AP Psychology PT 1

Genetics and Behavior

Genes

Genes: Defined as the basic units of heredity that influence various traits, behaviors, and genetic predispositions.

Chromosomal Makeup

  • Males: Possess 44 chromosomes, with an additional X and Y (XY).

  • Females: Possess 44 chromosomes, with an additional X and X (XX).

Genetic and Chromosomal Abnormalities

Turner's syndrome

  • Turner's syndrome: A condition where females have only one X$$ chromosome. Physical markers include a webbed neck and a lack of ovaries; these individuals fail to develop secondary sex characteristics at puberty.

Klinefelter's syndrome

  • Klinefelter's syndrome: A condition in males possessing an XXY chromosomal pattern. In this syndrome, male secondary sex characteristics fail to develop, while breast tissue develops instead.

Down syndrome

  • Down syndrome: Caused by having 3 copies of the 21st chromosome. Characteristics include mental retardation, a round head, and a flat nasal bridge.

Tay-Sachs syndrome

  • Tay-Sachs syndrome: Involves a progressive loss of nervous function leading to the death of a baby.

PKU (Phenylketonuria)

  • PKU (Phenylketonuria): A condition that results in severe, irreversible brain damage unless the individual is fed a special diet low in Phenylalanine. Patients lack the ability to process a specific type of amino acid, which otherwise builds up and becomes toxic.

Heritability

Heritability: The proportion of variation in a trait within a population that can be attributed to genetic factors.

  • Example: Research suggests that traits such as extraversion and openness to experience are heavily influenced by genetics, although the environment remains a factor.

Genotype vs. Phenotype

  • Genotype: The actual genetic makeup of an individual.

  • Phenotype: The observable expression of genes, which is influenced by environmental interaction.

Polygenic Traits

Polygenic Traits: Traits influenced by the interaction of multiple genes, such as intelligence and personality.

Evolutionary Psychology

Natural Selection

Natural Selection: Charles Darwin's theory stating that traits increasing an organism's chances of survival and reproduction are more likely to be passed down to subsequent generations.

Adaptation

Adaptation: Specific behaviors and traits that have evolved because they provided survival or reproductive advantages in the past.

Evolutionary Explanations of Behavior

Evolutionary Explanations of Behavior: Analyzes how behaviors like mating patterns or aggression evolved due to survival advantages.

The Two Types of Aggression

1. Instrumental Aggression

  1. Instrumental Aggression: Aggression with a specific goal to meet for a benefit. Example: Christmas shopping for Korean moms.

2. Hostile Aggression

  1. Hostile Aggression: Aggression resulting from pain, anger, or frustration. This is also called the frustration-aggression principle, where the aggression is an attempt to strike out against a perceived cause of discomfort. Example: Road rage.

Social Script

Social Script: Culturally provided mental files that dictate how to act. In novel situations where we do not know how to behave, we rely on these scripts. For example, after watching action movies, teen boys may follow a social script to act "manly" by intimidating others or eliminating threats.

Twin and Adoption Studies

Identical (Monozygotic) Twins

Identical (Monozygotic) Twins: Twins that share 100% of their genes; they are used to isolate the role of heredity in behavior.

Fraternal (Dizygotic) Twins

Fraternal (Dizygotic) Twins: Twins that share approximately 50% of their genes (similar to regular siblings); they serve as a comparison group in nature vs. nurture research.

Adoption Studies

Adoption Studies: Research used to separate genetic influences from environmental ones by comparing adopted children to both their biological and adoptive families.

Epigenetics and Neuroplasticity

Epigenetics

Epigenetics: The study of how environmental factors influence gene expression without changing the actual DNA sequence.

Important details:

  • Gene-Environment Interaction: The concept that genes affect how individuals respond to the environment, and environment affects how genes are expressed.

  • Methylation: A chemical modification of DNA that turns genes on or off, often influenced by diet or stress.

Neuroplasticity

Neuroplasticity: The brain's ability to reorganize and change in response to experience, learning, or recovery from injury. Example: Compensatory growth in blind or deaf individuals.

