Which visual cortex cell primarily responds to the orientation of the stimulus only?

The primary function of simple cells in the visual cortex is to respond selectively to the orientation of edges and lines within the visual field. These cells are characterized by their linear receptive fields that are organized in a way that they are sensitive to specific orientations of stimuli, such as vertical or horizontal lines. Each simple cell responds maximally when a stimulus correctly aligns with its preferred orientation and has little to no response to stimuli that deviate from this orientation.

This selectivity allows simple cells to play a crucial role in the initial processing of visual information, contributing to our ability to perceive shapes and edges. They are considered the first type of cortical neurons to process the orientation of visual stimuli, making them fundamental to our understanding of visual perception.

In contrast, complex cells also respond to orientation but have larger receptive fields and can be responsive to a wider range of stimulus conditions, including motion direction. End-stopped (or hypercomplex) cells further refine this processing by responding to specific lengths or angles and are sensitive to the termination of stimuli. Therefore, while all these cell types contribute to orientation detection and processing, simple cells are uniquely specialized for responding purely to the orientation of stimuli.