PubMed Health⌕ Search

Biomedical subjects

J Martineau

Publications and source records attributed to J Martineau.

At least 19 recordsLinked to original sources
PubMed2003

Visual perception in children: human, animal and virtual movement activates different cortical areas.

This study was designed to relate visual perception of motion (HUMAN, ANIMAL and VIRTUAL) to cortical activity (qEEG parameters). Thirty-four healthy right-handed children (29 months-94 months, mean age 5 years) viewed a video film showing a still image (a lake) and animated images with human, animal and virtual movement. EEGs were recorded while the children watched the video film. The power values of each frequency band theta 1: 3.5-5.5 Hz, theta 2: 5.5-7.5 Hz, alpha 1: 7.5-10.5 Hz, alpha 2: 10.5-13 Hz, beta 1: 13-18 Hz, beta 2: 18-25 Hz and beta 3: 25-35 Hz were analyzed in a four-way repeated-measures ANOVA (age x hemisphere x electrode x type of activation). Three main results were obtained: (1) younger children (< 5 years) showed higher power spectral values than older children; (2) there was specificity for real human movement in the left hemisphere; and (3) activations in the left- and right-hemispheres were different according to the movement visualized. These results indicate that in healthy children, human, animal and virtual movement activates different cortical areas.

Alpha Rhythm↗
PubMed2001

Regulation of cognitive activity and early communication development in young autistic, mentally retarded, and young normal children.

Based on the Piagetian framework, this study examined regulation of cognitive activity and developmental communication profiles and their interrelationship in groups of autistic, mentally retarded, and normal children of comparable overall, verbal, and oculo-manual developmental ages (from 6 to 24 months). Regulation of activity was assessed with both an object permanence test and an original behavior grid, and development of communication skills with the Guidetti-Tourrette scales (French adaptation of the Seibert-Hogan scales). The results showed evidence of certain types of dysregulation of cognitive activity and a general delay in communication ability in autistic children compared to the other two groups. Moreover, although the intensity of some of these disorders decreased in relation to the developmental levels of social interaction and joint attention in normal children, they were related to both high and low levels of development of social interaction only in autistic children. These findings raise the hypothesis of a relationship between a disorder of disengaging from an activity and developmental levels of social interaction noted at two transitory periods of early development (12 and 24 months) only in children with autism. Developmental and neuropsychological interpretations of this particular pattern are proposed.

Autistic Disorder↗
PubMed2001

Electroencephalographic activity during perception of motion in childhood.

The purpose of the present study was to relate observations of biological motion to cortical activity by evaluation of the association of quantified electroencephalogram (qEEG) parameters with a video film projection. Thirty right-handed healthy children (2-8-year-olds) viewed a video film showing still shots and moving shots with human movement or object movement. The EEG was recorded while children watched the video movie and was then subjected to spectral analysis; the spectral powers for theta, alpha and beta bands were matched with corresponding sequences of video film. The power values of each frequency band were analysed in a four-way repeated-measures ANOVA (Age x Hemisphere x Electrode x Sequence). Three main results were obtained: (i) younger children (2-4-year-olds) had higher power spectral values than older children (5-8-year-olds); (ii) greater EEG desynchronization of the left hemisphere was observed; (iii) observation of biological movement was related to a significant decrease in theta 1 and theta 2 power values of EEG in fronto-temporal and central regions of the left hemisphere compared with visual perception of still shots or nonhuman movement. These results indicated some support for the theory that the sensori-motor cortex and Broca's area are activated during visual observation of human motion.

Age Factors↗
PubMed2001

Plasma fatty acid levels in autistic children.

