Begin by identifying the lateral geniculate nucleus (LGN). Although it's small, the LGN is particularly distinctive because of its knee-shaped appearance. (Since the LGN is such a small structure, you may find that it appears on the surface of your slice only in one hemisphere: even a slight angle may cause the cut to miss the LGN.) The LGN is in approximately the same horizontal plane as the third ventricle. It's just lateral to the superior extent of the cerebral peduncle, a tract of white matter that's particularly easy to recognise. The LGN is sandwiched in between the cerebral peduncle and the anterior extent of the hippocampus. Again adopting the metaphor of a knee, you can picture the kneecap sticking up toward the internal capsule. The LGN is visible in coronal section in figure 36 (page 42) of Nieuwenhuys and in figure 103 (page 260) of Nauta, and in horizontal section in figure 54 (page 60) of Nieuwenhuys. Sketch the anatomical neighbourhood of the LGN, and label as many structures as you can.
In coronal sections anterior to the LGN you should be able to identify the optic tract in each hemisphere. This tract of white matter is composed of fibres from the ganglion cell layer of the retina. The portions of these fibres anterior to the optic chiasm are known as the optic nerves, but the sections that you're studying are posterior to the chiasm.
Another major projection of the ganglion cell layer of the retina is the superior colliculus. `Colliculus' literally means `little hill', and indeed the colliculus does seem like a hill of grey matter on the dorsal aspect of the midbrain, just above the superior cerebellar peduncle. The term `superior' is added to distinguish it from the inferior colliculus, a structure of similar appearance which is part of the auditory pathway. The superior colliculus is best viewed in midsagittal section, but it can also be seen in horizontal section if you look carefully. Find the superior colliculus (or a cut portion of it) on one of your brain slices.
In the cerebral white matter superior and lateral to the superior colliculus lie the optic radiations. These diffuse tracts of white matter consist of axon projections from the LGN to the striate cortex of the occipital pole, and they also incorporate reciprocal projections from striate cortex back to the LGN. They course around the occipital horns of the lateral ventricles. On one of your slices, identify the general area of the optic radiations.
Identify the occipital pole, and, on its medial aspect, the calcarine fissure. Before proceeding, consult with an instructor to make sure that you've correctly identified the calcarine fissure. Now, using a sharp scalpel, cut off the posterior two or three centimetres of the occipital pole. Make sure that your cut passes near the midpoint of the calcarine fissure, at right angles to it. The line of Gennari is a band of myelinated fibres in cortical layer 4C. This line, or stripe, is what gives the striate cortex its name. The fibres that constitute the line of Gennari are the inputs to striate cortex from the LGN. You should be able to identify the borders of striate cortex by seeing where the line of Gennari disappears. Sketch your cross-section of the calcarine fissure and adjacent cortex, indicating the boundary between striate cortex (Brodmann's area 17) and peristriate cortex (Brodmann's area 18).