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ABSTRACT: In this case study, two cystinosis-related uremic children were followed at the Department of Nephrology, University of Montreal Hospital Center Sainte-Justine. Pattern-reversal visual evoked potentials were recorded at two time points, during dialysis treatment (time 1) and after renal transplant (time 2). Data were compared with those obtained from a control group (n = 6). The P1 component was selected and analyzed as the electrophysiologic marker of interest. At time 1, P1 latency was delayed, and P1 amplitude was reduced compared with control subjects. Both responses fell within normal range after kidney transplantation. These results indicate that renal failure and dialysis are associated with abnormal visual evoked potentials in children with chronic renal failure, but such alterations of visual processing are reversible after kidney transplant.
Pediatric Neurology 06/2012; 46(6):390-2. · 1.52 Impact Factor
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ABSTRACT: Fragile X Syndrome (FXS) is the most common form of X-linked intellectual disability (ID), associated with a wide range of cognitive and behavioral impairments. FXS is caused by a trinucleotide repeat expansion in the FMR1 gene located on the X-chromosome. FMR1 is expected to prevent the expression of the "fragile X mental retardation protein (FMRP)", which results in altered structural and functional development of the synapse, including a loss of synaptic plasticity. This review aims to unveil the contribution of electrophysiological signal studies for the understanding of the information processing impairments in FXS patients. We discuss relevant event-related potential (ERP) studies conducted with full mutation FXS patients and clinical populations sharing symptoms with FXS in a developmental perspective. Specific deviances found in FXS ERP profiles are described. Alterations are reported in N1, P2, Mismatch Negativity (MMN), N2, and P3 components in FXS compared to healthy controls. Particularly, deviances in N1 and P2 amplitude seem to be specific to FXS. The presented results suggest a cascade of impaired information processes that are in line with symptoms and anatomical findings in FXS.
Frontiers in Human Neuroscience 01/2012; 6:264. · 2.34 Impact Factor
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ABSTRACT: Consequences of status epilepticus (SE) on psychomotor development and the specific impact of the convulsive event on emerging executive functions remain controversial. Infants treated for a single episode of SE, those treated for a single febrile seizure, and healthy infants were tested with respect to motor development, language, personal, and social skills and self-regulation. The children were divided into two age groups to investigate the impact of the convulsive event at different windows of brain maturation. We found that infants who had had SE were inferior to healthy controls on the development scales. Age differentiated SE impact on visuomotor development versus sociolinguistic development. Children who had been treated for SE had significantly more difficulties delaying a response to an attractive stimulus in one of the long-delay conditions. A single episode of SE can interfere with psychomotor and cognitive development in children without previous developmental delay, and it seems that the functions that are emerging at the time of insult are most vulnerable.
Epilepsy & Behavior 06/2011; 21(4):430-6. · 2.34 Impact Factor
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ABSTRACT: We followed the neuropsychological development of five children who underwent unilateral neurosurgery of the occipitoparietal lobes as a treatment for epilepsy caused by a developmental lesion (cortical dysplasia).
The follow-up period ranged from 3-7 years postsurgery.
Two participants had a verbal intelligence quotient (IQ) >100 and three had a verbal IQ between 65 and 80. All five children had abnormal nonverbal IQ and exhibited deficits related to visual attention, object recognition, and praxis. Nevertheless, our results suggest that brain plasticity after parietooccipital epilepsy surgery in young children allows for a schooling level of cognitive skills such as reading and arithmetic.
Although recovery for visual perceptual cognition was more limited than for verbal functions, long-term neuropsychological outcomes showed that early surgery for epilepsy offers the possibility of optimizing cognitive outcomes in children with posterior intractable epilepsies.
