Unit 1-A ID's: Biological Bases of Behavior

Nature

how much of human experience is biological/genetic

Nurture

how much is contributed by our environment

Twin studies

comparing similarities and differences between monozygotic (MZ) and dizygotic (DZ) twins

Monozygotic

identical twins, a fertilized egg split into two, twins share 100% of genes

Dizygotic

fraternal twins, two eggs are fertilized by two different sperm cells, twins share 50% of genes, no more similar than any other similar siblings → just born at the same time

Adoption studies

comparing similarities and differences between adoptive children and their biological and adoptive families

Family studies

comparing similarities and differences among parents, their children, and their siblings

Neurons

help us detect information and respond to impacts, neural cells that transmit signals throughout the body

Glial cells

non-neural cells in the nervous system that support neuron structure and function

Reflex arc

bypass the brain

Sensory neurons

afferent, sensory, detect sensory information

Interneurons

integrate info, communicate with brain, bypass

Motor neurons

efferent, output muscle or gland activity

Dendrites

receive messages from other cells

Soma (cell body)

the cell’s life-support center

Axon

passes messages away from the cell body to other neurons, muscles, or glands

Myelin sheath

covers the axon of some neurons and helps speed neural impulses

Terminal buttons 

axons buds, form junctions with other cells

Action potential

electrical charge that travels down a neuron (dendrite → terminal branches)

Resting potential

a neuron at rest (resting membrane potential) has a voltage of approx. -65mV

Threshold

min. voltage needed to fire an action potential

• if not strong enough, no electrical signal is passed along

All-or-none response

• if threshold is met, neuron fires a full response

• if threshold is not met, no response

Depolarization (Na+ ions)

increasing membrane potential, neuron becomes positive, Na+ in

Repolarization (K+ ions)

decreasing membrane potential, neuron returns to negative voltage, K+ out

Hyperpolarization

overshoots resting potential, neuron becomes too negative

Refractory period

hyperpolarization creates and refractory period → another action potential cannot be produced in that region

• ensures that action potential only moves one way (keeps one area further from the threshold)

Myelination

the fatty tissue layer segmentally encasing the axons of some neurons; increases transmission speed and provides insulation

Multiple sclerosis (MS)

an autoimmune disorder in which immune cells attack and destroy myelin on nerve cells in the central nervous system 

• reduces signaling speed 

Synapse

the space between adjacent neurons, electrical signal reaches terminal buttons; chemical signal is passed across synapse

Neurotransmitters

synthesizes and packages neurotransmitters (chemical) in synaptic vesicles

Signal termination: diffusion

neurotransmitters simply diffuse out of the synapse

Signal termination: reuptake

Neurotransmitters are taken back up by a neuron, recycled 

Signal termination: digestion

enzymes digest neurotransmitters, no longer bind to postsynaptic neurons

Excitatory NT

depolarizes neuron; encourages an action potential; more positive → approaches threshold

Inhibitory NT

further polarizes neuron; discourages an action potential; more negative

Acetylcholine

enables skeletal muscle movement; enhances learning, memory, and attention

• muscle

Norepinephrine

influences alertness and arousal; active in flight or fight response

• fight/flight response

Serotonin

influence mood, appetite, sleep, and physiological arousal

• mood and/or arousal

Dopamine

reward pathways; enhances muscle movement, emotion, and attention

• reward

GABA

major inhibitory neurotransmitter - inhibits electrical signaling

• inhibit

Glutamate

major excitatory neurotransmitter; important role in learning and memory 

• excitatory 

Endorphins

natural pain relievers and mood boosters, modulate pain response and replace with pleasure 

• pain to pleasure 

Substance p

role in pain perception and activating immune response 

• pain 

Myasthenia gravis

an autoimmune disease in which the body’s antibodies block acetylcholine receptors - causing muscle weakness and fatigue

Endocrine system

collection of glands throughout the body that produces hormones; chemicals that are released 

