Limbic system of the brain. Computer artwork showing the main parts of the limbic system from the human brain. At centre is the oval-shaped thalamus (red) which receives sensory stimuli. In front and above it is the corpus striatum (green) which consists of the two basal ganglia: the caudate nucleus (convex-lens shaped) and the lentiform nucleus (comma-shaped). Both contain large numbers of the cell bodies of neurons. This complex network of nerve pathways making up the limbic system is involved with the expression of instinct and mood. This includes the expression of fear, rage, pleasure, reproduction, self-preservation, and formation of memory patterns.