Phospholipid fatty acids are major structural components of neuronal cell membranes, which modulate membrane fluidity and hence function. Evidence from clinical and biochemical sources have indicated changes in the metabolism of fatty acids in several psychiatric disorders. We examined the phospholipid fatty acids in the plasma of a population of autistic subjects compared to mentally retarded controls. Our results showed a marked reduction in the levels of 22: 6n-3 (23%) in the autistic subjects, resulting in significantly lower levels of total (n-3) polyunsaturated fatty acids (PUFA) (20%), without significant reduction in the (n-6) PUFA series, and consequently a significant increase in the (n-6)/(n-3) ratio (25%). These variations are discussed in terms of potential differences in PUFA dietary intake, metabolism, or incorporation into cellular membranes between the two groups of subjects. These results open up interesting perspectives for the investigation of new biological indices in autism. Moreover, this might have new therapeutic implications in terms of child nutrition.

Adolescent↗
PubMed1999

Association study of the NF1 gene and autistic disorder.

Neurofibromatosis type 1 (NF1) is increased about 150-fold in autistic patients. The aim of this study was to test for an association between the NF1 locus and autistic disorder. The allele distributions of three markers of the NF1 gene were studied in 85 autistic patients and 90 controls. No differences in allele distributions were observed. However, we found a new allele (allele 5) of the GXAlu marker in four autistic patients. Allele 5 was absent in a larger control population (213 individuals). The patients with allele 5 had a more severe clinical picture, mainly in the fields of motility and tonus. Our preliminary results suggest that the NF1 region is not a major susceptibility locus for autism. However, the GXAlu marker of the NF1 gene appears as a possible candidate for a susceptibility locus in a small subgroup of severely affected autistic patients. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:729-732, 1999.

Adolescent↗
PubMed1999

Observation and execution of movement: similarities demonstrated by quantified electroencephalography.

Quantified electroencephalography (qEEG) was used to compare cerebral electrical variations while human subjects (10 males and 10 females) were observing and executing finger movements and while they were resting. Video recording enabled elimination of subjects performing involuntary movements. EEGs were recorded from 14 sites in seven frequency bands: theta 1, theta 2, alpha 1, alpha, beta 1, beta 2 and beta 3. Analyses were performed on logarithmically transformed absolute spectral power values. Both observation and execution of finger movements involved a decrease in spectral power compared with resting. This decrease was significant only for the alpha 1 frequency band (7.5-10.5 Hz) and it involved nine of the 14 electrode locations (F7, F8, F4, T6, T5, C3, C4, P3 and P4). This indicates that the motor cortex and the frontal cortex are specifically activated by both observation and execution of finger movements. These results provide evidence that observation and execution of movement share the same cortical network.

Adult↗
PubMed1998

Sry and the testis: molecular pathways of organogenesis.

The gene Sry acts as a switch, initiating pathways leading to the differentiation of a testis rather than an ovary from the indifferent gonad (genital ridge) in mammals. The early events following Sry expression include rapid changes in the topographical organization of cells in the XY gonad. Sry must therefore initiate signaling pathways that direct male-specific patterns of proliferation, migration, cell-cell organization, and vascularization. We have identified an increase in male-specific proliferation by 12.0 days post coitum, while proliferation in the female gonad declines. We have also observed male-specific cell migration from the mesonephros into the gonad in a composite organ culture system in which gonads from wild-type mice (CD1) and mesonephroi from a transgenic strain expressing beta-galactosidase in all its cells (ROSA26) were grafted together in vitro at the indifferent stage of gonadogenesis. Migration depends on an active signal that requires the presence of a Y chromosome in the gonadal portion of the graft. The signals that trigger migration operate over considerable distances, suggesting either a long-range diffusible factor or the involvement of a rapid and efficient relay mechanism. Identification of the somatic cells contributed from the mesonephros with cell-specific markers indicated that some of the migrating cells were endothelial, revealing differences in processes of vascularization between male and female gonads. A second distinct population of migrating cells lay in close apposition to endothelial cells, and a third population occupied positions circumscribing areas of condensing Sertoli cells.

Animals↗
PubMed1998

Perception of motion and qEEG activity in human adults.

