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[Sequence of clinical changes and evolution of MR images in a case of chronic SSPE].

Slow course case of subacute sclerosing panencephalitis is reported. The onset was at the age of 16 years and death followed after 5 years. He was observed during nine successive hospitalizations and the authors describe the changing clinical symptomatology parallelly with successive EEG records and brain MR imaging evolution. Successive phases of the disease were associated with hyperintense changes in T2-weighted.images, and were situated initially in occipital lobes, and involved later on periventricular areas and finally the whole white matter of both cerebral hemispheres. Subcortical brain atrophy developed parallelly.

Adolescent↗
PubMed2006

Visual influences on primate encephalization.

Primates differ from most other mammals in having relatively large brains. As a result, numerous comparative studies have attempted to identify the selective variables influencing primate encephalization. However, none have examined the effect of the total amount of visual input on relative brain size. According to Jerison's principle of proper mass, functional areas of the brain devoted primarily to processing visual information should exhibit increases in size when the amount of visual input to those areas increases. As a result, the total amount of visual input to the brain could exert a large influence on encephalization because visual areas comprise a large proportion of total brain mass in primates. The goal of this analysis is to test the expectation of a direct relationship between visual input and encephalization using optic foramen size and optic nerve size as proxies for total visual input. Data were collected for a large comparative sample of primates and carnivorans, and three primary analyses were undertaken. First, the relationship between relative proxies for visual input and relative endocranial volume were examined using partial correlations and phylogenetic comparative methods. Second, to examine the generality of the results derived for extant primates, a parallel series of partial correlation and comparative analyses were undertaken using data for carnivorans. Third, data for various Eocene and Oligocene primates were compared with those for living primates in order to determine whether the fossil taxa demonstrate a similar relationship between relative brain size and visual input. All three analyses confirm the expectations of proper mass and favor the conclusion that the amount of visual input has been a major influence on the evolution of relative brain size in both primates and carnivorans. Furthermore, this study suggests that differences in visual input may partly explain (1) the high encephalization of primates relative to the primitive eutherian condition, (2) the high encephalization of extant anthropoids relative to other primates, and (3) the very low encephalization of Eocene adapiforms.

Animals↗
PubMed2000

Evaluation of donor cardiac function for heart transplantation: experience of a French academic hospital.

OBJECTIVES: The diagnostic and therapeutic approaches for evaluation and management of cardiac function in brain-dead patients vary from country to country. The aim of the present study was to describe the results of the evaluation of brain-dead patients as potential cardiac donors in a French teaching hospital that manages the largest number of brain-dead patients in France. METHODS: Demographic parameters, the causes of brain death, clinical evolution, hemodynamic parameters, doses of inotropic and/or vasopressive drugs, the results of echocardiographic examination, and several biochemical markers of myocardial cell injury were retrospectively collected. RESULTS: Seventy-one consecutive brain-dead patients admitted to the intensive care unit of the Academic Hospital of Nancy from October 1st, 1998 to September 30, 1999 were analyzed. Twenty-nine patients were considered as potential heart donors: 22 males and 7 females aged 33 +/- 3 years (Mean + SEM). The cause of brain death was head trauma in 17 cases (59%), cerebrovascular disease in 10 cases (34%), and cerebral anoxia related to cardiac arrest in 2 cases (7%). Eighteen hearts (18/29 or 66%) were harvested and transplanted with a favorable outcome at one month in 17 cases. In 11 cases, the heart was not harvested, nine (9/29 or 31%) because of myocardial dysfunction upon subsequent echocardiographic examination and 2 because of the lack of matched recipients. CONCLUSION: Comparison of these results with those of other groups suggests that hormonal substitution with insulin and triiodothyronine in the presence of myocardial dysfunction could be of potential interest to correct myocardial dysfunction and increase the number of donor hearts.

Academic Medical Centers↗
PubMed2002

Somatosensory processing during movement observation in humans.

