PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Brain evolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,405 records · Page 78Linked to original sources
PubMed2006

A behavioral homeostasis theory of habituation and sensitization: II. Further developments and predictions.

Habituation may be viewed as a decremental behavioral change to iterative stimuli of little immediate relevance. It is observed from protozoa to humans, indicating its evolutionary significance. If habituation is interpreted as the process of filtering out unimportant repetitive stimuli, then how should sensitization be interpreted? The 'behavioral homeostasis theory' of these two behaviors is based on the notion that organisms at a high level of 'alertness' prior to experiencing a new iterative stimulus will show a large initial response followed by a decrement (habituation) if the stimulus is of little significance. Conversely, the same organism at a low level of 'alertness' will show a small initial response to the same stimulus followed by an increase in 'alertness' and a larger response to the next stimulus (sensitization) in order to receive enough information to assess its significance. Circadian rhythmicity is hypothesized to play a role in determining 'alertness' to a new iterative stimulus at any given time. The level of responsiveness in initial habituaters and sensitizers, as an asymptote is approached, is a balance between being too 'alert' to an unimportant stimulus and missing other significant stimuli, and being too 'un-alert' and missing a change in the relevance of the present iterative stimulus. The concept of 'behavioral homeostasis' includes behaviors beyond habituation and sensitization across phylogeny. It includes instinctive as well as learned, and group as well as individual behavior. Such behavioral homeostatic processes to optimize detection and assessment of constantly occurring external stimuli are critical for organism survival. Clinical implications of this theory are also examined.

Animals↗
PubMed2002

Pharmacological interventions for stroke: failures and future.

Given the few options currently available for patients following ischaemic stroke, the recent disappointing failures of several large-scale Phase III clinical trials has made the search for novel therapeutic approaches even more critical. Experimental evidence has suggested that the majority of stroke patients have a slow evolution of brain injury which can occur over several hours. Progressive microcirculatory failure following the initial onset of ischaemia may contribute to the expansion of brain injury. Included among the pathophysiological changes that are speculated to occur as a secondary response to the initial ischaemia are free radical production, excitotoxicity (for example, glutamate) disruption of ionic homeostasis (for example, sodium and calcium influx), enzymatic changes, stimulation of the inflammatory process, endothelin release, activation of platelets and leukocytes, delayed coagulation and endothelial dysfunction. All of these pathophysiological reactions could contribute to an increase in local vascular resistance and therefore cause progressive hypoperfusion of the brain following the onset of stroke. The scope of this review will focus on recent clinical failures in addition to agents currently in clinical development, comparing vascular targets to the common neuroprotective strategies.

Brain↗
PubMed1989

Freud, Janet and evolution: of statuettes and plants.

The systems of Janet and Freud are briefly presented, compared, and interpreted as different variations of the application of the theory of evolution to psychopathology. Although both men accepted a hierarchical view of the psyche, Freud held that there existed an ubiquitous and inherent conflict between phylogenetic strata of the mind, while Janet maintained that with the exception of disease states, the psyche was a unified organizational structure.

Biological Evolution↗
PubMed1996

Oxytocin: cellular and molecular approaches in medicine and research.

In May 1995 the third Hanseatic Endocrine Conference at Stade, Germany, attracted 140 scientists from all over the world to summarize the current knowledge on one hormone--oxytocin. This article presents the major findings of the meeting with the realisation that oxytocin provides major model systems with which to elaborate a whole series of novel endocrinological paradigms, as well as being the example of choice for establishing revolutionary new techniques, which will no doubt spread to studies of other hormone systems. The papers from this symposium will be published in full.

Amino Acid Sequence↗
PubMedDate not supplied

A median third eye: pineal gland retraces evolution of vertebrate photoreceptive organs.

In many vertebrates, the pineal gland serves as a photoreceptive neuroendocrine organ. Morphological and functional similarities between the pineal and retinal photoreceptor cells indicate their close evolutionary relationship, and hence the comparative studies on the pineal gland and the retina are the keys to deciphering the evolutionary traces of the vertebrate photoreceptive organs. Several studies have suggested common genetic and molecular mechanisms responsible for their similarities, but largely unknown are those underlying pineal-specific development and physiological functions. Recent studies have identified several cis-acting DNA elements that participate in transcriptional control of the pineal-specific genes. Genetic approaches in the zebrafish have also contributed to elucidating the genetic network regulating the pineal development and neurogenesis. These efforts toward elucidating the molecular instrumentation intrinsic to the pineal gland, back to back with those to the retina, should lead to a comprehensive understanding of the evolutionary history of the vertebrate photoreceptive structures. This article summarizes the current status of research on these topics.

Amino Acid Sequence↗
PubMed2003

Contributions to the history of psychology: CXIX. The Spanish Neurohistological School's legacy: Cajal and Lorente de Nó.

Santiago Ramón y Cajal made his mark in the history of science as a brilliant researcher of the histology of the nervous system. His bold efforts and the international recognition he received during his lifetime played an important role in the consolidation of the Spanish Neurohistological School which is composed of a large number of eminent disciples. Amongst these, and of outstanding repute, is Rafael Lorente de Nó whose research had a significant influence on the work of Canadian psychololgist Donald O. Hebb and, consequently, on the development of neurophysiological theory. This paper analyses some of the contributions of Cajal and his disciple Lorente de Nó which formed the anatomical and neuropsychological framework of contemporary psychology.

Biological Evolution↗
PubMed1984

The formation of the human paranasal sinuses.

The paranasal sinuses, which formed in mammals as turbinates and air spaces to perform or aid olfaction, eventually came to participate in the formation and maintenance of the entire cranium and to have concomitant functions as well. Evolving through primates to humans, they were influenced by the retraction of the maxillo-facial cranium and the enlargement of the cerebral cranium and thus reached the state unique to humans. The evolutionary phenomena involved in the formation and functions of the paranasal sinuses include adaptation to olfaction, respiration, and cranial formation. These were the phenomena which caused allometric development. Therefore, the paranasal sinuses did not always perform the same functions as they did when they originated, but, influenced by the evolutionary level of each animal and especially by the evolution to apes and humans, the original functions changed to different ones, mostly as instances of preadaptation, according to the evolutionary stage of each paranasal sinus. As the sense of smell ascribed to the mammalian nose began to regress together with the retraction of the jaw (maxilla and mandible), the orbits started to form in primates, and the ethmoturbinate became full of cavities and formed the lateral walls of the nasal cavity. This occurred because the evolution of primates and higher made olfaction non-essential and respiration foremost. When hominization began and the facial cranium distinctly retracted, the maxillary sinus enlarged because of the enlargement of the molars, the change in the dental arch, and the enlargement of the masticatory muscles, and its air-conditioning function became established. The secondary sinuses of the frontal and sphenoid sinuses, which had expanded in mammals, started to regress in response to the new conditions. Especially when the cranium became spherical in the transition from the homo sap. neanderthalensis stage to the homo sap. sap. stage, the transformation of the cerebral cranium forced an increase in the angle between the forehead and the frontal cranial base and a decrease in the angle of the cranial base at the sella turcica. The frontal and sphenoid sinuses then expanded in adjustment to this transformation.

Animals↗
PubMed1985

Collateralization in the mammalian nervous system.

After reviewing the loci of origin for neurons with collateralized axons, some hypotheses on their distribution in the mammalian nervous system, on their functional contributions and on their significance in the course of encephalization are discussed. In principle, the distribution of collateralized neurons seems to be restricted to anatomical circuits subserving unspecific activation of forebrain regions and controlling body balance and movements. Concerning the limbic system, a minor degree of collateralization seems to exist only in less encephalized species. Based on a number of anatomical and functional arguments, it is assumed that the significance of collateralization fades in the course of encephalization.

Animals↗
PubMed1996

Evolutionary ancient roles of serotonin: long-lasting regulation of activity and development.

Biogenic monoamines (catecholamines, indoleamines and histamine) are evolutionary old and important modulators of long-lasting changes in the functional state of cells. They are found in many protozoans and in almost all metazoans. Monoamines preserve their evolutionary old functions (first of all being intracellular signals and later hormones and growth factors) even in those animals in which they acquired the function of neurotransmitter. The older functions of serotonin, an important member of the family of indoleamines, are reviewed here. Described are: presence of serotonin in organisms at various phylogenetic levels; its role in embryonal, foetal and postnatal development, especially in the development of the central nervous system. It is concluded that in none of these functions serotonin is the only factor, but it is an ubiquitous and important modulator of a vast array of processes and functions taking part in development and plasticity.

Aging↗
PubMed1977

Language acquisition: the new synthesis.

Developments concerning the nature of language have taken place in the disparate disciplines of linguistics, ethology and neurology. It is not widely known that these developments have brought these fields of study into accord, and have helped clarify the mechanism of language acquisition in childhood. They carry practical implications important to the teaching of language and to the understanding of language disabilities. The conclusions have also led to the discovery of cranial vault asymmetries which promise insight into the evolution of language in man's prehistory. The learning of language has become better understood as a result of recent developments in the fields of linguistics, ethology and comparative neurology.

Animal Communication↗