Critical Periods

Critical Periods: Specific times during development (e.g., early childhood) when the brain is uniquely sensitive to environmental input.

Environmental Enrichment

Environmental Enrichment: Stimulating environments lead to increased brain development and cognitive function, whereas deprivation can stunt development.

Biopsychosocial Model

Definition

Definition: A framework integrating biological, psychological, and social-cultural factors to understand health, illness, and behavior.

Holistic Approach

Holistic Approach: Emphasizes that health and behavior result from complex interplay between genes, biology, environment, and psychology.

The Neuron and Neural Firing

Neurons

Neurons: The basic building blocks of the nervous system; individual nerve cells.

Structure of a Neuron

Cell Body (Soma)

  • Cell Body (Soma): The life-support center of the cell.

Dendrites

  • Dendrites: Branching structures that receive messages from other cells.

Axon

  • Axon: Long fiber that passes messages away from the cell body to other neurons, muscles, or glands.

Myelin Sheath

  • Myelin Sheath: A layer of fatty tissue covering the axon that speeds up neural impulses.

Terminal Branches/Buttons

  • Terminal Branches/Buttons: Form junctions and synapses with other cells.

The Neural Impulse (Action Potential)

Trigger

  • Triggered by stimulation from senses or chemical signals from neighboring neurons.

Action Potential

  • Action Potential: A brief electrical charge traveling down the axon.

Selective Permeability and Ion Movement

  • Process: The neuron is selectively permeable. During firing, the first section of the axon opens its gates; positively charged sodium ions flood in. This depolarizes the axon section, causing a domino effect where the next channel opens.

Important details:

  • In a resting axon, the fluid outside has mostly positively charged ions, and the fluid inside has mostly negatively charged ions.

Resting Pause

  • Resting Pause: Potassium channels open, potassium rushes out, and the neuron pumps sodium back outside and potassium inside to reset.

Signals

  • Signals: Most are excitatory (accelerator), while some are inhibitory (brake).

Threshold

  • Threshold: The minimum intensity required to trigger an action potential. If excitatory signals exceed inhibitory ones by a certain threshold, the neuron fires.

All-or-None Response

  • All-or-None Response: A neuron either fires completely or not at all.

Neural Communication

Synapse

Synapse: The tiny junction/synaptic gap separating one neuron from another.

Neurotransmitters

Neurotransmitters: Chemical messengers released from the axon terminals when an action potential reaches the end of a neuron. They cross the gap and bind to receptor sites (like a key in a lock).

Important details:

  • Neurotransmitters can either excite or inhibit the receiving neuron.

Reuptake

Reuptake: The process where the sending neuron reabsorbs excess neurotransmitters from the synapse.

Major Neurotransmitters and Functions

Acetylcholine (ACh)

  • Acetylcholine (ACh): Enables muscle action, learning, and memory. Malfunction: Alzheimer’s (ACh-producing neurons deteriorate).

Dopamine

  • Dopamine: Influences movement, learning, attention, and emotion. Malfunction: Oversupply linked to Schizophrenia; Undersupply linked to Parkinson’s disease (tremors/decreased mobility).

Serotonin

  • Serotonin: Affects mood, hunger, sleep, and arousal. Malfunction: Undersupply linked to depression.

Important details:

  • Some antidepressants raise serotonin levels.

Norepinephrine

  • Norepinephrine: Controls alertness and arousal. Malfunction: Undersupply can depress mood.

GABA (Gamma-aminobutyric acid)

  • GABA (Gamma-aminobutyric acid): A major inhibitory neurotransmitter. Malfunction: Undersupply linked to seizures, tremors, and insomnia.

Glutamate

  • Glutamate: A major excitatory neurotransmitter involved in memory. Malfunction: Oversupply can overstimulate the brain, causing migraines or seizures (reason some avoid MSG).

Endorphins

  • Endorphins: Natural painkilling neurotransmitters. Malfunction: Linked to addiction to opiate drugs.

