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 1,585 records · Page 88Linked to original sources
PubMedDate not supplied

[The functional role of the retino-tecto-thalamo-cortical system in rats].

After bilateral lesion of the posterior lateral thalamic nucleus in rats, studies been made of motor-feeding reflexes to light stimuli. Using spatial preference technique, it was shown that lesion of this nucleus (representing a part of the retino-tecto-thalamo-cortical system) disturbs differentiation of spatially uncoupled visual stimuli. These data confirm the idea on telencephalization of ancient retino-tectal part of the visual system in evolution and indicate that this part is involved into the analysis of spatial relationships.

Animals↗
PubMedDate not supplied

[Contribution of studies on animal memory to understanding human memory].

Studies of animal memory have contributed to the understanding of human memory from two points of view. Phylogenetic comparison of memory abilities in different animal groups demonstrates that human memory is a heterogeneous combination of various abilities, of different complexities, which appeared during the evolution. On the other hand, the use of animal models promotes better understanding of the physiological mechanisms underlying human memory. These models can be anatomic ones founded on the functional implication of encephalic areas, bioelectric ones founded on the implication of microscopic or macroscopic bioelectric phenomena or chemical ones founded on the molecular activity of the nervous system.

Animals↗
PubMed1997

Comparison of pediatric and adult cerebral arteriovenous malformations.

The authors report 19 consecutive children with cerebral arteriovenous malformations over the period 1978-1992. These patients are compared with a series of 120 consecutive adult patients with the same pathology, managed during the same period. The main clinical and angiographic features, as well as the treatment modalities and outcome are reviewed and compared. Children seem to harbour smaller and simpler lesions than adults. Furthermore, despite a more severe clinical presentation, children appears to fare better than adults. The possibility of evolution of brain arteriovenous malformations is discussed.

Adolescent↗
PubMed1989

[Evolution of the conditions for EEG recording in the diagnosis of brain death].

The authors trace the evolution of conditions of EEG recording parallel to the clinical criteria of certainty of the diagnosis of brain death, since the first definition of irreversible coma given by M. Goulon and P. Mollaret in 1959. They notice that over the past 30 years, the duration of the EEG has been reduced, their frequency decreased, and the delay between the clinical diagnosis of brain death with flat EEG and the switching off of the cardio-respiratory ventilation have been reduced from 48 to 6 h, thus enabling extremely early removal of organs; the slow progress of this evolution is explained by the difficulty over the years in distinguishing between brain death and certain reversible pathological conditions which resemble it, and by the fact that some EEGs may take some time to become flat. Actually, once these special cases have been eliminated, after the clinical diagnosis of brain death has been ascertained, we observe that two flat EEGs at an interval of 6 h are never subsequently modified. Finally, the EEG, a non-invasive method, seems always to be the quickest and the easiest method to carry out and especially to repeat, without any particular problem of staff or of place and is, thus, a reliable testimony in the event of medico-legal controversy.

Brain Death↗
PubMed1983

Exponential evolution: implications for intelligent extraterrestrial life.

Some measures of biologic complexity, including maximal levels of brain development, are exponential functions of time through intervals of 10(6) to 10(9) yrs. Biological interactions apparently stimulate evolution but physical conditions determine the time required to achieve a given level of complexity. Trends in brain evolution suggest that other organisms could attain human levels within approximately 10(7) yrs. The number (N) and longevity (L) terms in appropriate modifications of the Drake Equation, together with trends in the evolution of biological complexity on Earth, could provide rough estimates of the prevalence of life forms at specified levels of complexity within the Galaxy. If life occurs throughout the cosmos, exponential evolutionary processes imply that higher intelligence will soon (10(9) yrs) become more prevalent than it now is. Changes in the physical universe become less rapid as time increases from the Big Bang. Changes in biological complexity may be most rapid at such later times. This lends a unique and symmetrical importance to early and late universal times.

Animals↗
PubMed1982

Attenuation of brain free fatty acid liberation during global ischemia: a model for screening potential therapies for efficacy?

Whole brain free fatty acids (FFA) continue to rise appreciably even 1 h after decapitation, which may reflect the evolution of ischemic brain injury at least during global ischemia. If so, the attenuation of FFA liberation by various drugs may reflect their efficacy in ischemic brain injury. Rats were pretreated with either 0.9% NaCl (controls), ketamine, halothane, lofentanil, etomidate, Y-9179, R41-468, Innovar-Vet, pentobarbital, thiopental, or phenytoin and decapitated 15 to 30 min thereafter. The brains were kept normothermic for 10 min until they were frozen in liquid nitrogen. Whole brain FFAs were quantitated gy gas-liquid chromatography. After 10 min of ischemia in controls, total FFAs and arachidonic, stearic, oleic, and palmitic acids increased by 8- to 10-fold. The drugs, in order of decreasing effectiveness in attenuating FFA liberation, fell into the following three groups: (1) phenytoin, thiopental, pentobarbital, and Innovar-Vet; (2) R41-468, Y-9179, and etomidate; and (3) lofentanil, halothane and ketamine. The three groups reduced total FFAs by about 23%, 13%, and 8%, respectively. The effectiveness of drugs in attenuating FFA liberation appears to correlate with their efficacy in ischemic brain injury. However, a cause and effect relationship between FAA liberation and the evolution of ischemic brain injury must be established before accurate predictions of efficacy can be made by this method. The limitations of the proposed method of evaluation are discussed.

