How does spike-triggered averaging identify the stimuli that cause a neuron to fire?

Spike-triggered averaging is a technique used to characterize the stimulus selectivity and spatial structure of a neuron's receptive field.

Rather than presenting specific, discrete stimuli to map a response, this method involves looking backward in time from the occurrence of an action potential (or "spike") to determine which stimulus features, on average, preceded and elicited that firing event. Mathematically, this is achieved by computing a cross-correlation between the neuron's evoked spike train and the history of stimulus occurrences.

By analyzing these preceding stimuli, researchers can identify the specific parameters—such as spatial location, orientation, or frequency—that the neuron prefers. This approach is particularly useful for capturing the spatiotemporal dynamics of a receptive field, revealing how excitatory and inhibitory influences evolve over time to trigger a neural response.1