory neurotransmitter
 Too much glutamate (and too
little GABA) associated with
epileptic seizures
Neural Communication
Summary
z
z
z
z
z
z
Neuron structure
Action potentials
Synapse
Receptors and ions
Neurotransmitters
Agonists and
antagonists
The Nervous System
 Nerves
 neural “cables” containing many axons
 part of the peripheral nervous system
 connect the central nervous system with
muscles, glands, and sense organs
The Cerebral Cortex
 Cerebral Cortex
 the intricate fabric of interconnected
neural cells that covers the cerebral
hemispheres
 the body’s ultimate control and
information processing center
 Glial Cells
 cells in the nervous system that support,
nourish, and protect neurons
The Cerebral Cortex
 Frontal Lobes
 involved in speaking and muscle movements and in
making plans and judgments
 Parietal Lobes
 include the sensory cortex & processes somatic
information
 Occipital Lobes
 include the visual areas, which receive visual
information from the opposite visual field
 Temporal Lobes
 include the auditory areas
The Cerebral Cortex
 Motor Cortex
 area at the rear of the frontal lobes that
controls voluntary movements
 Sensory Cortex
 area at the front of the parietal lobes that
registers and processes body sensations