How do linearly arranged excitatory and inhibitory zones in visual cortex detect line orientation?

In the visual cortex, specifically within area 17, neurons possess receptive fields organized into linearly arranged excitatory (on) and inhibitory (off) zones. This specific spatial arrangement allows these neurons to function as orientation detectors.12

When a visual stimulus, such as a line, is presented in a specific orientation and position that aligns with these zones, it triggers a maximal response. For instance, a line might evoke an on-response when it falls on the excitatory zone, while falling on adjacent inhibitory zones results in an off-response. Because of this precise alignment, changing the orientation of the line—even by as little as 15°—can significantly reduce or completely abolish the neuron's response.1

The prevailing physiological interpretation is that these cortical cells achieve this selectivity by receiving convergent synaptic inputs from a set of neurons in the lateral geniculate nucleus, whose own receptive fields are arranged in a linear pattern. While excitation is fundamental, research suggests that the inhibition of other neurons in the visual cortex is also necessary to fully account for the precise detection of object orientation.12