Layers four and six (4 & 6) of the LGN also connect to the opposite eye, but to the P cells (color and edges) of the optic nerve. By contrast, layers two, three and five (2, 3, & 5) of the LGN connect to the M cells and P (parvocellular) cells of the optic nerve for the same side of the brain as its respective LGN.
A gyrus (gyri pl) is a rounded ridge, as on the surfaces of the cerebral hemispheres. A sulcus is a groove in the surface between gyri.
To return to the exercise , close this browser window. Sulci and Gyri on the Cerebral Hemispheres. To pack more grey matter into the limited space inside the skull, animals with big brains, especially humans, the cerebral cortex is wrinkled. The grooves that make these wrinkles are called sulci and the ridges between them are called gyri.