Drug Effects

Important details:

  • Psychoactive drugs may have excitatory or inhibitory effects on the nervous system.

Agonists

  • Agonists: Drugs that mimic the effect of a neurotransmitter.

Antagonists

  • Antagonists: Drugs that inhabit or block the effect of a neurotransmitter.

The Nervous System

Definition

Definition: The body’s speedy, electrochemical communication network.

Important details:

  • The nervous system consists of all the nerve cells of the peripheral and central nervous system.

Central Nervous System (CNS)

Central Nervous System (CNS): Consists of the Brain and Spinal Cord. It is the body’s decision-maker.

Important details:

  • The brain enables our humanity—our thinking, feeling, and acting.

Spinal Cord

  • Spinal Cord: A two-way highway. Ascending fibers send sensory info up; descending fibers send motor instructions down.

Reflexes

  • Reflexes: Automatic responses to stimuli. Example: Moving a hand from a flame; information travels through sensory neurons to interneurons in the spinal cord and then to motor neurons before the brain processes the pain.

Important details:

  • Example: knee-jerk/pain reflex.

Peripheral Nervous System (PNS)

Peripheral Nervous System (PNS): Gathers information and transmits CNS decisions.

Important details:

  • Nerves are electrical cables formed of bundles of axons that link the CNS with the body’s sensory receptors, muscles, and glands.

Types of Neurons

1. Sensory (Afferent)

  1. Sensory (Afferent): Carry messages from tissues inward to the CNS.

2. Motor (Efferent)

  1. Motor (Efferent): Carry instructions from CNS out to muscles.

3. Interneurons

  1. Interneurons: Process info between sensory and motor neurons.

PNS Subdivisions

1. Somatic Nervous System

  1. Somatic Nervous System: Controls voluntary movement of skeletal muscles.

Important details:

  • Example: using your mouse to use the computer.

2. Autonomic Nervous System (ANS)

  1. Autonomic Nervous System (ANS): Controls glands and internal organ muscles (heartbeat, digestion).

Sympathetic

  • Sympathetic: Arouses and expends energy (Fight or Flight).

Parasympathetic

  • Parasympathetic: Calms and conserves energy (Rest and Digest).

Important details:

  • It decreases your heartbeat, lowering your blood sugar, etc.

Homeostasis

  • Together they maintain Homeostasis.

The Endocrine System

Definition

Definition: The second communication system; uses glands to secrete hormones into the bloodstream.

Important details:

  • Hormones are chemical messengers that travel through the bloodstream and affect other tissues, including the brain.

Major Glands

Hypothalamus

  • Hypothalamus: Brain region that controls the pituitary gland.

Pituitary Gland

  • Pituitary Gland: The "Master Gland"; secretes many hormones affecting other glands.

Important details:

  • Pathway: Hypothalamus → Pituitary → Other gland → hormones → body and brain.

Adrenal Glands

  • Adrenal Glands: Release epinephrine and norepinephrine (adrenaline) for fight-or-flight.

Thyroid Gland

  • Thyroid Gland: Affects metabolism.

Pancreas

  • Pancreas: Regulates blood sugar levels.

Gonads (Testis/Ovary)

  • Gonads (Testis/Ovary): Secrete sex hormones (Androgen/Testosterone/Estrogen).

Parathyroids

  • Parathyroids: Regulate calcium levels in the blood.

Ways to Study the Brain

Accidents

Accidents: Studying injuries like Phineas Gage (frontal lobe damage led to emotional/impulsive behavior).

Important details:

  • These kinds of accidents give clues about the function of parts of the brain.

Lesions

Lesions: Intentional destruction of brain tissue (e.g., historical frontal lobotomies for the mentally ill).

Important details:

  • Lesions may involve intentional destruction or removal of part of the brain, usually because there is no other way of treatment, such as a huge brain tumor.

EEG (Electroencephalogram)

EEG (Electroencephalogram): Detects brain waves; used for sleep and dream research.

