Transcript neurotransmitters.

Myers’ PSYCHOLOGY
(7th Ed)
Chapter 2
Neuroscience, Genetics
and Behavior
James A. McCubbin, PhD
Clemson University
Worth Publishers
Everything psychological is
simultaneously biological!
 Your every idea, mood or urge is a biological
happening!!!!
 Without your body, you are nobody!
Chapter 2-Neuroscience-explains how our
biology underlies our mental & behavior
processes.
Biological Psychologists study the links between
biological activity and psychological events.
PHRENOLOGY
Invented by Franz Gall in the early 1800’s.
A theory that claimed that bumps on the
skull could reveal our mental abilities and
character traits.
Phrenology focused the attention that
various regions of the brain have
particular, specific functions.
Neuron
 a nerve cell
 the basic building block of the nervous
system
-our bodies information system is built from
100 billion of interconnected cells called
neurons.
-many different types of neurons, but all are
composed in the same way.
 Glial Cells
 cells in the nervous system that support, nourish, and
protect neurons
Dendrites (Greek for tree)
Are the bushy, branching extensions of a
neuron that receive messages and conduct
impulses toward the cell body. They
receive information from other nerve cells
and send it through the soma or cell
body to the:
Axon
 (Greek for axle)
 the extension of a neuron, (long fiber) ending
in branching terminal fibers, through which
messages are sent to other neurons or to
muscles or glands (senders). At the end of
the axon are thousands of terminal
buttons.
Vesicles and Neurotransmitters
The area where the axon ends, in the terminal
buttons just before the synapse, is filled with
small containers that look like bubbles..called
vesicles.
Inside the vesicles are thousands of chemical
messengers called neurotransmitters.
Myelin Sheath
 Myelin [MY-uh-lin] Sheath
 a layer of fatty cells segmentally encasing the
fibers of many neurons (insulating the axons)
 enables vastly greater transmission speed of
neural impulses
 Multiple Sclerosis, a disease in which the
myelin sheath degenerates, which results in a
slowing of communication to the muscles and
loss of muscle control.
Synapse [SIN-aps]
 (means junction point)
 The space between the axon tip of the
sending neuron and the dendrite of the
receiving neuron
 tiny gap at this junction is called the synaptic
gap or cleft
 Neurons work by electricity. Electricity will not
go over a space, so it stops.
Structure of a Neuron
Neural
Communication
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
 If the message is for arm movement, the vesicles
only release neurotransmitters involved in the
movement circuit.
 There are dozens of different neurotransmitters.
Neurotransmitters
Neurotransmitters
 Acetylcholine [ah-seat-el-KO-leen] (Ach)
 most common, best understood
 a neurotransmitter that, among its functions,
triggers muscle contraction
 is involved in memory (a shortage of causes
Alzheimer’s Disease)
 Endorphins [en-DOR-fins]
 “morphine within”
 natural, opiate like neurotransmitters
 linked to pain control and to pleasure
Neurotransmitters
DopamineInvolved in the control of bodily movements,
learning, attention, & emotion.
Shortage causes Parkinson’s disease
Excessive dopamine linked with schizophrenia
Seratonin
Affects mood, hunger, sleep and arousal
Addiction – the result of suppressing
the brain’s production of its own
opiates
 If indeed the endorphins lessen pain and boost mood, why
not flood the brain with artificial opiates, thereby
intensifying the brain’s own “feel-good” chemistry? One
problem is that when flooded with opiate drugs such as
heroin and morphine, the brain may stop producing its own
natural opiates. When the drug is withdrawn, the brain
may then be deprived of any form of opiate. For a drug
addict, the result is discomfort that persists until the brain
resumes production of its natural opiates or receives more
artificial opiates. Mood altering drugs, from alcohol to
nicotine to heroin, share a common effect: The trigger
unpleasant, lingering aftereffects.
Lithium
 Lithium is used to treat and prevent episodes of mania (frenzied, abnormally excited
mood) in people with bipolar disorder (manic-depressive disorder; a disease that
causes episodes of depression, episodes of mania, and other abnormal moods).
Lithium is in a class of medications called antimanic agents. It works by decreasing
abnormal activity in the brain.
 Lithium acts on a person's central nervous system (brain and spinal cord). Doctors
don't know exactly how lithium works to stabilize a person's mood, but it is thought
to help strengthen nerve cell connections in brain regions that are involved in
regulating mood, thinking and behavior.
