Neural bases of time estimation: a PET and ERP study.
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Adult↗
Biomedical subjects
B Renault
Publications and source records attributed to B Renault.
The effects of apomorphine on attentional processing in Parkinson's disease.
To ascertain whether variations in central dopaminergic transmission can differentially affect motor and cognitive processing, we studied the effects of apomorphine (APO) in 9 patients with Parkinson's disease (PD). The UPDRS motor scores and auditory event-related potentials (ERPs) obtained in the 'odd-ball' (OB) and in the 'covert orientation of attention' (COA) tasks were studied in the 'off' and in the 'on' state after an injection of APO. Although APO injection improved patients' motor status, it induced a significant increase in the latencies of the P2 and P3 ERP components in the OB. In the COA task, right-hand reaction times (RTs) were markedly shortened in the 'on' state while left hand RTs remained unchanged. The contrasting effects of dopaminergic stimulation on the motor performance and on some aspects of cognitive processing suggest the existence of complex interactions within pre- and postsynaptic brain dopamine receptors, and an intervention of segregated basal ganglia-prefrontal cortex loops in motor and cognitive behaviour.
Adult↗
ERPs and chronometry of face recognition: following-up Seeck et al. and George et al.
Seeck et al. found that event-related potentials (ERPs) evoked by repeated and non-repeated face photographs differ as early as 50-70ms post-onset. They thus suggested that faces are recognized at these latencies, in contrast with current opinions in ERP literature. However, the similar latencies obtained by George et al. for stimuli not perceived as faces suggest that Seeck et al.'s differences could index repetition rather than face recognition per se. To address this issue, we used matched faces of known and unknown persons. We found the earliest differences between the ERPs to these faces between 76 and 130 ms. These results, which are consistent with other data, suggest that the differentiation of faces takes approximately 100 ms of processing time in humans.
Adult↗
Entropy maps characterize drug effects on brain dynamics in Alzheimer's disease.
Non-linear quantifiers of brain electrical dynamics (entropy maps computed from the degradation of temporal forecasting of EEG signals) were studied in relation to drug treatment of Alzheimer's disease. A placebo condition was compared to three drug doses (50, 100 and 200 mg). A significant general effect of the drug was found when compared to placebo and specific contrasts between placebo and each of the three drug doses only reveal a significant entropy increase for the highest dose. These effects were localized bilaterally in fronto-temporal areas and support changes in the dynamics of the cerebral structures involved in memory processes.
Acoustic Stimulation↗
Type I transforming growth factor beta receptor maps to 9q22 and exhibits a polymorphism and a rare variant within a polyalanine tract.
In a search for mutations of the type I transforming growth factor beta receptor (TbetaR-I), we mapped the gene to 9q22 and found a common polymorphism [TbetaR-I(6A)] and a rare variant [TbetaR-I(10A)] of TbetaR-I, causing an in-frame deletion of three alanines and an in-frame insertion of one alanine, respectively, in the receptor's extracellular domain. The biological relevance of the polymorphism TbetaR-I(6A) was investigated. When TbetaR-I(6A) was transiently transfected into TbetaR-I-deficient cells, the growth-inhibitory effects of transforming growth factor beta were restored. TbetaR-I(6A) and TbetaR-I(10A) frequency were assessed in 108 tumor samples and 80 nontumor samples from patients with a diagnosis of cancer, as well as in 118 normal blood donors of comparable ethnic composition. The frequency of TbetaR-I(6A) heterozygotes was fairly similar in normal blood donors (8%), in nontumor DNA of patients with a diagnosis of cancer (10%), and in tumor samples (14%). However, the frequency of TbetaR-I(6A) homozygotes among nontumor (4%) and tumor (8%) samples obtained from patients with a diagnosis of cancer was higher than that predicted by the Hardy-Weinberg law. The clinical and biological significance of TbetaR-I(6A) homozygosity needs to be further investigated.
Acute Disease↗
Epileptic seizures can be anticipated by non-linear analysis.
