AP Psychology Unit 1 Review

Nature vs. Nurture

The age-old question of whether nature or nurture has a greater impact on human behavior is now considered outdated. It is understood that both nature and nurture play a role.
Nature refers to heredity, the passing of physical and mental traits from one generation to another.
Nurture refers to environmental factors such as family life, social groups, education, and societal influences.

Psychological Perspectives

Different psychological perspectives view heredity and environment differently.
The evolutionary approach, based on Darwin's theory of evolution, leans towards the nature side of the debate.
Charles Darwin's theory of evolution states that evolution happens by natural selection. Beneficial traits survive and are passed on, while undesirable traits die off.

Eugenics

Some individuals have used the principles of the evolutionary approach to support discriminatory practices such as eugenics.
Eugenics is the belief in improving the genetic quality of the human population by selectively breeding for desirable traits and discouraging reproduction among those with traits considered undesirable.

Epigenetics

Epigenetics studies how the environment and a person's behavior affect their genes and how they work.
Focuses on how an individual's body reads a DNA sequence.
The DNA itself is not changing; epigenetics happen slowly.
Genes are turned on or off due to sustained environmental pressures.
Epigenetics can explain why identical twins, who share nearly 100% of their genes, often develop vastly different physical and mental characteristics.

Minnesota Study of Twins Reared Apart

Examined similarities and differences in identical twins separated at birth and raised in different environments.

COL Adoption Project

Researchers have also conducted family studies and adoption studies.
A longitudinal study follows the biological and adoptive families to gain insight into the influences that genetics and the environment play on the individual's cognitive abilities, personalities, and mental processes.

Plasticity

Different from epigenetics.
Refers to the brain's ability to change and adapt as a result of experiences.
Involves the strengthening or weakening of neural connections.
Allows our brains to be flexible and adapt to our changing experiences.
As you're watching this video, you are building and strengthening your neural connections related to the information in Unit One from AP Psychology.

Nervous System

Central Nervous System (CNS)

Made up of the brain and spinal cord.
Sends out orders to the body.

Peripheral Nervous System (PNS)

Consists of different nerves that branch off from the brain and spine.
Connects the CNS to all of the body's organs and muscles.

Types of Nerves

Afferent Neurons

Also called sensory neurons.
Send signals from the sensory receptors to the central nervous system.

Efferent Neurons

Also known as motor neurons.
Send signals from the central nervous system to the peripheral nervous system.
Afferent approaches the brain and efferent exits the brain—A for approach and E for exit.

Somatic Nervous System

Also known as the skeletal nervous system.
Includes your five senses and skeletal muscle movements.
These movements happen consciously and voluntarily.

Autonomic Nervous System

Controls involuntary activities.
Makes sure that your heart keeps beating, your stomach keeps digesting, and you keep on breathing.

Sympathetic System

Mobilizes your body and gets it ready for action.
Makes your heartbeat faster, your eyes dilate, and increases your breathing.
Fight or flight response.

Parasympathetic System

Relaxes the body.
Slows your heart rate, increases your digestion, and helps you focus on saving and storing energy.
Both of these systems work together in emergencies to help with your fight or flight response.
Rest and digest.
To remember parasympathetic, think of it as a parachute; it slows you down before you land on the ground.

Neural Cells

Glial Cells

Provide structure, insulation, communication, and waste transportation.
Form the basis of the nervous system and are the building blocks of all behavior and mental processes.
The most abundant cells in the nervous system.
Support neurons through protection and also provide them with nutrients.
These cells do not process information, which means they do not send any messages or signals for your body.

Neurons

The basic functional units of the nervous system.
Communicate with each other by using electrical impulses and chemical signals to send information throughout the nervous system.

Reflex Arc

A nerve pathway that allows the body to respond to a stimulus without thinking.
Involves sensory neurons, motor neurons, and interneurons.
When touching something hot, skin receptors detect the heat and send a signal through a sensory neuron to the spinal cord.
The signal then goes to interneurons, which are neurons within the brain and spinal cord.
These neurons communicate internally and connect the sensory neurons to motor neurons within the CNS.
When the signal goes to the motor neurons, it goes back to the muscles in the hand and arm to move, resulting in your hand being pulled away from the hot surface.
All of this happens through the body's autonomic response; you do not even have to think about it.
The reflex arc helps protect us; it allows the body to respond to a threat before processing what is going on.

Neural Transmission

In order for neurons to send a message, they need to receive enough stimulation that causes an action potential.