OBJECTIVES: A neural system matching action observation and execution seems to operate in the human brain, but its possible role in processing sensory inputs reaching the cortex during movement observation is unknown. METHODS: We investigated somatosensory evoked potentials (SEPs), somatosensory evoked fields (SEFs) and the temporal spectral evolution of the brain rhythms (approximately 10 and approximately 20 Hz) following electrical stimulation of the right median nerve in 15 healthy subjects, during the following randomly intermingled conditions: a pure cognitive/attentive task (mental calculation); the observation of a motoric act (repetitive grasping) with low cognitive content ('Obs-grasp'); and the observation of a complex motoric act (finger movement sequence), that the subject had to recognize later on, therefore reflecting an adjunctive cognitive task ('Obs-seq'). These conditions were compared with an absence of tasks ('Relax') and actual motor performance. RESULTS: The post-stimulus rebound of the approximately 20 Hz beta magnetoencephalographic rhythm was reduced during movement observation, in spite of little changes in the approximately 10 Hz rhythm. Novel findings were: selective amplitude increase of the pre-central N(30) SEP component during both 'Obs-grasp' and 'Obs-seq', as opposed to the 'gating effect' (i.e. amplitude decrease of the N(30)) occurring during movement execution. The strength increase of the 30 ms SEF cortical source significantly correlated with the decrease of the approximately 20 Hz post-stimulus rebound, suggesting a similar pre-central origin. CONCLUSIONS: Changes took place regardless of either the complexity or the cognitive content of the observed movement, being related exclusively with the motoric content of the action. It is hypothesized that the frontal 'mirror neurons' system, known to directly facilitate motor output during observation of actions, may also modulate those somatosensory inputs which are directed to pre-central areas. These changes are evident even in the very first phases (i.e. few tens of milliseconds) of the sensory processing.

Adult↗
PubMed2001

Glial fibrillary acidic protein-immunopositive structures in the brain of a Crocodilian, Caiman crocodilus, and its bearing on the evolution of astroglia.

Caiman crocodilus, as a representative of the order Crocodilia, was used in immunohistochemical studies. Immunohistochemical procedures were performed on free-floating sections using a monoclonal antibody against porcine glial fibrillary acidic protein (GFAP) and employing standard avidin-biotin complex methodology. The astroglia of Caiman exhibited robust immunoreactivity to the antibodies raised against mammalian GFAP. In Caiman, the predominant GFAP-immunopositive elements are the radial ependymoglia, similar to other reptiles. The regional variability of glial architecture in Caiman, however, seems greater than in other reptiles so far examined, although it is less compared with chickens. We suggest that this finding corresponds to a more advanced "regional adaptation" of the glial structure in Caiman compared with other reptiles. The main feature that distinguishes the astroglia of Caiman from those of other reptiles is the widespread occurrence of GFAP-immunopositive astrocytes. These cells are limited in lizards and snakes, are not present in turtles, but are found in every major brain area in Caiman. However, even in Caiman, astrocytes are only intermingled with radial glia and are not the predominant glial element of any brain area. The occurrence of astrocytes does not correlate with brain wall thickness. Despite their origin from different ancestral groups of stem reptiles (synapsid or diapsid), mammals and birds exhibit some common general features in their glial architecture and GFAP distribution: 1) predominance of astrocytes and 2) absent or limited GFAP immunopositivity of several brain areas. The present study demonstrates that, even in Caiman, a representative of the reptilian group most closely related to birds, these features are present only in part, suggesting that, in mammals and birds, they have evolved independently.

Alligators and Crocodiles↗
PubMed2004

Brain mechanisms for the formation of new movements during learning: the evolution of classical concepts.

Current concepts hold that the role of the motor cortex is limited to the control of the appropriate motoneurons on the "point-to-point" principle during the performance of specialized movements of the distal parts of the limbs. However, the last decade has seen the appearance of many data on the plasticity of the motor cortex and its active participation in the process of motor learning. Expression of fos genes has been observed in the motor cortex during the formation of specialized movements. Increases in intracortical horizontal connections in layers II-III during learning fine movements has been seen. The cholinergic input to layers II-III of the motor cortex plays a significant role in this. At the same time, data obtained by functional brain mapping have provided evidence that the activity of the motor cortex also increases during the practice of previously learned movements. This raises the question of the specific function of the motor cortex in the process of motor learning. During the formation of new movements during motor training, a number of previously used synergies interfere with the performance of newly formed coordinations and must be inhibited. The central mechanisms of interference of coordinations in humans have only just started to receive study. At the same time, there is an experimental model for the reorganization and inhibition of interfering synergies in animals. Reorganization of coordinations and inhibition of synergies interfering with the performance of a new movement have been shown to be a specific function of the motor area of the cortex. Cortical control persists during the automation of these synergies, which is not the case in other types of learned movements, though this in itself does not mean that conscious control of their performance also persists.

