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At least 1,153 records · Page 64Linked to original sources
PubMed2003

Justification of glioma biology beyond a cellular basis of interpretation.

Gliomas as neoplasms primarily arising from and constituted by glial cells would appear to implicate cell types that inherently reflect variation of aspects of a putative reparative process. The prominence of an astrocytic type cell of origin would further perhaps constitute a system of malignant transformation based on aberrant progression in cell proliferation and of cell pathology related to aspects on one hand of a gliosis and on the other of an autonomous process of progressiveness. In such terms, perhaps, one might consider the molecular aspects of gliomatous pathogenesis as simply a process of integral aberration of various aspects of astrocytic or glial cell responsiveness outside the normal confines of the normal reparative process and inherently beyond a strict cellular basis of interpretation in pathobiologic terms of such processes as anti-apoptosis and amplification of growth factor receptivity.

Apoptosis↗
PubMed1997

Evolutionary sexology: the hypothesis of song and sex.

In subhuman mammalian species, lovemaps are homogeneous and are more or less biorobotically fixed, whereas in the human species they are emancipated from biorobotism and are personalized, idiosyncratic, and heterogenous-as, for example, in the paraphilias. The evolutionary sexological hypothesis described herein proposes that emancipation of all of the biorobotic mindbrain maps, the mating map included, was essential for, and coincident with the evolution of the human speechmap from the songmap. Accordingly the first human language was a love song rather than a howl of warning. The bare essentials of sexuoerotic arousal and response are in three categories: haptoerotic (cutaneous), morphoerotic (visual), and gnomoerotic (narrative).

Animals↗
PubMed1997

Evolution's 'missing link': a hypothesis upon neural plasticity, prefrontal working memory and the origins of modern cognition.

Many activities such as reading, mathematics and chess depend upon cognitive processes which arose after our evolution. Why could they arise if not evolved? I argue four things fortuitously came together to make our nonevolved cognitive skills possible: (i) neural plasticity; (ii) large functionally uncommitted prefrontal, temporal and parietal cerebral cortices; (iii) the ability of their neural circuits (due to neural plasticity), if trained, to take on novel symbolic and nonsymbolic skills; and (iv) a large prefrontal cortex which could use its working memory as a tuition management sketch pad in which to train them. Pre-evolved for other reasons, these four (together with invented symbolic systems and technology) together enable modern humans to 'upgrade' our already evolved cognitive skills to do new and nonevolved things.

Animals↗
PubMed1998

The neurology and evolution of humor, laughter, and smiling: the false alarm theory.

Laughter (and humor) involves the gradual build-up of expectation (a model) followed by a sudden twist or anomaly that entails a change in the model--but only as long as the new model is non-threatening--so that there is a deflation of expectation. The loud explosive sound is produced, we suggest, to inform conspecifics that there has been a 'false alarm', to which they need not orient. The same logic may underlie tickling (menacing approach followed by a light non-threatening contact). Thus tickling may serve as 'play', a rehearsal for adult laughter. And lastly, when one primate encounters another, he may have always begun with a threat gesture--to bare his canines--but upon recognizing the individual as kin he may stop the grimace halfway and 'smile'. When the insular cortex is damaged, patients giggle in response to pain, presumably because they can still sense the pain ('danger') but the pain is no longer aversive ('false alarm'), thereby fulfilling the two key requirements for laughter.

Biological Evolution↗
PubMedDate not supplied

Field homology as a way to reconcile genetic and developmental variability with adult homology.