Epilepsia 10/2010; 51(10):2047-57. · 3.96 Impact Factor
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ABSTRACT: The consequences of febrile seizures (FSs) in infants are still a matter of debate. It is important to develop non-invasive tools to determine markers of brain function that could have predictive value for the outcome of FSs infants.Pattern visual evoked potentials (pVEPs) were recorded in 18 FS infants (mean age of seizure 15.97 months). Spectral density and coherence analyses were performed in infants evaluated at 1.1 month (n = 4), 5.75 months (n = 4) or 30.33 months (n = 6) following a prolonged FS and compared to age-matched healthy controls. The impact of severity of seizures was assessed by comparing the children who had prolonged FSs to 4 infants that had experienced a simple FS. Cognitive tests (Bayley, Stanford-Binet) were administered at the time of testing in FS and control children. Behavioural measures (Achenbach Child Behavior Check List) were administered two years after the FS. pVEP responses and coherence measures failed to yield significant differences between the FS groups and healthy controls. However, spectral density measures showed a significant increase in delta band activity in both FS groups and a reduced high frequency density only in the prolonged FS groups that was seen up to 39 months post-seizure. Behavioural and cognitive measures revealed cognitive development within average, but lower attentional capacities in the FS infants. The persistent changes in spectral density patterns seen in children with prolonged FS may reflect seizure induced alterations in the developing brain or a result of a complex mode of inheritance. Further studies are needed to determine whether these observations can be used as a marker to predict the vulnerability of the child in developing behavioral deficits or epilepsy.
Epileptic disorders: international epilepsy journal with videotape 04/2009; 11(1):10-9. · 1.50 Impact Factor
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ABSTRACT: Although several clinical trials have evaluated the impact of n-3 polyunsaturated fatty acid (PUFA) on patients with attention-deficit hyperactivity disorder (ADHD), changes in plasma PUFA composition were not always assessed following n-3 supplementation. Furthermore, no reports are available on the efficacy of n-3 PUFA in Canadian youth with ADHD.
To determine fatty acid (FA) composition, and the efficacy and safety of n-3 PUFA supplementation on ADHD clinical symptoms in French Canadian primary school children.
The Strengths and Weaknesses in ADHD and Normal Behaviors (SWAN) and Conners' questionnaires were used to assess changes in ADHD symptoms in 37 children (only 26 children completed the study from zero to 16 weeks). They were divided into two groups (A and B), and participated in a 16-week, double-blind, one-way, crossover randomized study. In the first phase, group A received the n-3 PUFA supplement and group B received n-6 PUFA (sunflower oil) as a placebo. During the second phase, group B received the active n-3 PUFA supplement that was continued in group A. FA composition and lipid profile were assessed during the phases of the study.
FA differences between groups were observed in the 26 patients. Supplementation with n-3 PUFA resulted in significant increases in eicosapentaenoic and docosahexaenoic acids in group A, while group B was enriched with alpha-linolenic, gamma-linolenic and homo-gamma-linolenic acids. The n-3 PUFA supplement was tolerated without any adverse effects. A statistically significant improvement in symptoms was noted based on the parent version of the Conners' questionnaire from baseline to the end of phase 1, and this amelioration continued from phases 1 to 2, although the latter changes from phases 1 and 2 were not statistically significant in any of the subscales except for the subscale measuring inattention in group B. The improvement was greater in patients from group A in phase 1 and in patients from group B in phase 2. A subgroup of eight patients (four in each group) displayed a statistically significant clinical improvement following the administration of the n-3 PUFA supplement, particularly for the inattention and global Diagnostic and Statistical Manual of Mental Disorders, Fourth edition, total Conners' subscales.
A subgroup of children with ADHD who used n-3 PUFA supplements achieved and maintained symptom control. The data of the present study also supported n-3 PUFA safety and tolerability, but limited changes were noted in the FA profile in French Canadians with ADHD.