Animals↗
PubMed1979

The tasks of consciousness: how could the brain do them?

According to Darwin's theory of evolution by natural selection, the existence of mental operations proves their usefulness. Darwin called himself a mental materialist. This is one scientific theory of consciousness. Human consciousness has three useful aspects: awareness, intentionality and sharing with others. All have simple equivalents in animals. The latter two are neglected in neurophysiology and experimental psychology. Developmental, neuroanatomical and neuropsychological evidence shows that the human brain has innate structures of awareness, intentionality and interpersonal sharing. Human life depends on interpersonal cooperation. We may have a conscious self, but consciousness of others is essential in us. Studies of commissurotomy patients demonstrate the elaborate interconnected neural organization of consciousness and provide evidence of underlying and necessary levels of motivation, perception and motor integration below consciousness. Additionally, they show that awareness may be split into two different modes. These regulate one another during development and are complementary in culturally sophisticated adult life. One hemisphere, usually the left, has responsibility for expressing ideas and purposes in language. The other responds to the phenomenal context and the subjective situation. Both have human experiences and purposes. Both still collaborate in a unified intentional system after commissurotomy. Infant studies reveal that language develops out of an interpersonal mental process. This seems to control development of thinking. Thus notions of the newborn as an isolated amoral id, and of the infant as an egocentric discoverer of the object concept, must be rejected. Cultivation of moral awareness and a sense of purpose guided by meanings and values depends on innate organization of the human brain for interpersonal consciousness.

Awareness↗
PubMed2002

Dysregulation of neuronal differentiation and cell cycle control in Alzheimer's disease.

Degeneration in Alzheimer's disease primarily occurs in those neurons that in the adult brain retain, a high degree of structural plasticity and, is associated with the activation of mitogenic signaling and cell cycle activation. Brain areas affected by neurofibrillary degeneration in Alzheimer's disease are structures involved in the regulation of "higher brain functions" that become increasingly predominant as the evolutionary process of encephalization progresses. The functions these areas subserve require a life-long adaptive reorganization of neuronal connectivity. With the increasing need during evolution to organize brain structures of increasing complexity, these processes of dynamic stabilization and de-stabilization become more and more important but might also provide the basis for an increasing rate of failure. The hypothesis is put forward that it is the labile state of differentiation of a subset of neurons in the adult brain that allows for ongoing morphoregulatory processes after development is completed but at the same time renders these neurons particularly vulnerable. Interferring with neuronal differentiation control might, thus, be a potential strategy to prevent neurodegeneration in Alzheimer's disease and related disorders.

Aged↗
PubMed2005

Georg N. Koskinas (1885-1975) and his scientific contributions to the normal and pathological anatomy of the human brain.

Georg N. Koskinas is invariably recognised by neuroanatomists as Constantin von Economo's co-author on the celebrated Die Cytoarchitektonik der Hirnrinde des erwachsenen Menschen, published 80 years ago in Vienna and Berlin. That text and Atlas are generally accepted as a monumental landmark in the evolution of morphological brain research. A number of neuroanatomists and neurophysiologists continue to use to this day the parcellation scheme of the cerebral cortex into 107 areas, proposed by von Economo and Koskinas (and logically denoted by alphabetical characters from the initials of the respective lobes), despite the commoner adoption of Brodmann's scheme of 52, randomly numbered, areas. Several works have been written about the life and work of von Economo; on the other hand, virtually nothing can be found in the biomedical literature about Koskinas. This study aims at posthumously restoring part of the fame due this illustrious man of 20th century science -- and giant figure of brain anatomy -- whom history has not treated in the fairest of ways. We present newly gathered biographical data, as well as lesser known aspects of his scientific productivity. Koskinas' neuropathological studies, in collaboration with Ernst Sträussler -- of Gerstmann-Sträussler-Scheinker disease fame -- include findings from patients inoculated with malaria as a form of therapy for progressive general paresis (research related to psychiatrist Wagner von Jauregg's 1927 Nobel Prize), colloid degeneration, and the laminar distribution of status spongiosus lesions. Koskinas' neuropsychiatric activities in Greece upon his return from Vienna in 1927, and until his parting in 1975, are further related, including his successful -- and "Hippocratic" -- practice in the suburbs of Athens, his association with the Vogt Institute for Brain Research at Neustadt, and lesser known neuroanatomical works.

