Unit 1: Biological Bases of Behavior

Evolutionary Perspective

The idea that traits and behaviors that help survival and reproduction are passed down through genetics

Natural Selection

Traits that improve survival are more likely to be passed on to offspring

Nature

Genetic and hereditary influences

Nurture

Environmental influences such as social and physical surroundings

Twin Studies

Studies comparing identical and fraternal twins to determine genetic vs environmental influences

Identical (Monozygotic) Twins

Twins from one fertilized egg that splits; genetically identical and same sex

Fraternal (Dizygotic) Twins

Twins from two separate eggs fertilized by two sperm; genetically similar to siblings

Family/Adoption Studies

Studies comparing biological and adoptive relatives to separate genetic and environmental factors

Central Nervous System (CNS)

Consists of the brain and spinal cord

Peripheral Nervous System (PNS)

All nerves outside the brain and spinal cord

Somatic Nervous System

Controls voluntary muscle movement

Autonomic Nervous System

Controls involuntary bodily functions

Sympathetic Nervous System

Prepares the body for stress (fight-or-flight)

Fight-or-Flight Response

Physiological response to perceived threats

Parasympathetic Nervous System

Calms the body and returns it to normal after stress

Glial Cells

Support, insulate, and protect neurons

Neuron

A nerve cell that transmits information

Sensory Neurons

Carry information from sensory receptors to the brain

Interneurons

Neurons within the CNS that connect sensory and motor neurons

Motor Neurons

Carry commands from the brain to muscles

Reflex Arc

A fast, automatic response involving sensory, interneuron, and motor neurons

Dendrites

Receive incoming messages from other neurons

Axon

Transmits messages away from the neuron

Myelin Sheath

Fatty covering that insulates the axon and speeds neural impulses

Multiple Sclerosis

A disease caused by breakdown of the myelin sheath

Action Potential

An electrical impulse that travels down the axon

All-or-Nothing Principle

A neuron fires completely or not at all

Resting Potential

The neuron's charged but inactive state

Threshold

The minimum stimulation needed to trigger an action potential

Depolarization

Positive ions rush into the neuron during firing

Refractory Period

The time when a neuron cannot fire again

Axon Terminal Buttons

End of the axon that releases neurotransmitters

Synapse

The gap between neurons where neurotransmitters travel

Neurotransmitters

Chemical messengers that transmit signals between neurons

Excitatory Neurotransmitters

Increase the likelihood of neuron firing

Inhibitory Neurotransmitters

Decrease the likelihood of neuron firing

Reuptake

The reabsorption of neurotransmitters by the sending neuron

Agonist Drugs

Mimic or increase neurotransmitter effects

Reuptake Inhibitors

Block reuptake, increasing neurotransmitter availability

Antagonist Drugs

Block neurotransmitter receptors

Acetylcholine (ACh)

Involved in learning, memory, and muscle contraction; undersupply linked to Alzheimer's

Myasthenia Gravis

Autoimmune disorder destroying ACh receptors, causing muscle weakness

Dopamine

Involved in movement, mood, and reward; oversupply linked to schizophrenia, undersupply to Parkinson's

Endorphins

Pain control and pleasure neurotransmitters

GABA

Inhibitory neurotransmitter that reduces anxiety

Glutamate

Major excitatory neurotransmitter involved in learning and memory

Norepinephrine

Affects alertness and arousal

Serotonin

Regulates mood, sleep, appetite, and body temperature

Substance P

Involved in pain perception

Hormones

Chemical messengers that travel through the bloodstream

Adrenaline

Hormone that increases heart rate during stress

Leptin

Hormone that decreases appetite

Ghrelin

Hormone that increases hunger

Melatonin

Regulates sleep-wake cycles

Oxytocin

Bonding and social connection hormone

Psychoactive Drugs

Substances that alter perception and mood

Tolerance

Needing more of a drug to achieve the same effect

Withdrawal

Physical or psychological discomfort after stopping drug use

Physiological Dependence

Physical need for a drug

Psychological Dependence

Mental craving for a drug

Depressants

Slow down the central nervous system

Stimulants

Increase central nervous system activity

Hallucinogens

Alter perception and sensory experiences

Opiates

Pain-relieving drugs that mimic endorphins

Phineas Gage

A man whose frontal lobe injury revealed links between brain and personality

Lesioning Procedure

Destruction or removal of brain tissue

Phantom Limb

Sensation of pain or movement in an amputated limb

Brain Plasticity

The brain's ability to reorganize after damage

EEG

Electroencephalogram measuring brain wave activity

fMRI

Brain scan showing blood flow and activity

Brainstem

Controls basic life functions

Medulla

Regulates heart rate, breathing, and blood pressure

Reticular Activating System

Controls arousal and alertness

Limbic System

Involved in emotion and memory

Thalamus

Sensory relay station (except smell)

Cerebellum

Balance and coordination

Hippocampus

Formation of new memories

Amygdala

Emotion processing

Hypothalamus

Regulates hunger, thirst, sex, and body temperature

Cerebral Cortex

Outer layer of the brain responsible for higher thinking

Frontal Lobe

Planning, judgment, decision-making, emotion

Parietal Lobe

Sensory processing and touch

Occipital Lobe

Vision

Temporal Lobe

Hearing and language processing

Association Areas

Higher mental functions like thinking and learning

Aphasia

Impaired language ability

Broca's Area

Speech production

Broca's Aphasia

Difficulty speaking

Wernicke's Area

Language comprehension

Wernicke's Aphasia

Difficulty understanding language

Motor Cortex

Controls voluntary movement

Sensory Cortex

Processes touch sensations

Split-Brain Patients

Patients with severed corpus callosum

Contralateral Organization

Each hemisphere controls the opposite side of the body

Corpus Callosum

Connects the two brain hemispheres

Consciousness

Aware state of ourselves and our environment

Circadian Rhythm

24-hour biological clock

Sleep Cycle

Pattern of sleep stages lasting about 90 minutes

Stage 1 Sleep

Light sleep with hallucinations

Stage 2 Sleep

Light sleep, easily awakened