Epileptic seizures are a principal brain dysfunction with important public health implications, as they affect 0.8% of humans. Many of these patients (20%) are resistant to treatment with drugs. The ability to anticipate the onset of seizures in such cases would permit clinical interventions. The view of chronic focal epilepsy now is that abnormally discharging neurons act as pacemakers to recruit and entrain other normal neurons by loss of inhibition and synchronization into a critical mass. Thus, preictal changes should be detectable during the stages of recruitment. Traditional signal analyses, such as the count of focal spike density, the frequency coherence or spectral analyses are not reliable predictors. Non-linear indicators may undergo consistent changes around seizure onset. Our objective was to follow the transition into seizure by reconstructing intracranial recordings in implanted patients as trajectories in a phase space and then introduce non-linear indicators to characterize them. These indicators take into account the extended spatio-temporal nature of the epileptic recruitment processes and the corresponding physiological events governed by short-term causalities in the time series. We demonstrate that in most cases (17 of 19), seizure onset could be anticipated well in advance (between 2-6 minutes beforehand), and that all subjects seemed to share a similar 'route' towards seizure.
Electrophysiology↗
[Pelvic trauma and pregnancy. Literature review and case report].
The authors are dealing with a case of a pelvic fracture (right superior pubic ramus) after a road traffic accident to a patient who arise a pregnancy with twins at twenty five weeks pregnant. Seven per cent of a road traffic accident affect pregnancy with a maternal death rate from eight to sixteen per cent and a fetal death rate up to fifty seven per cent. Pelvic trauma are more deleterious during the pregnancy because of the gravide uterus, of the abdominal injuries binding more often, and of pregnancy secondary maternal physiology which lead to delay diagnosis and therapeutics. Blunt fetomaternal consequences are ruled by pelvic haematomas, uterine rupture, prematurity, acute fetal distress, fetal injuries and in utero death. At mid and long range arise the problem of child birth way and the risk of mechanical dystocy. Cesarean is store in case of vesical and urethral injuries, or perineal injury, several pelvic fractures or in case of the pelvic belt fracture moved and not reduced, bringing to a surgical unsymmetrical pelvis. In the other cases, the obstetrical prognoses will be done after a dialogue with all medical staff and a full synthesis of the file based on the fetopelvic comparisons (obstetrics previous, clinic, fetal biometry, pelvimetry X ray).
Abdominal Injuries↗
A sequence-ready physical map of a region of 12q24.1.
We developed a sequence-ready map of a part of human chromosome 12q24.1. We utilized a number of sequence-tagged site (STS) markers from 12q24.1 to screen large insert bacterial chromosome libraries and a chromosome 12-specific cosmid library. The clones were assembled into contiguous sets (contigs) by STS-content analysis. Contigs were extended by obtaining end sequences of bacterial clones, generation of additional STSs, rescreening the libraries, and screening the additional clones for the presence of STSs. The resulting contig covers nearly 2 Mb of DNA and provides an average marker resolution of 16 kb. Based on the STS content, we developed fingerprints of a subset of clones. The STS content and fingerprint data allowed us to define a minimal tiling path of clones. These clones are being used to sequence this part of chromosome 12. This contig contains the Ataxin 2 gene, and it covers the interval harboring the gene responsible for Darier disease.
Ataxins↗
Temporal patterns in human epileptic activity are modulated by perceptual discriminations.
We studied subdural recordings from a patient with an unusually focal and stable occipito-temporal epileptic discharge under four experimental conditions. The series of time intervals between successive spike discharges displayed a few (3-5) clusters of periodic values representing statistically significant short-term periodicities when tested against surrogate data. This short-term predictability was modulated during the different experimental conditions by periodicity shifts of the order of 15-30 ms. Correspondingly, there was an increased gamma-band (30-70 Hz) coherence between the epileptic focus and surrounding recording sites. We conclude that the focal epileptic activity is part of an extended network of neural activities which exert a fast modulation reflected in changes of transiently periodic activities.
Adult↗
Face and shape repetition effects in humans: a spatio-temporal ERP study.
The neural bases of repetition effects for faces and non-significant shapes was studied using Mooneys' faces presented upright (face) or upside down (shape) with a repetition interval of 8 min 30 s-1. Scalp potentials and current density maps on 30 electrodes were compatible with an involvement of the infero-temporal and fusiform gyri (from 50 to at least 250 ms), mainly on the right, for both faces and shapes; the hippocampus and adjacent areas (around 300 ms), specifically for faces; the medial temporal lobes (450-650 ms) again independent of stimulus meaning. These results suggest that the facilitation of perception due to repetition involves both neocortical specialized areas and the medial temporal lobe, with different timings of activation. They further suggest that memory updating takes place more rapidly for faces than for meaningless shapes and that face recognition may be, at least partly, functionally encapsulated.
