The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

The von Economo neurons (VENs) are large bipolar neurons located in frontoinsular (FI) and anterior cingulate cortex in great apes and humans, but not other primates. We performed stereological counts of the VENs in FI and LA (limbic anterior, a component of anterior cingulate cortex) in great apes and in humans. The VENs are more numerous in humans than in apes, although one gorilla approached the lower end of the human range. We also examined the ontological development of the VENs in FI and LA in humans. The VENs first appear in small numbers in the 36th week post-conception, are rare at birth, and increase in number during the first 8 months after birth. There are significantly more VENs in the right hemisphere than in the left in FI and LA in postnatal brains of apes and humans. This asymmetry in VEN numbers may be related to asymmetries in the autonomic nervous system. The activity of the inferior anterior insula, which contains FI, is related to physiological changes in the body, decision-making, error recognition, and awareness. The VENs appear to be projection neurons, although their targets are unknown. We made a preliminary study of the connections of FI cortex based on diffusion tensor imaging in the brain of a gorilla. The VEN-containing regions connect to the frontal pole as well as to other parts of frontal and insular cortex, the septum, and the amygdala. It is likely that the VENs in FI are projecting to some or all of these structures and relaying information related to autonomic control, decision-making, or awareness. The VENs selectively express the bombesin peptides neuromedin B (NMB) and gastrin releasing peptide (GRP) which are also expressed in another population of closely related neurons, the fork cells. NMB and GRP signal satiety. The genes for NMB and GRP are expressed selectively in small populations of neurons in the insular cortex in mice. These populations may be related to the VEN and fork cells and may be involved in the regulation of appetite. The loss of these cells may be related to the loss of satiety signaling in patients with frontotemporal dementia who have damage to FI. The VENs and fork cells may be morphological specializations of an ancient population of neurons involved in the control of appetite present in the insular cortex in all mammals. We found that the protein encoded by the gene DISC1 (disrupted in schizophrenia) is preferentially expressed by the VENs. DISC1 has undergone rapid evolutionary change in the line leading to humans, and since it suppresses dendritic branching it may be involved in the distinctive VEN morphology

Comparison of Life Theories for Rolling-Element Bearings

Nearly five decades have passed since G. Lundberg and A. Palmgren published their life theory in 1947 and 1952 and it was adopted as an ANSI/ABMA and ISO standard in 1950 and 1953. Subsequently, many variations and deviations from their life theory have been proposed, the most recent being that of E. Ioannides and T.A. Harris in 1985. This paper presents a critical analysis comparing the results of different life theories and discussing their implications in the design and analysis of rolling-element bearings. Variations in the stress-life relation and in the critical stress related to bearing life are discussed using stress fields obtained from three-dimensional, finite-element analysis of a ball in a nonconforming race under varying load. The results showed that for a ninth power stress-life exponent the Lundberg-Palmgren theory best predicts life as exhibited by most air-melted bearing steels. For a 12th power relation reflected by modern bearing steels, a Zaretsky-modified Weibull equation is superior. The assumption of a fatigue-limiting stress distorts the stress-life exponent and overpredicts life

Stable H_2-optimal controller synthesis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57868/1/StableH2CorradoOCAM2000.pd

Phenotypic plasticity in the Caribbean sponge Callyspongia vaginalis (Porifera: Haplosclerida)

Sponge morphological plasticity has been a long-standing source of taxonomic difficulty. In the Caribbean, several morphotypes of the sponge Callyspongia vaginalis have been observed. To determine the taxonomic status of three of these morphotypes and their relationship with the congeneric species C. plicifera and C. fallax, we compared the spicule composition, spongin fiber skeleton and sequenced fragments of the mitochondrial genes 16S and COI and nuclear genes 28S and 18S ribosomal RNA. Phylogenetic analyses with ribosomal markers 18S and 28S rRNA confirmed the position of our sequences within the Callyspongiidae. None of the genetic markers provided evidence for consistent differentiation among the three morphotypes of C. vaginalis and C. fallax, and only C. plicifera stood as a distinct species. The 16S mtDNA gene was the most variable molecular marker for this group, presenting a nucleotide variability (π = 0.024) higher than that reported for COI. Unlike recent studies for other sponge genera, our results indicate that species in the genus Callyspongia maintain a high degree of phenotypic plasticity, and that morphological characteristics may not reflect reproductive boundaries in C. vaginalis