Anesthetics↗
PubMed1994

Significance of studies of the avian brain from three perspectives.

The avian brain has been one of the most popular subjects in neuroscience. Recent developments and findings related to avian studies from three different fields are described and their significance is discussed. These topics are: 1) paleontological discoveries indicating that birds are the successors of dinosaurs; 2) neuroanatomical findings indicating that there is a general pattern of information processing in the avian brain; and 3) an evolution hypothesis suggesting that the avian brain has neurons corresponding to those of the mammalian neocortex.

Animals↗
PubMed1997

Brain death.

The development and evolution of the concept of brain death has been necessary due to our technologic advances in medical care and organ transplantation. The current operational definition of brain death is based on coma, absent brain stem reflexes, and apnea, with use of confirmatory testing only as necessary. This definition has demonstrated functional utility and may be further refined over time. Medical providers and the public continue to become increasingly comfortable with the concept of brain death.

Brain Death↗
PubMed2004

High-resolution computed tomography study of the cranium of a fossil anthropoid primate, Parapithecus grangeri: new insights into the evolutionary history of primate sensory systems.

Extant anthropoids have large brains, small olfactory bulbs, and high-acuity vision compared with other primates. The relative timing of the evolution of these characteristics may have important implications for brain evolution. Here computed tomography is used to examine the cranium of a fossil anthropoid, Parapithecus grangeri. It is found that P. grangeri had a relatively small brain compared with living primates. In addition, it had an olfactory bulb in the middle of the range for living primates. Methods for relating optic foramen area and other cranial measurements to acuity are discussed. Multiple regression is used to estimate retinal ganglion cell number in P. grangeri. Given currently available comparative data, P. grangeri seems to have had retinal ganglion cell counts intermediate for living primates, overlapping with the upper end of the range for strepsirrhines and possibly with the lower end for anthropoids.

Animals↗
PubMed2003

Diffusion imaging may predict reversible brain lesions in eclampsia and severe preeclampsia: initial experience.

OBJECTIVE: The purpose of this study was to validate diffusion-weighted magnetic resonance imaging in the prediction of the evolutive course of brain edema and to establish its pathophysiologic presence in patients with eclampsia/severe preeclampsia. STUDY DESIGN: Seventeen patients with a clinical diagnosis of severe eclampsia/preeclampsia and T2 hyperintense brain lesions on routine magnetic resonance imaging were evaluated at hospital admission and 8 weeks later. RESULTS: Brain edema was reversible in 13 patients and irreversible in 4 patients, as indicated on follow-up magnetic resonance imaging. Sixteen of 17 patients were differentiated accurately into reversible and irreversible groups on the basis of diffusion imaging on hospital admission. Diffusion-weighted magnetic resonance imaging demonstrated a significant increase in water mobility in abnormal regions compared with normal-appearing brains in patients in the reversible group (1.34+/-0.10 mm(2) vs 0.79+/-0.08 mm(2)/s x 10(-3), P<.001). In the irreversible group, restricted water diffusion was present, which was consistent with cytotoxic edema and early brain infarction in 3 of 4 patients. CONCLUSION: Diffusion-weighted magnetic resonance imaging can predict successfully the evolutive course of brain edema in an acute setting in these patients. Our findings indicate that brain edema is vasogenic, although ischemic/cytotoxic edema was observed less commonly.

Adolescent↗
PubMed2001

Otx genes in brain morphogenesis.

Most of the gene candidates for the control of developmental programmes that underlie brain morphogenesis in vertebrates are the homologues of Drosophila genes coding for signalling molecules or transcription factors. Among these, the orthodenticle group includes the Drosophila orthodenticle (otd) and the vertebrate Otx1 and Otx2 genes, which are mostly involved in fundamental processes of anterior neural patterning. These genes encode transcription factors that recognise specific target sequences through the DNA binding properties of the homeodomain. In Drosophila, mutations of otd cause the loss of the anteriormost head neuromere where the gene is transcribed, suggesting that it may act as a segmentation "gap" gene. In mouse embryos, the expression patterns of Otx1 and Otx2 have shown a remarkable similarity with the Drosophila counterpart. This suggested that they could be part of a conserved control system operating in the brain and different from that coded by the HOX complexes controlling the hindbrain and spinal cord. To verify this hypothesis a series of mouse models have been generated in which the functions of the murine genes were: (i) fully inactivated, (ii) replaced with each others, (iii) replaced with the Drosophila otd gene. Otx1-/- mutants suffer from epilepsy and are affected by neurological, hormonal, and sense organ defects. Otx2-/- mice are embryonically lethal, they show gastrulation impairments and fail in specifying anterior neural plate. Analysis of the Otx1-/-; Otx2+/- double mutants has shown that a minimal threshold level of the proteins they encode is required for the correct positioning of the midbrain-hindbrain boundary (MHB). In vivo otd/Otx reciprocal gene replacement experiments have provided evidence of a general functional equivalence among otd, Otx1 and Otx2 in fly and mouse. Altogether these data highlight a crucial role for the Otx genes in specification, regionalization and terminal differentiation of rostral central nervous system (CNS) and lead to hypothesize that modification of their regulatory control may have influenced morphogenesis and evolution of the brain.

