Unit 1: Biological Bases of Behavior

Transduction – The process of converting sensory stimuli into neural impulses. For example, light waves hitting the retina are transformed into electrical signals sent to the brain.

Sensory Adaptation – Reduced sensitivity to a stimulus after prolonged exposure. Example: Not noticing a strong perfume after a few minutes.

Cocktail Party Effect – The ability to focus on one voice among many. Example: Hearing your name in a loud room while tuning out other conversations.

Synesthesia – A condition where stimulation of one sense triggers another. Example: Seeing colors when hearing music.

Prosopagnosia – The inability to recognize faces, often due to brain damage.

Wavelengths – The distance between peaks in a wave, affecting color in vision and pitch in hearing.

Accommodation – The process by which the lens changes shape to focus images on the retina.

Lens – The transparent structure behind the pupil that focuses light onto the retina.

Nearsightedness (Myopia) – A condition where distant objects appear blurry because light is focused in front of the retina.

Farsightedness (Hyperopia) – A condition where nearby objects appear blurry because light is focused behind the retina.

Retina – The light-sensitive layer at the back of the eye containing photoreceptors.

Thalamus – The brain’s sensory relay station; directs sensory signals to the appropriate cortical areas.

Photoreceptors – Cells in the retina that detect light, including cones and rods.

Cones – Photoreceptors responsible for color vision and fine detail.

Rods – Photoreceptors responsible for black-and-white vision and night vision.

Ganglion Cells – Neurons in the retina that transmit visual information to the brain.

Blind Spot – The point where the optic nerve leaves the eye, lacking photoreceptors.

Trichromatic Theory – The theory that color vision is based on three types of cones detecting red, green, and blue.

Afterimages – Visual illusions that persist after the original stimulus is removed. Example: Staring at a green image then seeing a red afterimage.

Dichromatism – Color blindness where one type of cone is missing.

Monochromatism – Complete color blindness due to a lack of functioning cones.

Opponent-Process Theory – The theory that color perception is controlled by opposing retinal processes (red-green, blue-yellow, black-white).

Amplitude (Vision & Hearing) – The height of a wave; determines brightness in vision and loudness in hearing.

Frequency – The number of waves passing a point per second; determines pitch in hearing.

Loudness – Perceived volume of sound, related to amplitude.

Pitch – The perceived highness or lowness of a sound, related to frequency.

Sound Localization – The ability to determine the source of a sound.

Place Theory – The idea that pitch is determined by where in the cochlea hair cells respond.

Conduction Deafness – Hearing loss due to damage in the mechanical parts of the ear.

Nerve (Sensorineural) Deafness – Hearing loss due to damage to hair cells or the auditory nerve.

Gate Control Theory – The idea that pain signals can be blocked by competing stimuli or endorphins.

Taste Receptors – Sensory cells responsible for detecting taste.

Supertasters – People with a higher-than-average number of taste buds, making them more sensitive to flavors.

Nontasters – People with fewer taste buds, leading to less sensitivity to taste.

Medium Tasters – People with a moderate number of taste buds.

Semicircular Canals – Structures in the inner ear involved in balance.

Kinesthesis – The sense that detects body position and movement.

Gustation – The sense of taste.

Olfaction – The sense of smell.

Vestibular Sense – The sense of balance, controlled by the inner ear.

Sweet – A taste sensation often associated with energy-rich foods.

Sour – A taste associated with acidic foods.

Salty – A taste related to sodium intake.

Bitter – A taste often associated with potentially toxic substances.

Umami – A savory taste associated with amino acids.

Oleogustus – The taste of fat.

Priming – Exposure to one stimulus influences response to a later stimulus.

Blind Sight – The ability to respond to visual stimuli without conscious awareness.

Consciousness – Awareness of self and surroundings.

Psychoactive Drugs – Substances that alter brain chemistry and perception.

Agonists – Drugs that mimic neurotransmitters.

Antagonists – Drugs that block neurotransmitters.