Important details:

  • EEG helps examine which type of waves are produced during different stages of consciousness.

CT Scan (Computerized Axial Tomography)

CT Scan (Computerized Axial Tomography): X-ray that creates a 3-D picture of brain structure (uses some radiation).

Important details:

  • CT shows only the structure of the brain.

MRI (Magnetic Resonance Imaging)

MRI (Magnetic Resonance Imaging): Uses magnetic fields and radio waves for detailed images of soft tissue and density.

Important details:

  • MRI can measure the density of the brain and the location of brain material.

  • MRI is more detailed than CT.

PET Scan (Positron Emission Tomography)

PET Scan (Positron Emission Tomography): Shows brain activity by tracking where radioactive glucose goes during tasks.

Important details:

  • PET can check which areas of the brain are most active during a task.

fMRI (Functional MRI)

fMRI (Functional MRI): Shows both structure and function by tracking blood flow to active areas.

Important details:

  • fMRI combines elements of MRI and PET scan.

Brain Structures

The Hindbrain (Oldest Part)

Medulla

  • Medulla: Controls heartbeat and breathing.

Pons

  • Pons: Coordinates movement; controls sleep and dreaming.

Important details:

  • Pons connects the hind-brain with mid and fore-brain.

Cerebellum

  • Cerebellum: The "Little Brain"; controls voluntary movement, posture, balance, and equilibrium.

The Midbrain

Reticular Formation

  • Reticular Formation: Controls arousal and being alert. Damage can result in a coma.

The Forebrain (Complex Behavior)

Important details:

  • Responsible for complex behaviors and mental processes.

Thalamus

  • Thalamus: Sensory relay station for all senses except smell.

The Limbic System (Emotion and Drives)

  • The Limbic System (Emotion and Drives): Associated with emotions and drives.

Hypothalamus

  • Hypothalamus: Controls instincts (hunger, thirst, temperature, sexual behavior). Includes the Suprachiasmatic Nucleus (SCN) which regulates melatonin via light input.

Hippocampus

  • Hippocampus: Processes conscious memories.

Important details:

  • Memory cue: Campus → Memories.

Amygdala

  • Amygdala: Responsible for processing emotions like fear and aggression.

Cerebral Cortex

Definition

  • Definition: The ultimate control and processing center. Divided into hemispheres and lobes.

Important details:

  • The cerebral cortex is what distinguishes humans from animals.

Hemispheric Specialization (Lateralization)

  • Hemispheric Specialization (Lateralization):

Left Hemisphere

  • Left Hemisphere: Logic, sequential tasks, speech, math.

Important details:

  • Example: speech/memory for numbers.

Right Hemisphere

  • Right Hemisphere: Spatial tasks, creativity, music, images.

Important details:

  • Example: music, understanding images.

Contralateral Control

  • Contralateral Control: The left hemisphere controls the right side of the body and vice versa.

Corpus Callosum

  • Corpus Callosum: Axon fibers connecting the two hemispheres. It is severed in split-brain patients (studied by Roger Sperry and Michael Gazzaniga).

Important details:

  • It is sometimes severed to treat epileptic seizures.

  • In split-brain patients, the two hemispheres can no longer send each other messages.

Lobes

  • Lobes:

1. Frontal Lobe

  1. Frontal Lobe: Abstract thought, emotional control, decision-making. Contains the Motor Cortex and Broca’s Area (speech production).

Important details:

  • Frontal lobe is behind your forehead.

  • Contains the pre-frontal cortex, which is in the front of the frontal lobe and makes decisions and motives.

  • Contains the motor cortex, at the back of the frontal lobe, which controls our voluntary movements.

  • The left hemisphere of frontal lobe contains Broca’s area, which is responsible for producing speech.

2. Parietal Lobe

  1. Parietal Lobe: Interprets bodily sensations. Contains the Sensory/Somato-sensory Cortex.

Important details:

  • Parietal lobe is behind the frontal lobe, but still at the top.

