psych processes most important

Action potential sequence

Threshold → sodium enters (depolarization) → potassium exits (repolarization) → possible hyperpolarization → recovery.

Direction of neural communication

Dendrites → cell body → axon hillock → axon → axon terminals → synapse.

Excitatory vs. inhibitory signals

Excitatory signals increase the likelihood of firing; inhibitory signals decrease it.

All-or-none principle

An action potential occurs fully once threshold is reached; stronger stimuli can increase firing frequency, not action potential size.

Myelin and multiple sclerosis

Myelin speeds neural transmission; MS damages CNS myelin and can slow or disrupt communication.

Agonist vs. antagonist vs. reuptake inhibitor

Agonists mimic or enhance neurotransmitter effects; antagonists block effects; reuptake inhibitors prevent reabsorption.

H.M.'s memory impairment

H.M. struggled to form new explicit memories, but some implicit skill learning remained intact.

Phineas Gage's significance

Frontal brain injury helped demonstrate the role of frontal regions in judgment and impulse control.

Hippocampus

Essential for forming new explicit memories.

Amygdala

Contributes to threat processing and emotional learning.

Thalamus

Relays most sensory information to the cerebral cortex.

Cerebellum

Supports balance, coordination, timing, and motor learning.

Hypothalamus

Regulates homeostasis and influences endocrine and autonomic responses.

Prefrontal cortex

Supports planning, judgment, working memory, and impulse control.

Split-brain visual fields

Right visual field information reaches the left hemisphere first; left visual field information reaches the right hemisphere first.

Motor vs. somatosensory homunculus

Motor representation relates to movement precision; somatosensory representation relates to sensory sensitivity.

Sympathetic vs. parasympathetic

Sympathetic activates fight-or-flight; parasympathetic supports rest-and-digest.

Reflex withdrawal

A sensory signal can trigger a spinal reflex through interneurons and motor neurons before conscious awareness.

Longer-term stress response

The hypothalamus and pituitary activate the adrenal cortex, which releases cortisol.

EEG vs. fMRI

EEG records electrical activity; fMRI estimates activity through blood-oxygenation changes.

CT vs. MRI

CT uses X-rays for structural images; MRI provides detailed soft-tissue images.

N1 vs. N3

N1 is light transitional sleep; N3 is deep slow-wave sleep.

NREM vs. REM

NREM includes N1, N2, and N3; REM features rapid eye movements and temporary muscle atonia.

Night terrors vs. nightmares

Night terrors are commonly associated with deep NREM sleep; nightmares are commonly associated with REM sleep.

Circadian rhythm vs. sleep pressure

Circadian rhythm is the body's approximate 24-hour clock; sleep pressure increases with time awake.

Caffeine and adenosine

Caffeine blocks adenosine receptors, reducing the sensation of sleepiness.

Neuroplasticity vs. neurogenesis

Neuroplasticity is the brain's ability to reorganize connections or functions; neurogenesis is the creation of new neurons.

Parkinson's disease and dopamine

Parkinson's is associated with loss of dopamine-producing neurons involved in movement.

Alzheimer's disease and acetylcholine

Alzheimer's is associated with loss of cholinergic neurons and reduced acetylcholine signaling.

Depression and serotonin

Serotonin is involved in mood, but depression cannot be explained simply as low serotonin.