Models of atypical development must also be models of normal development

Functional magnetic resonance imaging studies of developmental disorders and normal cognition that include children are becoming increasingly common and represent part of a newly expanding field of developmental cognitive neuroscience. These studies have illustrated the importance of the process of development in understanding brain mechanisms underlying cognition and including children ill the study of the etiology of developmental disorders

Are developmental disorders like cases of adult brain damage? Implications from connectionist modelling

It is often assumed that similar domain-specific behavioural impairments found in cases of adult brain damage and developmental disorders correspond to similar underlying causes, and can serve as convergent evidence for the modular structure of the normal adult cognitive system. We argue that this correspondence is contingent on an unsupported assumption that atypical development can produce selective deficits while the rest of the system develops normally (Residual Normality), and that this assumption tends to bias data collection in the field. Based on a review of connectionist models of acquired and developmental disorders in the domains of reading and past tense, as well as on new simulations, we explore the computational viability of Residual Normality and the potential role of development in producing behavioural deficits. Simulations demonstrate that damage to a developmental model can produce very different effects depending on whether it occurs prior to or following the training process. Because developmental disorders typically involve damage prior to learning, we conclude that the developmental process is a key component of the explanation of endstate impairments in such disorders. Further simulations demonstrate that in simple connectionist learning systems, the assumption of Residual Normality is undermined by processes of compensation or alteration elsewhere in the system. We outline the precise computational conditions required for Residual Normality to hold in development, and suggest that in many cases it is an unlikely hypothesis. We conclude that in developmental disorders, inferences from behavioural deficits to underlying structure crucially depend on developmental conditions, and that the process of ontogenetic development cannot be ignored in constructing models of developmental disorders

Dyslexia Diagnosis by EEG Temporal and Spectral Descriptors: An Anomaly Detection Approach.

Diagnosis of learning difficulties is a challenging goal. There are huge number of factors involved in the evaluation procedure that present high variance among the population with the same difficulty. Diagnosis is usually performed by scoring subjects according to results obtained in different neuropsychological (performance-based) tests specifically designed to this end. One of the most frequent disorders is developmental dyslexia (DD), a specific difficulty in the acquisition of reading skills not related to mental age or inadequate schooling. Its prevalence is estimated between 5% and 12% of the population. Traditional tests for DD diagnosis aim to measure different behavioral variables involved in the reading process. In this paper, we propose a diagnostic method not based on behavioral variables but on involuntary neurophysiological responses to different auditory stimuli. The experiments performed use electroencephalography (EEG) signals to analyze the temporal behavior and the spectral content of the signal acquired from each electrode to extract relevant (temporal and spectral) features. Moreover, the relationship of the features extracted among electrodes allows to infer a connectivity-like model showing brain areas that process auditory stimuli in a synchronized way. Then an anomaly detection system based on the reconstruction residuals of an autoencoder using these features has been proposed. Hence, classification is performed by the proposed system based on the differences in the resulting connectivity models that have demonstrated to be a useful tool for differential diagnosis of DD as well as a method to step towards gaining a better knowledge of the brain processes involved in DD.This work was partly supported by the MINECO/FEDER under PGC2018-098813-B-C31, PGC2018-098813-B-C32 and PSI2015-65848-R projects. We gratefully acknowledge the support of NVIDIA Corporation with the donation of one of the GPUs used for this research. Work by F.J.M.M. was supported by the MICINN “Juan de la Cierva - Formaci´on” Fellowship. We also thank the Leeduca research group and Junta de Andaluc´ıa for the data supplied and the support

The role of the cerebellum in unconsciuos and conscious processing of emotions: a review

Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that subserve emotional processing, although conflicting data have been reported on its function in unconscious and conscious mechanisms. This review discusses the available clinical, neuroimaging and neurophysiological data on this issue. We also propose a model in which the cerebellum acts as a mediator between the internal state and external environment for the unconscious and conscious levels of emotional processing