Action Potential

When a neuron fires and sends an impulse down the axon.
Positively charged and negatively charged ions.
Cell membrane separates the ions and creates an environment on either side of the barrier that is overall positive or negative.
Ions are able to cross the membrane more easily than others, which is a trait known as permeability.
When a neuron is not sending a signal, it has more negative ions on the inside than the outside, which is known as resting potential.
To trigger an action potential, a neuron must depolarize, which happens when an outside stimulus is strong enough to meet the threshold that causes depolarization to occur, and the neuron then fires an action potential.
If the stimulus does not meet the threshold, there is no firing, and the neuron will return to its resting state.
All-or-nothing game here; the neuron will only fire if the threshold is met.
When an action potential occurs, it sends a signal down the axon to other neurons in the nervous system.

Repolarization

A neuron goes through the process of repolarization, which brings the neuron back to resting potential.
During this process, channels will be opened to try and rebalance the charges by letting more positive ions back outside the cell membrane.

Refractory Period

When the signal is moving down a neuron's axon, the neuron cannot respond to any other stimulus.
The cell cannot fire and needs to wait until repolarization occurs and the cell goes back to resting potential.

Synapse

Once a signal makes its way down the axon of a neuron, it is sent down to the axon terminal, where the signal is converted and sent to another neuron through a small pocket of space between the axon terminal of one neuron and the dendrite of another neuron.
Synapses can be chemical or electrical.

Chemical Synapses

Use neurotransmitters, which are chemical messengers that send messages through the nervous system.

Electrical Synapses

Messages that need to be sent quickly and immediately.
When neurotransmitters are sent, they diffuse through the synaptic gap to deliver their messages.

Synaptic Gap

A narrow space between two neurons, specifically the presynaptic terminal of one neuron and the postsynaptic terminal of another neuron.

Presynaptic Terminal

The axon terminal of the neuron, which converts the electrical signal to a chemical one and sends the neurotransmitters into the synaptic gap

Postsynaptic Terminal

Where the neurotransmitters are accepted in the dendrite of the receiving neuron.
Once the neurotransmitters pass their message onto the postsynaptic neuron, they unbind with the receptors. Some of the neurotransmitters are destroyed, and others get reabsorbed.

Reuptake

The process of taking excess neurotransmitters left in the synaptic gap is known as reuptake.
When the sending neuron reabsorbs the extra neurotransmitters.
Depending on what receptors the neurotransmitters bind to, we can see that the neuron will either get excited or become inhibited.

Excitatory Neurotransmitters

Increase the likelihood that a neuron will fire an action potential through the depolarization process in the postsynaptic neuron.

Inhibitory Neurotransmitters

Decrease the likelihood that a neuron will fire an action potential.
This leads to hyperpolarization to occur, which is when the inside of the neuron becomes more negative, moving the neuron farther away from its threshold or intensity level needed for an action potential.

Chain of Events

Action potential sends a signal down the axon of the neuron to the presynaptic terminal.
Channels in the axon terminal are opened, and the neurotransmitters are released into the synaptic gap.
Neurotransmitters diffuse through the synaptic gap and bind to receptor sites in the postsynaptic terminal.
Neurotransmitters unbind with the receptors, and some are destroyed while others go through the process of reuptake.

Neurological Disorders

This process gets disrupted, it can lead to neurological disorders

Multiple Sclerosis

Occurs when the myelin sheath is damaged, which disrupts the transmission of electrical signals, leading to symptoms like muscle weakness, coordination problems, and possibly fatigue.

Myasthenia Gravis

An autoimmune disorder that affects the communication between nerves and muscles.
Antibodies block or destroy acetylcholine receptors, preventing muscle contraction and causing muscle weakness and fatigue.

Neurotransmitters

Each neurotransmitter has a specific function which connects to different behaviors and mental processes.

Acetylcholine

Enables muscle action, learning, and helps with memory.

Substance P

Helps with transmitting pain signals from the sensory nerves to the CNS.

Dopamine

Helps with movement, learning, attention, and emotions.

Serotonin

Impacts an individual's hunger, sleep, arousal, and mood.

Endorphins

Help with pain control and impact an individual's pain tolerance.

Epinephrine

Helps with the body's response to high emotional situations and helps form memories.

Norepinephrine

Increases your blood pressure, heartbeat, and alertness; norepinephrine is part of the body's fight or flight response.

Glutamate

Involved with long-term memory and learning.

GABA

Helps with sleep, movement, and slows down your nervous system.

