Homeβ€ΊBiologyβ€ΊNeuroscience
🧠 Biology · Neuroscience

Memory tricks for the brain & nervous system

From cranial nerves to neurotransmitters β€” neuroscience is full of lists that beg for mnemonics. These memory tricks lock in brain structures, action potentials, and nervous system divisions for your next exam.

Study with others
πŸ“‹
Neuroscience Forum
Ask questions Β· Share techniques
 πŸ’¬
Live Study Room
Study together now
🧠 Neuroscience

Memory Tricks

Proven mnemonics — fast to learn, hard to forget.

Cranial Nerves
Oh Oh Oh To Touch And Feel Very Good Velvet β€” AH! β€” Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal
12 cranial nerves in order β€” one of the most tested lists in neuroscience
The 12 cranial nerves in order: I Olfactory (smell), II Optic (vision), III Oculomotor (eye movement), IV Trochlear (eye down/in), V Trigeminal (face sensation/chewing), VI Abducens (eye lateral), VII Facial (facial expression/taste), VIII Vestibulocochlear (hearing/balance), IX Glossopharyngeal (taste/swallowing), X Vagus (parasympathetic/organs), XI Accessory (neck/shoulder muscles), XII Hypoglossal (tongue).
Difficulty: Intermediate
Sensory, Motor, or Both?
Some Say Marry Money But My Brother Says Big Brains Matter More. S=Sensory, M=Motor, B=Both. CN I,II,VIII = purely sensory. CN III,IV,VI,XI,XII = purely motor. CN V,VII,IX,X = both.
Most commonly tested nerves
Vagus (CN X): longest cranial nerve, parasympathetic to heart/lungs/gut. Trigeminal (CN V): largest cranial nerve, three branches (ophthalmic, maxillary, mandibular). Facial (CN VII): damaged in Bell's palsy β€” unilateral facial drooping.
Clinical connections
CN II damage β†’ blindness. CN III damage β†’ drooping eyelid (ptosis), dilated pupil. CN VI damage β†’ can't look laterally. CN VIII damage β†’ deafness or vertigo. CN X damage β†’ hoarse voice, difficulty swallowing.
Brain Lobes
FTOP β€” Frontal (executive), Temporal (hearing/memory), Occipital (vision), Parietal (sensation/spatial)
Four cerebral lobes and their primary functions
The cerebrum has four lobes: Frontal lobe β€” executive function, decision-making, motor control, Broca's area (speech production). Temporal lobe β€” auditory processing, memory (hippocampus), Wernicke's area (language comprehension). Occipital lobe β€” visual processing. Parietal lobe β€” somatosensory processing, spatial awareness, body position.
Difficulty: Beginner
Broca's vs Wernicke's
Broca's area (frontal lobe): speech production. Damage β†’ Broca's aphasia: can understand but can't speak fluently. Wernicke's area (temporal lobe): language comprehension. Damage β†’ Wernicke's aphasia: fluent but meaningless speech.
Motor and sensory cortex
Primary motor cortex: posterior frontal lobe, controls voluntary movement. Primary somatosensory cortex: anterior parietal lobe, receives touch/pain/temp signals. Homunculus: distorted body map on cortex β€” hands and lips have largest representation.
Limbic system
Includes hippocampus (memory formation), amygdala (fear/emotion), hypothalamus (homeostasis), cingulate gyrus (attention/emotion). H.M. case: bilateral hippocampus removal β†’ couldn't form new long-term memories.
Action Potential
ReDePo β€” Resting, Depolarization, Repolarization β€” then Hyperpolarization (undershoot)
Resting β†’ stimulus β†’ Na⁺ in β†’ K⁺ out β†’ reset
Action potential steps: Resting potential (βˆ’70mV, Na⁺/K⁺ pump maintains). Depolarization β€” stimulus opens voltage-gated Na⁺ channels, Na⁺ rushes IN, membrane reaches +40mV. Repolarization β€” Na⁺ channels close, K⁺ channels open, K⁺ rushes OUT. Hyperpolarization β€” brief undershoot below βˆ’70mV (refractory period). Na⁺/K⁺ pump restores resting potential.