Speech-brain synchronization: a possible cause for developmental dyslexia

152 p.Dyslexia is a neurological learning disability characterized by the difficulty in an individual¿s ability to read despite adequate intelligence and normal opportunities. The majority of dyslexic readers present phonological difficulties. The phonological difficulty most often associated with dyslexia is a deficit in phonological awareness, that is, the ability to hear and manipulate the sound structure of language. Some appealing theories of dyslexia attribute a causal role to auditory atypical oscillatory neural activity, suggesting it generates some of the phonological problems in dyslexia. These theories propose that auditory cortical oscillations of dyslexic individuals entrain less accurately to the spectral properties of auditory stimuli at distinct frequency bands (delta, theta and gamma) that are important for speech processing. Nevertheless, there are diverging hypotheses concerning the specific bands that would be disrupted in dyslexia, and which are the consequences of such difficulties on speech processing. The goal of the present PhD thesis was to portray the neural oscillatory basis underlying phonological difficulties in developmental dyslexia. We evaluated whether phonological deficits in developmental dyslexia are associated with impaired auditory entrainment to a specific frequency band. In that aim, we measured auditory neural synchronization to linguistic and non-linguistic auditory signals at different frequencies corresponding to key phonological units of speech (prosodic, syllabic and phonemic information). We found that dyslexic readers presented atypical neural entrainment to delta, theta and gamma frequency bands. Importantly, we showed that atypical entrainment to theta and gamma modulations in dyslexia could compromise perceptual computations during speech processing, while reduced delta entrainment in dyslexia could affect perceptual and attentional operations during speech processing. In addition, we characterized the links between the anatomy of the auditory cortex and its oscillatory responses, taking into account previous studies which have observed structural alterations in dyslexia. We observed that the cortical pruning in auditory regions was linked to a stronger sensitivity to gamma oscillation in skilled readers, but to stronger theta band sensitivity in dyslexic readers. Thus, we concluded that the left auditory regions might be specialized for processing phonological information at different time scales (phoneme vs. syllable) in skilled and dyslexic readers. Lastly, by assessing both children and adults on similar tasks, we provided the first evaluation of developmental modulations of typical and atypical auditory sampling (and their structural underpinnings). We found that atypical neural entrainment to delta, theta and gamma are present in dyslexia throughout the lifespan and is not modulated by reading experience

Parietal function in good and poor readers

BACKGROUND: While there are many psychophysical reports of impaired magnocellular pathway function in developmental dyslexia (DD), few have investigated parietal function, the major projection of this pathway, in good and poor readers closely matched for nonverbal intelligence. In view of new feedforward-feedback theories of visual processing, impaired magnocellular function raises the question of whether all visually-driven functions or only those associated with parietal cortex functions are equally impaired and if so, whether parietal performance is more closely related to general ability levels than reading ability. METHODS: Reading accuracy and performance on psychophysical tasks purported to selectively activate parietal cortex such as motion sensitivity, attentional tracking, and spatial localization was compared in 17 children with DD, 16 younger reading-age matched (RA) control children, and 46 good readers of similar chronological-age (CA) divided into CA-HighIQ and a CA-LowIQ matched to DD group nonverbal IQ. RESULTS: In the age-matched groups no significant differences were found between DD and CA controls on any of the tasks relating to parietal function, although performance of the DD group and their nonverbal IQ scores was always lower. As expected, CA and RA group comparisons indicated purported parietal functioning improves with age. No difference in performance was seen on any of the parietally driven tasks between the DD and age-nonverbal IQ matched groups, whereas performance differentiated the DD group from the age-matched, higher nonverbal IQ group on several such tasks. An unexpected statistical difference in performance between lower reading age (DD and RA children) and all higher reading age (CA) children was seen on a test of chromatic sensitivity, whereas when high and low nonverbal IQ normal readers were compared performance was not different CONCLUSION: The results indicate that performance on purported parietal functions improves with age and may be more associated with nonverbal mentation than reading accuracy. Performance on a cognitively demanding task, traditionally considered to rely on ventral stream functions, was more related to reading accuracy