3. Occipital Lobe

  1. Occipital Lobe: Processes vision; contains the Visual Cortex.

Important details:

  • Occipital lobe is at the very back of our brain, across from our eyes.

4. Temporal Lobe

  1. Temporal Lobe: Processes sound; contains the Auditory Cortex and Wernicke’s Area (speech understanding).

Important details:

  • Temporal lobe is located on each side of the brain above our ears.

  • The left temporal lobe contains Wernicke’s area, which is responsible for understanding speech.

Consciousness and Sleep

Consciousness

Consciousness: It is our level of awareness about ourselves and our environment. It is not like an on/off switch.

Examples Explaining Consciousness

Mere-exposure effect

  • Mere-exposure effect: We prefer stimuli we have experienced before over new stimuli, even if we do not remember seeing the old stimuli.

Priming

  • Priming: Research participants respond more quickly and accurately to stimuli they have been exposed to.

Blindsight

  • Blindsight: A condition in which a person can respond to a visual stimulus without consciously experiencing it.

Levels of Consciousness

Conscious

  • Conscious: Current awareness.

Nonconscious

  • Nonconscious: Automatic processes (heartbeat).

Preconscious

  • Preconscious: Information you aren’t thinking about but could recall easily.

Subconscious

  • Subconscious: Information demonstrated through behavior (e.g., Mere-exposure effect, Priming, Blindsight).

Unconscious

  • Unconscious: Repressed unacceptable thoughts (Freudian view).

Altered States of Consciousness

  • Altered States of Consciousness: Sleep / Drug-induced / Hypnotized.

Sleep Cycle

Circadian Rhythm

  • Circadian Rhythm: Biological clock on a 24-hour cycle (25-hours without environmental cues).

Biological Factor for Sleep Patterns

  • Suprachiasmatic Nucleus (SCN): A pair of cell clusters in the hypothalamus that responds to light-sensitive retinal proteins; causes pineal gland to increase or decrease production of melatonin; thus modifying our feelings of sleepiness.

Alert and Awake

  • Alert and Awake: Produces Beta waves.

Sleep Onset (Hypnagogic state)

  • Sleep Onset (Hypnagogic state): Produces Alpha waves.

Stage 1 & 2

  • Stage 1 & 2: Theta waves. Stage 1 has Hypnic Jerks; Stage 2 has Sleep Spindles.

Important details:

  • Stage 2 is where you spend the most time.

Stage 3 & 4 (Delta/Deep Sleep)

  • Stage 3 & 4 (Delta/Deep Sleep): Hard to wake; important for body restoration and immune health.

Important details:

  • Delta waves are produced in Stage 3 and 4.

  • People deprived of these stages will be susceptible to illness.

REM (Rapid Eye Movement)

  • REM (Rapid Eye Movement): "Paradoxical sleep"; brain is active (Beta-like waves) but body is paralyzed. Most dreaming occurs here. REM Rebound occurs if deprived.

Cycle Duration

  • Cycle Duration: Approximately 90 minutes. Repeats 4-7 times per night. REM increases as morning approaches.

Important details:

  • We spend about 20–25 percent of our sleep in REM.

Sleep Disorders

Insomnia

  • Insomnia: Difficulty falling/staying asleep. Most common; caused by stress.

Important details:

  • It can be treated with reduction of caffeine, exercising at appropriate times, and maintaining a consistent sleep pattern.

Narcolepsy

  • Narcolepsy: Uncontrollable sleep attacks.

Sleep Apnea

  • Sleep Apnea: Stopping breathing during sleep; common.

Important details:

  • It is characterized by temporary cessation of breathing during sleep and repeated momentary awakenings.

Night Terrors

  • Night Terrors: Screaming/moving in deep sleep (Stage 3).

Sleep Walking / Sleep Talking

  • Sleep walking (somnambulism) / Sleep talking: They also occur in deep sleep.

Dream Theories

Freudian

  • Freudian: Wish fulfillment. Contains Manifest Content (storyline) and Latent Content (hidden meaning).