This study was designed to relate visual perception of motion to cortical activity, by evaluation of the association of quantified electroencephalogram (qEEG) parameters with a video film projection. The EEG was recorded from 14 sites according to the International 10-20 system and a common average reference was used. Forty right-handed volunteers (mean age = 24 years) were examined. The video film consisted of 20 s sequences showing still shots and moving shots with human movements or object movements. The EEG was then subjected to spectral analysis; the spectral powers for the theta, alpha and beta bands were calculated for 14 s epochs and compared with sequences of the video film. All analyses were based on logarithmically transformed absolute spectral power values. The power values of each frequency band were analysed in a 3-way repeated measure ANOVA (Hemisphere x Electrode x Sequence). The results were represented by EEG cartography. Significant decreases in the alpha 1, beta 1 and beta 2 power values of EEG in centro-parietal regions of both hemispheres were shown during perception of human motion sequences. This suggests participation of the sensorimotor cortex during visual observation of human motion.

Adolescent↗
PubMed1998

Immunoreactivity of sera to a peptide derived from the serotonin 5-HT1A receptor in a group of children with developmental disorders: possible role in non-autistic epilepsy.

The presence of autoantibodies against the serotoninergic 5-HT1A receptor has been reported in serum from an autistic child using radioligand binding studies. It is now well established that, in cardiovascular diseases with an autoimmune component, patients present in their sera autoantibodies directed against the second extracellular loop of some G-protein coupled membrane receptors. We thus investigated by an enzyme-immunoassay method the presence of anti-5-HT1A receptor antibodies in sera of children with developmental disorders using synthetic peptides corresponding to the first and the second extracellular loops of this receptor. The population of children with developmental disorders was divided in autistic children with or without EEG abnormalities, and in non-autistic children with or without EEG abnormalities. We found that 6 out of 10 sera of non-autistic children with an abnormal EEG recognized the second extracellular loop of the 5-HT1A receptor. This is significantly higher than the other groups of children with developmental disorders or a healthy control group. These observations support the existence of an autoimmune component in epilepsy.

Adolescent↗
PubMed1998

[Latent imitation of human movements presented on a videoscopic screen, disclosed by electroencephalographic mapping in the spectator].

Trend to imitate human movement is studied here by EEG mapping. The effects of three kinds of situations are compared: a movement on a TV screen is presented to the subject; a movement is realized by the experimenter in front of the subject; the subject is asked to perform a movement. These three situations elicited important modifications in alpha 1 rhythms over the centroparietal area of the scalp. These results are discussed according to neurophysiological and neuropsychological data, including the possible role of frontal lobe in imitation. Preliminary experiments in psychopathology concern imitation disturbances in autistic children.

Adolescent↗
PubMed1997

Male-specific cell migration into the developing gonad.

BACKGROUND: The gene Sry acts as a developmental switch, initiating a pathway of gene activity that leads to the differentiation of testis rather than ovary from the indifferent gonad (genital ridge) in mammalian embryos. The early events following Sry expression include rapid changes in the topographical organization of cells in the XY gonad. To investigate the contribution of mesonephric cells to this process, gonads from wild-type mice (CD1), and mesonephroi from a transgenic strain ubiquitously expressing beta-galactosidase (ROSA26), were grafted together in vitro. After culture, organs were fixed and stained for beta-galactosidase activity to identify cells contributed from the mesonephros to the male or female gonad. RESULTS: Migration of mesonephric cells occurred into XY but not XX gonads from 11.5-16.5 days post coitum (dpc). Somatic cells contributed from the mesonephros were distinguished by their histological location and by available cell-specific markers. Some of the migrating cells were endothelial; a second population occupied positions circumscribing areas of condensing Sertoli cells; and a third population lay in close apposition to endothelial cells. CONCLUSIONS: OFFgration from the mesonephros to the gonad is male specific at this stage of development and depends on an active signal that requires the presence of a Y chromosome in the gonad. The signals that trigger migration operate over considerable distances and behave as chemoattractants. We suggest that migration of cells into the bipotential gonad may have a critical role in initiating the divergence of development towards the testis pathway.

Animals↗
PubMed1996

Serotonin and autism: biochemical and molecular biology features.