Paediatrics & child health 03/2009; 14(2):89-98. · 0.78 Impact Factor
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ABSTRACT: Brain development carries with it a large number of structural changes at the local level which impact on the functional interactions of distributed neuronal networks for perceptual processing. Such changes enhance information processing capacity, which can be indexed by estimation of neural signal complexity. Here, we show that during development, EEG signal complexity increases from one month to 5 years of age in response to auditory and visual stimulation. However, the rates of change in complexity were not equivalent for the two responses. Infants' signal complexity for the visual condition was greater than auditory signal complexity, whereas adults showed the same level of complexity to both types of stimuli. The differential rates of complexity change may reflect a combination of innate and experiential factors on the structure and function of the two sensory systems.
Frontiers in Human Neuroscience 01/2009; 3:48. · 2.34 Impact Factor
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ABSTRACT: Acallosal participants usually do not display any disconnection signs in tasks requiring an explicit or declarative type of response. They can accurately compare stimuli placed in each hand and they perform normally on lateralized recognition tasks. They, however, show impairment in tasks assessing interdependent motor control, bilateral coordination and they are also unable to intermanually transfer an implicit procedural motor skill. These deficits suggest that compensation might be limited when a motor component is involved. Alternately, it is also possible that interhemispheric transmission in callosal agenesis might be limited when implicit or unconscious processes are involved (Berlucchi et al. in Neuropsychologia 33:923-936, 1995; De Guise et al. in Brain 122:1049-1062, 1999). The aim of the present study was to assess interhemispheric transfer in two distinct nondeclarative tasks, namely visuoperceptual skill learning and perceptual priming, with a lateralized version of the fragmented picture task developed by Snodgrass et al. (Behav Res Methods Inst Comp 19:270-274, 1987) that did not involve any motor component. The performance of five acallosal and one early-callosotomized individuals was compared to that of control participants divided into four groups (n = 10) according to which hemisphere was trained (left or right) and which response mode was used (manual or verbal). Visuoperceptual skill learning was observed in all control groups except for the group submitted to training of the left hemisphere in the manual modality of response. The acallosal and early-callosotomized participants did not show any implicit learning of the visuoperceptual skill on any of the conditions. The evaluation of the perceptual priming effect in the second part of the testing revealed that the priming effect was restricted to the trained hemisphere in participants without corpus callosum, as opposed to all neurogically intact participants who presented interhemispheric transfer of the priming effect. These findings indicate that the compensatory pathways, most probably subcortical commissures, are insufficient to allow interhemispheric transfer of perceptual priming, confirming the limits of neural plasticity in the absence of the corpus callosum. They also support the dissociation between declarative and nondeclarative memory in the split-brain and acallosal participants suggested by Berlucchi et al. (1995) and observed by De Guise et al. (Brain 122:1049-1062, 1999). These results are further discussed within the context of neurobiological theories of memory systems.
Experimental Brain Research 12/2008; 192(3):443-54. · 2.39 Impact Factor
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ABSTRACT: The visual system undergoes major modifications during the first year of life. We wanted to examine whether the magnocellular (M) and parvocellular (P) pathways mature at the same rate or if they follow a different developmental course. A previous study carried out in our laboratory had shown that the N1 and P1 components of pattern visual evoked potentials (PVEPs) were preferentially related to the activity of P and M pathways, respectively. In the present study, PVEPs were recorded at Oz in 33 infants aged between 0 and 52 weeks, in response to two spatial frequencies (0.5 and 2.5 c deg(-1)) presented at four contrast levels (4, 12, 28 and 95%). Results indicate that the P1 component appeared before the N1 component in the periods tested and was unambiguously present at birth. The P1 component showed a rapid gain in amplitude in the following months, to reach a ceiling around 4-6 months. Conversely, the N1 component always appeared later and then gained in amplitude until the end of the first year without reaching a plateau. Latencies were also computed but no developmental dissociation was revealed. Results obtained on amplitude are interpreted as demonstrating a developmental dissociation between the underlying M and P pathways, suggesting that the former is functional earlier and matures faster than the latter during the first year of life.
Documenta Ophthalmologica 12/2003; 107(3):225-33. · 2.11 Impact Factor