Hormones

The body also has different hormones that perform different functions similar to neurotransmitters.

Adrenaline (Epinephrine)

Helps with the body's response to high emotional situations.
Expands air passages in the lungs, redistributes blood to muscles, and is involved in the body's fight or flight response.

Leptin

Helps regulate energy balance by inhibiting hunger; it signals to the brain that the body has enough stored fat, reducing a person's appetite.

Ghrelin

Signals to the brain that we are hungry and also helps promote the release of growth hormones.

Melatonin

Produced by the pineal gland in the brain and helps regulate the sleep-wake cycles, also known as circadian rhythms.
Melatonin is released and helps promote sleep and is typically more prevalent in the evening in response to darkness.

Oxytocin

Produced in the hypothalamus and released by the pituitary gland.
This hormone is also known as the love hormone because it promotes feelings of affection and emotional bonding.

Endocrine System

Slower moving.
Sends hormones throughout the body's blood to target larger areas of the body, all to help regulate different biological processes.

Psychoactive Drugs

Agonist Drugs

Increase the effectiveness of a neurotransmitter.
Bind to the receptors that are in the synapse that are for neurotransmitters.
These substances increase the effectiveness of the neurotransmitters by mimicking them and increasing the production of the neurotransmitter or by blocking the reuptake that would usually absorb extra neurotransmitters, which makes them more available in the synapse.

Examples

Xanax, which increases the neurotransmitter known as GABA.
Prozac delays the reuptake of the neurotransmitter serotonin.
Opioids.

Antagonist Drugs

Decrease the effectiveness of a neurotransmitter.
Either block the neurotransmitters from being released from the presynaptic axon terminal, or they connect to the postsynaptic receptors and block the intended neurotransmitters from binding.

Examples

Medication for schizophrenia blocks dopamine receptors
Alcohol blocks the release of glutamate, which acts as a depressant for our nervous system.

Categories of Psychoactive Drugs

Stimulants

Excite and promote neural activity.
Give an individual energy, reduce a person's appetite, and can cause them to become irritable.
Examples: caffeine, nicotine, or cocaine.

Depressants

Reduce neural activity in an individual.
Cause drowsiness, muscle relaxation, lowered breathing, and if abused, possibly death.
Examples: alcohol or sleeping pills.

Hallucinogens

Cause an individual to sense things that are not actually there.
They can also reduce an individual's motivation and can lead to an individual to panic.
Examples: marijuana, peyote, or LSD.

Opioids

Function as a depressant but have their own category due to their addictive nature.
Give an individual pain relief.
Examples: morphine, heroin, or oxycodone.

Tolerance, Addiction, and Withdrawal

Using different psychoactive drugs can lead a person to develop a higher tolerance, which would require more of the drug to be consumed to achieve the same effect.
This could result in addiction and withdrawal symptoms.

Brain Structures

The brain has three major regions:

Hindbrain
Midbrain
Forebrain

Hindbrain

Located at the bottom of the brain

Spinal Cord

Connects your brain to the rest of your body.
Think about this as the information highway.
Allows for your nerves to send information to your brain and vice versa.

Brain Stem

Located at the base of your brain on top of the spinal cord.
Includes the medulla, the pons, and the midbrain.
If ever severely damaged, it will most likely result in death since it controls autonomic functions.

Medulla Oblongata

Right above the spinal cord and below the pons.
Helps with the regulation of a person's cardiovascular and respiratory systems.
Also takes care of autonomic functions.

Pons

The bridge between different areas of the nervous system.
Connects the medulla with the cerebellum and helps with coordinating movement.
Helps with sleep and dreams.

Reticular Activating System

A network of nerve cell bodies and fibers within the brain stem.
Involved in the regulation of arousal, alertness, and sleep-wake cycles.
Helps stimulate other brain structures when something important happens that needs our immediate attention.

Cerebellum

Located in the back of the brain, just below the occipital lobes and behind the pons.
Helps with coordinating voluntary movements, maintaining posture and balance, refining motor skills, and plays a role in cognitive functions.
This part of the brain is sometimes referenced as the little brain.

Midbrain

Helps with processing visual and auditory information, motor control, and integrating sensory and motor pathways.

Forebrain

The top of the brain

Cerebrum

Deals with complex thoughts.
Divided into two hemispheres, the left and the right, and each hemisphere can be further subdivided into four different lobes.

Cerebral Cortex

Made up of gray matter.
A thin outer layer of billions of nerve cells that cover the whole brain.

