What is the name for the concept that certain neurons in the visual cortex are activated only by specific patterns?

Feature Detection

Explanation:

Feature Detection processes operations via the neurons (individual neuron or groups of neurons) in the visual cortex that located in the brain. The visual cortex is a primary cortical region in the brain that specialize in handling visual information that is being sent from the retina. Feature Detectors function is to determine for a significant stimuli. e. g responding and decoding every bit of information in a pixel to see if there is an information preset.

At the early stage feature detectors tends to have the same function but as they become specialized, they become more specific for a particular role.