The development of print tuning in children with dyslexia: evidence from longitudinal ERP data supported by fMRI.

A consistent finding in functional brain imaging studies of reading with dyslexia is reduced inferior occipito-temporal activation linked to deviant processing of visual word forms. Time-sensitive event-related potentials (ERP) further revealed reduced inferior occipito-temporal N1 tuning for print in dyslexic 2nd graders suggesting the reduction affects fast processing and the initial development of dyslexia. Here, we followed up the same groups with ERP recordings and investigated how fast print tuning deficits in dyslexia develop from 2nd to 5th grade.

The left occipitotemporal system in reading: disruption of focal fMRI connectivity to left inferior frontal and inferior parietal language areas in children with dyslexia.

Developmental dyslexia is a severe reading disorder, which is characterized by dysfluent reading and impaired automaticity of visual word processing. Adults with dyslexia show functional deficits in several brain regions including the so-called "Visual Word Form Area" (VWFA), which is implicated in visual word processing and located within the larger left occipitotemporal VWF-System. The present study examines functional connections of the left occipitotemporal VWF-System with other major language areas in children with dyslexia.

Microstructural development: organizational differences of the fiber architecture between children and adults in dorsal and ventral visual streams.

Visual perceptual skills are basically mature by the age of 7 years. White matter, however, continues to develop until late adolescence. Here, we examined children (aged 5-7 years) and adults (aged 20-30 years) using diffusion tensor imaging (DTI) fiber tracking to investigate the microstructural maturation of the visual system.

Simultaneous EEG-fMRI during a working memory task: modulations in low and high frequency bands.

Background: EEG studies of working memory (WM) have demonstrated load dependent frequency band modulations. FMRI studies have localized load modulated activity to the dorsolateral prefrontal cortex (DLPFC), medial prefrontal cortex (MPFC), and posterior parietal cortex (PPC). Recently, an EEG-fMRI study found that low frequency band (theta and alpha) activity negatively correlated with the BOLD signal during the retention phase of a WM task.

Children with dyslexia lack multiple specializations along the visual word-form (VWF) system.

Developmental dyslexia has been associated with a dysfunction of a brain region in the left inferior occipitotemporal cortex, called the "visual word-form area" (VWFA). In adult normal readers, the VWFA is specialized for print processing and sensitive to the orthographic familiarity of letter strings. However, it is still unclear whether these two levels of occipitotemporal specialization are affected in developmental dyslexia.

Reading for meaning in dyslexic and young children: distinct neural pathways but common endpoints.

Developmental dyslexia is a highly prevalent and specific disorder of reading acquisition characterised by impaired reading fluency and comprehension. We have previously identified fMRI- and ERP-based neural markers of impaired sentence reading in dyslexia that indicated both deviant basic word processing and deviant semantic incongruency processing. However, it remained unclear how specific these impairments are for dyslexia, as they occurred when children with dyslexia (DYS) were compared to chronological age-matched controls (CA) who also differ in the amount of reading experience.

Neurophysiology in preschool improves behavioral prediction of reading ability throughout primary school.

Background: More struggling readers could profit from additional help at the beginning of reading acquisition if dyslexia prediction were more successful. Currently, prediction is based only on behavioral assessment of early phonological processing deficits associated with dyslexia, but it might be improved by adding brain-based measures.

Methods: In a 5-year longitudinal study of children with (n = 21) and without (n = 23) familial risk for dyslexia, we tested whether neurophysiological measures of automatic phoneme and tone deviance processing obtained in kindergarten would improve prediction of reading over behavioral measures alone.

Tuning of the visual word processing system: distinct developmental ERP and fMRI effects.

Visual tuning for words vs. symbol strings yields complementary increases of fast occipito-temporal activity (N1 or N170) in the event-related potential (ERP), and posterior-anterior gradients of increasing word-specific activity with functional magnetic resonance imaging (fMRI) in the visual word form system (VWFS). However, correlation of these coarse ERP and fMRI tuning responses seems limited to the most anterior part of the VWFS in adult and adolescent readers (Brem et al.

Role of dorsal and ventral stream development in biological motion perception.

Little is known about the functional development of dorsal and ventral visual streams. The right posterior superior temporal sulcus (pSTS) represents a pivotal point of the two streams and is involved in the perception of biological motion. Here, we compared brain activity between children (aged 5-7 years) and adults (aged 20-32 years) while they were viewing point-light dot animations of biological motion.

Impaired semantic processing during sentence reading in children with dyslexia: combined fMRI and ERP evidence.

Developmental dyslexia is a specific disorder of reading acquisition characterized by a phonological core deficit. Sentence reading is also impaired in dyslexic readers, but whether semantic processing deficits contribute is unclear. Combining spatially and temporally sensitive neuroimaging techniques to focus on semantic processing can provide a more comprehensive characterization of sentence reading in dyslexia.

Dorsal stream development in motion and structure-from-motion perception.

