JOHNSON, J.I.; SWITZER III, R.C.; MARINO, L.; FERREIRA, F.M.; MORRIS, J.A.; SUDHEIMER, K.D.; FOBBS JR., A.J.; Michigan State Univ., East Lansing; Neuroscience Associates, Inc., Knoxville, TN; Emory Univ., Atlanta, GA; Michigan State Univ., East Lansing; Michigan State Univ., East Lansing; Michigan State Univ., East Lansing; Natl. Mus. Health Med., Armed Forc. Inst. Pathol., Washington, DC; : Smooth-surfaced striatal lobes of the cerebral hemispheres of six species of whales and dolphins.

In addition to cortical lobes recognized as fronto-orbital, temporal, and occipital, cetacean mammals present an additional lobe on the inferior surface of each cerebral hemisphere. Paul Broca (1878, Revue d’Anthropologie, 1, 385-408) described this smooth-surfaced projection as a �desert lobe”. We examined, in three orthogonal planes, stained sections from brains of bottlenose dolphins Tursiops truncatus, and magnetic resonance images (MRI) of brains of this and five other cetacean species: white (beluga) whale Delphinapterus leucas, pygmy sperm whale Kogia simus, common dolphin Delphinus delphis, spinner dolphin Stenella longirostrus, and harbor porpoise Phocoena phocoena. In each species the desert lobe is present, and contains the rostro-inferior polar regions of the corpus striatum, where the head of the caudate nucleus, the rostral putamen, and the nucleus accumbens converge at the rostro-inferior limit of the internal capsule. Here the corpus striatum cups around the rostral end of a unitary pallidal column, which extends back to the pons and includes the substantia nigra. This striatal surface projection is related to the paucity of overlying olfactory cortex, the large amount of cerebral cortex being served, and the flexure of the forebrain in cetaceans. Supported by NSF Grants IBN 0131267, 0131826, and 0131028,