Adrenaline

adrenal glands: release adrenaline and cortisol (flight or fight hormones)

Oxytocin

pituitary gland: can release oxytocin into the bloodstream, love hormone

• facilitate childbirth, sexual excitement, and physical touch

Narcotics (opiates)

• bind endorphin receptors

• pain relief, euphoria (dopamine release) 

• ex. opium, morphine, heroin 

Stimulants

• stimulate neural activity (excitatory NT) 

• ex. caffeine, nicotine, meth, cocaine

Depressants

• depress neural activity, can stimulate release of GABA

• ex. alcohol, barbiturates 

Hallucinogens

• distorts sensory perception or cognition 

• LSD, MDMA, marijuana

Agonists

a drug molecule that binds receptor sites and increases a neurotransmitter’s action

Antagonists

a drug molecule that binds receptor sites and inhibits or blocks a neurotransmitter’s action 

Reuptake inhibitors

a drug molecule that prevents reuptake of a neurotransmitter; increases NT’s action 

Tolerance

drug’s effect lessons after repeated use, takes larger doses to feel high

Dependence

physiological and/or psychological need to use a drug

Addiction

compulsive drug craving and use, despite adverse consequences 

Withdrawal

the discomfort and distress that followed discontinued use of an addictive drug 

Central nervous system

brain and spinal cord, integrate signals from various regions of the body, includes interneurons 

Peripheral nervous system

outside of the brain and spinal cord, carries info

Somatic

controls the body’s skeletal muscles, voluntary control 

Autonomic

controls the glands and the muscles of internal organs (heart), operates automatically 

Sympathetic

• “Flight or fight” 

• arouses the body, mobilizing its energy inhibits 

• pupils dilate, heart rate accelerates, digestion 

Parasympathetic

• “Rest and digest”

• calms the body, conserving its energy

• pupils constrict, waste processed

Lesions

areas of brain tissue that are damaged or deteriorating

CAT/CT scan

x-rays (radiation) to visualize the brain’s structure 

MRI

magnetic fields to visualize the brain’s structure (expensive, detailed, timely)

EEG

measures electrical activity in the brain (electrodes placed on head), good temporal resolution (fast), unclear where activity happens

fMRI

magnetic fields and radio waves, functional MRI, oxygen use, visualize what areas of the brain are involved in diff. tasks 

PET

radioactive tracers, visualize blood flow, oxygen movement, glucose, bad temporal resolution (slow)

Brainstem

reptilian, instinctual, survival

Medulla oblongata

control of heart rate, breathing

Reticular activating system

some motor function, breathing, eye movement, arsoual (sleep/wake cycle)

Cerebellum

coordinates voluntary movement, balance

Limbic system

Mammalian, emotional or feeling

Thalamus

sensory relay station; directs sensory information (touch, vision, hearing, taste) to other parts of the brain 

Amygdala

response of strong emotion; fear, aggression 

Hippocampus

encodes and processes memory

Hypothalamus

governs pituitary gland (hormone release)

• 4 F’s feeling, fighting, fleeing, “mating”

Frontal lobe

higher ordering thinking, language processing, judgement and decision making, motor cortex (motor movement)

Parietal lobe

processes sensory input for touch and body position

• somatosensory cortex - touch sensitivity 

Temporal lobe

auditory information and linguistic processing, primarily from opposite ear

Occipital lobe

visual information processing, primarily from opposite visual field

Broca’s Area

language center located in the left frontal lobe, involved in expressive language (speech)

Wernicke’s area

language center located in the left temporal lobe, involved in language comprehension/coherence

Corpus callosum

a wide band of axon fibers connecting the two hemispheres of the brain

Contralateral hemisphere organization

left visual field processed by right hemisphere, right visual field processed by left

Left hemisphere

speaking and language, math calc., controlling the right side of brain

Right hemisphere

perceptual tasks, making inferences, spatial perception, emotion, controlling left side of the brain 

Neuroplasticity

the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience