AP Psychology Notes: Neuron and Neural Firing & The Brain
Neurotransmitters in Brief
Chemical messengers of the nervous system.
Each neurotransmitter has a different impact on thinking and behavior.
Can be excitatory or inhibitory.
Glutamate
Most abundant excitatory neurotransmitter.
Enhances learning and memory by strengthening synaptic connections.
Mnemonic: "Think how excited you would be if you were glued to your mate."
GABA (Gamma Aminobutyric Acid)
Most abundant inhibitory neurotransmitter.
Associated with various anxiety-related disorders.
Mnemonic: "Get A Brake Adjustment."
Acetylcholine (Ach)
Found in both the central and peripheral nervous systems.
All movement involves Ach.
Involved in learning and memory.
Alzheimer’s disease is associated with diminished Ach functioning.
Mnemonic: "To hit an ACE in tennis you need acetylcholine. To ACE your upcoming psych exam, you need acetylcholine."
Dopamine
Linked to the anticipation of pleasurable or rewarding activities.
Also involved in movement, attention, and learning.
Lack of dopamine is associated with Parkinson’s disease.
Excess dopamine is associated with Schizophrenia.
Mnemonic: "Use the ‘p’ to remind yourself that dopamine is linked to pleasure and Parkinson's" or "Think dopamine - It’s mine, mine, mine -> because we are consumer with the pursuit of pleasure"
Endorphins
Body’s natural painkiller, involved in pain reduction and reward.
Can be stimulated by intense and prolonged exercise, creating euphoric feelings.
Mnemonic: "Endorphins end pain."
Epinephrine/Adrenaline
Both a neurotransmitter and a hormone, boosts energy.
Primary chemical in "fight or flight" responses.
Norepinephrine/Noradrenaline
Arousal, alertness, vigilance (heightened sensitivity to surroundings).
Heavily involved in the sleep cycle.
Low levels associated with depression.
Serotonin
Plays a significant role in mood, appetite, sleep, and dreams.
Low levels have been associated with depression.
Mnemonic: "Serotonin—think ‘rotten’—you try to avoid rotten food, rotten moods, and rotten nights of sleep."
Takeaway
There are dozens of neurotransmitters in the human nervous system, and each plays a role in various cognitive and behavioral processes.
Psychoactive Drugs
Psychoactive drugs and some other substances have a direct impact on one or more neurotransmitters at the synapse.
Psychoactive drugs work as agonists or antagonists based on how they influence neural transmission.
Agonists
Enhance the actions of neurotransmitters in various ways.
Direct agonists mimic the neurotransmitter and bind with the receptor of the next neuron.
Indirect agonists block reuptake of a neurotransmitter; these are also known as reuptake inhibitors.
Heroin
An agonist for endorphins.
The receptor site can’t distinguish between an endorphin and the chemical structure of heroin.
Nicotine
An agonist for Ach (acetylcholine).
Stimulates skeletal muscles and causes increased heart rate.
Black Widow Venom
An agonist for Ach (acetylcholine).
Causes Ach to be released continuously at neuromuscular junctions.
Reuptake Inhibitors
Drugs in this category bind to uptake pumps and prevent the process of reuptake.
Prozac: Inhibits the reuptake of serotonin, flooding the synapse with serotonin.
Cocaine: Inhibits the reuptake of dopamine, flooding the synapse with dopamine.
Antagonists
Block a neurotransmitter from being released by the terminal or from binding the receptor site.
Inhibit the normal functioning of the neurotransmitter.
Often bind to a receptor but do not stimulate it.
Botox
An antagonist for Ach (acetylcholine).
Blocks Ach from reaching receptors; affected muscles can’t move.
Thorazine
An antagonist for dopamine.
Blocks dopamine receptors, thereby blocking the transmission of dopamine.
Takeaway
Many chemicals work as agonists or antagonists, significantly altering how neural transmission occurs. These changes can impact both cognitive and behavioral processes.
Common Aspects of Psychoactive Drugs
Alter mental states.
Activate dopamine-producing neurons in the brain's reward system.
Increase dopamine is associated with greater reward, which can lead to a stronger desire to take the drug again.
Many drugs create tolerance: increasing amounts of the drug to create the original high/desired effect.
Many drugs lead to physical dependence: With repeated use, a person may need to administer the drug to prevent withdrawal symptoms.
The effect of a drug is primarily dependent on which neurotransmitter(s) is affected.
Synaptic Transmission
All psychoactive drugs have a direct impact on one or more neurotransmitters at the synapse.
Psychoactive drugs can be classified as agonists or antagonists based on how they influence neural transmission.
Blood-Brain Barrier
A barrier that allows some chemicals to pass from the blood into the brain but prevents other chemical structures from entering.
All drugs discussed here are able to pass this barrier to get from the blood into the brain.
Categories of Psychoactive Drugs
Depressants
Opioids
Stimulants
Hallucinogens/Psychedelics
Depressants
Slow or inhibit central nervous system functions.
Create drowsiness, sedation or sleep—relieve anxiety and lower inhibition.
Combining depressants can be deadly.
Alcohol:
2nd most widely used drug in the United States.
Agonist for GABA (gamma-aminobutyric acid).
Lessens inhibitions by depressing brain centers responsible for judgment and self-control.
Opiates/Opioids
Agonist for endorphins.
Heroin, Oxycodone, fentanyl.
Incredibly addictive and create powerful withdrawal symptoms.
Stimulants
Activate sympathetic nervous system.
Increase brain activity, arouse behavior, and increase mental alertness.
Caffeine:
Most widely used drug in the world.
Promotes wakefulness, mental alertness, and faster thought processes by stimulating the release of dopamine.
Antagonist for adenosine—blocks sleep-inducing effects.
Is physically addictive and creates withdrawal symptoms.
Cocaine:
Dopamine agonist (reuptake inhibitor); also elevates serotonin and norepinephrine.
Intense euphoria, alertness, and heightened self-confidence.
Crash after high dissipates.
Highly addictive.
Hallucinogens/Psychedelics
Create sensory and perceptual distortions, alter mood, and affect thinking.
There is much current research on psychedelics in therapeutic settings (anxiety, depression, and more), but still in the experimental phase.
THC:
Very mild hallucinogen.
Produces sense of well-being, mild euphoria, dream-like state of relaxation.
Interferes with muscle coordination, learning, memory, and overall cognitive function.
Various therapeutic uses.
Takeaway
Each psychoactive drug discussed directly influences neural firing, which can significantly alter cognitive and behavioral processes.
The Hindbrain
Medulla
Functions:
Basic autonomic functions: heart rate, breathing, blood pressure.
Reflexes: swallowing, sneezing, vomiting.
Pons
Functions:
Bridge that connects the brainstem and cerebellum.
Helps coordinate and integrate movements on each side of the body.
Plays a role in sleep functions.
Reticular Activating System (RAS)
A network of nerve fibers involved in attention, arousal, and alertness.
Cerebellum
Functions:
Balance and equilibrium.
Coordinated sequences of movements.
Implicit memory (without conscious thought).
Midbrain
Functions:
Nerve system connecting higher and lower portions of the brain.
Relays info between the brain and the ears and eyes.
Takeaway
Every brain area or structure has its own unique functions that contribute to daily behavioral and cognitive experiences.
The hindbrain coordinates functions that are fundamental to survival, including breathing, motor coordination, sleep, and wakefulness.
The Limbic System
A specific set of structures greatly involved in emotion, motivation, learning, and memory.
Structures
Thalamus
Hypothalamus
Amygdala
Hippocampus
Thalamus
Functions:
Sensory switchboard.
Receives and sorts sensory information, then sends it to the cortex for further interpretation.
Smell is the only sensory exception.
Hypothalamus
Function: Fight or flight, feeding, fornication.
