Download The Brain - Miami Arts Charter School

The Brain
Created by David Silverman
A neuron “fires” when the terminal
buttons of neuron A are stimulated and
release neurotransmitters into the
synapse. The neurotransmitters fit into
receptor sites on the dendrites of
neuron B. If enough neurotransmitters
are received (threshold is achieved),
positive ions rush through the now
permeable cell membrane of neuron B.
This rapid electric message firing is
called an action potential. When the
charge reaches the terminal buttons of
neuron B, the buttons release their
neurotransmitters into the synapse. A
neuron either fires completely or it does
not fire; this is called the all-or-none
principle.
* A neuron cannot fire a little or a lot;
the impulse is the same every time. *

Some neurotransmitters are excitatory, meaning that they excite the next cell
into firing. Other neurotransmitters are inhibitory, meaning that they inhibit the
next cell from firing


Afferent Neurons (or Sensory Neurons)


Afferent neurons take information from the senses to the brain
Interneurons


The amount and type of neurotransmitters received on the receptor sites of the neuron
determine whether it will pass the threshold and fire
When information reaches the brain or spinal cord, interneurons send messages to other
areas of the brain or on to efferent neurons
Efferent Neurons (or Motor Neurons)

Efferent neurons send information from the brain to the rest of the body


The Central Nervous System

Our brain and spinal cord make up our central nervous system

The spinal cord is a bundle of nerves that run through the center of the spine. It transmits information
from the rest of the body to the brain.
The Peripheral Nervous System

The peripheral nervous system consists of all the other nerves in your body not encased in bone. This is
divided into the somatic and autonomic nervous system.

The somatic nervous system controls our voluntary muscle movements through signals from the motor cortex of
the brain

The autonomic nervous system controls the automatic functions of our body—our heart, lungs, internal organs,
glands, and so on. These nerves control our responses to stress—the fight or flight response that prepares our body
to respond to a perceived threat. The autonomic nervous system is divided into the sympathetic and
parasympathetic nervous systems.
Autonomic nervous system


SYMPATHETIC NERVOUS SYSTEM

The sympathetic nervous system readies our body to respond to stress by sending
messages to the control systems of the organs (glands and muscles that direct our
body’s response to stress)

Accelerates heart rate, blood pressure, and respiration

Slows down other functions like digestion
PARASYMPATHETIC NERVOUS SYSTEM

The parasympathetic nervous system is responsible for slowing down our body after
a stressful response.

The parasympathetic nervous system is the “brake pedal” that slows down the
body’s autonomic nervous system.
Ways to study the brain

Accidents- in 1848 Phineas Gage was a railroad worker who damaged the front part of his brain
in an accident which drastically changed his behavior and personality

Lesions- Lesioning is the removal of part of the brain which can cause changes in behavior or
functioning

Electroencephalogram (EEG)- Detects brain waves to determine what type of waves the brain
produces during different stages of consciousness

Computerized axial tomography (CAT)- Uses multiple X-ray cameras that combine the pictures
into a 3D image of the brain’s structure

Magnetic Resonance Imaging (MRI)- Like a CAT scan but provides more detailed images of the
brain using magnetic fields which does not expose the patient to carcinogenic radiation like a
CAT does

Positron Emission Tomography (PET)- Allows research's to see which areas of the brain are
active during certain tasks (like measuring glucose levels)

Functional MRI- Combines elements of MRI and PET scans to show brain structure and blood flow
to the brain to study brain activity
Brain Structure and Function

Hindbrain- Made up of structures located in the top part of the spinal cord
and controls the basic biological functions that keep us alive

Medulla (or medulla oblongata)- involved in controlling our blood pressure, heart
rate, and breathing

Pons- Involved in facial expression control and connects the hindbrain to the
midbrain and forebrain

Cerebellum- coordinates habitual muscle movements like tracking something with
your eyes or playing an instrument

Cerebellum looks like a smaller version of the brain (Cerebellum means little brain)

Midbrain- coordinates simple movements with our senses

If you turn your head to the right while reading this, your midbrain helps keep your
eyes focused on the text

Located between the hindbrain and forebrain

Reticular formation is a collection of cells throughout the midbrain that controls
body arousal and the ability to focus

If our reticular formation doesn’t function we will fall into a deep coma

Forebrain- controls aspects of our thought and reasoning skills and is made up
of various areas like the thalamus, hypothalamus, amygdala, and
hippocampus

Thalamus- located at the top of the brain stem and is responsible for receiving
sensory signals coming from the spine to the forebrain

Hypothalamus- Controls metabolic functions like body temperature, sexual arousal
(libido), hunger, thirst, and the endocrine system

Hippocampus- Though memories are not stored in the hippocampus, memories are
processed and sent to other locations in the cerebral cortex for permanent storage

Amygdala- Essential to our experiences of emotion
Cerebral Cortex


The cerebral cortex is the thin, gray, wrinkly (1-mm) layer of densely packed
neurons that covers the rest of the brain

When we are born we have more neurons than we have as adults, but they are not well
connected

The wrinkles in our cerebral cortex are called fissures, which provides more surface area
in our skull (without the wrinkles our skull would be 3 square feet)
The cerebral cortex is divided into our left and right hemispheres

Though the hemispheres look identical, they have different functions

The left gets sensory information and controls motor functions in the right half of the
body

The right gets sensory information and control the motor functions on the left half of the
body

Contrary to popular belief, it is NOT yet proven that the left controls logic and
sequential tasks while the right dictates spatial and creative tasks