Difficulty: Intermediate
All-or-nothing principle
Once threshold (βˆ’55mV) is reached, action potential fires at full strength every time β€” no partial action potentials. Stimulus strength coded by frequency of firing, not size of action potential.
Refractory period
Absolute refractory: Na⁺ channels inactivated β€” no action potential possible regardless of stimulus. Relative refractory: K⁺ channels still open β€” stronger stimulus can fire AP. Ensures one-way propagation.
Saltatory conduction
Myelinated neurons: action potential jumps node to node (nodes of Ranvier) β€” much faster than unmyelinated. Multiple sclerosis: myelin degradation β†’ slowed/blocked conduction β†’ neurological symptoms.
Neurotransmitters
GASSED β€” GABA, Acetylcholine, Serotonin, Substance P, Endorphins, Dopamine
6 major neurotransmitters and their primary roles
Key neurotransmitters: GABA (inhibitory β€” reduces neuronal excitability, anxiety relief). Acetylcholine (neuromuscular junction, learning, parasympathetic). Serotonin (mood, sleep, appetite β€” low levels linked to depression). Substance P (pain transmission). Endorphins (natural pain relief, euphoria). Dopamine (reward, motivation, motor control β€” low in Parkinson's, dysregulated in schizophrenia).
Difficulty: Intermediate
Excitatory vs Inhibitory
Excitatory (increase chance of action potential): glutamate (most common excitatory), acetylcholine, dopamine, norepinephrine. Inhibitory (decrease chance): GABA (most common inhibitory), glycine. Effect depends on receptor, not just neurotransmitter.
Clinical connections
Depression: low serotonin/norepinephrine β†’ SSRIs block reuptake. Parkinson's: low dopamine (substantia nigra) β†’ tremors, rigidity. Alzheimer's: low acetylcholine. Anxiety: low GABA β†’ benzodiazepines enhance GABA. Schizophrenia: excess dopamine hypothesis.
Synapse mechanics
AP arrives at terminal β†’ Ca²⁺ channels open β†’ vesicles fuse β†’ neurotransmitter released into synaptic cleft β†’ binds postsynaptic receptors β†’ reuptake or enzymatic degradation. Cocaine blocks dopamine reuptake β€” excess dopamine in cleft.
CNS vs PNS
CNS = Brain + Spinal Cord Β· PNS = Everything else (Somatic + Autonomic)
Somatic (voluntary) Β· Autonomic: Sympathetic (fight-or-flight) vs Parasympathetic (rest-and-digest)
CNS: brain + spinal cord β€” integration and command center. PNS: all nerves outside CNS. Somatic PNS: voluntary control of skeletal muscles. Autonomic PNS: involuntary β€” smooth muscle, cardiac muscle, glands. Sympathetic: fight-or-flight (↑heart rate, dilate pupils, ↓digestion). Parasympathetic: rest-and-digest (↓heart rate, constrict pupils, ↑digestion).
Difficulty: Beginner
Sympathetic specifics
Thoracolumbar (T1-L2). Preganglionic: short, releases ACh. Postganglionic: long, releases norepinephrine (except sweat glands β€” ACh). Effects: ↑heart rate, bronchodilation, glycogenolysis, vasoconstriction, pupil dilation, ↓GI motility.
Parasympathetic specifics
Craniosacral (CN III, VII, IX, X + S2-S4). Preganglionic: long, releases ACh. Postganglionic: short, releases ACh. Effects: ↓heart rate, bronchoconstriction, ↑GI motility, pupil constriction, bladder contraction.
Enteric nervous system
Sometimes called the "second brain" β€” intrinsic nervous system of GI (gastrointestinal) tract with 500 million neurons. Can function independently of CNS. Contains as many neurons as spinal cord. Communicates with CNS (central nervous system) via vagus nerve.
Sleep Stages
1-2-3-REM, repeat β€” "Non-REM climbs down then REM dreams"
N1 (light) β†’ N2 (sleep spindles) β†’ N3 (deep/slow-wave) β†’ REM (dreaming) β€” cycle repeats ~90 min
Sleep cycles through 4 stages repeating ~every 90 minutes. N1: lightest sleep, easily awakened, hypnic jerks. N2: sleep spindles and K-complexes, ~50% of sleep. N3: slow-wave/deep sleep, hardest to wake, memory consolidation, growth hormone release. REM (Rapid Eye Movement): dreaming, muscle atonia, memory consolidation, brain nearly as active as waking.