Amygdala
Functions:
Anger, aggression, afraid (fear response).
Also helps ingrain highly emotional memories.
Hippocampus
Functions:
Converts short-term memory into long-term memory.
Involved in processing and retrieving declarative (facts and events) memory.
Spatial relationship memories.
Dysfunction: Alzheimer’s and anterograde amnesia.
Takeaway
The Limbic System is heavily involved in several vital functions: emotions, memory, integration of sensory info, and motivation.
Cerebral Cortex
Cortex is Latin for "bark" (as in, tree bark).
The brain consists of two hemispheres, each containing four lobes.
Left Hemisphere: Four Lobes (F.P.O.T.)
Frontal Lobe:
Prefrontal Cortex:
Involved in the highest-level cognitive functions: thinking, planning, decision-making, impulse control.
Undergoes massive reorganization from 18-25 years old.
Motor Cortex:
Involved in initiating voluntary movement.
Contralateral (left hemisphere controls movement on the right side of the body).
Body areas that make diverse and precise movements get more tissue on this strip in the brain.
Parietal Lobe:
Somatosensory Cortex:
This strip of tissue represents your sense of touch.
Contralateral.
Parts of your body that are more sensitive have more tissue devoted to them on this strip.
Occipital Lobe:
Primary Visual Cortex.
Temporal Lobe:
Primary Auditory Cortex.
Auditory Association Cortex
Unique Aspects of the Left Cerebral Cortex
For the vast majority of people, language is lateralized almost exclusively to the left side.
Broca’s Area (Frontal Lobe):
Involved in expressive speech.
Broca’s aphasia (expressive aphasia).
Wernicke’s Area (Temporal Lobe):
Involved in understanding/comprehending language.
Wernicke’s Aphasia.
Takeaway
There are four lobes in each hemisphere of the brain. Each contains areas that have great specificity in term of how the influence cognitive and behavioral processes.
Split-Brain Procedure
Corpus Callosum
A massive bundle of nerves connecting the two hemispheres.
Allows constant communication between the right and left hemisphere.
Split-Brain Research
Done to relieve life-threatening epilepsy.
Roger Sperry and Michael Gazzaniga did extensive research with split-brain subjects to see how cutting the corpus callosum impacted behavioral and mental processes.
Visual Field Processing
Left Visual Field (processed by right hemisphere):
Spatial abilities
Facial recognition
Stronger at controlling and recognizing emotional expression.
More active while creating/appreciating art and music.
Right Visual Field (processed by left hemisphere):
Language (expression, comprehension, reading)
Interpreter
Brain Lateralization
Some things are lateralized to the left hemisphere and others are lateralized to the right.
For most people, language functions are lateralized to the left hemisphere.
Broca’s area (cortical area involved in expressive speech). - When images are flashed to the LVF, it goes to the right hemisphere, but that info can’t travel across to get to Broca’s area The ability to recognize faces is primarily lateralized as a right hemisphere function.
Gazzaniga argues the left hemisphere is the interpreter.
Takeaways
People are not left- or right-brain dominant.
Most thoughts and behaviors require the left and right hemispheres to work together.
Neuroplasticity
False Statements
Humans use only 10 percent of their brain.
You are born with all the brain cells that you will ever have.
Brain development is finished by the time children reach puberty.
True Statement
The brain can rewire itself to overcome damage or trauma.
Neuroplasticity
Throughout life, the brain can grow new connections and new neurons.
The ability of the brain to change because of experience or injury.
Examples of Neuroplasticity
Neurogenesis
Long-term potentiation
Neurogenesis
The creation of new cells.
Exercise seems to increase neurogenesis, while social isolation seems to decrease it.
Structural Plasticity: Long Term Potentiation (LTP)
"Cells that fire together, wire together." - Donald Hebb
When a network of neurons fires together repeatedly, that neural pathway becomes smoother and more efficient.
Changes is physical structure in response to learning, practice, environmental influences.
LTP may represent the biological basis of learning.