Brain lateralization, or hemispheric specialization is the specialization of how each
hemisphere functions

Split-brain patients- Most of the research conducted to study each hemisphere is by examining patients
whose corpus callosum (the nerves that connect the two hemispheres) has been split in half to treat
severe epilepsy (seizures)

This operation was created by Roger Sperry and Michael Gazzinga

Split-brain patients can’t orally report information presented in the right hemisphere because the spoken
language regions of the brain are usually located in the left hemisphere
Areas of the Cerebral Cortex

The cerebral cortex is made up of 8 different lobes, 4 on each hemisphere (frontal, parietal,
temporal, and occipital

Any area of the cerebral cortex that isn’t associated with receiving sensory information or controlling
muscle movement is called an association area


These are thought to be responsible for complex, sophisticated thoughts like judgment and humor
Frontal Lobes are large areas of the cerebral cortex at the top front part of the brain

The front of the frontal lobe is called the prefrontal cortex, which is thought to direct thought process

Believed to be vital in foreseeing consequences, pursuing goals, maintaining emotional control, abstract thought, and
emotional control

Broca’s area (Paul Broca 1824-1880)- is located in the left frontal area and is responsible for controlling muscles involved in
speech production


If damaged, we might not be able to move our muscles needed for speech
The thin vertical strip at the back of our frontal lobe is the motor cortex, which sends signals to our muscles
which controls our voluntary movements

Parietal Lobes- located behind the frontal lobe and contains the sensory cortex (somato-sensory
cortex) which receives incoming tactile sensations from the rest of our body

Occipital Lobes- interprets impulses from our retinas that are sent to our visual cortex


Impulses from the right half of each retina are processed in the visual cortex in the right occipital lobe

Impulses from the left part of each retina are sent to the visual cortex in our left occipital lobe
Temporal Lobe- processes sound waves by turning them into neural impulses that are located in our
auditory cortices

Sound received by each ear is processed in both hemispheres

Wernicke’s area interprets both written and spoken speech

Damage to this area would affect our ability to understand language, specifically lacking the proper syntax and grammatical
structures needed for communication
Brain Plasticity

While we know many functions are associated with certain areas of the brain,
our brain is somewhat “flexible”

If needed, our brain can actually adapt to perform other functions associated with
different areas

If one part of our brain is damaged, our dendrites might be able to make new connections
in a different part of the brain

Many times these connections are not as strong/fast as the original connections (Like taking
Biscayne instead of 95)

Dendrites grow faster in young children, therefore brains of children are more likely to be able to
compensate for permanent damage
Endocrine System

The endocrine system is made up of glands that secrete hormones that affect
different biological process in our bodies and is controlled by the
hypothalamus

Adrenal Glands- produce adrenaline that signals the body to prepare for fight or
flight (also associated with the autonomic nervous system)

Ovaries and Testes- produce our sex hormones (estrogen for women, testosterone
for men)
Genetics

Another factor contributing to human thought and behavior is genetics

Most of our traits like temper, extroversion, and body shape result from the
combined effect of nature (genetic code) and nurture (environment)

Human cells contain 46 chromosomes in 23 pairs, and the genetic material that
makes this up is called DNA (deoxyribonucleic acid)

DNA segments control production of proteins that control certain human traits which are
called genes

These can be dominant or recessive

If we inherit a dominant and a recessive gene, the dominant trait will be expressed

If we inherit two recessive genes, then that trait will be expressed
Twins

Identical twins are called monozygotic because they develop from one
fertilized egg and share all the same genetic material

These situations are especially useful for studying the influence of genes on human
traits

Thomas Bouchard conducted a study of more than 100 identical twins who were
given up for adoption and raised in different families to study the effects of nature
vs nurture

On average, identical twins raised in separate homes had a correlation of .69 on an IQ test

On average, identical twins raised in the same home had a correlation of .88 on an IQ test

These results show that both nature and nurture influence IQ, however other confounding variables
could have skewed these results (like how they are treated based on their physical looks or being
raised in similar environments)
Chromosomal Abnormalities

Sex is determined by our 23rd pair of chromosomes

Women have two X chromosomes, and Men have one X and one Y

Usually if a man contributes an X chromosome the child will be a girl, and if he
contributes a Y the child will be a boy

Chromosomal abnormalities occur when the chromosomes either fail to combine or
combine in unusual ways

Turner’s syndrome babies are born with only one X chromosome which can cause
shortness, webbed necks, and differences in physical sexual development

Klinefelter’s syndrome babies have an extra X chromosome (XXY) which can cause
minimal sexual development, extreme introversion, and a range of other abnormalities

Down syndrome babies are born with an extra chromosome on the 21st pair which can
cause mental retardation

Physical differences of Down syndrome are often characterized by rounded faces, shorter toes,
shorter fingers, and slanted eyes

Resources

Mr. Duez- powerpoints and videos




References

This powerpoint presentation was adapted
using information from the Barron’s AP
Psychology 5th edition prep book.
http://appsych.mrduez.com/p/2biological-bases-of-behavior.html
Crash Course Psychology

The Chemical Mind

Getting to Know Your Brain
Discovering Psychology

The Behaving Brain

The Responsive Brain


Weseley, Allyson, Robert McEntarffer,
and Robert McEntarffer. AP®
Psychology. Hauppauge, N.Y.: Barron's
Educational Series, 2014. Print.
Fineburg, A., & Myers, D. (2010). Myers'
Psychology for AP*: Teacher's
edition (Teacher's ed.). New York: Worth
/BFW.