Corpus Callosum

Beneath the cerebral cortex
A thick band of nerve fibers that connects the two cerebral hemispheres.
Allows your hemispheres to communicate with each other.

Lobes

Frontal Lobe

Located just behind your forehead.
Deals with higher-level thinking and is separated into two important areas.

Prefrontal Cortex

Deals with foresight, judgment, speech, and complex thought

Motor Cortex

Deals with voluntary movement and is located in the back of the frontal lobe.
The left motor cortex controls movement on the right side of your body, and the right motor cortex controls movement on the left side of your body.
This is an example of the brain's contralateral hemispheric organization, which refers to the way in which the brain's hemispheres control opposite sides of the body and process sensory information.

Motor Homunculus

Visually, we can see the functions of the motor cortex represented by the motor homunculus.
Shows a visual representation of the amount of brain area that is dedicated towards a specific body part.

Broca's Area

Found only in the left hemisphere in front of the motor cortex.
Crucial for language production, particularly in controlling the movements of the muscles involved in speech.
If this part of the brain is damaged, an individual will experience Broca's aphasia, which is the loss in ability to produce language. Individuals with Broca's aphasia can still understand language and speech but will struggle to speak fluently.

Parietal Lobe

Located in the upper part of the brain, right behind the frontal lobe.
The main function is to receive sensory information.
Lets you understand things such as touch, pain, temperature, and spatial orientation.

Somatosensory Cortex

Situated parallel to and directly behind the motor cortex.
Responsible for processing touch, pressure, temperature, and body position.
The left sensory cortex controls sensations for the right side of your body, and the right sensory cortex controls sensations for the left side of your body.

Sensory Homunculus

We can visualize the amount of brain area that is dedicated towards specific body parts when looking at the sensory homunculus.

Temporal Lobe

Located right above your ears.
Involved in processing auditory and linguistic information, recognizing faces, and assists with memory.

Hippocampus

Helps us learn and form memories, but remember it is not where memories are stored.

Amygdala

At the end of each arm of the hippocampus.
Where you get your emotional reactions from, so you can think of your amygdala for your fear, anxiety, and aggression.

Auditory Cortex

Located in the superior temporal gyrus of the temporal lobe.
Processes the different sounds that you hear and allows you to recognize things like music and speech.

Wernicke's Area

Typically located in the left temporal lobe.
Responsible for creating meaningful speech.
If this part of the brain is ever damaged, a person will lose the ability to create meaningful speech. This is known as Wernicke's aphasia.

Occipital Lobe

Responsible for processing visual information.

Primary Visual Cortex

Receives visual input from the eyes.
Processes basic information but more complex visual tasks as well, such as recognizing objects, understanding spatial relationships, and perceiving depth and movement.
Vision does not confine to just one area of the brain.

Thalamus

Located deep within the brain, just above the brain stem.
Receives sensory information from your sensory organs for everything except for the sense of smell.
Relays information to the appropriate areas of the cerebral cortex for processing.
People often call the thalamus a relay station.
For instance, visual information from the eye is sent to the thalamus, which is then relayed to the occipital lobe for visual processing.

Limbic System

Located on both sides of the thalamus.
Emotions, learning, memory, and some of our basic drives.

Hypothalamus

Helps keep your body balanced and allows you to have homeostasis. This is also what controls your drives, such as thirst, hunger, temperature, and sex.
Works with the pituitary gland to regulate and control your hormones.

Pituitary Gland

Often referenced as the master gland because it produces and releases hormones that regulate many bodily functions and controls other endocrine glands throughout the body.

Brain Lateralization

The differing functions of the left and right hemisphere.
Essentially, it is the division of labor between the two hemispheres.
Each hemisphere has different areas that it is more efficient in.
Overall, we can see that the brain does have hemispheric specialization, which we can see with the left hemisphere being better at recognizing words, letters, and interpreting language, while the right hemisphere is better at spatial concepts, facial recognition, and discerning direction.

Examining the Brain

Phineas Gage

A railroad worker who was injured when a tamping rod shot clean through his head.
He lived and even walked away from the accident without any cognitive defects.
But Phineas Gage did have a pretty severe personality change, and it was discovered that it was because the rod had severed his limbic system. Remember, these areas are important for judgment and emotional regulation.