Important details:

  • Freud proposed that dreams provide a psychic safety valve that discharges otherwise unacceptable feelings.

Information Processing

  • Information Processing: Sorting the day’s stress and experiences.

Activation-Synthesis

  • Activation-Synthesis: Brain's attempt to make sense of random neural firing.

Cognitive Development

  • Cognitive Development: Reflecting the dreamer’s knowledge.

Hypnosis and Drugs

Hypnosis

Hypnosis: A social interaction in which one person suggests to another that certain perceptions, feelings, thoughts, or behaviors, will spontaneously occur. It can help alleviate ailments and control pain.

Posthypnotic Amnesia

  • Posthypnotic amnesia: People report forgetting events that occurred while they were hypnotized.

Posthypnotic Suggestions

  • Posthypnotic suggestions: A suggestion that a hypnotized person behave in a certain way after he or she is brought out of hypnosis.

Hypnosis Theories

Dissociation Theory (Ernest Hilgard)

  • Dissociation Theory (Ernest Hilgard): A split in consciousness; the "Hidden Observer" stays aware of reality.

Role Theory

  • Role Theory: People act out the role based on Hypnotic Suggestibility.

Important details:

  • People high in hypnotic suggestibility may have characteristics such as having richer fantasy lives, following directions well, and being able to focus intensely on a single task.

State Theory

  • State Theory: Hypnosis is an altered state with beneficial physical effects.

Important details:

  • When hypnotized, it has some beneficial effects on our body such as pain control and reduction in specific physical ailment.

Drug Terms

Drug Terms: Tolerance (needing more for the same effect), Addiction, Withdrawal, Dependence.

Psychoactive Drugs

  • Psychoactive drugs: A chemical substance that alters perceptions and moods.

Tolerance

  • Tolerance: With repeated use, achieving the desired effect requires larger doses.

Addiction

  • Addiction: Compulsive drug craving despite adverse consequences.

Withdrawal

  • Withdrawal: The discomfort and distress that follow discontinuing the use of an addictive drug.

Dependence

  • Dependence: The cravings to relieve physical or psychological side effect.

Drug Types

Stimulants

  • Stimulants: Quicken body functions (Caffeine, Nicotine, Cocaine, Amphetamines, MDMA/Ecstasy).

Important details:

  • They excite neural activity and speed up body functions.

Nicotine

  • Nicotine: A stimulating and highly addictive psychoactive drug in tobacco.

Cocaine

  • Cocaine: It enters the bloodstream quickly, producing a rush of euphoria that depletes the brain’s supply of dopamine, serotonin, and norepinephrine.

Methamphetamine

  • Methamphetamine: Related to its parent drug amphetamine and short for meth, it triggers the release of dopamine which stimulates brain cells that enhance energy and mood, leading to 8 or so hours of heightened energy and euphoria.

Ecstasy / MDMA

  • Ecstasy: Street name MDMA, is both a stimulant and a mild hallucinogen. It triggers dopamine release, but the major effect is the blockage of serotonin reuptake, thus prolonging feel-good mood. People experience high energy, emotional elevation and connectedness with those around them.

Depressants

  • Depressants: Slow body functions (Alcohol, Barbiturates/Tranquilizers).

Important details:

  • They calm neural activity and slow body functions.

Alcohol

  • Alcohol: It can slow neural processing, disrupt memory, reduce self-awareness and self-control, and create expectancy effects.

Barbiturates

  • Barbiturates: It is a tranquilizer. It is sometimes prescribed to induce sleep or reduce anxiety. When it is taken with alcohol, the effect can be lethal.

Opiates

  • Opiates: Endorphin agonists; powerful painkillers (Heroin, Morphine).

Important details:

  • They act as agonist for endorphins and thus are powerful painkillers.

Hallucinogens

  • Hallucinogens: Distort perceptions (LSD, Marijuana).

LSD

  • LSD: It is also known as acid. People who use this substance reported to experience near-death experience.