Functional Plasticity
The brain can shift functions from damaged areas to undamaged areas.
Case Study: Gabby Giffords
Brain damage as a victim of gun violence.
Experienced significant aphasia, and for the vast majority of people, language is lateralized almost exclusively to the left side.
Paralysis but has regained many of those abilities.
Takeaways
The brain has a remarkable plasticity and can wire and rewire itself as we go through life.
Case studies demonstrated both structural and functional examples of neuroplasticity.
Brain Scan Technology
Methods
Autopsy
Case studies (such as Phineas Gage)
Surgery (such as lesioning various parts of the brain)
Brain scan technology
Scans
Scans tell us about Brain Structure and Function:
Structure and Function
fMRI (both structure and function)
Function
EEG
EEG (Electroencephalograph)
Measures electrical activity coming off the surface of the brain.
Can be used to identify issues such as epilepsy or various sleep disorders.
fMRI (Functional Magnetic Resonance Imaging)
Shows both structure and function.
Measures changes in oxygen levels as brain areas activate/deactivate.
Takeaways
The various brain scans have revolutionized our ability to study the bran.
Some scans provide amazing detail about the structure of the brain, while others can show which parts of the brain are active when we engage in various thoughts and behaviors.
While we have learned much from this technology, we have only begun to scratch the surface of the vast complexity of the human brain.
Sleep Cycles and Stages
Sleep Cycles
We sleep in cycles.
Throughout the night, we go through a full cycle approximately every 90-120 minutes.
Each sleep cycle involves four different stages of sleep.
Some involve Rapid Eye Movement (REM), some involve Nonrapid Eye Movement (NREM).
Stages of Sleep
Awake (Beta Waves)
NREM 1 (Alpha Waves)
NREM 2 (Theta Waves)
NREM 3 (Delta Waves)
REM (Beta Waves)
Each stage involves different psychological and physical changes.
Transitions
At first, we transition down to deeper stages, where our brain and body become less responsive to stimuli.
Later in each cycle, we transition back up to more internally active stages.
NREM 3 gets shorter throughout the night.
REM gets longer throughout the night.
REM vs. NREM Sleep
REM (Stage 4)
Rapid eye movement.
Increases in length as night of sleep progresses.
Vivid dreaming.
Nightmares (bad dreams).
Paralyzed body (paradoxical sleep).
Essential part of sleep for the mind.
NREM (Stages 1-3)
Non-rapid eye movement.
Decreases in length as night of sleep progresses.
Vague, partial images and stories.
Night terrors (NREM 3).
Sleepwalking and talking (NREM 3).
Essential part of sleep for the body.
Takeaways
We sleep in 90-minute cycles.
Each cycle, we go through four stages of sleep, each involving unique brainwave patterns, physiological changes, and psychological phenomena.
NREM 3 is the stage where sleepwalking and sleep talking occur.
REM sleep is dream sleep, where our large muscles are paralyzed.
Sleep Research and Theories
Sleep Lab Research
Tracks:
Muscle tone
Heart rate
Brainwaves
Oxygen Levels
Temperature
Restoration Theory of Sleep
Our bodies wear out during the day and use up hormones, neurotransmitters, and energy.
Sleep is necessary to restore these resources and reenergize the body.
Sleep helps restore and repair muscles and brain tissue, sleep supports growth.
Memory Consolidation Theory of Sleep
Sleep helps us restore and rebuild our memories of the day’s experiences.
Memory consolidation occurs during REM.
Sleep deprived individuals struggle both physically and cognitively.
Energy Conservation Theory of Sleep
Based on the evolutionary approach.
Sleep protects us.
As animals evolved, sleep emerged to preserve energy and protect us during the part of the day when movement and activity are less likely to yield value and more likely to expose us to danger.
Sleep helps animals adapt to their environments to survive.
Dream Theories
Psychological Theories
Sigmund Freud’s “The Interpretation of Dreams” (1900).