 Bipolar Disorder
Neural
Communication
Serotonin Pathways
Dopamine Pathways
Neural Communication
Neural communication refers to how the neurons
relay messages to each other. It is referred to
an electrochemical reaction.
Neurons are surrounded by fluid. The fluid inside
a neuron contains negative charged atoms,
called ions, ( - ) from the fluid located outside
the neuron, which has positive charged ions
(+).
Ions
The neural membrane only allows certain ions
through the membrane.
Positively charged sodium and potassium ions and
negatively charged chloride ions flow back and
forth across the cell membrane, but they do not
cross at the same rate. The difference in the
flow leads to a higher concentration of
negatively charged ions inside the cell.
Electrical and Resting Potential
Positive ions will flow into the neuron if not
stopped or pumped out by the membrane. This
is called the electrical potential, which is
measured in millivolts.
The resting potential is the neuron’s usual
charge, which is –70 millivolts.
When the resting potential has changed
enough, about +10mv, the membrane changes
and this is called the action potential.
A neuron fires an impulse, when it
receives signals from sense
receptors…the impulse is called
 Action Potential
 a neural impulse; a brief electrical charge that
travels down an axon, each tripping the next
(depolarization)
 generated by the movement of positively
charged ions (atoms) in and out of channels in
the axon’s membrane.
 The speed at which an action potential travels
the axon ranges from 2 to 250 mph.
 Refractory Period- a resting pause, when the neuron
pumps the positively charged ions back outside…then it
can fire again.
 Excitatory-signal to send the message
 Inhibitory-signal to stop the message
 Threshold -the level of stimulation required to trigger a
neural impulse
 Agonist-excite by mimicking particular neurotransmitters
or block their reuptake.
 Antagonists-inhibit a neurotransmitter’s release or block
its effect.
All or nothing neural reaction
The neuron’s reaction is an “all or none
response.”
Neurons either fire or they don’t. (like a gun)
HW Assignment: How is the action potential
neuron like flushing a toilet? or like using a
camera?
Neural
Communication
Cell body end
of axon
Direction of neural impulse: toward axon terminals
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
 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
The Nervous System
Nervous
system
Central
(brain and
spinal cord)
Peripheral
Autonomic (controls
self-regulated action of
internal organs and glands)
Somatic or Skeletal (controls
voluntary movements of
skeletal muscles)
Sympathetic
(arousing)
Parasympathetic
(calming)
Three Types of Neurons
 that carry information throughout the nervous system:
 Sensory Neurons (Afferent)
 neurons that carry incoming information from the
sense receptors to the brain & spinal cord (CNS)
 Interneurons
 CNS neurons that internally communicate and
intervene between the sensory inputs and motor
outputs
 Motor Neurons (Efferent)
 carry outgoing information from the CNS to muscles
and glands
The sensory & motor axons carrying the PNS
information are bundled into electrical cables
called:
 Nerves
 neural “cables” containing many axons
 part of the peripheral nervous system
 connect the central nervous system with
muscles, glands, and sense organs
The Peripheral Nervous
System
 Somatic Nervous System
 the division of the peripheral nervous system
that controls the body’s skeletal muscles,
composed of sensory & motor nerves.
 Controls our voluntary movements & reflexes.
The Nervous System
 Autonomic Nervous System
 the autonomic control system of the body
(the peripheral nervous system)
It regulates breathing, heartbeat & digestion.
It sometimes can be overridden by the brain.
It is a dual system composed of:
 Sympathetic Nervous System
 division of the autonomic nervous system that
arouses the body, mobilizing its energy in
stressful situations, slows digestion. Raises
blood sugar & pressure, heart rate, dilates
eyes. Gets body ready for “fight or flight”
 Parasympathetic Nervous System
 division of the autonomic nervous system that
calms the body, conserving its energy
 It decreases your heartbeat, lowers your
blood sugar and pressure.
These two systems work together to keep us in
balance.
The Nervous System
The 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 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
or inhibits connections
Outputs
that produce certain
results
 computer simulations
of neural networks
show analogous
learning
Methods Used in Studying The
Brain
1. Accidents
In 1848, a railroad worker named Phineas Gage was
involved in an accident that damaged the front part of
his brain. Gage’s doctor took detailed notes
documenting the brain damage and about Gage’s
behavior & personality changes.
Before the accident, Gage was a nice guy, after the
accident he was highly emotional and impulsive.
