Paleoneurology concerns the study and analysis of fossil endocasts. Together with cranial capacity and discrete anatomical features, shape can be analysed to consider the spatial relationships between structures and to investigate the endocranial structural system. A sample of endocasts from fossil specimens of the genus Homo has been analysed using traditional metrics and 2D geometric morphometrics based on lateral projections of endocranial shape. The maximum and frontal widths show a size-related pattern of variation shared by all the taxa considered. Furthermore, as cranial capacity increases in the non-modern morphotypes there is a general endocranial vertical stretching (mainly centred at the anterior ascending circumvolution) with flattening and relative shortening of the parietal areas. This pattern could have involved some structural stress between brain development and vault bones at the parietal midsagittal profile in the heavy encephalised Neandertals. In contrast, modern humans show a species-specific neomorphic hypertrophy of the parietal volumes, leading to a dorsal growth and ventral flexion (convolution) and consequent globularity of the whole structure. Brain tensors such as the falx cerebri have been hypothesised to represent one of the main physical constraints on morphogenetic trajectories, with additional influences from cranial base structures. The neurofunctional inferences discussed here stress the role of the parietal areas in the visuo-spatial coordination and integration, which can be involved in higher cerebral functions and related to conceptual thinking.

The pars triangular is a portion of Broca's area. The convolutions that form the inferior and caudal extent of the pars triangularis include the anterior horizontal and anterior ascending rami of the sylvian fissure, respectively. To learn if there are anatomic asymmetries of the pars triangularis, these convolutions were measured on volumetric magnetic resonance imaging scans of 11 patients who had undergone selective hemispheric anesthesia (Wada testing) to determine hemispheric speech and language lateralization. Of the 10 patients with language lateralized to the left hemisphere, 9 had a leftward asymmetry of the pars triangularis. The 1 patient with language lateralized to the right hemisphere had a significant rightward asymmetry of the pars triangularis. Our data suggest that asymmetries of the pars triangularis may be related to speech-language lateralization.

Northern blotting studies have demonstrated mRNA for the serotonin 5-HT1A receptor in human neonatal kidney (B. K. Kobilka, T. Frielle, S. Collins, T. Yang-Feng, T. S. Kobilka, U. Francke, R. J. Lefkowitz, and M. G. Caron. Nature Lond. 329: 75-79, 1987). To confirm expression of receptor protein in kidney, we raised antibodies to two peptides derived from the third intracellular loop of the human 5-HT1A receptor. Specific immunoglobulin G (IgG) was purified sequentially on protein A-Sepharose and peptide-Affigel 10 columns. Each IgG was able to: 1) quantitatively immunoprecipitate [3H]8-OH-2-(di-n-propylamino)1,2,3,4-tetrahydronaphthalene ([3H]8-OH-DPAT)-labeled human and rat receptors; 2) immunoblot a new protein in cells transfected with human 5-HT1A receptor DNA; and 3) immunoautoradiographically label areas of rat brain (frontal cortex, hippocampus, and lateral septum) in a highly characteristic pattern similar to that labeled by 125I-Bolton-Hunter-8-methoxy-2-(N-propyl-N-propylamino)Tetralin, a specific 5-HT1A receptor autoradiography ligand. By use of a light microscopic immunoperoxidase labeling technique, incubation of each IgG antibody with sections of rat and human kidney demonstrated an identical pattern of immunoreactivity. Specific labeling of basolateral plasma membranes was detected throughout medullary and cortical thick ascending limbs (TAL), in distal convoluted tubules (DCT), in connecting tubule cells of the connecting tubule, and in principal cells of the initial collecting tubule. There was no labeling in the inner medulla, glomeruli, or blood vessels. The labeling was blocked by preincubation with the corresponding peptide, but not with noncorresponding peptide or carrier protein. There was no labeling with preimmune IgG. Electron microscopic immunoperoxidase labeling confirmed the specific localization of the IgG antibody along the basolateral plasma membrane in all positively staining cells in rat kidney. Radioligand binding studies with the specific 5-HT1A receptor ligand [3H]8-OH-DPAT confirmed the presence of 5-HT1A receptor binding sites in bulk-isolated rat medullary TAL. These studies provide the first evidence that the 5-HT1A receptor is expressed on the basolateral surface of TAL and DCT cells of human and rat kidney. The specific localization to these cells suggests a possible role for the 5-HT1A receptor in the regulation of salt and water transport in mammalian kidney.