Proposed that dreams are the road to the unconscious mind, filled with content we cannot face in conscious, waking life.
Manifest content.
Latent content.
Biological & Information Processing Theories
Dreams provide a way to sort out the day’s events and serve to consolidate our memories for storage.
Activation-Synthesis Model:
REM helps preserve and develop neural connections.
As REM cycles activate the brain, we make sense out of the random activations and weave together a storyline that becomes a dream.
Takeaways
Sleep lab research allows us to answer questions about what happens when we sleep and why we sleep.
Each of the major theories provides an explanation for sleep:
Restoration
Memory consolidation
Energy consolidation
Each of the major dream theories provides an explanation for why we dream:
Psychological theories
Activation synthesis
Sleep Disorders
Insomnia
Insomnia deprives us not only of sleep but also of the many cognitive and physical benefits sleep provides.
Symptoms:
The inability to fall asleep.
The inability to stay asleep.
Both.
The most common of all sleep disorders.
Average adult needs 7 – 9 hours of sleep per night
Average teen needs 8 – 10 hours of sleep per night
Causes and Treatments:
Causes: Stress, irregular sleep schedule, pain/illness, diet/medication.
Treatments (depends on cause): Stress management, medications/melatonin, treatment of pain/illness, changing habits.
Sleep Apnea
Symptoms:
Cessation of breathing while sleeping.
Breathing stops repeatedly throughout the night.
Snoring.
Gasping.
Never feel rested and restored, even after a full night of sleep.
Three Types: Obstructive, Central (CNS), Complex.
Causes/Risk Factors:
Weight, smoking, gender, age, thick neck, narrow airway, nasal obstruction.
Treatments (depends on cause): Lose weight, surgery, CPAP machine.
Narcolepsy
Symptoms:
Fall into uncontrollable “sleep attacks” throughout the day.
Drowsiness.
Muscle paralysis (cataplexy).
Triggered by strong emotions.
REM sleep.
Cause: Genetic.
Treatments: Medication, support.
Takeaways
Insomnia (most common), Apnea, Narcolepsy.
Sensation: Anatomy of the Eye
Lens
Your lens in the front of your eye inverts the image so that it is “projected” onto the back of the eye (retina) upside down.
Your lens should focus the image to pinpoint clarity onto the center of your retina (fovea).
Anatomy of the Eye
The lens is supposed to precisely focus the image onto the fovea.
Blind Spot
The area where the optic nerve enters the eye.
There are two blind spots.
There is always an area in your visual field that each eye cannot see but the other eye can.
Mnemonics
Sclera: shell
Cornea: windshield
Lens: clear, flexible
Iris: colored sphincter
Pupil: light hole
Retina: movie screen (Rods, black & white, peripheral vision)
Fovea: Focus of the movie screen (Center, cones, color)
Cones are concentrated in the fovea. Rods are spread all over the retina.
If color stimulates the edge of the retina, where the rods are, then color can’t be see.
Sensation: Visible Light and Color Vision
Visible Light
Visible light is a very small portion of all the types of radiation in the universe. There is a lot of radiation we can’t sense. Snakes can sense infrared.
RGB
Light is like any other kind of wave.
Some waves are longer than others.
The shape or length of the wave is what gives the radiation its meaning.
Blue waves are short, red waves are longer.
Waves
Waves, whether they are sound waves or light waves, have several dimensions.
Length and Amplitude
Objective Sensation
What is the afferent message
Subjective perception of light
Length of wave
Frequency
Color/hue
Height of wave
Amplitude
Brightness
Problems with Sensing Color
Most color blindness happens in the eye, not in the brain.
Certain neurological conditions can cause different types of color blindness.
Most color blindness means difficulty distinguishing between certain colors.
The genes that are responsible for cone formation are carried on the X chromosome. That means males are far more likely to have trouble distinguishing colors.