Animals↗
PubMed1987

Computed imaging stereotaxy: experience and perspective related to 500 procedures applied to brain masses.

The evolution of more sophisticated imaging techniques has initiated a renewed interest in stereotactic devices, methods, and applications. The Brown-Roberts-Wells instrument was available to us early in its prototype stage, and this report reviews the first 500 cases using the system at the University of Southern California Medical Center Hospitals. Procedures were undertaken after recognition of apparent structural alterations on imaging studies, with objectives being both diagnostic and therapeutic. Target locations were predominantly within the cerebral centrum-basal ganglia (284 cases) and diencephalic-mesencephalic regions (129 cases). Operative objectives included: histological and microbiological assay, cyst and abscess aspiration, installation of temporary or permanent drainage conduits, point source and colloid base brachytherapy, cerebroscopy and ventriculoscopy with biopsy, aspiration, and excision, and intraoperative vascular localization. Using multiple instrumentation at the target point (741 point placements), we realized procedural objectives in 95.6% of the cases. The mortality was 0.2% and the morbidity was 1%: hematoma, 2 cases; infection, 1 case; increased deficit, 1 case; intraprocedural seizure, 1 case. A specific diagnosis was not obtained in 4.4% (necrosis, 10 cases; inflammatory response, 9 cases; granuloma, 1 case; gliosis, 1 case; diagnostic error, 1 case). Individual guidelines for case selection, technique, institutional requirements, and applications of the method are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Change of accumulation and filling pattern in evolution of cerebral infarction with I-123 IMP brain SPECT.

Twenty-eight patients with cerebral infarction were examined by brain SPECT with I-123 IMP a total of 46 times from Day 2 to Day 84 after the onset of stroke. Depending on the pattern of change in the abnormal accumulation of I-123 IMP between the early and delayed images, the patients were classified into one of five types. The number of patients in each type and the number of days after infarction at which each type occurred were as follows: Type (I), n = 5 and 4 +/- 2 days; Type (II), n = 8 and 12 +/- 4 days; Type (III), n = 17 and 21 +/- 11 days; Type (IV), n = 13 and 38 +/- 18 days; and Type (V), n = 3 and 60 +/- 16 days. In 12 patients, 30 brain SPECT were performed that showed the chronological evolution of infarction in sequence from Types (I) to (IV). Hyperactivity in the early image was seen in Type (I) with a subsequent image defect, while in Type (II) there was persistent hyperactivity. Hypoactivity in the early image was seen in Types (III), (IV), and (V), and the activity in the delayed image gradually decreased as the process of infarction terminated. The early image reflected the distribution of lipophilic I-123 IMP, indicating regional cerebral blood flow, while the delayed image showed the distribution of hydrophilic I-123 IMP metabolites superimposed on that of lipophilic I-123 IMP which had accumulated in the brain at the first extraction. Combining the early and delayed images of I-123 IMP brain SPECT may help to understand the evolution of cerebral infarction.

Adult↗
PubMed1997

The evolution of the frontal lobes: a volumetric analysis based on three-dimensional reconstructions of magnetic resonance scans of human and ape brains.

Scenarios regarding the evolution of cognitive function in hominids depend largely on our understanding of the organization of the frontal lobes in extant humans and apes. The frontal lobe is involved in functions such as creative thinking, planning of future actions, decision making, artistic expression, aspects of emotional behavior, as well as working memory, language and motor control. It is often claimed that the frontal lobe is disproportionately larger in humans than in other species, but conflicting reports exist on this issue. The brain of the apes in particular remains largely unknown. In this report we measure the volume of the frontal lobe as a whole and of its main sectors (including cortex and immediately underlying white matter) in living humans, and in post-mortem brains of the chimpanzee, gorilla, orang-utan, gibbon and the macaque using three-dimensional reconstructions of magnetic resonance (MR) scans of the brain. On the basis of these data we suggest that although the absolute volume of the brain and the frontal lobe is largest in humans, the relative size of the frontal lobe is similar across hominoids, and that humans do not have a larger frontal lobe than expected from a primate brain of the human size. We also report that the relative size of the sectors of the frontal lobe (dorsal, mesial, orbital) is similar across the primate species studied. Our conclusions are preliminary, because the size of our sample, although larger than in previous studies, still remains small. With this caveat we conclude that the overall volume of the frontal lobe in hominids enlarged in absolute size along with the rest of the brain, but did not become relatively larger after the split of the human line from the ancestral African hominoid stock. Aspects other than relative volume of the frontal lobe have to be responsible for the cognitive specializations of the hominids.

Animals↗