Split-Brain Patients

Split-brain patients go through a procedure that cuts the corpus callosum, which is what connects the left and right hemisphere of the brain.
This is done to help treat people with severe epilepsy.
When the corpus callosum is cut, the right and left hemisphere can no longer communicate.
Researchers studying split-brain patients test for cortex specialization, which allows researchers to understand how different areas of the cerebral cortex are specialized for specific functions.
When patients were shown a word in their right visual field, the patient was able to say the word without any problem. But when the words were shown to the left visual field, the patient would say they did not see anything. However, even though the individuals said they saw nothing, they could draw the word with their left hand. Once they drew the word, then they could identify it because now their right visual field would see the picture they drew.
This is because the left hemisphere contains language.

Lesion Studies

Doctors and researchers will destroy specific parts of the brain to gain insight into different functions of the brain.
Today, this can be done to try and treat specific disorders.

Autopsies

An examination of an individual's body who has died to discover the cause of death.
This allows individuals to better understand the extent of a disease, help determine the exact cause of death, and can also help provide important information for an individual's next of kin.

Neuroplasticity

The human brain has the ability to change, modify itself, and even repair itself.

Neuroimaging Techniques

EEG

Uses electrodes that are placed on the individual's scalp.
Allows researchers to record electrical signals from neurons firing, which can help with sleep and seizure research.

fMRI

Similar to an MRI but shows metabolic functions.
Can help with better understanding brain activity.
Shows a much more detailed picture compared to other scans like a PET scan.

Sleep

When we are sleeping, we are still conscious.

Consciousness

Our awareness of ourselves and our environment.

Wakefulness

When we are awake.
During this state, we are typically aware of our surroundings and can think, feel, and react to events.

Sleep

Involves a lower level of awareness.
During this state, we are not fully aware of our surroundings, but our brains are still active and can process some information like sounds or sensations.

Cognitive Neuroscience

Studies how brain activity is linked with cognition.

Circadian Rhythm

Biological clock that is about a 24-hour cycle and involves changing your blood pressure, internal temperature, hormones, and regulating your sleep-wake cycle.
Impacts when we feel alert and awake and when we feel sleepy and ready for bed.
Over time, we'll see it adjust with our age and our different life experiences.

Jet Lag

Internal clock will almost become out of sync with the local time.
Causes an individual to feel tired, disoriented, and sluggish.

Brain Waves

EEG can visualize different brain waves to help us understand which stage we are in.
We can measure the frequencies of a wave, which is the number of waves per second, and the amplitude, which is the size of the wave.

Alpha Waves

Slower waves that have a high amplitude.

Beta Waves

Low in amplitude and are the fastest brain waves.
Generally occur when we're engaged in mental activities.

Theta Waves

Have a greater amplitude compared to beta waves and alpha waves and even a slower frequency.
These are strong during times of relaxation.

Delta Waves

Have the greatest amplitude and the slowest frequency.
These occur when you are most relaxed, often times during the deepest levels of sleep.

Stages of Sleep

Non-REM stage one.
Non-REM stage two.
Non-REM stage three.
REM.

Non-REM Stage One

Very light sleep that only lasts about 5 to 10 minutes.
Your body will start to relax, and your mind starts to slow.
The most common waves during this stage are alpha waves.

Non-REM Stage Two

Transitional stage.
Lasts normally around 10 to 20 minutes.
An individual will experience K-complexes and sleep spindles, which are bursts of neural activity.
The most common waves are theta waves during this stage.

Non-REM Stage Three

One of the deepest states of sleep and normally lasts around 30 minutes.
Growth hormones are produced, and an individual may experience sleepwalking or sleeptalking.
The most common waves during this stage are delta waves.

REM (Rapid Eye Movement)

Last stage.
Your external muscles are paralyzed while your internal muscles and structures become active.
Your brain emits beta waves during this stage.
Lasts about 10 minutes.
An individual may experience dreams or nightmares.
REM sleep is considered paradoxical sleep since the brain waves during this stage are similar to wakefulness, but the body is at its most relaxed.
As the sleep cycle progresses, the periods of REM sleep become longer and more frequent.

REM Deprivation and Rebound

*Experience REM deprivation, which may cause them to experience REM rebound, which means that the next time they sleep, they will enter REM sleep more quickly and also spend more time in REM to make up for the lost sleep.

Hypnagogic Sensations

Occur during non-REM stage one.
An individual experiences sensations that you imagine are real.
These sensations happen when you are in a light sleep.
For example, if you feel like you are falling in a dream, you may wake up quickly thinking that you're falling in real life.

Theories of Dreams

Activation Synthesis Theory

Dreams are the brain's way of making sense of random neural activity during sleep.
When we enter REM sleep, we experience activity in our brain, and the brain tries to make sense of this activity by creating a story or dream.