Little is known about the neural development underlying high order visual perception. For example, in detection of structures by coherently moving dots, motion information must interact with shape-based information to enable object recognition. Tasks involving these different motion-based discriminations are known to activate distinct specialized brain areas in adults.

Impaired tuning of a fast occipito-temporal response for print in dyslexic children learning to read.

Developmental dyslexia is defined as a disorder of learning to read. It is thus critical to examine the neural processes that impair learning to read during the early phase of reading acquisition, before compensatory mechanisms are adapted by older readers with dyslexia. Using electroencephalography-based event-related imaging, we investigated how tuning of visual activity for print advances in the same children before and after initial reading training in school.

Coarse neural tuning for print peaks when children learn to read.

Adult readers exhibit increased fast N1 activity to wordlike strings in their event-related brain potential. This increase has been linked to visual expertise for print, implying a protracted monotonic development. We investigated the development of coarse neural tuning for print by studying children longitudinally before and after learning to read, and comparing them to skilled adults.

Electrophysiological and hemodynamic evidence for late maturation of hand power grip and force control under visual feedback.

Several human imaging studies have described the neural network involved in power grip under visual control and the subset of cortical areas within this network that are sensitive to force modulation. As there is behavioral evidence for late maturation in even simple hand motor tasks involving visual feedback, we aimed at identifying the neural correlates of these developmental changes. Subjects from three developmental age groups (9-11, 15-17, and adults) performed the same power grip task in both a functional magnetic resonance imaging and an event-related potential (ERP) session.

Maturation of luminance- and motion-defined form perception beyond adolescence: a combined ERP and fMRI study.

Abilities to discriminate forms defined by motion continue to develop throughout childhood. To investigate late development of the visual motion system, we measured brain activity with event-related EEG potentials (ERPs) and functional magnetic resonance imaging (fMRI) in groups of adolescents (15-17 years) and adults (20-30 years) during a visual form discrimination task--with forms being either defined by motion or luminance contrast. We further explored whether possible developmental changes varied with the degree of motion coherence reflecting maturation specific to global motion processing.

Preserved aspects of cortical foot control in paraplegia.

While several recent imaging studies confirm that motor foot areas can still be activated in complete and chronic paraplegia, it remains unclear whether their functionality is also maintained or declines after years of "non-use". Force control is one of the most important and best investigated functions within the motor cortex. It has been repeatedly reported that the motor cortex is more active when higher forces have to be applied.

Emerging neurophysiological specialization for letter strings.

In adult readers, printed words and other letter strings activate specialized visual functions within 200 msec, as evident from neurophysiological recordings of brain activity. These fast, specialized responses to letter strings are thought to develop through plastic changes in the visual system. However, it is unknown whether this specialization emerges only with the onset of word reading, or represents a precursor of literacy.

Evidence for developmental changes in the visual word processing network beyond adolescence.

Late development of specialization in the visual word processing system was examined using event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) of word and symbol string processing in groups of adolescents (15.2-17.3 years) and adults (19.

Electrophysiological evidence for cortical plasticity with movement repetition.

The role of movement repetition and practice has been extensively studied as an aspect of motor skill learning but has rarely been investigated in its own right. As practice is considered a prerequisite for motor learning we expected that even the repetitive execution of a simple movement would rapidly induce changes in neural activations without changing performance. We used 64-channel event-related potential mapping to investigate these effects of movement repetition on corresponding brain activity in humans.

Neurophysiological signs of rapidly emerging visual expertise for symbol strings.

The current study examined whether the repeated visual presentation of novel, meaningless symbol strings triggers rapid changes in event related potentials (ERP). Adult participants performed three versions of a word and symbol string repetition detection task in the same experimental session. Analyses focussed on the occipito-temporal N1 (approximately 150 ms) known to reflect early word-specific processing and stimulus categorisation.

Altered responses to tone and phoneme mismatch in kindergartners at familial dyslexia risk.

Differences in automatic auditory processing between kindergartners with (n = 31) and without (n = 29) familial dyslexia risk were investigated using frequency and phoneme mismatch negativity (MMN) paradigms with small deviance and short intervals. During an early mismatch response segment children at risk tended to have more mid-frontal positivity than controls, especially to phoneme deviance. Significant group differences were found in the late MMN segment, where the mismatch response of children at risk was attenuated to frequency deviance and less left lateralised to phoneme deviance.

Development of the automatic mismatch response: from frontal positivity in kindergarten children to the mismatch negativity.

Objective: The automatic event-related potential (ERP) response to auditory deviance typically consists of a frontocentral mismatch negativity (MMN), which has been shown to be quite stable during development. Whereas in some infant studies, positive frontal mismatch responses have been reported instead of a MMN; to date, such positivities have not been reported for older children.

Methods: Oddball sequences with small frequency and phoneme deviance (standard: 1000 Hz, 'ba'; larger deviance: 1060 Hz, 'ta'; smaller deviance: 1030 Hz, 'da') and short intervals (every 0.