Color Vision Theories
Trichromatic Theory
Opponent Processing Theory
Hermann von Helmholtz
Ewald Hering
Works for the eyes
Works for the brain
Sensation – objectively observed and measured
There are three type of cones in the retina (actually, the fovea)
S-cone = blue
M-cone = green
L-cone = red
Perception – no one can independently measure what another person perceives.
Afterimage
An afterimage happens in the mind. It doesn’t exist “out there”, even though you “see it.”
Before we can have an afterimage, we need to stare at an “before” image.
Sets of Opponents
Red-Green: when green neural circuitry is over stimulated (excited), that means the red neural circuitry is inhibited.
The other sets are: Yellow-Blue, Black-White
Sensation: Hearing
Hearing
Hearing is pretty much a mechanical process. Objects bang against each other, and that is transduced into a neural signal.
Transduction is the process of external stimuli becoming perceptions, thoughts, and emotions.
Anatomy of the Ear
Outer Ear (2 Main Parts):
Pinna: The thing you put the back of sunglasses on. Acts like a satellite dish or concert shell to help focus the signal into the ear hole.
Ear Canal: Think of it like a cave. Caves are great at carrying echoes.
Middle Ear:
Ear Drum: Tympanic membrane. Literally a drum. Air vibrations are carried to it from the ear canal.
Attached to the ear drum is one of 3 bones:
Hammer = Malleus
Anvil = Incus
Stirrup = Stapes
Inner Ear: Is primarily made of the cochlea:
About the size of a pea.
Snail shell shaped
Filled with fluid
The stirrup/stapes bangs against the oval window.
That, of course, sets up a wave in the fluid inside the cochlea.
The size of the wave depends on how hard the stirrup hits the oval window.
Organ of Corti and Cilla
Along the inside of the snail-shell cochlea is the organ of Corti. Think of it like a membrane with tiny hairs (cilia) sticking out of it. Each hair is like a blade of grass and the roots are neurons that bundle together to form the auditory nerve.
The frequency at which the grass/hair is stimulated, tells the nerve to fire at a certain rate.
Previously we talked about Afterimages. When neurons are over stimulated for too long, they can be inhibited or have a prolonged refractory period.
Similar to what happens if you have been in a loud place for a long time.
Theories of Hearing
Placed Theory: Explains high pitch well
Frequency Theory: Explains low pitch well
Also known as spatial coding.
Think of this as temporal coding.
When a wave of cochlear fluid crashes on a place on the organ of Corti, cilia are stimulated.
A nerve cell attached to the root of the cilia sends a signal to the brain.
The brain knows that if certain cilia are stimulated, it should interpret that as different pitch.
That means time is important.
The frequency of neural signals (action potentials) tells the brain what pitch to interpret.
Maximum and Minimum Hearing
Maximum:
Highest amplitude 150 dB
Pain
Highest frequency 20,000 Hz
Minimum:
Lowest amplitude 3-5 dB
Lowest frequency 25 Hz
Using Echoes to Perceive Depth (Auditory Disparity)
Depth Perception
Not only is there the original sound from the source, but often there are echoes of that sound.
Bats can emit a sound wave, wait for it to bounce off an insect, and use that echo to know where that insect is.
Hypothesis
If a person uses echoes, then they can perceive depth.
Independent variable: Use of echoes.
Dependent variable: Depth perception.
Marco Polo
Kids can play it because of something called auditory disparity. This means our brain processes the disparity in the slightly different signals that our two ears send to it.
Types of Auditory Disparity
Difference in Loudness
If a sound source is on our left, it will sound slightly louder in the left ear.
We probably don’t consciously know this difference.
The brain does this automatically.
Your head might muffle some of the sound that goes to your right ear.
Difference in Arrival Times
If a sound source in on our left, it will get to the left ear slightly before the right ear.
We probably don’t consciously notice this difference.
Your brain does this automatically.
It’s probably a good idea for us to not have to think about this.
Types of Hearing Impairment
Conduction Deafness
Neurological Deafness
Something is not functioning in the outer or middle ear.
