Neuroscience and Biological psychology
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Transcript of Neuroscience and Biological psychology
NEUROSCIENCE AND BIOLOGICAL PSYCHOLOGY
AP PsychMyers, Ch. 2
Everything psychological is also biological.
The Mystery of the Human Brain
The brain is not completely understood. How does our brain organize and
communicate with itself? How do our heredity and our
experiences work together to wire our brain?
How do memories work in the brain?
Biological psychology – a branch of psychology concerned with the links between biology and behavior. Scientists have discovered partial
answers to these questions but much is left to discover!
Early Brain Research
Phrenology – theory that the shape of and bumps on the skull could reveal mental abilities and character traits. Early 1800s – mid-20th century
(used to justify racism and discrimination)
Quackery (fraudulent medical practice)
Correctly focused attention on the idea that various brain regions have certain functions
Contemporary Brain Research In the last century,
scientists have discovered that the body is made of cells.
Nerve cells (neurons) conduct electricity to “talk” to one another by sending chemical messages across a tiny gap that separates them.
NEURONS
Neuron Nerve cell Building block of the nervous system
Found all over the body Brain Legs Eyes Anywhere there are nerves – We will mainly focus on the basic neuron (below)
Dendrites
The bushy extensions of a neuron that receive messages
Dendrite
s
Soma
Cell body Contains nucleus – DNA, genetics,
etc
Soma
Axon The extension of a neuron through
which electrical messages pass Like the “backbone” of a neuron, if
broken, the neuron dies.
AXON
DENDRITES LISTEN…
… AXONS SPEAK
The dendrites can receive messages to make the neuron fire or not fire. If the message is to “fire,” the axon will send the message to the axon terminals.
Myelin Sheath Layer of fatty tissue on the axon that…
Protects axon Speeds neural impulse (the message)
Made of glial cells, which also bind neurons together.
Myelin
Sheath
Multiple sclerosis – a disease in which the
myelin sheath degenerates resulting in a
slowing of all communication to
muscles and the eventual loss of muscle control
Axon Terminals
Branches at the end of an axon that send messages to the dendrites of another neuron. End in axon terminal buttons – contain
vesicles that hold neurotransmittersAxo
n
Term
inal
s
Axon TerminalButtons
Action Potential A neural impulse in the form of a brief
electrical charge that travels down the axon A neuron fires an impulse when it receives a
signal from sense receptors or by the neurotransmitters from another neuron.
Direction of ACTION POTENTIAL
Synapse
The junction between neurons. Synaptic gap, synaptic cleft, etc Less than a millionth of an inch wide
Synapse
I need 5 volunteers…
Stand next to each other facing the class.
Hold hands. The person farthest to the RIGHT wants
to send a message to the person farthest to the LEFT (without actually talking)– how will we do this?
When you feel the squeeze of your right hand, squeeze the right hand of the person beside you.
Right hand and arm DENDRITES
Chest SOMA
Left arm AXON
Left hand AXON TERMINALS
How Nerve Impulses Work
Threshold - the level of stimulation required to trigger a neural impulse. “all-or-none/nothing” principle
It either fires…… or it
doesn’t.
How Nerve Impulses Work
Resting potential – the electrical charge of a neuron at rest.
Ions – electrically charged molecules Inside axon: overall - Outside axon: overall +
“I’m so HAPPY (+) that I’m OUTSIDE playing!”
How Nerve Impulses WorkNeuron receives chemical message.1. Axon’s ion channels (holes in the axon membrane) open, allowing
Na+ ions inside.2. Ion channels open like a domino effect, traveling from the soma
to the axon terminal.3. After the impulse passes, the neuron dips below resting potential
and cannot fire. The “ion pump” flushes out positive ions as it releases K+ ions outside.
Less than 1/100 of a second.