Consolidation Theory

Help process and strengthen our memories and experiences while we sleep, especially during REM sleep.
*Brain organizes and strengthens the connections between neurons related to recent experiences and information.
*Focuses on the role of sleep in memory consolidation and learning.
*Dreams are merely a reflection of the brain's effort to process and integrate new information.

Restoration Theory

*We sleep because we get tired from daily activities, and we sleep to restore our energy and resources.
*Memory consolidation theory and the restoration theory are two of the main current theories about why sleep occurs.

Reasons for Sleep

*We sleep for a variety of different reasons.

Protection

*Different animals sleep for different lengths of time and at different times of day, depending on when they are active and when other threats may be out.

Memory Consolidation

Strengthen the neural pathways, allowing for better recall in the future.

Supports Growth and Conserves Energy

*We are able to conserve our energy and save it for when we need it during the day.
The pituitary gland releases growth hormones, which help with muscle development.

Creativity

*Help an individual become more creative. Many individuals talk about the benefits of thinking about a problem before they go to bed or reference their dreams as what sparked their curiosity about an idea.

Sleep Disorders

Insomnia

A sleeping disorder where an individual will have trouble falling asleep or staying asleep.

Sleep Apnea

When an individual has a hard time falling asleep or staying asleep because they are struggling with their breathing.
This prevents an individual from being able to get a good night's sleep and go into REM since they keep waking up due to their breathing problems.

REM Sleep Behavior Disorder

A condition where a person acts out their dreams during REM sleep.
Normally, the body is paralyzed during REM sleep, but in RBD, this paralysis is absent or possibly incomplete.
Individuals with RBD may be at risk for self-injury since they may leave their bed and could get hurt when acting out their dreams.

Somnambulism (Sleepwalking)

A disorder where a person gets up and walks around while still sleeping.
Commonly occurs during stage three sleep when an individual is in deep sleep.
More common in children but can also occur in adults.

Sleep Terrors (Night Terrors)

When an individual will experience intense fear while sleeping, which can cause an individual to experience sleep deprivation and a disrupted sleep schedule.

Narcolepsy

Individuals will struggle to sleep at night and will uncontrollably fall asleep during the day.

Sensation

The process of detecting information from the environment.

Sensory Transduction

Whenever you are taking an outside stimulus through one of your senses, you activate your sensory neurons, which end up creating a sensation for you.

Absolute Threshold

The smallest amount of stimulation needed for you to notice a sensation at least 50% of the time.

Sensory Adaptation

Happens when we have a stimulus that is continuous and doesn't change.
If you light a candle in a room, at first you can smell it, but as the day goes on, eventually you can no longer smell the candle. But if someone else comes into the room, they will smell it right away.

Habituation

When you are repeatedly exposed to a stimulus and start to have a reduced response to the stimulus.
*With habituation, you are learning from a repeated stimulus, which then results in a decrease in your responsiveness to the stimulus, and with sensory adaptation, you are getting used to an unchanging stimulus.

Difference Threshold

The minimum change between two stimuli that is needed to cause an individual to detect the change.
At what point can you no longer tell the difference?

Weber's Law

For us to notice a difference between two stimuli, the two stimuli must differ by a constant percent, not a constant amount.

Sensory Interaction

When our sight, hearing, taste, touch, and smell work together.

Sensory Systems

Visual Sensory System

Synesthesia

A neurological condition where one sense experiences through another.
*For example, a person with synesthesia might see colors when they hear music or taste flavors when they read words in a book.

Eye

Whenever light enters the eye through the cornea, it passes through the pupil, where the lens focuses the light onto the retina at the back of the eye.

Retina

Made up of layers of light-sensitive cells known as photoreceptors.
These convert the light into neural impulses that allow for the brain to process what the eye is seeing.
*Transduction occurs when the retina captures light and visual information.
*Neural impulses travel through the optic nerve from the eye, briefly stop at the thalamus, then travel to the primary visual cortex, where the information will be processed in the occipital lobe.

Blind Spot

A small area of the retina where there are no photoreceptors because this is where the optic nerve is located.
We normally do not notice this because our brain fills in the missing information from the other eye and surrounding area.

Photoreceptors: Rods and Cones

Rods: mainly located in the periphery of the retina.
Cones: mainly located in the fovea, which is a small depression in the back of the retina.
*Cones are what allow you to see fine details; they allow you to have clear vision and help you see color, while rods are visual receptors that allow you to see in dim light but do not provide any color information.