Marijuana

  • Marijuana: It amplifies sensations to colors, sounds, tastes and smells. It also relaxes like alcohol, and produces euphoric high. It lingers in the body for a week or more.

Sensation and the Senses

Sensation

  • Sensation: Activation of our 5 senses. Vision, hearing, touch, taste and smell.

Transduction

Transduction: Receiving sensory stimulation and transforming it into neural impulses for the brain.

Sensory Transduction Process

  1. Receive sensory stimulation.

  2. Transform that stimulation into neural impulses.

  3. Deliver the neural information to our brain.

Vision

Light

  • Light: Wavelength = Color; Intensity = Brightness.

Vision / Energy

  • Vision / Energy: Our eyes receive light energy and transduce it into neural impulses that our brain processes.

Process

  • Process: Cornea → Pupil (Iris) → Lens (Accommodation) → Retina.

Cornea

  • Cornea: Protects the eye and bends light to provide focus.

Pupil and Iris

  • Pupil: The small adjustable opening surrounded by the iris.

  • Iris: A colored muscle that controls the size of the pupil by either dilating or contracting.

Lens and Accommodation

  • Lens: A transparent lens that focuses incoming light rays by changing its curvature and thickness.

  • Accommodation: The process by which the lens changes its curvature and thickness.

Retina

  • Retina: A multilayered tissue on the eyeball’s sensitive inner surface.

Retinal Cells

  • Retinal Cells: Rods (black/white, periphery, dim light) and Cones (color, detail, fovea).

Important details:

  • Light entering eye triggers photochemical reaction in rods and cones.

  • Rods: Located around the fovea, detect black, white, and gray; necessary for peripheral and twilight vision.

  • Cones: Concentrated near the center of the fovea, detect fine detail and give rise to color sensations.

Path

  • Path: Bipolar cells → Ganglion cells → Optic Nerve → Thalamus → Visual Cortex (Feature Detectors by Hubel and Wiesel).

Important details:

  • The chemical reaction in rods and cones activates bipolar cells.

  • The bipolar cells then trigger the ganglion cells, whose axons twine together to form the optic nerve.

  • Where the optic nerve leaves the eye, there are no receptor cells—creating a blind spot.

Feature Detectors

  • Feature Detectors: Special neurons in the visual cortex that respond to a scene’s specific visual features—edges, lines, angles, and movements.

Parallel Processing

  • Parallel Processing: The brain divides a scene into subdimensions such as color, motion, form, depth, and integrates them in the blink of an eye.

Vision Recognition Sequence

  • Scene → Retinal processing → Feature detection → parallel processing → Recognition.

Color Theories

  • Color Theories: Trichromatic (3 receptors: red, green, blue) and Opponent-Process (pairs: red/green, yellow/blue, white/black).

Trichromatic Theory

  • Trichromatic Theory: The retina contains three different color receptors for red, green, and blue. When they are stimulated in combination, they can produce any color.

Important details:

  • It cannot explain why red-green color blind people can still see yellow.

  • It cannot explain the effect of afterimage.

Opponent-Process Theory

  • Opponent Process Theory: Three sets of opponent retinal processes—red/green, yellow/blue, and white/black—enable color vision.

Important details:

  • In the retina and in the thalamus, some neurons are turned on by red but turned off by green.

Hearing

Sound Waves

  • Amplitude: Determines loudness.

  • Frequency: Determines pitch.

Process

  • Process: Outer ear → Eardrum → Middle ear (Ossicles: hammer, anvil, stirrup) → Cochlea (Basilar membrane hair cells) → Auditory Nerve.

Important details:

  • The outer ear funnels sound waves to the eardrum.

  • The bones of the middle ear amplify and relay the eardrum’s vibration through the oval window into the fluid-filled cochlea.

  • Pressure changes in the cochlear fluid cause the basilar membrane to ripple, bending the hair cells on its surface.

  • Hair cell movements trigger impulses at the base of the nerve cells, whose fibers converge to form the auditory nerve.