How Neurons Communicate Neurotransmitters - chemical
messengers that travel across the synaptic gap between neurons
1. Action potential reaches the axon’s terminal buttons.
2. Buttons release neurotransmitters (chemicals)
3. Travel across the synapse4. Bind/connect to receptor sites on the
next neuron’s dendrites
Neurotransmitters Lock-and-key relationship between
the neurotransmitter and the receptor site. When the neuron receives
neurotransmitters, it will fire/not fire
Neurotransmitters Many types of neurotransmitters that
affect us differently and are found in different parts of the brain
Neurotransmitter
Function Examples of Malfunction
Acetylcholine (ACh)
MovementLearningMemory
Too little - Alzheimer’s disease
Dopamine MovementLearningAttentionReward/Pleasure
Too little – Parkinson’s disease
Too much – schizophrenia• “Too much dopamine can make you
‘dopey.’”Serotonin Mood
HungerSleep
Too little – depression• “Sarah’s tone is sad.”
Norepinephrine Alertness Arousal
Too little – depressed mood Too much – mania (linked to bipolar disorder)
DopamineSerotonin
Chart on pg. 58
Endorphins Natural, opiate-like
neurotransmitters linked to pain control and pleasure
Inhibit (block) pain Ex: Runner’s high One of the top
suggested remedies for depression is exercise naturally produce chemicals that will stimulate pleasure and happiness
INTERACTIVE NEURON
“Happy people don’t kill their husbands!”
Brain, Neurotransmitters, and Other Chemicals Cocaine, heroin, morphine, anti-depressants, anti-
psychotics, etc manipulate the production of neurotransmitters.
Too much manipulation brain may stop naturally producing similar transmitters.
When the medication or drug is withdrawn, the
brain may be deprived of the neurotransmitters until the it can naturally start producing its own again. Explains the uncomfortable withdrawal period when a
drug addict ceases using the drug.
Brain, Neurotransmitters, and Other Chemicals Various drugs and substances can effect
communication at the synapse, by exciting or inhibiting a neuron to fire. Agonist – molecules that are similar to
neurotransmitters and can mimic their effects. Eg: the venom of a black widow spider floods the brain
with agonists similar to ACh which results in muscle contractions, convulsions, and even death.
Antagonist – a molecule that block a neurotransmitter’s release Eg: Botulin (a poison in improperly canned food), causes
paralysis by blocking the release of ACh from the sending neuron.
Neural Networks
Interconnected neural cells; with experience, networks can learn and strengthen
Neurons can receive and send information from and to many neurons at the same time.
Neurons cluster to work in groups to produce shorter, faster connections (bound together by glial cells). Experience causes neural networks
to grow and strengthen eg: practicing the piano builds neural connections that help this behavior.
IMPORTANT
Communication WITHIN a neuron… ELECTRICAL – action potential
Communication BETWEEN neurons… CHEMICAL - neurotransmitters
NERVOUS SYSTEM
Central Nervous System (CNS) The brain and the spinal cord
Peripheral Nervous System (PNS) the sensory and motor neurons that
connect the CNS to the rest of the body. Everything but the brain and spinal cord
Nerves
In the PNS Neural cables Connect the CNS to
muscles, glands, and sense organs Ex: optic nerve
connects the eye to the brain Eye = sense organ Optic nerve = PNS Brain = CNS
Nervous System Neurons
Information travels through the nervous system in 3 type of neurons.
1. Sensory neurons – (aka afferent neurons) carry incoming information from the senses to the CNS
2. Interneurons – CNS neurons that internally communicate between sensory inputs and motor outputs
3. Motor Neurons – (aka efferent neurons) carry out going information from the CNS to muscles and glands
Sensory feel… Inter interpret… Motor move
The Spinal Cord and Reflexes CNS is the highway between the brain
and the PNS. However, sometimes the body can react without the message reaching the brain. Reflex – simple, autonomic, inborn
response to a sensory stimulus, such as the knee-jerk response.
Reflex pathway = 1 sensory neuron + 1 communication interneuron + 1 motor neuron
Ex: simple pain reflex, simple knee-jerk reflex
The Spinal Cord and Reflexes Simple pain reflex
– hand jerks away when touching a hot surface. The movement is
initiated in the spinal cord.
Later, the pain is perceived in the brain.
Short delay between movement and sensation.
