Final answer:
Simple cells in the primary visual cortex are most excited by lines of specific orientation. Visual stimuli from the upper-left visual field are processed in the lower and opposite side of the primary visual cortex. The retina's signal processing for visual perception involves complex modulation and signal enhancement through various cell types.
Step-by-step explanation:
The simple cells in the primary visual cortex are most strongly excited by lines of specific orientation. These neurons specialize in detecting edges and borders in the visual field and are particularly responsive to their preferred stimulus—the orientation of a line or edges
Visual stimuli in the upper-left visual field are processed in the contralateral (opposite side) and lower bank of the calcarine sulcus in the primary visual cortex, due to the organization of visual pathways and the representation of the visual field on the cortex.
The visual system, including retinal processing, involves various cell types like photoreceptors, bipolar cells, and ganglion cells, which participate in creating a visual signal the brain can interpret. The statement referring to ganglion cells converting light rays into electrical signals simplifies the complex interactions and signal modulation occurring among these cells, including the roles of horizontal and amacrine cells in enhancing contrast and distributing information.