Difficulty: Beginner
REM details
REM sleep: rapid eye movements, vivid dreams, muscle paralysis (atonia β€” prevents acting out dreams). REM behavior disorder: atonia fails β†’ physically acts out dreams. REM increases across night β€” most REM in last third of sleep. Sleep deprivation β†’ REM rebound.
Sleep disorders
Insomnia: difficulty falling/staying asleep. Sleep apnea: breathing stops repeatedly (OSA most common). Narcolepsy: sudden sleep attacks, cataplexy (muscle tone loss triggered by emotion) β€” hypocretin deficiency. Sleepwalking occurs in N3 (not REM).
Circadian rhythm
~24-hour biological clock controlled by suprachiasmatic nucleus (SCN (suprachiasmatic nucleus)) of hypothalamus. Light β†’ retina β†’ SCN β†’ suppresses melatonin (pineal gland). Melatonin rises at night β†’ promotes sleep. Jet lag/shift work disrupts circadian alignment.
Neuron Structure
DABS β€” Dendrites (receive), Axon (transmit), Body (soma), Synapse (communicate)
Signals flow: dendrites β†’ soma β†’ axon β†’ axon terminal β†’ synapse
Neuron anatomy: Dendrites β€” tree-like extensions that receive signals from other neurons. Cell body (soma) β€” contains nucleus, integrates signals. Axon hillock β€” where action potential is initiated if threshold is met. Axon β€” transmits electrical signal. Myelin sheath (from Schwann cells in PNS, oligodendrocytes in CNS) β€” speeds conduction. Axon terminals β€” release neurotransmitters into synapse.
Difficulty: Beginner
Neuron types
Sensory (afferent): carry signals from body to CNS. Motor (efferent): carry signals from CNS to muscles/glands. Interneurons: connect neurons within CNS β€” most numerous type. Unipolar (one process), bipolar (two), multipolar (many dendrites β€” most motor neurons).
Glial cells
Astrocytes: BBB (Blood-Brain Barrier) maintenance, nutrient support. Oligodendrocytes: myelin in CNS. Schwann cells: myelin in PNS. Microglia: immune defense of CNS. Ependymal cells: line ventricles, produce CSF (cerebrospinal fluid). Outnumber neurons ~10:1.
Neuroplasticity
Brain's ability to reorganize by forming new neural connections. Hebbian learning: "neurons that fire together, wire together." LTP (Long-Term Potentiation β€” the strengthening of synapses with repeated use) = cellular basis of memory. Occurs throughout life but greatest in childhood.
Brainstem
MMP β€” Midbrain, Medulla, Pons β€” "Must Monitor Pulse"
Midbrain (reflexes) Β· Pons (breathing/sleep) Β· Medulla (vital functions)
The brainstem connects the brain to the spinal cord with 3 parts: Midbrain β€” visual/auditory reflexes, dopamine production (substantia nigra). Pons β€” breathing rhythm, sleep, relays signals between cerebrum and cerebellum. Medulla oblongata β€” vital functions: heart rate, blood pressure, breathing, vomiting, swallowing. Brainstem death = no spontaneous breathing or reflexes.
Difficulty: Intermediate
Cerebellum
Not part of brainstem but sits behind it. "Little brain" β€” coordinates movement, balance, fine motor control. Damage β†’ ataxia (uncoordinated movement), dysmetria (misjudging distances), intention tremor. Receives input from motor cortex and sensory systems.
Reticular formation
Network throughout brainstem β€” regulates arousal, sleep-wake cycle, attention. RAS (reticular activating system β€” the network that keeps the brain alert) β€” keeps brain alert. Damage β†’ coma. Anesthetics suppress RAS. Caffeine β†’ blocks adenosine (sleep signal) β†’ increased RAS activity.
