Action Potential
Brief electrical impulse (spike) generated by neurons, typically lasting 1–2 ms with amplitude of 50–500 µV extracellularly.
An action potential (also called a spike) is a brief electrical impulse generated by a neuron to transmit information, lasting approximately 1–2 milliseconds.
Why it matters: Action potentials are the fundamental unit of neural communication. Recording them is the primary goal of extracellular electrophysiology — each detected spike represents a specific neuron firing at a specific time.
Extracellular characteristics: When recorded extracellularly with a silicon probe, spikes appear as brief biphasic or triphasic waveforms with amplitudes of 50–500 µV, depending on distance from the neuron and electrode impedance.
Detection requirements: Reliable spike detection requires sampling rates ≥20 kHz, bandpass filtering (typically 300–6000 Hz), and sufficient signal-to-noise ratio (typically >4:1).