Mahdi Mahmoudzadeh

Mahdi Mahmoudzadeh
Université de Picardie Jules Verne | UPJV · INSERM U 1105, Medicine

PhD. HDR

About

97
Publications
12,695
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890
Citations
Additional affiliations
August 2008 - August 2009
Radboud University
Position
  • Researcher

Publications

Publications (97)
Article
Full-text available
Optically pumped magnetometers (OPMs) are new, room-temperature alternatives to superconducting quantum interference devices (SQUIDs) for measuring the brain’s magnetic fields. The most used OPM in MagnetoEncephaloGraphy (MEG) are based on alkali atoms operating in the spin-exchange relaxation-free (SERF) regime. These sensors do not require coolin...
Article
Full-text available
Temporal theta activity in coalescence with slow-wave (TTA-SW) is one of the first neurobiomarkers of the neurodevelopment of perisylvian networks in the electroencephalography (EEG). Dynamic changes in the microstructure and activity within neural networks are reflected in the EEG. Slow oscillation slope can reflect synaptic strength, and cross-fr...
Preprint
Full-text available
Background Autism spectrum disorder (ASD) is associated with atypical neural activity in resting-state. Most of the studies have focused on abnormalities in alpha-frequency, as a marker of ASD dysfunctions. However, few have explored alpha synchronization, with a specific interest in resting-state networks: the default mode network (DMN), the senso...
Article
Full-text available
The neonatal transition involves physiological modifications as a consequence of the complexity of the perinatal period. Various strategies can be used to attain the same level of postnatal cerebral oxygenation, depending on the status of the infant at birth. We evaluated such strategies by recording 20 full-term newborns by near-infrared spectrosc...
Preprint
Full-text available
Rhythm is a fundamental component of the auditory world, present even during the prenatal life. While there is evidence that some auditory capacities are already present before birth, whether and how the premature neural networks process auditory rhythm is yet not known. We investigated the neural response of premature neonates at 30-34 weeks gesta...
Article
Diffuse optical tomography is a non-invasive and non-irradiating medical imaging technique that is particularly suitable for cerebral monitoring of newborns since it can be used at the bedside of the patient. Here, a new model for optical tomography in the neonatal brain is presented that takes into account the presence of arachnoid trabeculæ in th...
Article
Objectives Reversal learning is widely used to analyze cognitive flexibility and characterize behavioral abnormalities associated with impulsivity and disinhibition. Recent studies using fMRI have focused on regions involved in reversal learning with negative and positive reinforcers. Although the frontal cortex has been consistently implicated in...
Article
Full-text available
Rhythm processing involves building expectations according to the hierarchical temporal structure of auditory events. Although rhythm processing has been addressed in the context of predictive coding, the properties of the oscillatory response in different cortical areas are still not clear. We explored the oscillatory properties of the neural resp...
Preprint
Full-text available
Background: Reversal learning is widely used to analyze cognitive flexibility and characterize behavioral abnormalities associated with impulsivity and disinhibition. Recent studies using fMRI have focused on regions involved in reversal learning with negative and positive reinforcers. Although the frontal cortex has been consistently implicated in...
Article
Full-text available
Subthalamic nucleus deep brain stimulation (STN-DBS) is an effective treatment for idiopathic Parkinson’s disease. Despite recent progress, the mechanisms responsible for the technique’s effectiveness have yet to be fully elucidated. The purpose of the present study was to gain new insights into the interactions between STN-DBS and cortical network...
Article
Full-text available
Interictal spikes (IISs) may result from a disturbance of the intimate functional balance between various neuronal (synaptic and non-synaptic), vascular, and metabolic compartments. To better characterize the complex interactions within these compartments at different scales we developed a simultaneous multimodal-multiscale approach and measure the...
Preprint
Full-text available
Rhythm processing involves building expectations according to the hierarchical temporal structure of auditory events. Although rhythm processing has been addressed in the context of predictive coding, the properties of the oscillatory response in different cortical areas is still not clear. We explored the oscillatory properties of the neural respo...
Article
Full-text available
Electroencephalography is the only clinically available technique that can address the premature neonate normal and pathological functional development week after week. The changes in the electroencephalogram (EEG) result from gradual structural and functional modifications that arise during the last trimester of pregnancy. Here, we review the stru...
Article
Full-text available
Behavioral data on episodic recollection in autism spectrum disorders (ASD) point limited relational memory functioning. However, the involvement of successive memory processes in the profile of episodic memory in ASD needs more study. Here, we used event‐related potentials (ERP) to investigate the time course of episodic recollection with an assoc...