The cochlea is not sending the correct signals to the brain.
Vibrations are not making it to the cochlea.
Inherited disease, over-use of loud noises, regular long use of normal noises, damage
Swelling, blockage
Can be treated with medicine and even surgery.
Can be treated with: Hearing aid, cochlear implant
Chemical Senses: Smell (Olfaction) and Taste (Gustation)
Chemical Senses
Molecules float up our nose, and some of these odorant molecules bind with receptor sites in olfactory receptor neurons. Olfactory receptor sites have axons that group together to go to the olfactory bulb which is in the brain and processes the data from the sense organ just as the occipital lobe processes information from the eyes.
Unlike other senses, smell bypasses the thalamus, which is the brain’s router of sensory or afferent signals.
Signals from the olfactory bulb are split and go directly to the frontal lobe, amygdala, hippocampus, and other structures. Evolutionarily smell is probably our oldest sense.
Smell is directly tied to emotional structures and circuits in the brain and to its memory structures
Smell (Olfaction)
There are hundreds of receptor neurons that only get excited when certain odorant molecules stimulate them.
However, we can sense thousands of smells.
The ratio of which neurons firing that make up the perception of different smells.
Vision and Olfaction Comparison
Vision: Photoreceptors are concentrated in the fovea. There are only 3 types of cones, but we can perceive countless colors. The ratio of the signals from the three cone cells tells the brain which color to perceive.
Olfaction: Olfactory receptor neurons are (ORN’s) in the mucus membranes of the nose (olfactory epithelium.) There are hundreds of receptor neurons that only get excited when certain odorant molecules stimulate them, but we can sense thousands of smells. It is the ratio of which neurons are firing that make up the perception of different smells.
Taste (Gustation)
We can only sense 5 tastes, though we can perceive more: Salty, Sour, Sweet, Bitter, Umami.
Taste might be the most personal and mysterious because we are very careful about what we put in our mouth (voluntary).
Bumpy Tongues
The thousands of bumps on your tongue are called papilla with taste buds found on those papilla.
Each papilla has hundreds of taste buds which have receptors that look for ‘tastant’ molecules.
We have thousands of taste buds all over our tongue with young kids having more taste buds leading to them being picky eaters.
Taste Receptors
Salty receptors – easily stimulated by table salt
Sour receptors – respond to acids (vinegar, citrus)
Sweet receptors – stimulated by a few chemicals (sugar, artificial sweeteners)
Bitter receptors – stimulated by many combinations of food
Umami receptors – respond to chemicals that produce a savory sensation (Monosodium glutamate/MSG).
Spice, such as hot sauce, isn’t a taste; it is a chemical burn.
Chocolate Taste
Chocolate is a perception which results from the interaction between: sweet sensations from the tongue, smell from the olfactory system, and pressure on tongue and gums.
Embodied Cognition
Senses Overview
These work through transduction (outside physical and chemical energy, measurable neural energy (action potentials), perceptions and thoughts).
Vision, Audition, Touch, Olfaction, Gustation
Body and Embodied Cognition
The body isn’t just a dumb collector of information, but works with the brain to help process and digest the amount of data that is happening in your nervous system every second.
Feedback Loop
The body gives the brain information, the brain then tells the body information, and the body adjusts to information from the brain.
Brain and Kinetic Awareness
Sensory neurons/Afferent – arrive at the brain from the body.
The brain tells the arm muscles to flex. For every fraction of an inch the arm moves, it sends a signal to the brain, the brain takes the information from the shoulder muscles and arm muscles and does a calculation. From that calculation, the brain has a constant sensation of where the arm is as it moves the arm to where the nose is.
This is called kinesthetic awareness (awareness of how your body moves).
The sense of balance.
Balance is created by the vestibular system ( brain-muscle feedback loop will react instantly and automatically to fix it.
Inside each ear, attached to the cochlea are three semi-circular canals (shape with fluid in them).
Canals help your brain process in which direction it is moving by