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