Neuroscience — NEUR 1520 cheat sheet · Chivero · UNomaha Fall 2026

Anatomy

• CNS = brain + spinal cord; PNS = nerves + ganglia outside.
• 5 divisions: tel · di · mes · met · myel.
• Lobes: frontal (motor) · parietal (somatic) · temporal (audio + memory) · occipital (visual).
• Planes: sagittal · coronal · horizontal.
• Gray = bodies/dendrites; white = myelinated tracts.
• Ventricles: 2 lateral → 3rd → aqueduct → 4th → cc.

Cells

• Neurons: soma · dendrites · axon hillock · axon · terminal.
• Cajal neuron doctrine — discrete cells + synapses.
• Glia: astrocyte (K⁺ buffer, EAAT, BBB end-feet); oligodendrocyte (CNS myelin); Schwann cell (PNS myelin); microglia (immune); ependymal (CSF).
• BBB: tight junctions of brain endothelium + astrocyte end-feet + pericytes.

V_rest

• ~−65 mV; set by K⁺ leak (V drifts toward E_K ~−85).
• Inside: high K⁺ · low Na⁺ · low Cl⁻ · low Ca²⁺. Outside: opposite.
• Nernst: E_ion = (RT/zF) ln([out]/[in]); E_K −85, E_Na +60, E_Ca +120.
• GHK: V_m weighted by permeabilities.
• Na/K ATPase: 3 Na⁺ out + 2 K⁺ in / ATP (electrogenic ~−5 mV).

Action potential

• Threshold ~−55 mV; all-or-none ~100 mV swing, 1-2 ms.
• Na_v: 3 states — closed · open · inactivated (refractory).
• Phases: rising (Na in) · overshoot · falling (K out, Na inact) · AHP · rest.
• Absolute (~1 ms) vs relative (~2-4 ms) refractory.
• Saltatory conduction: jumps between nodes of Ranvier.
• TTX blocks Na_v.

Synapse

• Electrical = connexons; chemical = NT-mediated.
• Sequence: AP → Ca²⁺ in → SNARE fusion → NT release → receptor → termination.
• SNAREs: synaptobrevin (v) + syntaxin + SNAP-25 (t); synaptotagmin = Ca²⁺ sensor.
• EPSP depolarizes; IPSP hyperpolarizes.
• Spatial vs temporal summation.
• Ionotropic (fast ms) vs metabotropic (GPCR slow modulatory).
• NMDA coincidence detector: glutamate + depolarization (Mg²⁺ unblock) → Ca²⁺ in.
• LTP: NMDA → Ca²⁺ → CaMKII → AMPA insertion. LTD opposite.

NTs

NT	Type	Receptors
Glutamate	Excite	AMPA, NMDA, kainate, mGluR
GABA	Inhibit	A (Cl⁻), B (GPCR-K⁺)
Glycine	Inhibit (cord)	Cl⁻ channel
ACh	NMJ + ANS + brain	nAChR, mAChR
DA	Reward, motor	D1-D5 (GPCR)
NE	Arousal	α, β adrenergic
5-HT	Mood	14 subtypes; 5-HT3 ionotropic

• Sources: DA from VTA + SNc; NE from locus coeruleus; 5-HT from raphe; ACh from basal forebrain + brainstem.
• Endocannabinoids retrograde via CB1.

Sensory + somatosensory

• Receptors: mechano · thermo · photo · chemo · noci.
• 4 touch: Meissner RA flutter · Pacinian RA vibration · Merkel SA pressure · Ruffini SA stretch.
• DC-ML: fine touch + vibration + proprioception. Decussates in MEDULLA. → VPL → S1.
• Spinothalamic: pain + temp + crude touch. Decussates at SPINAL LEVEL. → VPL → S1.
• Sensory homunculus: hands + face overrep.

Pain

• Aδ fast sharp; C slow dull throbbing.
• TRPV1 = capsaicin/heat >43°C.
• Gate control: Aβ touch fibers gate pain in dorsal horn.
• PAG → raphe + LC → spinal inhibition (descending).
• Endogenous opioids: end, enk, dyn → μ δ κ receptors.