Article
Full-text available
Functional responses recorded during the last trimester of gestation reveal that human sensory activity begins before birth, allowing the brain to process the external environment. Along with the maturation of the brain, new cognitive skills emerge in the human infant’s brain. The development of non-invasive techniques provides the opportunity to s...
Article
Full-text available
Objective: Characterization of the spatial and temporal dynamics of interictal epileptic discharges (IED) using time-frequency analysis (TFA) and electrical-source localization (ESL). Methods: TFA was performed on IED (spikes, spike waves, and polyspike waves) recorded by high-density-EEG (HD-EEG) in 19 refractory focal epileptic children. Temporal...
Article
Full-text available
Temporal theta slow‐wave activity (TTA‐SW) in premature infants is a specific neurobiomarker of the early neurodevelopment of perisylvian networks observed as early as 24 weeks of gestational age (wGA). It is present at the turning point between non‐sensory driven spontaneous networks and cortical network functioning. Despite its clinical importanc...
Article
Full-text available
The neonatal brain is an extremely dynamic organization undergoing essential development in terms of connectivity and function. Several functional imaging investigations of the developing brain have found neurovascular coupling (NVC) patterns that contrast with those observed in adults. These discrepancies are partly due to that NVC is still develo...
Data
MEDELOPT® - Systèmes diagnostiques de l’activité cérébrale issus des recherches hospitalo-universitaires amiénoises Mieux comprendre l’épilepsie, ou les Accidents Vasculaires Cérébraux est l’ambition de Medelopt®, premier casque d’imagerie cérébrale ambulatoire créé, au bout de 15 années de recherche en neurodéveloppement, au sein du Service d’Exp...
Article
Full-text available
Epilepsy with Centrotemporal Spikes (ECTS) is the most common form of self-limited focal epilepsy. The pathophysiological mechanisms by which ECTS induces neuropsychological impairment in 15–30% of affected children remain unclear. The objective of this study is to review the current state of knowledge concerning the brain structural and functional...
Article
Full-text available
Abstract Sensory development of the human brain begins prenatally, allowing cortical auditory responses to be recorded at an early age in preterm infants. Despite several studies focusing on the temporal characteristics of preterm infants’ cortical responses, few have been conducted on frequency analysis of these responses. In this study, we perfor...
Article
Full-text available
Background Epilepsy with Centrotemporal Spikes (ECTS) is the most common form of self-limited focal epilepsy. The pathophysiological mechanisms by which ECTS induces neuropsychological impairment in 30% of affected children remain unclear. Objectives The objective is to review the current state of knowledge concerning the brain structural and func...
Article
Background Temporal theta slow-wave activity (TTA-SW) in premature infants is a specific signature of the early development of temporal networks, as it is observed at the turning point between nonsensory driven spontaneous local processing and cortical network functioning. Previous studies have demonstrated that preterms from 28 weeks of gestationa...
Article
Background The early identification of preterm infants at high neurological risk is essential. EEG is the only functional tool, which allows evaluating the cerebral maturation during the neonatal period. One of the EEG neuro-biomarker is the length Burst Activity (BA) adjusted to Post-Menstrual Age (PMA). For extremely preterms, studies about the p...
Article
Background Spontaneous endogenous generators are key elements in immature systems. Theta activity (TA) and the coalescent slow waves (SW) occur from 25wGA and address the basic mechanisms of cross frequency interdependencies in oscillations that compose brain rhythms in premature. Objectives To evaluate the interactions between the two oscillation...
Article
Introduction Le cerveau du nouveau-né prématuré subit un processus dynamique de maturation avec la mise en place de générateurs spécifiques au cours de développement. L’activité thêta temporale est l’un des premiers neurobiomarqueurs. Le but de cette étude était de mieux caractériser les localisations des générateurs de ces activités. Méthodes Des...
Article
Objectives EEG-HR source localization is a non-invasive method to better delineate the source of the epileptic activity and thus the schema for electrodes implantation. Such source localization method relies on solving an inverse problem. In this study we evaluate the impact of bone conductivity, different head models and filtering, different metho...
Article
Objectives To better define the physiopathology of Interictal Epileptic Spikes (IES) and specially: (i) the mechanisms that propel neurons to hypersynchronizations, and (ii) the local and distant dynamic changes of neuronal population activities, we performed a time frequency analysis (TFA) of the surrounding activation of the IES. Methods HD EEG...
Article
Si le taux de survie des enfants prématurés a augmenté, cette population reste à haut risque de développer des troubles neurocognitifs, notamment pour les prématurités extrêmes. L’EEG est le meilleur outil d’exploration fonctionnelle cérébrale en période néonatale, en faisant un excellent examen prédictif du devenir neurodéveloppemental. Parmi ces...