What happens if the Spinal Cord is severed? Paralysis because
sensory messages cannot reach brain and motor messages cannot leave brain
Paraplegia - patient can still move two limbs
Quadriplegia - all four limbs are paralyzed
Most famous case in recent times was the actor Christopher Reeves ( d. 2004)
Replicating Neural Pathways in the Body Everyone stand in a circle in the
hallway and await further instructions…
Shoulder squeeze Wrist squeeze
Somatic and Autonomic Nervous Systems
Somatic – controls the body’s skeletal muscles Running, dancing, etc
Autonomic – controls the glands and the muscles of internal organs Heartbeat, digestion, sweating
PNS
Autonomic Somatic
Somatic – Skeletal
Autonomic - Automatic
Sympathetic and Parasympathetic Nervous Systems Sympathetic – arouses
the body When someone is in crisis, we
feel sympathy for them
Parasympathetic – calms the body Parasympathetic - paralyzing
Autonomic
Sympathetic Parasympathetic
Let’s Put It All Together! Nervous
System
Peripheral(PNS)
SomaticAutonomic
ParasympatheticSympathetic
Central(CNS)
THE ENDOCRINE SYSTEM
Endocrine System
The body’s “slow” chemical communication system made of glands that secrete hormones into the bloodstream
Hormones – chemical messengers manufactured by glands Travel slowly in the bloodstream When hormones act on the brain, they can trigger
interest in sex, food, aggression, “flight or fight”
Gland - An organ in the body that secretes a substance for use somewhere else in the body
Hormones vs NeurotransmittersHormones Neurotransmitters
chemical messengers for the endocrine system
Travel in the blood stream
Chemical messengers in the brain
Travel in the brain in the synapse between neurons
The endocrine system tries to keep a balance in the body while we respond to feelings of stress, anger, fear, and
exertion.
Adrenal Gland
Pair of glands above the kidneys that release adrenaline and noradrenalin which helps to arouse the body in times of stress Increase heart rate, blood
pressure, and blood sugar for energy
Hormones can last in the bloodstream after the triggering event.
Daughter Lifts Car Off Dad
Pituitary Gland
Small pea-shaped gland in the limbic system of the brain Most influential gland –
“master” gland Regulates growth
(growth hormone) and controls other glands
Controlled by the hypothalamus
Gigantism – caused by a tumor on the
pituitary gland
THE BRAIN
The Brain Brain size ≠ Intelligence Brain structure and complexity =
Intelligence
Older Brain Structures
Perform unconscious simple tasks necessary for survival… Breathing Coordinating movement Heartbeat
Brainstem Medulla Pons Reticular formation
Thalamus Cerebellum
Brainstem Oldest part and central core of the
brain Beginning where the spinal cord
swells as it enters the skull Responsible for automatic survival
functions
Brainstem = area in the red box
Medulla
The base of the brainstem Controls heartbeat and breathing
Pons
Above the medulla Helps coordinate movement by
relaying information to the cerebellum
Reticular Formation A nerve network in the brainstem Helps control arousal and sleep
When stimulated, it arouses your focus. If severed, you could enter a coma. Narcolepsy = malfunction of reticular
formation
Thalamus The brain’s sensory switchboard,
located on top of the brainstem Directs messages to the sensory
receiving areas in the cortex and transmits replies to the cerebellum and medulla
Cerebellum The “little brain” attached at the rear
of the brainstem Processes sensory input and
coordinates movement output and balance An injured cerebellum would cause
difficultly walking and keeping balance jerky movements
The Limbic System A doughnut-shaped system of neural
structures at the border of the brainstem and cerebral hemispheres
Associated with EMOTIONS, MEMORIES, and SMELL Hippocampus Amygdala Hypothalamus
Hippocampus In the temporal lobe Processes/stores memories
Amnesia can result from injury to the hippocampus
“You’d remember if you saw a hippo on campus!”
Amygdala Two lima bean-sized
structures above the hippocampus
Influences fear and aggression Larger in males more
aggression Emotional problems
result from which part of the amygdala is stimulated/damaged (too much aggression, no fear, no emotions, etc)
Hypothalamus Below the thalamus Directs maintenance
activities Eating Drinking Body temperature
Controls the pituitary gland Interprets emotions
and tells the pituitary gland which glands need to secrete hormones
Reward/pleasure center
The Cerebral Cortex
The intricate fabric of interconnected neural cells that covers the cerebral hemispheres
The body’s ultimate control and information-processing center higher level functions Like bark on a tree – a thin surface that
covers the brain hemispheres Contains billions of neurons and even
more glial cells that bind together and nourish them.
