4 research outputs found
Development of auditory repetition effects with age : evidence from EEG time-frequency analysis
La preĢsentation reĢpeĢteĢe dāun son inconnu conduit aĢ des effets de reĢpeĢtition comprenant la suppression (ārepetition suppressionā ou RS) ou lāaugmentation (ārepetition enhancementā ou RE) de lāactiviteĢ neuronale. Ces pheĢnomeĢnes refleĢtent des meĢcanismes ceĢreĢbraux impliquant un apprentissage perceptuel. Lāobjectif de ce meĢmoire de maitrise eĢtait dāapporter une perspective deĢveloppementale de lāactiviteĢ ceĢreĢbrale sous-tendant lāapprentissage perceptuel auditif. LāEEG a eĢteĢ enregistreĢ chez 101 participants sains aĢgeĢs de 3 aĢ 40 ans pendant un paradigme auditif passif durant lequel 30 pseudo-mots eĢtaient reĢpeĢteĢs 6 fois chacun. Des analyses en temps- freĢquence ont eĢteĢ calculeĢes pour chaque reĢpeĢtition. La puissance spectrale enregistreĢes en EEG entre chaque reĢpeĢtition a eĢteĢ compareĢe au moyen de modeĢles lineĢaires mixtes. Les reĢsultats montrent quāun effet de reĢpeĢtition survient au cours du deĢveloppement mais varie en fonction de lāaĢge et des bandes de freĢquences. Du RS et RE ont eĢteĢ observeĢs aĢ tous les aĢges dans le theĢta bas et le gamma respectivement. Un effet deĢveloppemental a eĢteĢ trouveĢ de facĢ§on plus preĢcoce pour le RS dans le theĢta haut et de facĢ§on tardive pour le RE dans le theĢta bas. Ces reĢsultats montrent que les processus impliquant un apprentissage perceptif auditif, tel que le RS et le RE, suivent une trajectoire deĢveloppementale speĢcifique en fonction des rythmes ceĢreĢbraux. Les effets de reĢpeĢtition refleĢteraient diffeĢrents niveaux de traitement des stimuli qui se deĢvelopperaient de manieĢre indeĢpendante. Des recherches suppleĢmentaires seront neĢcessaires pour preĢciser le roĢle fonctionnel des effets de reĢpeĢtitions sur le deĢveloppement cognitif.The repeated presentation of unfamiliar sounds leads to repetition effects comprising repetition suppression (RS) and enhancement (RE) of neural activity. These phenomena reflect mechanisms involved in perceptual learning and are associated with a decrease or increase in EEG spectral powers. The objective of this Masterās thesis is to provide a developmental perspective of the cortical activity underlying auditory perceptual learning. EEG was recorded in 101 healthy participants ranging from 3 to 40 years during an auditory paradigm comprising 30 pseudowords repeated six times each. EEG time-frequency spectral power was calculated for each presentation and was compared to quantify repetition effects. Linear mixed model analysis revealed that some repetition effects occurred across ages and others varied with age in specific frequency bands. More precisely, RS and RE were found across ages in lower theta and gamma frequency bands respectively between the first and all subsequent pseudoword presentations. Developmental effects were seen in the RS observed in the higher theta/low alpha band and in the later occurring RE in the lower theta band. These results show that processes involved in auditory perceptual learning, such as RS and RE, are modulated by maturation. Further, repetition effects reflect different levels of stimulus processing and these levels seem to develop independently. More research is required to identify the exact functional roles of auditory repetitions effects on cognitive development
Effects of eight neuropsychiatric copy number variants on human brain structure
Many copy number variants (CNVs) confer risk for the same range of neurodevelopmental symptoms and psychiatric conditions including autism and schizophrenia. Yet, to date neuroimaging studies have typically been carried out one mutation at a time, showing that CNVs have large effects on brain anatomy. Here, we aimed to characterize and quantify the distinct brain morphometry effects and latent dimensions across 8 neuropsychiatric CNVs. We analyzed T1-weighted MRI data from clinically and non-clinically ascertained CNV carriers (deletion/duplication) at the 1q21.1 (nā=ā39/28), 16p11.2 (nā=ā87/78), 22q11.2 (nā=ā75/30), and 15q11.2 (nā=ā72/76) loci as well as 1296 non-carriers (controls). Case-control contrasts of all examined genomic loci demonstrated effects on brain anatomy, with deletions and duplications showing mirror effects at the global and regional levels. Although CNVs mainly showed distinct brain patterns, principal component analysis (PCA) loaded subsets of CNVs on two latent brain dimensions, which explained 32 and 29% of the variance of the 8 Cohenās d maps. The cingulate gyrus, insula, supplementary motor cortex, and cerebellum were identified by PCA and multi-view pattern learning as top regions contributing to latent dimension shared across subsets of CNVs. The large proportion of distinct CNV effects on brain morphology may explain the small neuroimaging effect sizes reported in polygenic psychiatric conditions. Nevertheless, latent gene brain morphology dimensions will help subgroup the rapidly expanding landscape of neuropsychiatric variants and dissect the heterogeneity of idiopathic conditions
