Biological Bases of Behavior

Nature (天生)

Behavior influenced by genes and heredity (e.g.

Nurture (後天)

Behavior shaped by experience

Heritability (遺傳率)

The proportion of individual differences in a trait that can be attributed to genetics

Evolutionary Perspective

Studies how natural selection shapes behavior for survival and reproduction

Twin Studies

Compare identical (100% same genes) vs. fraternal twins (50% same) to separate genetic vs. environmental influences

Family Studies

Track traits across multiple generations to see inheritance patterns

Adoption Studies

Compare adopted children to biological and adoptive families to separate nature from nurture

Central Nervous System (CNS)

Brain + spinal cord; processes sensory info

Peripheral Nervous System (PNS)

Nerves outside brain and spine; connects CNS to rest of body

Somatic Nervous System (SNS)

Controls voluntary movements and senses

Autonomic Nervous System (ANS)

Controls involuntary body functions (no conscious control)

Sympathetic Division

"Fight-or-flight" response; reacts to threats (increases heart rate

Parasympathetic Division

"Rest-and-digest" system; calms body down after threat

Dendrites

Part of neuron that receives signals from other neurons

Soma (Cell Body)

Part of neuron that contains nucleus and provides energy

Axon

Part of neuron that carries electrical impulse away from soma

Myelin Sheath

a fatty, insulating layer around nerve fibers (axons) that allows electrical nerve impulses (action potentials) to travel fast and efficiently

Axon Terminal

End branches of axon that release neurotransmitters into synapse

Sensory (Afferent) Neurons

Carry signals from sense organs to the brain

Motor (Efferent) Neurons

Carry signals from brain to muscles

Interneurons

Connect sensory and motor neurons; found in spinal cord

Reflex Arc

A reflex arc is the shortest, fastest nerve pathway that allows your body to react instantly to danger without waiting for your brain to think about it.: Receptor → Sensory Neuron → Interneuron → Motor Neuron → Muscle

Resting Potential

-70mV charge when neuron is at rest (polarized)

Action Potential

Electrical charge shift (depolarization) that travels down axon

All-or-Nothing Principle

Neuron either fires completely or not at all

Depolarization

Process where inside of neuron becomes more positive (leading to action potential)

Refractory Period

Brief recovery time after neuron fires when it cannot fire again

Reuptake

Process where leftover neurotransmitters are reabsorbed by sending neuron

Multiple Sclerosis

Disorder where immune system attacks the myelin sheath

Myasthenia Gravis

autoimmune neuromuscular disorder where the immune system attacks acetylcholine receptors at the neuromuscular junction—the place where motor neurons communicate with skeletal muscles

Medulla (Hindbrain)

Controls basic autonomic functions (heart rate

Pons (Hindbrain)

Connects brainstem and cerebellum; coordinates movement; involved in sleep

Reticular Activating System (RAS)

Network in the brainstem that acts as a filter for sensory information

Cerebellum

Controls balance

Thalamus

Sensory "switchboard" (except smell); sorts and sends sensory info to cortex

Hypothalamus

Body’s control center that regulates homeostasis by directing the pituitary gland

Amygdala

Involved in fear

Hippocampus

Converts short-term to long-term memory; spatial memory

Frontal Lobe

Prefrontal cortex-Decision-making, planning.

- Motor cortex- Voluntary movement.

- Broca’s Area- Speech production.

Broca's Area

In frontal lobe; responsible for speech production

Parietal Lobe

Simple definition: The parietal lobe is the part of your brain that processes touch sensations (like temperature, pain, and pressure) and helps you understand spatial awareness (like knowing where your body is and navigating your environment).

Occipital Lobe

Contains primary visual cortex; processes visual information

Temporal Lobe

Contains primary auditory cortex and Wernicke's area (language comprehension)

Wernicke's Area

In temporal lobe; responsible for language comprehension

Corpus Callosum

Bundle of nerves connecting left and right brain hemispheres

Split-Brain Research

Studies of patients with severed corpus callosum; shows hemispheric specialization

Left Hemisphere

Specialized for language

Right Hemisphere

Specialized for spatial ability (managing functions like imagination, art, face recognition, and social cues)

Neuroplasticity

Brain's ability to rewire itself after injury or through experience

Long-Term Potentiation (LTP)

"Neurons that fire together

EEG (Electroencephalograph)

Measures electrical activity in brain; used for seizures

MRI (Magnetic Resonance Imaging)

Shows detailed brain structure using magnetic fields

fMRI (Functional MRI)

Shows both brain structure and function by measuring blood oxygen levels

PET Scan (Positron Emission Tomography)

Shows brain activity by tracking glucose consumption

CT Scan (Computed Tomography)

Uses X-rays to create brain slice images; good for injuries

NREM 1

Light sleep stage with alpha waves; may have hypnagogic sensations (jerks

NREM 2

Slightly deeper sleep stage with theta waves

NREM 3

Deepest sleep stage with delta waves; where night terrors and sleepwalking occur

REM Sleep

Dream sleep with rapid eye movements

Restoration Theory of Sleep

Sleep helps restore energy and repair body/brain tissue

Memory Consolidation Theory

Sleep (especially REM) helps transfer short-term memories to long-term storage

Energy Conservation Theory

Sleep evolved to keep us safe and conserve energy during non-productive times

Insomnia

Difficulty falling or staying asleep

Sleep Apnea

Disorder involving breathing interruptions during sleep (obstructive

Narcolepsy

Disorder with sudden sleep attacks during the day

Somnambulism

Sleepwalking; occurs during NREM 3

REM Sleep Behavior Disorder

Acting out dreams because body is not paralyzed during REM sleep

Sensation

Process of detecting environmental stimuli and converting them into neural signals

Transduction

Conversion of sensory stimulus energy into neural impulses

Absolute Threshold

Minimum stimulus intensity needed for detection 50% of the time

Just-Noticeable Difference (JND)

Smallest change between two stimuli that can be detected

Weber's Law

This means that the larger the original stimulus, the larger the just noticeable difference needs to be for it to be detected.

Sensory Adaptation

Decreased sensitivity to a constant stimulus over time

Sensory Interaction

Senses influence each other (e.g.

Rods

Retinal receptors for low light

Cones

Retinal receptors responsible color and detail; found in fovea; three types (red/green/blue)

Trichromatic Theory

Color vision theory based on three cone types (red

Opponent-Process Theory

Explains how our senses work in pairs, where the activation of one part of a pair leads 2 the other, causing effects,

ex: seeing afterimages or developing drug tolerance

Place Theory (Hearing)

Pitch perception based on location of vibration along the cochlea

Frequency Theory (Hearing)

Pitch perception based on rate of neural firing

Conduction Deafness

Hearing loss due to problem in outer/middle ear (e.g.

Sensorineural Deafness

Hearing loss due to problem in inner ear or auditory nerve

Olfaction

Sense of smell; receptors in nose send signals directly to brain (bypassing thalamus)

Gustation

Sense of taste; includes sweet

Gate Control Theory

Pain signals can be blocked or enhanced by spinal cord "gates"

Vestibular Sense

Sense of balance; controlled by semicircular canals in inner ear

Kinesthesis

Sense of body position and movement