Reuptake – The process of reabsorbing neurotransmitters into the presynaptic neuron.

Tolerance – The need for larger doses of a drug to achieve the same effect.

Withdrawal – Unpleasant symptoms when a drug is discontinued.

Caffeine – A stimulant that blocks adenosine receptors.

Cocaine – A stimulant that increases dopamine levels.

Stimulants – Drugs that increase nervous system activity.

Alcohol – A depressant that slows brain function.

Depressants – Drugs that slow the nervous system.

Hallucinogens – Drugs that alter perception.

Marijuana – A drug affecting perception and memory.

Opiates – Drugs that relieve pain and elevate mood.

Heroin – A powerful opiate that mimics endorphins.

Circadian Rhythm – The body’s internal clock.

NREM Stage 1 – Light sleep with theta waves.

NREM Stage 2 – Sleep spindles appear.

NREM Stage 3 – Deep sleep with delta waves.

Restoration of Resources – The body replenishes energy during sleep.

REM Sleep – Dreaming occurs; brain activity resembles wakefulness.

Paradoxical Sleep – Another name for REM sleep.

REM Rebound – Increased REM sleep after deprivation.

Insomnia – Difficulty falling or staying asleep.

Narcolepsy – Sudden sleep attacks.

Sleep Apnea – Breathing stops during sleep.

Somnambulism – Sleepwalking.

Activation-Synthesis Theory – Dreams are the brain’s attempt to make sense of random activity.

Consolidation Theory – Dreams help process and store memories.

Genetic Predisposition – Increased likelihood of traits due to genetics.

Neurons – Nerve cells.

Multiple Sclerosis – A disease that damages the myelin sheath.

Neural Transmission – The process of nerve signal transmission.

Resting Potential – A neuron’s inactive state.

Threshold – The level needed to trigger an action potential.

Action Potential – The electrical signal sent down an axon.

All-or-None Principle – A neuron either fires completely or not at all. Example: Like flipping a light switch, it doesn’t “half-fire.”

Depolarization – The process during action potential when positive ions rush into the neuron, making it more likely to fire.

Excitatory Neurotransmitters – Chemicals that increase the likelihood of a neuron firing. Example: Glutamate.

Inhibitory Neurotransmitters – Chemicals that decrease the likelihood of a neuron firing. Example: GABA.

Dopamine – A neurotransmitter involved in movement, pleasure, and motivation. Too much is linked to schizophrenia; too little to Parkinson’s disease.

Serotonin – A neurotransmitter involved in mood regulation. Low levels are linked to depression.

Norepinephrine – A neurotransmitter that controls alertness and arousal. Low levels are linked to depression.

Glutamate – The brain’s primary excitatory neurotransmitter. Excess is linked to migraines and seizures.

GABA (Gamma-Aminobutyric Acid) – The brain’s main inhibitory neurotransmitter, involved in relaxation and sleep. Deficiency is linked to anxiety disorders.

Endorphins – Natural painkillers produced by the body. Example: The "runner’s high" after intense exercise.

Substance P – A neurotransmitter responsible for transmitting pain signals to the brain.

Acetylcholine (ACh) – A neurotransmitter involved in muscle contraction and memory. Deficiency is linked to Alzheimer’s disease.

Alzheimer’s Disease – A degenerative brain disorder associated with memory loss and linked to low acetylcholine levels.

Myasthenia Gravis – A disorder that causes muscle weakness due to problems with acetylcholine receptors.

Sensory Neurons (Afferent Neurons) – Neurons that carry information from the senses to the brain. Example: Feeling heat from a stove.

Interneurons – Neurons within the brain and spinal cord that process information and connect sensory and motor neurons.

Motor Neurons (Efferent Neurons) – Neurons that carry signals from the brain to muscles. Example: Moving your hand away from a hot surface.

Central Nervous System (CNS) – Consists of the brain and spinal cord.