Aged, 80 and over↗
PubMed1987

BSER audiometry in haemodialysis patients.

The object of this paper was to study the brain stem evoked response in 20 patients suffering from chronic renal failure and having haemodialysis, and to evaluate the effects of this treatment. A further 5 successful renal transplant patients were investigated to analyse the evolution of the brain stem conduction when the metabolic abnormality is removed. In the first group, the responses were minimally abnormal in 30% of cases before the dialysis. The dialysis session showed an improvement of the brain stem conduction. This variation was temporary and, 24 hours following the dialysis treatment, the patients showed the pathological values observed before the dialysis. The results of the successful transplanted patients were consistent with the data obtained in the dialysis group. Before transplantation the nerve impulse conduction was found to be abnormal in 3 subjects. These abnormalities disappeared completely after successful transplantation. These results support the view of those who favour the use of evoked potentials to follow the status of the central nervous system in uraemic patients.

Adult↗
PubMed1975

Group selection, altruism, reinforcement, and throwing in human evolution.

Evolution of altruism by group selection involves sacrifice of some individuals, not to the "group as a whole," but to other individuals in the group. Deme-group selection may establish strictly altruistic genes in a population, but only under limited conditions, and perhaps never among vertebrates, among which apparently altruistic behaviors may always potentially benefit the altruists. Responsive-group selection is a more effective mode of evolution of altruism, conspicuous in man. Evolutionary reinforcement increases the force of selection of advantageous behaviors, including altruistic ones, by making them pleasant or rewarding. It is probably involved also in ecological habitat selection, and may be the source of many human emotions, including esthetic ones. Throwing (of stones and weapons) exemplifies both the possible importance of a difficult-to-measure evolutionary factor and the role of reinforcement; in human evolution throwing may have been decisive in food-getting and fighting, in shifting emphasis from brute force to skill, and in inducing evolution of a brain able to handle three-body geometric problems precisely and thus preadapted for more complex functions.

Anthropology, Physical↗
PubMed1976

[Role of craniocerebral trauma in the development of Alzheimer's disease].

The report deals with a clinico-anatomical description of 3 cases of Alzheimer's disease, developing after a brain trauma. The evolution of the disease justifies the question concerning the role of traumas in the pathogenesis. The atrophical process, lying at the basis of the disease is considered in the aspect of the aging of the colloid brain system under the influence of a mechanical action of a trauma.

Aged↗
PubMed2003

Non-invasive imaging methods for the characterization of the pathophysiology of brain ischemia.

Non-invasive imaging methods are increasingly used to study the evolution and therapy of brain diseases under both clinical and experimental conditions. In the animal experiment, these methods can be supplemented by invasive tissue assays to allow precise characterization of the underlying pathophysiology. Based on such an approach, this review evaluates the importance of in vivo nuclear magnetic resonance (NMR) and positron emission tomography (PET) for the understanding of the pathophysiology of brain ischemia.

Animals↗
PubMed2002

Interactive nervous system development: control of cell survival in Drosophila.

The non-autonomous control of cell survival has long been thought to be a mechanism of adjusting cell populations in the vertebrate nervous system, enabling connectivity and myelination to produce a functional brain. Despite cellular evidence that analogous mechanisms occur in invertebrates, scepticism has long reigned over whether they operate in model organisms such as Drosophila. This has led to speculation that there are inherent differences between the development and evolution of simple brains and the brains of vertebrates. The great paradox has, until recently, been the absence of molecular evidence of trophic factors in Drosophila. Recent data have finally shown that EGFR (epidermal-growth-factor receptor) ligands function in the Drosophila CNS to maintain glial survival. Trophic interactions are, thus, a general mechanism of nervous system development.

