In topographic mapping, how is the visual field represented as it reaches the cortex?

In topographic mapping, how is the visual field represented as it reaches the cortex?

• A. It is inverted and scrambled.
• B. It is maintained as a retinotopic map.
• C. It becomes color-coded by wavelengths.
• D. It disappears before cortex.

Answer: (B)

Spatial organization is preserved from retina to cortex, forming a retinotopic map. The image that falls on the retina is inverted by the eye’s optics, so the cortical representation is inverted relative to the visual field, but the important point is that neighboring points in the visual field activate neighboring neurons on the cortex, maintaining the spatial layout. This topographic mapping is contralateral (the left visual field projects to the right visual cortex and vice versa) and features cortical magnification, with the fovea occupying a large portion of cortex due to its high acuity. It’s not color-coding by wavelength and it doesn’t disappear before reaching the cortex—the arrangement remains organized as a retinotopic map.

Spatial organization is preserved from retina to cortex, forming a retinotopic map. The image that falls on the retina is inverted by the eye’s optics, so the cortical representation is inverted relative to the visual field, but the important point is that neighboring points in the visual field activate neighboring neurons on the cortex, maintaining the spatial layout. This topographic mapping is contralateral (the left visual field projects to the right visual cortex and vice versa) and features cortical magnification, with the fovea occupying a large portion of cortex due to its high acuity. It’s not color-coding by wavelength and it doesn’t disappear before reaching the cortex—the arrangement remains organized as a retinotopic map.