The theoretical and developmental fundament of field homology is here examined, particularly as applied by the authors to comparative neurobiology. Preliminary considerations explore conceptual differences between sameness (homology) and similarity. The source of sameness (the biological evolutionary relationship properly sought in homology analysis) is thought to lie in morphostatic evolutionary and morphogenetic processes, which constrain organismal variation at the level of its fundamental structural organization (Bauplan). This occurs via regulation of the branching mode of the morphogenetic sequence or epigenetic landscape. Of fundamental importance in this context is the role of developmental (morphogenetic) fields. The latter concept is analyzed in its general properties and is postulated to underpin the stability of the developing Bauplan down to the ultimate conserved details. Developmental fields subdivide during ontogenesis into ever smaller fields in a complex hierarchy, defining at each stage the developmental entities which are subjected to regulatory, morphostatic effects via the genome and indirect phenotypic selection. These fields thus represent the natural characters for considerations of embryonic homology, and underlie adult homology, rather than arbitrarily selected embryonic parts. Field subdivision proceeds into the constitution of individually specified cell populations. Field regulatory properties, however, do not extend to all differentiation phenomena observed in embryos. This means there is a limit to the applicability of field homology analysis, leaving space for biological variation and convergence outside of proper homology relationships. Genetic and developmental variability are compensated by the regulatory functions of the developmental fields insofar as they relate to correct Bauplan construction. These ideas suggest the convenience of a more systematic use of field homology methods, which start with appropriately identified developmental fields to expand knowledge on adult homology (sameness) and eventually also on accessory structural and functional similarities or differences.

Aging↗
PubMedDate not supplied

Understanding the basic circuitry of the cerebral hemispheres: the case of lizards and its implications in the evolution of the telencephalon.

The organization of the cerebral hemispheres of mammals is characterized by corticostriatal glutamatergic projections and striatopallidal GABAergic ones, plus the descending projections of the pallium and subpallium to extratelencephalic targets. The present review of the available neuroanatomical data on the forebrain of lizards suggests that the telencephalon of reptiles also follows this basic pattern of connectivity. In addition, we show that this basic circuitry includes a pallido-cortical projection, therefore forming a cortico-striato-pallido-cortical circuit. The analysis of this circuitry for the medial, dorsal, lateral, and ventral pallial divisions in reptiles and mammals leads to the following conclusions: (1) The medial and dorsal cortices of lizards together appear to be equivalent to the medial pallium of mammals. (2) The projection from the lacertilian dorsal cortex to the striatum proper resembles the subiculo-striatal projection of mammals, rather than the isocortical projection to the caudatus-putamen. (3) Most of the dorsal striatum of reptiles is engaged in the corticostriatal circuit corresponding to the ventral pallium (the anterior dorsal ventricular ridge), and therefore, it is not equivalent to the mammalian caudatus-putamen, which is involved in the circuit of the dorsal pallium. (4) The main and accessory olfactory bulbs also follow this pattern of connections.

Animals↗
PubMed2002

Predicting functional properties of visual cortex from an evolutionary scaling law.

The number of neurons in the primary visual cortex (V1) is, across primate species, related to the number of neurons in the visual thalamus (the lateral geniculate nucleus [LGN]) by a power law with an exponent of 3/2. This evolutionary scaling law is explained by a simple relation according to which the fineness of resolution in cortex is related to the number of neurons in the area of cortex used to process the information from a single point of light (the point-spread area). The same theory provides a link between two functional properties of the visual cortex, the areal cortical magnification factor (ACMF) and the receptive field (RF) area.

Animals↗
PubMed1987

Stress-induced activation of the sympathetic nervous system.

Discrepancies between perceptions of internal or external circumstances and innate or acquired expectations lead to patterned stress responses involving several homeostatic systems, of which the sympathoadrenomedullary system (SAMS) is one. Severe, generalized threats such as hypoglycaemia, hypoxia, haemorrhage, circulatory collapse, and fight/flight situations elicit generalized SAMS activation, including cardiac stimulation, splanchnic, cutaneous, and renal vasoconstriction, and usually preserved skeletal muscle blood flow. Patterned sympathetic neural responses, resulting in redistribution of blood volume or changes in glandular activity, occur during orthostasis, exercise, altered environmental temperature, the postprandial state, and performance of attention-requiring tasks. In all these situations, SAMS activity is co-ordinated with that of the parasympathetic nervous system, the pituitary-adrenocortical system, and probably several neuropeptide systems. Although acute stress-induced SAMS activation can be a health hazard, the role of chronically repeated, stress-induced SAMS activation in the development of cardiovascular disease remains unclear. Benzodiazepines, beta-adrenoceptor blockers, and alpha 2-adrenoceptor agonists can attenuate effects of stress-induced SAMS activation, but pressor responses often are maintained.