Lobes of the Brain Geographical
subdivisions of the cerebral cortex separated by prominent fissures (folds) in the brain.
LOBES OF THE BRAIN AND THEIR FUNCTIONS (FPOT)Lobe Where in Cerebral
Cortex?Function
Frontal Behind the forehead Involved in speaking, muscle movements, and making plans/judgments
Parietal At the top of the head, towards the rear
Receives sensory input for touch and body position
Occipital At the back of the head Includes the visual areas, which receive visual information from the opposite visual field
Temporal
Roughly above the ears (near the “temples”)
Includes auditory areas, each of which receive auditory information primarily from the opposite ear
Tempora
l
Frontal
Occipital
Parietal
Sensory and Motor CortexesSensory Cortex Motor Cortex
An area at the front of the PARIETAL lobe that registers and processes body touch and movement sensations Parallel to the motor
cortex, behind it Stimulation – sensation
of being touch depending on the area
An area at the rear of the FRONTAL lobe that controls voluntary movements Sends outgoing
movements Stimulation – movement
in the body depending on the area
Motor and Sensory Cortexes The more sensitive a body region,
the larger the area in the sensory cortex
Visual and Auditory CortexesVisual Cortex Auditory Cortex
An area in the OCCIPITAL lobe that processes vision from the opposite eye
An area in the TEMPORAL lobe that processes sounds from the opposite ear
Association Areas
Areas of the cerebral cortex that are involved in HIGHER MENTAL FUNCTIONS such as learning, remembering, thinking, and speaking. Any area in the cerebral cortex that is
not in the motor, sensory, visual, or auditory cortexes.
In all 4 lobes
The Brain and Language Aphasia – impairment
of language, usually caused by left hemisphere damage either to… Broca’s area – frontal
lobe, left hemisphere, directs movement necessary for speech
Wernicke’s area – temporal lobe, left hemisphere, involved in language comprehension
Brain Plasticity The brain’s capacity for modification, as evident
in the reorganization following damage to the brain and in experiments on the effects of the experience on brain development SOME neural tissue can reorganize (not regenerate)
as the brain repairs itself after damage.
Blindness - when reading Braille, the brain area dedicated to that finger expands as the sense of touch invades the visual cortex, which normally helps people see
Deafness - the auditory cortex receives no information from sound, so it expands to new functions like visual tasks, which is why deaf people have been found to have enhanced peripheral vision.
Lateralization The brain’s two hemispheres are not
exactly alike and perform certain functions Right hemisphere – controls left side of
body Left hemisphere – controls right side of
body
Split Brain When the two brain
hemispheres are not attached by the corpus callosum
Corpus callosum Band of neural fibers
that connects the two brain hemispheres together and allows them to communicate
Possible to survive with a split brain, but may have difficultly integrating vision, speech, and motor skills.
Crash Course - Brain
Studying the Brain Lesion – damage to brain tissue
Allows us to study the functions of the brain in circumstances that would be unethical to replicate
Ex: Phineas Gage
Gabrielle Giffords’ brain after attempted assassination still has difficulty speaking, limited vision in both eyes and
no peripheral in the right eye, and her right arm and leg are paralyzed. She continues to undergo speech and physical therapy.
Electroencephalogram (EEG) Records the waves of electrical
activity that sweep across the brain’s surface; measured by electrodes placed on the scalp
Positron emission tomography (PET) Scan Scan detects where a radioactive form
of glucose goes while the brain performs a given task. Glucose = energy Red areas = glucose activity =
most active (while performing that given task)
Magnetic Resonance Imaging (MRI)
Uses magnetic fields and radio waves to images that distinguish among different types of soft tissue, allowing us to see structures within the brain.
Functional MRI (fMRI) -
A technique for revealing blood flow and therefore, brain activity by comparing successive MRI scans
Crash Course – The Chemical Mind