2. Lesion
is the removal
or destruction of
part of the
brain.
a brain lesion is a
naturally or
experimentally
caused destruction of
brain tissue
 Frontal lobotomies
3. 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
 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
 It creates a 3-D image of brain’s structure. Does not show
function or activity.
 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
 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, not function
MRI Scan
PET Scan
The Cerebral Cortex
 Functional MRI
scan shows the
visual cortex
activated as the
subject looks at
faces
Three regions of the brain
1. the forebrain
-most recently evolved section
2. the midbrain
-contains the upper part of the brain stem
3. the hindbrain
-consists of structures in top part of the
spinal cord, most of the brain stem.
The Hindbrain
 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
 Medulla [muh-DUL-uh]
 base of the brainstem, attaches to spinal cord
 controls heartbeat and breathing
The Brain
 Reticular Formation (Reticular Activating
System)
 a nerve network in the brainstem that plays
an important role in controlling arousal &
sleep.
 Involved in controlling muscle reflexes,
breathing & perception.
The Brain
The Brain
 Cerebellum [sehruh-BELL-um]
 the “little brain”
attached to the
rear of the
brainstem
 it helps coordinate
voluntary
movement and
balance
The Midbrain
A segment of the brainstem located
between the hindbrain & forebrain,
containing the reticular formationregulating sleep & arousal.
The Forebrain
 Thalamus [THAL-uh-muss]
 the brain’s sensory switchboard, located on
top of the brainstem
 it directs messages to the sensory receiving
areas in the cortex and transmits replies to
the cerebellum and medulla
The Forebrain
 Limbic System
 a doughnut-shaped system of neural structures at the
border of the brainstem and cerebral hemispheres
 associated with emotions such as fear and aggression
and drives such as those for food and sex, regulates
emotion, memory & motivation
 includes the hippocampus, amygdala, and
hypothalamus.
 Amygdala [ah-MIG-dah-la]
 two almond-shaped neural clusters that are
components of the limbic system and are linked to
emotion, aggression & fear
The Forebrain
 Hypothalamus
 neural structure lying
below (hypo) the
thalamus; directs several
maintenance activities
 eating
 drinking
 body temperature
 helps govern the
endocrine system via the
pituitary gland
 is linked to emotion
The Limbic System
The Cerebrum
Is the largest & most complex part of the
human brain. It includes the brain areas
that are responsible for the most complex
mental activities: learning,
rememebering, thinking & consciousness
itself.
The Cerebral Cortex
 Cerebral Cortex
Is the convoluted outer layers of the cerebrum.
The cortex is folded & bent & divided into 2
hemispheres. The hemispheres are the left &
right halves of the cerebrum.
 the intricate fabric of interconnected neural cells
that covers the cerebral hemispheres
 the body’s ultimate control and information
processing center
The Cerebral Cortex
 Frontal Lobes
 involved in speaking and muscle movements and in
making plans and judgments
 Parietal Lobes
 includes the sensory cortex, registers body sensations
 Occipital Lobes
 include the visual areas
Temporal Lobes
 includes the auditory areas, processes hearing &
speech
The Cerebral Cortex
The Cerebral Cortex
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
Brain Structures and
their Functions
Visual and Auditory
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
 an area of the left frontal lobe that directs the
muscle movements involved in speech
 Wernicke’s Area
 an area of the left temporal lobe involved in
language comprehension and expression
Specialization and
Integration
Specialization and
Integration
 Brain activity when hearing, seeing, and speaking
words
Association Areas
 More intelligent animals have increased
“uncommitted” or association areas of the cortex
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
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
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. They work the
same as neurotransmitters
 Pituitary Gland
 under the influence of the hypothalamus, the
1)pituitary regulates growth and 2)controls other
endocrine glands, “Master Gland” small bean
shaped unit, located in base of the brain
The Thyroid Gland
-the pituitary gland signals the thyroid,
its job is to control metabolism.
-It is located inside the neck and looks like a
bow tie.
 Adrenal [ah-DREEN-el] Glands
 a pair of endocrine glands just above the
kidneys
 secrete the hormones epinephrine
(adrenaline) and norepinephrine
(nonadrenaline), which help to arouse the
body in times of stress
The Gonads
are sex glands that make the sperm or
eggs.
Male sex hormones are androgen &
testosterone
Female hormones is estrogen
We have both hormones in our body