Peripheral Nervous System (PNS) – The network of nerves outside the CNS, connecting it to the rest of the body.

Reflex Arcs – Simple, automatic responses to stimuli that bypass the brain. Example: The knee-jerk reflex.

Somatic Nervous System – The part of the PNS that controls voluntary muscle movements.

Autonomic Nervous System – The part of the PNS that controls involuntary bodily functions.

Sympathetic Nervous System – Activates the body's fight-or-flight response. Increases heart rate, dilates pupils.

Parasympathetic Nervous System – Calms the body after stress; responsible for rest and digestion.

Endocrine System – The body's system of glands that release hormones.

Hormones – Chemical messengers released by endocrine glands that travel through the bloodstream.

Adrenaline (Epinephrine) – A hormone released by the adrenal glands that prepares the body for fight-or-flight.

Leptin – A hormone that regulates hunger by signaling fullness.

Ghrelin – A hormone that increases hunger signals.

Melatonin – A hormone that regulates sleep-wake cycles.

Oxytocin – A hormone involved in bonding, trust, and love. Example: Released during childbirth and hugging.

Lesioning – The deliberate destruction of brain tissue to study its effects.

Electroencephalogram (EEG) – A device that measures electrical activity in the brain. Used to study sleep and epilepsy.

Functional MRI (fMRI) – A brain imaging technique that shows both structure and activity by measuring blood flow.

Medulla – The part of the brainstem responsible for vital functions like heart rate and breathing.

Cerebellum – The “little brain” at the back of the brain that controls balance, coordination, and fine motor movements.

Reticular Formation – A network of neurons in the brainstem that controls arousal and attention.

Thalamus – The brain’s relay center for sensory information (except smell).

Hypothalamus – Regulates body temperature, hunger, thirst, and the endocrine system.

Amygdala – The brain structure involved in processing emotions, especially fear and aggression.

Hippocampus – A brain structure involved in memory formation. Damage leads to an inability to form new memories.

Brain Stem – The oldest part of the brain responsible for basic survival functions.

Cerebral Cortex – The outer layer of the brain, responsible for higher-level thinking, perception, and voluntary movement.

Limbic System – A group of structures (amygdala, hippocampus, hypothalamus) involved in emotion and memory.

Contralateral Hemispheric Organization – The concept that the left hemisphere controls the right side of the body and vice versa.

Hemispheric Specialization (Lateralization) – The idea that the two hemispheres of the brain have different functions. Example: The left hemisphere is typically dominant for language, while the right hemisphere is better at spatial tasks.

Split-Brain Patients – Individuals who have had their corpus callosum severed, leading to difficulties in integrating information between hemispheres.

Corpus Callosum – The bundle of nerve fibers connecting the two hemispheres of the brain.

Lobes of the Brain – The four main sections of the cerebral cortex: frontal, parietal, temporal, and occipital.

Association Areas – Areas of the cerebral cortex involved in higher mental functions like thinking and planning.

Frontal Lobes – Responsible for reasoning, planning, problem-solving, and voluntary movement.

Prefrontal Cortex – The part of the frontal lobe involved in decision-making, social behavior, and personality.

Central Executive – A concept in working memory that controls attention and decision-making.

Broca’s Area – Located in the left frontal lobe, responsible for speech production. Damage results in Broca’s aphasia (difficulty speaking).

Aphasia – A language disorder caused by brain damage.

Wernicke’s Area – Located in the left temporal lobe, responsible for understanding language. Damage leads to Wernicke’s aphasia (difficulty understanding speech).

Motor Cortex – A strip of the frontal lobe responsible for voluntary movement.

Parietal Lobes – Involved in processing sensory information like touch and spatial awareness.

Somatosensory Cortex – A strip of the parietal lobe that processes body sensations.

Phantom Limb Syndrome – The perception of sensations, including pain, in a limb that has been amputated.

Occipital Lobes – The area of the brain responsible for vision.

Temporal Lobes – The area of the brain responsible for processing auditory information.