Memory Types
EELS β€” Explicit (Episodic + Semantic), Implicit (Skills + Priming)
Explicit = conscious recall Β· Implicit = unconscious, automatic
Memory types: Explicit (declarative) β€” requires conscious recall. Episodic: personal events ("my graduation"). Semantic: facts/knowledge ("Paris is in France"). Implicit (non-declarative) β€” unconscious. Procedural: motor skills (riding a bike). Priming: prior exposure influences later response. Classical conditioning. Explicit memory requires hippocampus; implicit does not β€” explains why amnesiacs can still learn skills.
Difficulty: Intermediate
Memory stages
Encoding β†’ Storage β†’ Retrieval. Sensory memory: fraction of a second (iconic, echoic). Short-term/working memory: 7Β±2 items, ~20 seconds without rehearsal. Long-term memory: potentially unlimited, indefinite duration. Rehearsal and emotion strengthen long-term storage.
LTP and memory
Long-term potentiation: repeated stimulation strengthens synaptic connections. NMDA (N-methyl-D-aspartate) receptors: require simultaneous pre- and postsynaptic activity ("coincidence detectors"). AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor insertion β†’ stronger synapse. Blocked by alcohol (explains blackouts).
Hypothalamus Functions
The 4 Fs β€” Feeding, Fighting, Fleeing, mating (the Four F's of survival)
Hunger Β· Aggression Β· Fear response Β· Reproduction β€” plus temperature and homeostasis
The hypothalamus is the master regulator of homeostasis. Controls: body temperature (thermostat of the body), hunger and thirst, sleep-wake cycles (circadian rhythm via SCN), autonomic nervous system, hormone release via pituitary (releasing/inhibiting hormones), emotion and stress responses. Also controls the "4 Fs" β€” feeding, fighting, fleeing, and reproduction.
Difficulty: Intermediate
Hypothalamus-pituitary axis
Hypothalamus releases releasing hormones (CRH (corticotropin-releasing hormone), TRH, GnRH, GHRH) into portal blood β†’ anterior pituitary releases tropic hormones (ACTH, TSH, LH/FSH, GH) β†’ target glands respond. Negative feedback closes the loop. Posterior pituitary stores/releases ADH and oxytocin (made in hypothalamus).
Thermoregulation
Anterior hypothalamus: responds to overheating β€” triggers sweating, vasodilation. Posterior hypothalamus: responds to cold β€” triggers shivering, vasoconstriction. Fever: pyrogens raise hypothalamic set point β†’ body temperature rises to fight infection.
Neurological Disorders
PASS β€” Parkinson's (dopamine↓), Alzheimer's (ACh↓/plaques), Schizophrenia (dopamine↑), Stroke (FAST)
FAST for stroke: Face drooping, Arm weakness, Speech difficulty, Time to call 911
Major neurological disorders: Parkinson's disease β€” loss of dopamine neurons in substantia nigra β†’ tremor, rigidity, bradykinesia. Alzheimer's β€” amyloid plaques, neurofibrillary tangles, loss of ACh β†’ progressive memory loss. Schizophrenia β€” excess dopamine hypothesis β†’ hallucinations, delusions. Stroke β€” blocked (ischemic) or burst (hemorrhagic) blood vessel β†’ FAST symptoms. Multiple sclerosis β€” myelin destruction β†’ varied neurological deficits.
Difficulty: Advanced
Parkinson's treatment
L-DOPA (crosses blood-brain barrier, converted to dopamine). Dopamine agonists. Deep brain stimulation. Cannot give dopamine directly β€” does not cross BBB. MPTP (toxin) destroys substantia nigra β†’ acute Parkinson's β€” led to discovery of dopamine's role.
Alzheimer's pathology
Amyloid-Ξ² plaques (extracellular) β€” from APP (amyloid precursor protein) cleavage by beta and gamma secretase. Tau tangles (intracellular) β€” hyperphosphorylated tau disrupts microtubules. ApoE4 allele = major genetic risk. Cholinesterase inhibitors (donepezil) slow ACh breakdown β€” symptomatic treatment only.
0
correct
0
missed
11
remaining
Card 1 of 11
What does this stand for?
cards correct  Β· 
0
correct
0
wrong
5
remaining
correct  Β· 
No saved cards yet.
Click β˜† Save on any memory trick to save it here.
🎓 Common Exam Questions
Q: Name all 12 cranial nerves using the mnemonic, and give the function of each.