Adult↗
Gene amplification and proliferative kinetics in relation to prognosis of patients with gastric carcinoma.
BACKGROUND: The differences in survival of gastric carcinoma patients who have identical clinical or pathologic stages prompted the authors to investigate the prognostic significance of biologic features that are known to affect the clinical aggressiveness of other tumor types. METHODS: One hundred twenty-four tumor samples from patients who had received radical or palliative surgery were analyzed for c-myc, c-K-ras, hst, and c-erb B-2 gene amplification by means of the Southern blot technique. Of these tumors, 70 were also examined for cell kinetics by means of the thymidine labeling index (TLI). RESULTS: The analysis of associations between gene amplification and the anatomicopathologic variables (TNM classification, site of tumor, and histology) showed that amplification represents a late event in the natural history of gastric carcinoma. Gene amplification showed a slight, statistically insignificant, negative impact on overall survival (OS) (P = 0.09). Amplification of c-erb B-2 correlated in a statistically significant way with reduced OS (P = 0.03). Cox multiple regression analysis revealed that neither c-erb B-2 amplification nor TLI had prognostic significance in relation to OS. CONCLUSIONS: These data indicate that amplification of the examined oncogenes did not reveal a new independent prognostic factor for patients with gastric carcinoma. However, the authors' results did show a strong correlation between gene amplification and tumor progression, which warrants further study involving larger series of patients. At the same time, the TLI results underlined the need to identify the most suitable biologic material for use in the estimation of proliferative indexes in gastric carcinoma.
Adult↗
Functional anatomy of human auditory attention studied with PET.
Positron emission tomography was used to investigate the functional anatomy of selective auditory attention in 17 right-handed male volunteers who submitted to different tasks: silent rest (REST) listening to frequent low- or rare high-pitched tones (LIS) delivered randomly to the right or the left ear, selective auditory attention where subjects had to attend to deviants in one ear, right (ATTR) or left (ATTL). Six subjects had the series REST, LIS, ATTR twice, eight subjects the series REST, LIS, ATTL, and the last three subjects the sereis REST, ATTR, ATTL. Event-related potentials were simultaneously recorded with PET and showed significant task and electrode site effects on the N100 amplitude. When compared to REST, LIS elicited bilateral temporal activations of the Heschl's gyri and the planum temporale, with a significant rightward asymmetry, and of the posterior part of the superior temporal gyrus. Significant right precentral and anterior cingulate gyri normalized regional cerebral blood flow increases were observed in the frontal lobe. Both the ATTR and the ATTL conditions, compared to LIS, activated the supplementary motor area, bilateral precentral, and left postcentral cortices without any temporal cortex activation. In addition, the ATTL condition resulted in a right prefrontal cortex activation. Pooling the 14 subjects revealed an asymmetry in the superior temporal gyrus favoring the cortex contralateral to the attended ear. Two major networks seem thus to be involved during selective auditory attention: (1) a local temporal network, on which selective attention produces a modulation of the functional lateralization, and (2) a frontal network that could mediate the temporal cortex modulation by attention.
Adult↗
Mutations in human TBX5 [corrected] cause limb and cardiac malformation in Holt-Oram syndrome.
Holt-Oram syndrome is characterized by upper limb malformations and cardiac septation defects. Here, we demonstrate that mutations in the human TBX5 gene underlie this disorder. TBX5 was cloned from the disease locus on human chromosome 12q24.1 and identified as a member of the T-box transcription factor family. A nonsense mutation in TBX5 causes Holt-Oram syndrome in affected members of one family; a TBX5 missense mutation was identified in affected members of another. We conclude that TBX5 is critical for limb and heart development and suggest that haploinsufficiency of TBX5 causes Holt-Oram syndrome.
Abnormalities, Multiple↗
Physical mapping of the human neurotensin gene (NTS) between markers D12S1444 and D12S81 on chromosome 12q21.
Neurotensin (NTS) is an endogenous tridecapeptide of the central nervous system and the gastrointestinal tract of different mammalian species including human. The human gene encoding neurotensin has previously been assigned to chromosome 12 but no regional localization was available. We now confirm this assignment and place the NTS gene on the physical and cytogenetic maps. The NTS gene is located on a yeast artificial chromosome contig that contains several polymorphic markers and is close to a polymorphic marker located at 95.8 cM on the Généthon linkage map. NTS is immediately proximal to four polymorphic markers, including D12S81 (AFM102xg9) and D12S88 (AFM158yb4). Using fluorescence in situ hybridization, we map the gene cytogenetically to band 12q21.