Animals↗
PubMed1997

Transient global brain ischemia in the rat: spatial distribution, extension, and evolution of lesions evaluated by magnetic resonance imaging.

A newly developed model of transient global ischemia in the rat was evaluated by magnetic resonance imaging (MRI) in terms of localization of brain lesions, their extent and severity, and temporal evolution. Such a model, consisting of bilateral occlusion of common carotid arteries for 10 minutes and mild hypoxia (15% O2) for 20 minutes induces delayed neuronal degeneration, necrosis, and gliosis (detected histologically and immunohistochemically). Ischemia was assessed by full suppression of spontaneous electroencephalographic activity. A "hybrid" T2-/diffusion-weighted MR sequence enhancing more effectively the contrast between injured and intact tissues as compared to T2-weighted MRI was used at 24, 48, 72, and 96 hours and at 7 days postischemia. Twenty hypoxic-ischemic rats showed a considerable variability in brain damage. In 8, there were no MRI-detectable lesions at any interval. In the other 12 rats, the severity and extension of neuronal damage varied markedly, but the lesions were always localized (monolaterally in 8 and bilaterally in 4 rats) in the occipital, temporal, or parietal cerebral cortex. Mainly, they were of intermediate severity or were severe (as assessed by MRI hyperintensity) and were accompanied by usually less severe lesions in the thalamus and/or caudate putamen. The hippocampus was affected moderately or severely in 4 of 12 rats. In most cases, there was at 48 hours a considerable growth in severity and/or extension of lesions, which usually remained stable at later intervals. In conclusion, MRI allowed us to follow brain lesions during the first week in this relatively simple and noninvasive model of transient global ischemia.

Animals↗
PubMed2000

Multispectral analysis of the temporal evolution of cerebral ischemia in the rat brain.

A major difficulty in staging and predicting ischemic brain injury by magnetic resonance (MR) imaging is the time-varying nature of the MR parameters within the ischemic lesion. A new multispectral (MS) approach is described to characterize cerebral ischemia in a time-independent fashion. MS analysis of five MR parameters (mean diffusivity, diffusion anisotropy, T2, proton density, and perfusion) was employed to characterize the progression of ischemic lesion in the rat brain following 60 minutes of transient focal ischemia. k-Means (KM) and fuzzy c-means (FCM) classification methods were employed to define the acute and subacute ischemic lesion. KM produced an estimate of lesion volume that was highly correlated with postmortem infarct volume, independent of the age of the lesion. Overall classification rates for KM exceeded FCM at acute and subacute time points as follows: KM, 90.5%, 94.4%, and 95. 9%; FCM, 82.4%, 90.6%, and 82.6% (for 45 minutes, 180 minutes, and 24-120 hours post MCAO groups). MS analysis also offers a formal method of combining diffusion and perfusion parameters to provide an estimate of the ischemic penumbra (KM classification rate = 70.3%). J. Magn. Reson. Imaging 2000;12:842-858.

Acute Disease↗
PubMed1991

Surface coil spectroscopic imaging: time and spatial evolution of lactate production following fluid percussion brain injury.

Detailed temporal and spatial distributions of lactate production are presented for graded fluid-percussion brain injury in the rat. A one-dimensional proton spin-echo spectroscopic imaging (1D SESI) technique, performed with a surface coil, is presented and evaluated. This technique, which represents a practical compromise, provides spatially localized proton nuclear magnetic resonance (NMR) brain spectra from a series of small voxels (less than 0.15 cm3) in less than 10 min, thus enabling both spatial and temporal monitoring of lactate production. These high-resolution lactate maps are correlated with hyperintense regions observed in T2-weighted images taken 10 h after impact, which, in turn, correlate with histology. The data demonstrate that, following severe trauma there is delayed production and propagation of lactate to regions of the brain that are remote from the trauma site. The extent of lactate production depends on the severity of impact. More significantly, the data show that following severe trauma, local lactate concentrations exceed 15 mumol/g, the concentration that has been claimed as the threshold for brain injury. Therefore high lactate levels cannot be ruled out a priori as a possible factor in brain injury following severe head trauma.

Animals↗