  • The auditory nerve sends neural messages to the thalamus and then to the auditory cortex.

Perceiving Loudness

  • Perceiving Loudness: The brain interprets loudness from the number of activated hair cells.

Pitch Theories

  • Pitch Theories: Place Theory (High pitch), Frequency Theory (Low pitch), Volley Theory (Intermediate pitch).

Place Theory

  • Place Theory: We hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane.

Important details:

  • This cannot explain low-pitched sounds because the neural signals generated by low-pitched sounds are not so neatly localized on the basilar membrane.

Frequency Theory

  • Frequency Theory: The brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve.

Important details:

  • An individual neuron cannot fire faster than 1000 times per second.

Volley Theory

  • Volley Theory: Neural cells alternate firing. By firing in rapid succession, they can achieve a combined frequency above 1000 waves per second.

Locating Sounds

  • Locating sounds: Sound location depends on comparing information from both ears.

Hearing Loss

  • Hearing Loss: Sensorineural (nerve damage) vs. Conduction (mechanical damage).

Sensorineural Hearing Loss

  • Sensorineural hearing loss (nerve deafness): Caused by damage to the cochlea’s hair cells or their associated nerves.

Conduction Hearing Loss

  • Conduction hearing loss: Caused by damage to the mechanical system that conducts sound waves to the cochlea.

Other Senses

Touch

  • Touch: Pressure, warmth, cold, pain. Gate-Control Theory explains how the spinal cord blocks/allows pain signals.

Important details:

  • Our sense of touch is a mix of 4 basic and distinct skin senses and others are just variations of the 4: pressure / warmth / cold / pain.

Pain

  • Pain: Pain is your body’s way of telling you something has gone wrong. Without it, we would not survive.

Gate-Control Theory

  • Gate-Control Theory: The theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass onto the brain.

Important details:

  • The “gate” is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.

Taste (Gustation)

  • Taste (Gustation): Sweet, sour, salty, bitter, umami. Sensed via papillae/taste buds.

Important details:

  • Umami is a meaty taste / MSG.

Process of Taste

Important details:

  • Inside each little bump on the top and sides of your tongue are 200 or more taste buds, each containing a pore that catches food chemicals.

  • Into each taste bud pore, 50 to 100 taste receptor cells project antenna-like hairs that sense different tastes.

  • Taste triggers a response that alerts your brain’s temporal lobe.

Smell (Olfaction)

  • Smell (Olfaction): Olfactory receptor cells → Olfactory bulb → Temporal lobe/Limbic system.

Process of Smell

Important details:

  • We smell something when molecules of a substance carried in the air reach a tiny cluster of 5 million or more receptor cells at the top of each nasal cavity.

  • Olfactory receptor cells respond selectively to different aroma.

  • They send messages to the brain’s olfactory bulb, then to the temporal lobe, and to the part of the limbic system involved in memory and emotion.

Vestibular Sense

  • Vestibular Sense: Monitors head position/balance via semicircular canals in the ear.

Important details:

  • Semicircular canals contain fluid that moves when your head rotates or tilts.

  • This movement stimulates hairlike receptors, which send messages to the cerebellum.

Kinesthesis

  • Kinesthesis: Monitors position and movement of body parts via sensors in joints and muscles.

Important details:

  • Important sensors in joints, tendons, and muscle enable the detection of position and movement of your body parts.

Senses and Associated Receptors

Energy Senses

  • Vision: Rods, Cones (in Retina).

  • Hearing: Hair cells connected to the organ of Corti (in cochlea).

  • Touch: Temperature, pressure, pain nerve endings (in the skin).

Chemical Senses

  • Taste (Gustation): Sweet, sour, salty, bitter, umami taste buds (in papillae on the tongue).

  • Smell (Olfaction): Smell receptors connected to the olfactory bulb (in the top of the nose).

Body Position Senses

  • Vestibular Sense: Hairlike receptors in three semicircular canals (in the inner ear).

  • Kinesthetic Sense: Receptors in muscles and joints.