Animals↗
Linkage of asthma and total serum IgE concentration to markers on chromosome 12q: evidence from Afro-Caribbean and Caucasian populations.
To identify genes potentially relevant in atopic asthma, we analyzed markers in chromosome 12q15-q24.1 for linkage to asthma and total serum IgE concentration. Sib-pair analyses of 10 markers in 345 full- and 219 half-sib pairs from 29 multiplex Afro-Caribbean families provided evidence for linkage to this region for both asthma and total serum IgE. Certain alleles at these loci showed significant evidence of transmission disequilibrium with both asthma and high IgE. Using 6 of these markers and 11 additional markers, evidence for linkage of total IgE to 12q was also found in 12 Caucasian Amish kindreds (24 nuclear families) by both sib-pair and transmission disequilibrium analyses. These findings suggest that the 12q15-q24.1 region may contain a gene(s) controlling asthma and the associated "high total IgE" trait.
Adolescent↗
Physical mapping of a commonly deleted region, the site of a candidate tumor suppressor gene, at 12q22 in human male germ cell tumors.
A candidate tumor suppressor gene (TSG) site at 12q22 characterized by a high frequency of loss of heterozygosity (LOH) and a homozygous deletion has previously been reported in human male germ cell tumors (GCTs). In a detailed deletion mapping analysis of 67 normal-tumor DNAs utilizing 20 polymorphic markers mapped to 12q22-q24, we identified the limits of the minimal region of deletion at 12q22 between D12S377 (proximal) and D12S296 (distal). We have constructed a YAC contig map of a 3-cM region of this band between the proximal marker D12S101 and the distal marker D12S346, which contained the minimal region of deletion in GCTs. The map is composed of 53 overlapping YACs and 3 cosmids onto which 25 polymorphic and nonpolymorphic sequence-tagged sites (STSs) were placed in a unique order. The size of the minimal region of deletion was approximately 2 Mb from overlapping, nonchimeric YACs that spanned the region. We also developed a radiation hybrid (RH) map of the region between D12S101 and D12S346 containing 17 loci. The consensus order developed by RH mapping is in good agreement with the YAC STS-content map order. The RH map estimated the distance between D12S101 and D12S346 to be 246 cR8000 and the minimal region of deletion to be 141 cR8000. In addition, four genes that were previously mapped to 12q22 have been excluded as candidate genes. The leads gained from the deletion mapping and physical maps should expedite the isolation and characterization of the TSG at 12q22.
Chromosomes, Human, Pair 12↗
Heterogeneity of information-processing alterations according to dimensions of depression: an event-related potentials study.
To identify alterations in elementary cognitive operations according to dimensions of depression, two stages of information processing, namely the response choice and the motor preparation stages, were explored using an event-related potential paradigm in two subgroups of depressed patients (retarded and blunted affect versus anxious-agitated and impulsive) compared to controls. Two results are common to all depressed patients: a slow encoding of stimuli (P1 wave) and a prolonged processing of stimulus-response compatibility (after P3b). This is compensated by a global velocity increase in stimulus evaluation or decision making (P3b) in anxious-agitated patients or, on the contrary, cumulated with its velocity decrease in retarded-blunted-affect patients. Such results could provide an explanation for the massive retardation observed in blunted-affect patients, contrary to anxious-agitated patients, whose normal reaction times may come from a very high energetical involvement at the P3b level. Results as a whole suggest that impairments in blunted-affect patients concern effort mechanisms, whereas those in anxious-agitated patients concern perceptual processes.
Adult↗
Depression as a dynamical disease.
Mathematical models are helpful in the understanding of diseases through the use of dynamical indicators. A previous study has shown that brain activity can be characterized by a decrease of dynamical complexity in depressive subjects. The present paper confirms and extends these conclusions through the use of recent methodological advances: first episode and recurrent patients strongly differ in their dynamical response to therapeutic interventions. These results emphasize the need for clinical follow-ups to avoid recurrence and the necessity of specific therapeutic intervention in the case of recurrent patients.
Adult↗