A: Mnemonic: 'Oh Oh Oh To Touch And Feel Very Good Velvet AH!' I Olfactory (smell), II Optic (vision β€” CN II damage β†’ blindness), III Oculomotor (most eye movement, pupil constriction β€” damage β†’ drooping eyelid/ptosis, dilated pupil), IV Trochlear (eye moves down and in), V Trigeminal (face sensation + chewing), VI Abducens (eye moves laterally β€” damage β†’ can't look sideways), VII Facial (facial expression + taste front 2/3 tongue), VIII Vestibulocochlear (hearing + balance β€” damage β†’ deafness or vertigo), IX Glossopharyngeal (taste + swallowing), X Vagus (parasympathetic to thorax/abdomen, voice β€” damage β†’ hoarse voice, difficulty swallowing), XI Accessory (neck/shoulder muscles), XII Hypoglossal (tongue movements).
Q: Explain the action potential β€” what happens at each stage?
A: Resting potential (-70mV): Na+/K+ pump maintains 3 Na+ out, 2 K+ in per ATP. Depolarization: stimulus opens voltage-gated Na+ channels β†’ Na+ rushes IN β†’ membrane potential rises to +40mV (threshold = -55mV). Repolarization: Na+ channels close, voltage-gated K+ channels open β†’ K+ rushes OUT β†’ membrane returns toward -70mV. Hyperpolarization (undershoot): K+ channels close slowly β†’ brief dip below -70mV. Refractory period: absolute (no AP possible β€” Na+ channels inactivated) then relative (strong stimulus can trigger AP). The Na+/K+ pump restores ion gradients. Saltatory conduction in myelinated axons: AP jumps node-to-node (nodes of Ranvier) β€” much faster than unmyelinated.
Q: What are the GASSED neurotransmitters and what is the role of each?
A: GASSED: GABA (gamma-aminobutyric acid β€” main inhibitory neurotransmitter; reduces neuronal excitability; benzodiazepines enhance GABA β†’ anxiety relief). Acetylcholine (ACh β€” neuromuscular junction; learning/memory; parasympathetic; Alzheimer's involves ACh deficiency). Serotonin (mood, sleep, appetite, body temperature; SSRIs block its reuptake to treat depression). Substance P (pain signal transmission in spinal cord and brain). Endorphins (endogenous opioids β€” natural pain relief and euphoria; released by exercise). Dopamine (reward, motivation, motor control; Parkinson's = dopamine neuron loss in substantia nigra; cocaine blocks dopamine reuptake β†’ euphoria).
Q: What is neuroplasticity and what is LTP (Long-Term Potentiation)?
A: Neuroplasticity is the brain's ability to reorganize by forming new neural connections throughout life β€” greatest in childhood but continues in adults. Hebbian learning: 'neurons that fire together, wire together' β€” simultaneous activity strengthens connections. LTP (Long-Term Potentiation) is the cellular mechanism of memory: repeated stimulation β†’ NMDA receptors (N-methyl-D-aspartate β€” coincidence detectors requiring simultaneous pre- and postsynaptic activity) open β†’ Ca2+ enters β†’ AMPA receptors inserted into postsynaptic membrane β†’ synapse becomes stronger and more responsive. LTP is blocked by alcohol (explaining memory blackouts) and enhanced by sleep (memory consolidation occurs during slow-wave and REM sleep).
Q: Compare the sympathetic and parasympathetic nervous systems.
A: Both are divisions of the autonomic nervous system (ANS) β€” part of the PNS (peripheral nervous system). Sympathetic (fight-or-flight): activated by stress/danger. Effects: increases heart rate, dilates airways, dilates pupils, redirects blood to muscles, inhibits digestion, releases adrenaline from adrenal medulla. Preganglionic neuron (short) β†’ paravertebral ganglion β†’ postganglionic (long). Neurotransmitters: ACh (preganglionic) β†’ norepinephrine (postganglionic). Parasympathetic (rest-and-digest): active during rest. Effects: decreases heart rate, constricts pupils, promotes digestion, stimulates salivation. Preganglionic (long) β†’ ganglion near target organ β†’ postganglionic (short). Neurotransmitter: ACh at both synapses. Vagus nerve (CN X) carries most parasympathetic fibers.