Animals↗
PubMed2000

Neuropeptides and the evolution of social behavior.

Comparative studies over the past year have revealed two new insights into the role of neuropeptides in the evolution of social behaviors. First, across vertebrate taxa, certain neuropeptide effects appear to be gender-specific. Second, species variations in receptor gene structure can alter neuropeptide receptor distribution and thereby contribute to species differences in social behavior.

Animals↗
PubMed2003

Phylogeny of ruminants secretory ribonuclease gene sequences of pronghorn (Antilocapra americana).

Phylogenetic analyses based on primary structures of mammalian ribonucleases, indicated that three homologous enzymes (pancreatic, seminal and brain ribonucleases) present in the bovine species are the results of gene duplication events, which occurred in the ancestor of the ruminants after divergence from other artiodactyls. In this paper sequences are presented of genes encoding pancreatic and brain-type ribonuclease genes of pronghorn (Antilocapra americana). The seminal-type ribonuclease gene could not be detected in this species, neither by PCR amplification nor by Southern blot analyses, indicating that it may be deleted completely in this species. Previously we demonstrated of a study of amino acid sequences of pancreatic ribonucleases of a large number of ruminants the monophyly of bovids and cervids, and that pronghorn groups with giraffe. Here we present phylogenetic analyses of nucleotide sequences of ribonucleases and other molecules from ruminant species and compare these with published data. Chevrotain (Tragulus) always groups with the other ruminants as separate taxon from the pecora or true ruminants. Within the pecora the relationships between Bovidae, Cervidae, Giraffidae, and pronghorn (Antilocapra) cannot be decided with certainty, although in the majority of analyses Antilocapra diverges first, separately or joined with giraffe. Broad taxon sampling and investigation of specific sequence features may be as important for reliable conclusions in phylogeny as the lengths of analyzed sequences.

Amino Acid Sequence↗
PubMed2001

A critique of the neuroecology of learning and memory.

Recent years have seen the emergence of neuroecology, the study of the neural mechanisms of behaviour guided by functional and evolutionary principles. This research has been of enormous value for our understanding of the evolution of brain- and species-specific behaviour. However, we question the validity of the neuroecological approach when applied to the analysis of learning and memory, given its arbitrary assumption that different 'problems' engage different memory mechanisms. Differences in memory-based performance in 'natural' tasks do not prove differences in memory capacity; similarly, differences in the use of memory in the natural environment do not provide a sound basis for expecting differences in anatomical structures that subserve learning and memory. This critique is illustrated with examples taken from the study of the neurobiology of food storing and song learning in birds.

Journal Article↗
PubMed2002

The first word.

Explore the source record for details and available documents.

Biological Evolution↗
PubMed1983

Human behavioral development and genetics.

Behavioral development during childhood is examined in relation to recent concepts and data from evolutionary theory and developmental genetics. The epigenetic framework of Waddington is proposed as a powerful tool for analyzing the progressions in behavior, particularly for recognizing that development involves coordinated pathways of change over time. Many of these pathways appear to depend upon the activity of timed gene-action systems that switch off and on according to a predetermined plan. Behavioral development thus gives expression to the dynamics of preprogrammed change; and in this perspective, behavioral discontinuities may be as strongly rooted in the epigenetic ground plan as the continuities are. The present paper aims to pull together some common themes from different areas that bear on the central issues of behavioral development--the neural foundations, the time course followed, the interplay of maturation and experience, the extent of preorganization furnished by the genetic program, and the adaptive significance of such behaviors in an evolutionary perspective. The final section touches on some hypotheses drawn from developmental neurobiology and developmental genetics that may enrich the analyses of human behavioral development.

Biological Evolution↗