Plasticidad fenotípica de la esponja Callyspongia vaginalis (Porifera: Haplosclerida)

Sponge morphological plasticity has been a long-standing source of taxonomic difficulty. In the Caribbean, several morphotypes of the sponge Callyspongia vaginalis have been observed. To determine the taxonomic status of three of these morphotypes and their relationship with the congeneric species C. plicifera and C. fallax, we compared the spicule composition, spongin fiber skeleton and sequenced fragments of the mitochondrial genes 16S and COI and nuclear genes 28S and 18S ribosomal RNA. Phylogenetic analyses with ribosomal markers 18S and 28S rRNA confirmed the position of our sequences within the Callyspongiidae. None of the genetic markers provided evidence for consistent differentiation among the three morphotypes of C. vaginalis and C. fallax, and only C. plicifera stood as a distinct species. The 16S mtDNA gene was the most variable molecular marker for this group, presenting a nucleotide variability (π = 0.024) higher than that reported for COI. Unlike recent studies for other sponge genera, our results indicate that species in the genus Callyspongia maintain a high degree of phenotypic plasticity, and that morphological characteristics may not reflect reproductive boundaries in C. vaginalis.La gran plasticidad morfológica de ciertas esponjas dificulta una correcta clasificación taxonómica. En el Caribe, se han observado varios morfotipos de la esponja Callyspongia vaginalis a nivel de colores y formas. Con el fin de determinar su clasificación taxonómica, se muestrearon y analizaron tres morfotipos de C. vaginalis y sus especies congenéricas C. plicifera y C. fallax. Para cada muestra, se observó la composición espicular y del esqueleto dermal y se secuenciaron parte de los genes mitocondriales 16S y COI y parte de los genes ribosomales 28S y 18S. Los análisis filogenéticos con los genes ribosomales 18S y 28S confirmaron la posición taxonómica de las secuencias obtenidas. Ninguno de los marcadores genéticos utilizados reveló diferencias consistentes entre los tres morfotipos de C. vaginalis y C. fallax, y sólo C. pleicifera apareció en los análisis como una especie distinta. El gen mitocondrial 16S fue el marcador molecular más variable para este grupo, presentando una variabilidad nucleotídica (p = 0.024) superior a la descrita para COI. Nuestros resultados indican que las especies del género Callyspongia presentan una gran plasticidad fenotípica y que estas diferencias morfológicas no suponen barreras reproductivas para C. vaginalis

The connections of the insular VEN area in great apes: A histologically-guided ex vivo diffusion tractography study

We mapped the connections of the insular von Economo neuron (VEN) area in ex vivo brains of a bonobo, an orangutan and two gorillas with high angular resolution diffusion MRI imaging acquired in 36 h imaging sessions for each brain. The apes died of natural causes without neurological disorders. The localization of the insular VEN area was based on cresyl violet-stained histological sections from each brain that were coregistered with structural and diffusion images from the same individuals. Diffusion MRI tractography showed that the insular VEN area is connected with olfactory, gustatory, visual and other sensory systems, as well as systems for the mediation of appetite, reward, aversion and motivation. The insular VEN area in apes is most strongly connected with frontopolar cortex, which could support their capacity to choose voluntarily among alternative courses of action particularly in exploring for food resources. The frontopolar cortex may also support their capacity to take note of potential resources for harvesting in the future (prospective memory). All of these faculties may support insight and volitional choice when contemplating courses of action as opposed to rule-based decision-making