Limbic system. Artwork of the anatomical structures of the limbic system of the brain. It is found at the centre of the cerebrum. It consists of the oval-shaped thalamus (green), which is encircled by the caudate nucleus (blue) and the hippocampus (ribbed, lower centre). Above these is the large C-shaped corpus callosum (blue). Also seen is the pituitary gland (hanging at lower left). This complex network of nerve pathways is involved with the expression of instincts and moods, such as fear, rage, pleasure, reproduction, self-preservation and formation of memory patterns.