Whole blood and urinary levels of serotonin (5-hydroxytryptamine; 5-HT) and the derivative urinary 5-hydroxyindoleacetic acid (5-HIAA) were measured in normal and autistic subjects. An association was tested between autism and a marker coding for the 5-HT2A serotonergic receptor gene. Significant group (high urinary 5-HT and low whole blood 5-HT in autism) and age effects (urinary 5-HT decrease with age) were found. Moreover, whole blood 5-HT levels were correlated with clinical state. No differences in allele and genotype frequencies for the 5-HT2A receptor marker were found in this autistic population compared with age-matched healthy students.

Adolescent↗
PubMed1995

Autism and genetics: clinical approach and association study with two markers of HRAS gene.

Twin studies and familial aggregation studies indicate that genetic factors could play a role in infantile autism. In an earlier study, we identified a possible positive association between autism and a c-Harvey-ras (HRAS) oncogene marker at the 3' end of the coding region. In an attempt to confirm this finding, we studied a larger population, well-characterized clinically and genetically. We report a positive association between autism and two HRAS markers, the 3' marker used in the initial study and an additional marker in exon 1.

Adolescent↗
PubMed1995

Disorders of regulation of cognitive activity in autistic children.

Infantile autism is a pervasive developmental disorder characterized by disturbances concerning not only the areas of socialization and communication ("aloneness") but also the ability to modify and change behavior ("need for sameness"). In most recent studies, various abnormal and deviant cognitive activities, such as the ability to regulate one's behavior, were considered as accounting for these signs. In this report, we examined the regulation of cognitive activity, from a developmental perspective in comparing autistic with mentally retarded children matched in a pairwise manner by global, verbal, and nonverbal developmental ages. All children were tested with tasks adapted from the Object Permanence Test which corresponds to Piaget's sensorimotor development Stages IV to VI. Results showed that autistic children had a pervasive difficulty in maintenance set, made more perseverative errors when the abstraction degree of task was higher, and were more variable in their behavioral strategies. Discussion is focused on the interests and limits of these tasks for the examination of regulation activity from diagnostic and developmental perspectives. Finally, interpretations about recent neuropsychological and neurophysiological works, and additional interdisciplinary studies are suggested.

Attention↗
PubMed1995

Association study with two markers of a human homeogene in infantile autism.

Epidemiological data and family studies in autism show that there is a genetic susceptibility factor in the aetiology of this syndrome. We carried out an association study in infantile autism. Two markers of the homeogene EN2 involved in cerebellar development were tested in a population of 100 autistic children and in a population of 100 control children. With the MP4 probe showing a PvuII polymorphism, significant differences in the allele frequencies between the two populations were found (chi 2 = 7.99, df = 1, p < 0.01). With the MP5 probe showing an SstI polymorphism, no difference appeared (chi 2 = 1.17, not significant). Several clinical examinations allowed us to characterise the autistic children. Most of them had high scores for autistic behaviour and language disorders but low scores for neurological syndromes. Two children had a significant family history and six children had confirmed syndromes or diseases of genetic origin. Discriminant analysis between clinical and molecular data did not give significant results. These preliminary results must be supported by further analyses of this gene and by studies of its potential involvement in the pathophysiology of the autistic syndrome.

Adolescent↗
PubMed1994

Catecholaminergic metabolism and autism.

The authors determined levels of dopamine (DA) and its derivatives homovanillic acid (HVA), 3-4 dihydroxyphenylacetic acid (DOPAC), 3 methoxytyramine and norepinephrine + epinephrine (NE + E) in the urine, and DA, E and NE in the whole blood of 50 autistic children aged between 1 year 11 months and 16 years. An association was tested for between markers coding for the enzymes and D3 dopaminergic receptor genes implicated in the monoaminergic pathway and autism, using restriction fragment-length polymorphism. There were significant modifications of catecholamine metabolites, but no difference for allele frequencies of the genes coding for tyrosine hydroxylase, dopamine beta hydroxylase and DRD3 in this population compared with a healthy school population matched for chronological age. However, some of the data encourage a more complete study of chromosome 11.

Adolescent↗