Steady-state visual evoked potentials in children with neurofibromatosis type 1:associations with behavioral rating scales and impact of psychostimulant medication
BACKGROUND: Neurofibromatosis type 1 (NF1) is a genetic disorder often associated with cognitive dysfunctions, including a high occurrence of deficits in visuoperceptual skills. The neural underpinnings of these visuoperceptual deficits are not fully understood. We used steady-state visual evoked potentials (SSVEPs) to investigate possible alterations in the synchronization of neural activity in the occipital cortex of children with NF1. METHODS: SSVEPs were measured using electroencephalography and compared between children with NF1 (n = 28) and neurotypical controls (n = 28) aged between 4 and 13 years old. SSVEPs were recorded during visual stimulation with coloured icons flickering at three different frequencies (6 Hz, 10 Hz, and 15 Hz) and analyzed in terms of signal-to-noise ratios. A mixed design ANCOVA was performed to compare SSVEP responses between groups at the three stimulation frequencies. Pearsonās correlations with levels of intellectual functioning as well as with symptoms of ADHD, ASD and emotional/behavioral problems were performed. The impact of psychostimulant medication on the SSVEP responses was analyzed in a subset of the NF1 group (n = 8) with paired t-tests. RESULTS: We observed reduced signal-to-noise ratios of the SSVEP responses in children with NF1. The SSVEP responses were negatively correlated with symptoms of inattention and with symptoms of emotional/behavioral problems in the NF1 group. The SSVEP response generated by the lowest stimulation frequency (i.e., 6 Hz) was rescued with the intake of psychostimulant medication. CONCLUSIONS: Impaired processing of rhythmic visual stimulation was evidenced in children with NF1 through measures of SSVEP responses. Those responses seem to be more reduced in children with NF1 who exhibit more symptoms of inattention and emotional/behavioral problems in their daily life. SSVEPs are potentially sensitive electrophysiological markers that could be included in future studies investigating the impact of medication on brain activity and cognitive functioning in children with NF1. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s11689-022-09452-y
Effects of eight neuropsychiatric copy number variants on human brain structure.
Many copy number variants (CNVs) confer risk for the same range of neurodevelopmental symptoms and psychiatric conditions including autism and schizophrenia. Yet, to date neuroimaging studies have typically been carried out one mutation at a time, showing that CNVs have large effects on brain anatomy. Here, we aimed to characterize and quantify the distinct brain morphometry effects and latent dimensions across 8 neuropsychiatric CNVs. We analyzed T1-weighted MRI data from clinically and non-clinically ascertained CNV carriers (deletion/duplication) at the 1q21.1 (n = 39/28), 16p11.2 (n = 87/78), 22q11.2 (n = 75/30), and 15q11.2 (n = 72/76) loci as well as 1296 non-carriers (controls). Case-control contrasts of all examined genomic loci demonstrated effects on brain anatomy, with deletions and duplications showing mirror effects at the global and regional levels. Although CNVs mainly showed distinct brain patterns, principal component analysis (PCA) loaded subsets of CNVs on two latent brain dimensions, which explained 32 and 29% of the variance of the 8 Cohen's d maps. The cingulate gyrus, insula, supplementary motor cortex, and cerebellum were identified by PCA and multi-view pattern learning as top regions contributing to latent dimension shared across subsets of CNVs. The large proportion of distinct CNV effects on brain morphology may explain the small neuroimaging effect sizes reported in polygenic psychiatric conditions. Nevertheless, latent gene brain morphology dimensions will help subgroup the rapidly expanding landscape of neuropsychiatric variants and dissect the heterogeneity of idiopathic conditions