Midsagittal perspective of deep cerebral anatomy. A midsagittal dissection of white matter tracts of the deep white matter reveals the limbic system. The limbic system is a complex system responsible for emotion, long-term memory and behavior composed of the hippocampus, amygdala, and the fornix, serving as the major output tract from the hippocampus to the mammillary bodies. The mammillothalamic fasciculus (bundle of Vicq d’Azyr) connects the mammillary body to the anterior thalamic nuclei and midbrain. The cingulum is a white matter tract of the limbic system connecting the frontal lobe to the hippocampus and entorhinal cortex within the temporal lobe. The nucleus accumbens is visible rostral to the cingulum in the basal forebrain and is part of the ventral striatum, with outputs predominantly to the hypothalamus. Commissural fibers – white matter tracts which connect cerebral hemispheres – are visible in this sagittal view and include the anterior commissure and the corpus callosum. The anterior commissure is a tract projecting between temporal lobes, and the corpus callosum is the thickest band of commissural fibers connecting the cerebral hemispheres. (Image courtesy of AL Rhoton, Jr.)