Decoding Signals: How Neurons Communicate

Action Potentials: The Electrical Impulse

Neurons communicate through electrical signals known as action potentials. These are rapid changes in membrane potential that travel along the neuron’s axon.

The resting membrane potential of a neuron is typically around -70mV, due to differences in ion concentrations across the cell membrane. When a stimulus exceeds a threshold (the ‘all-or-none’ principle), voltage-gated sodium channels open, allowing positive ions (sodium) to rush into the cell.

Vm = (K+ * R*t) / (C*m)

Propagation: Spreading the Signal

Once initiated, an action potential propagates down the axon. This is achieved through a series of depolarization and repolarization events.

In myelinated axons (axons covered in fatty myelin sheaths), the signal jumps between gaps in the myelin called Nodes of Ranvier, dramatically increasing conduction speed – this is known as saltatory conduction.

v = ΔVm / τ

Synaptic Transmission: Chemical Communication

When an action potential reaches the axon terminal, it triggers the release of neurotransmitters – chemical messengers – into the synaptic cleft.

These neurotransmitters bind to receptors on the postsynaptic neuron, causing a change in its membrane potential. This can either excite (depolarize) or inhibit (hyperpolarize) the neuron.

ΔV = F * β

Neurotransmitters and Receptors

Numerous neurotransmitters exist, each with specific effects. Examples include glutamate (excitatory), GABA (inhibitory), dopamine (involved in reward and movement), and serotonin (mood regulation).

Receptor types vary – ionotropic receptors cause immediate changes while metabotropic receptors initiate a cascade of intracellular events.

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