Brain Anatomy for Genomics, Proteomics & Bioinformatics

In Chapter 7 of GP&B, there is a section about the genomic circuitry of learning. In order to ground your understanding of this section, there are a few terms you might want to have defined graphically. These figures are intended to provide a context for your understanding of the textbook mateirals. Do not try to memorize these names or brain anatomy.

Figure 1. Sagittal section through an unstained human brain, with three major parts labeled.

Figure 2. Sagittal section of a rat brain with most of the tissue stained red but the hippocampus stained dark blue. (modified from Science. Roush. Vol. 275: 32.)

Figure 3. Cross section of rat brain showing the characteristic curvature of the hippocampus. This particular section is not symetrical which makes the hippocampus structures in the two hemispheres look different but this is only an artifact of the way the brain was sectioned. (modified from )

Figure 4. Close up of rat hippocampus. Red labels indicate the location of the cerebrum and two layers of the hippocampus called CA1 and CA2. In this photomicrograph, the CA1 layer is not shown in its entirety; there is a bend connecting the two CA1 portions to the right of this figure. The complete structure connecting these two is evident in figure 3 above. (from

Figure 5. Semithin section from area CA1. This unique felty substance, believed to be one of the most highly organized in the Universe, is called neuropil. It represents a complicated spatial network comprising interconnected neuronal processes intermingled with irregularly shaped processes of astrocytic glia. In the hippocampus, most synapses occur in the neuropil. They are located mainly on dendritic spines. Synaptic neuropil is the basic constituent of the gray matter of the brain and spinal cord. (from

Figure 6. An electron micrograph of an ultrathin section through the neuropil contains a great number of neuronal profiles represented by axons (Ax) which form synaptic contacts (Sy) on dendritic shafts (D) or spines (S) and are intervened by glial processes of astrocytes. Also cell bodies and processes of oligodendroglia and microglia can be sporadically present and, of course, numerous blood capillaries. (from


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