Vision

• Cornea + lens; iris/pupil.
• Rods (scotopic) vs cones (photopic, S/M/L).
• Dark: cGMP open CNG → depolarized → glutamate.
• Light: rhodopsin → transducin → PDE → ↓cGMP → CNG closed → hyperpolarized → ↓ glutamate.
• Layer order (light path): ganglion → bipolar → photoreceptor.
• Center-surround = lateral inhibition by horizontal cells.
• Optic n. → CHIASM (decussate nasal) → optic tract → LGN → V1.
• Magno (motion, dorsal) vs Parvo (color, ventral).

Hearing + balance

• Outer (pinna, canal) → middle (malleus-incus-stapes, ×22) → cochlea.
• Cochlea: 3 scalas; basilar membrane; organ of Corti; IHC sense, OHC amplify.
• Tonotopy: base = high freq, apex = low freq.
• Pathway: hair cell → spiral g → cochlear n → SUPERIOR OLIVE → IC → MGN → A1.
• ITD (low freq, MSO) + ILD (high freq, LSO) for localization.
• Vestibular: 3 SCC angular accel + utricle/saccule linear+gravity.

Chem senses

• Olfaction: ~400 OR genes; one OR per ORN; glomeruli converge; mitral → piriform (NO thalamus!).
• Taste: sweet/bitter/umami via T1R/T2R GPCRs; salty/sour via channels.
• Taste pathway: CN VII/IX/X → solitary n → VPM → insula gustatory cortex.

Motor

• LMN lesion: flaccid + atrophy + fasciculations.
• UMN lesion: spastic + hyperreflexia + Babinski.
• Stretch reflex: spindle Ia → monosynaptic LMN; reciprocal inh of antagonist.
• Corticospinal: M1 → IC → ped → pyramids DECUSSATE → lat CST → ventral horn.
• BG direct (D1, GO) vs indirect (D2, NO-GO) pathways via thalamus.
• Parkinson = SNc DA loss; Huntington = caudate degen.
• Cerebellum: coord + balance + motor learn; lesion → ataxia.

Glia & NLRP3 (CHIVERO)

• Microglia = yolk-sac CNS macrophages; M1 pro-inflam vs M2 restorative.
• NLRP3 inflammasome: Signal 1 priming (TLR/NF-κB upregs NLRP3 + pro-IL-1β). Signal 2 activation (DAMP/PAMP) → ASC → procasp-1 → casp-1 → cleaves IL-1β + IL-18 + gasdermin D → pyroptosis.
• HIV-Tat: crosses BBB → primes microglia → HAND despite ART.
• Methamphetamine: oxidative stress + microglia activation → synergy with HIV.
• Astrocyte EAAT clears glutamate; reactive astrocytosis A1 (toxic) vs A2 (protective).
• Microglial pruning via complement (C1q, C3); excessive in Alzheimer.

Pharmacology

• Agonist · antagonist · inverse agonist; PAM/NAM allosteric.
• Mesolimbic VTA→NAc = reward circuit.
• Cocaine BLOCKS DAT/NET/SERT.
• Meth REVERSES DAT + depletes vesicles.
• Opioids: μ → presyn Ca↓ + postsyn K↑ → inhibit pain.
• EtOH: ↑GABA_A + ↓NMDA.
• Nicotine: nAChR α4β2 on VTA DA.
• THC: CB1 presyn, ↓ NT release.
• Benzos = GABA_A PAM.

Methods

• EEG: scalp; ms temporal, poor spatial.
• fMRI: BOLD; ~mm spatial, seconds temporal.
• Patch clamp: single channel or whole cell V/I.
• Optogenetics: ChR2 excite (blue) / NpHR inhibit (yellow).
• DREADDs: hM3Dq excite / hM4Di inhibit via CNO.
• GCaMP = Ca²⁺ imaging.