Lecture Notes: Neurons, Reflexes, and Neural Engineering

Vocabulary-style flashcards covering neuron theories, signaling, reflexes, glia, genetic engineering methods, neurotech tools, and experimental techniques.

Neuron Doctrine (Cajal)

Neurons are discrete cells that communicate by contact rather than continuity.

Reticular Theory (Golgi)

Neurons communicate through a continuous nerve net rather than discrete cells.

Convergent signaling

Multiple presynaptic neurons converge to signal a single postsynaptic neuron.

Divergent signaling

A single presynaptic neuron synapses onto multiple postsynaptic neurons.

Na+/K+ pump mechanism

Maintains resting potential by pumping 3 Na+ out and 2 K+ in.

Knee-Jerk Reflex

A stretch reflex: tapping the knee stretches the extensor, triggering a spinal cord reflex that extends the leg.

Sensory Neurons (Afferent)

Carry information from the periphery to the spinal cord.

Interneurons

Relay and process information between afferent and efferent neurons within the CNS.

Motor Neurons (Efferent)

Carry signals from the CNS to the periphery to cause muscle contraction.

Hamstring (flexor)

Flexor muscle involved in the knee-jerk reflex (posterior thigh muscles).

Quadriceps (extensor)

Extensor muscle involved in the knee-jerk reflex (front thigh muscles).

Cardenolides

Toxic compounds produced by milkweeds that bind to Na+/K+ ATPase and disrupt function.

Monarch butterfly Na+/K+ pump mutation

Mutation that prevents cardenolide binding, enabling toxin tolerance.

Dynamic Polarization

Unidirectional flow of electrical signals in neurons.

Signal flow

Dendrite → Cell body → Axon → Axon terminal.

Neuronal cytoskeleton

Networks of microtubules and actin filaments that support shape and transport.

Microtubules

Tubulin polymers involved in axon guidance and synapse formation.

Actin filaments

G-actin and F-actin; form filopodia in dendrites and support growth cones.

Growth cones

Dynamic structures at growing tips that guide dendrite/axon extension.

Astrocytes

Glial cells supporting neurons and regulating the CNS environment.

Oligodendrocytes

Glial cells that form myelin in the CNS.

Microglia

Immune defense cells of the CNS.

Schwann Cells

Glial cells that myelinate PNS neurons.

Genetic Engineering

Methods to alter a gene of interest.

Mutagenesis

Random gene damage to generate mutants.

Cre/Lox system

Conditional mutagenesis system allowing targeted gene modification.

CRISPR-Cas9

Targeted gene editing technology.

GCaMP

Ca2+ sensor that fluoresces green to monitor calcium dynamics.

Channelrhodopsin

Light-gated cation channel that depolarizes neurons upon light exposure.

Halorhodopsin

Light-gated Cl- channel that inhibits neurons by hyperpolarization.

Permeability of leak channels

Leak channels are most permeable to K+, then Cl-, then Na+ (K+ > Cl- > Na+).

Na+/K+ pump role

Moves Na+ out and K+ into the cell against their gradients.

K+ leak channels

Help stabilize the resting membrane potential by allowing K+ leak.

Voltage clamp

Method that clamps membrane voltage while measuring resulting ion currents.

Tetrodotoxin (TTX)

Blocks voltage-gated Na+ channels.

Tetraethylammonium (TEA)

Blocks voltage-gated K+ channels.

Patch clamp

Technique to measure ion currents through individual or small groups of channels.

Neher

Erwin Neher, pioneer of the patch-clamp technique.