Article
Introduction High Density electroencephalography (HD EEG) is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons t...
Article
Introduction Many questions concerning the mechanisms that drive neurons to hypersynchronize remain unsolved, but synaptic as well as non-synaptic events are likely to be involved. Here Optical Imaging (OI) of the epileptic brain by concomitant electroencephalography (FOS-ECoG/HD-EEG), allow investigating the changes in the cellular environment ass...
Article
Full-text available
Infancy is the most critical period in human brain development. Studies demonstrate that subtle brain abnormalities during this state of life may greatly affect the developmental processes of the newborn infants. One of the rapidly developing methods for early characterization of abnormal brain development is functional connectivity of the brain at...
Article
Full-text available
Intraventricular Hemorrhage (IVH) is the leading cause of neurological and cognitive impairment in preterm neonates with an incidence that increases with increasing prematurity. In the present study, we tested how preterm neonates with IVH react to external stimulation (i.e. speech syllables). We compared their neural responses measured by electroe...
Conference Paper
Using multimodal-multiscale analysis of Fast Optical, ECoG and HD-EEG data, we demonstrated complex changes in the dynamics of cortical networks at synaptic and non-synaptic level surrounding the interictal epileptic spike (IES).
Article
58th Annual Meeting of the Society-for-Psychophysiological-Research, Quebec City, CANADA, OCT 03-07, 2018
Article
The non-invasive multimodal analysis of brain function in the premature babies makes it possible to evaluate the implementation of neural networks involved in various functions such as language. The establishment of neural networks is the result of (1) initial genetic factors that participate in the structural and functional development of networks...
Article
Full-text available
Objective: Interictal epileptic spikes (IES) represent a signature of the transient synchronous and excessive discharge of a large ensemble of cortical heterogeneous neurons. Epilepsy cannot be reduced to a hypersynchronous activation of neurons whose functioning is impaired, resulting on electroencephalogram (EEG) in epileptic seizures or IES. Th...
Article
Preterm infants (born at 24–34 weeks of gestational age) suffer from a high incidence of neurological complications. Cerebrovascular lesions (intraventricular hemorrhages, IVH, and ischemic injury) due to the immaturity of the vascular system and its inability to adapt to the extra-uterine environment are the major causes of adverse neurological ou...
Article
The mechanisms of neuronal hypersynchronization during Interictal Epileptic Spikes (IES) remain unsolved. IES’s multimodal analysis figure out the dynamic of the neurovascular unit considering the interactions between the neuronal, vascular networks and the extra cellular space occurring around the IES. To evaluate these multiscale interactions, a...
Article
Objectives Although many studies in epilepsy have examined the synaptic mechanisms constituting the basis for most of the current principles of brain activity, relatively less studies have tried to characterize changes in the cellular environment that might predispose a network to pathologic synchronization. Methods In this study, near-infrared op...
Article
Objective Although infantile spasms can be caused by a variety of etiologies, the clinical features are stereotypical. The neuronal and vascular mechanisms that contribute to the emergence of infantile spasms are not well understood. Methods We performed a multimodal study by simultaneously recording electroencephalogram and functional Near-infrar...
Article
Full-text available
Objective High Density electroencephalography is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons to the hypers...
Article
Full-text available
Interictal spikes can be generated by blocking GABAA receptor-mediated inhibition. The nature of the hemodynamic activities associated with interictal spikes in acute models of focal epilepsy based on GABA deactivation has not been determined. We analyzed systemic changes in hemodynamic signals associated with interictal spikes generated by acute m...
Article
Full-text available
Although infantile spasms can be caused by a variety of etiologies, the clinical features are stereotypical. The neuronal and vascular mechanisms that contribute to the emergence of infantile spasms are not well understood. We performed a multimodal study by simultaneously recording electroencephalogram and functional Near-infrared spectroscopy in...
Article
Full-text available
The mechanisms responsible for coupling between relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative cerebral metabolic rate of oxygen (rCMRO2), an important function of the microcirculation in preterm infants, remain unclear. Identification of a causal relationship between rCBF-rCBV and rCBF-rCMRO2 in preterms m...
Article
Full-text available
Speech is a complex auditory stimulus which is processed according to several time-scales. Whereas consonant discrimination is required to resolve rapid acoustic events, voice perception relies on slower cues. Humans, right from preterm ages, are particularly efficient to encode temporal cues. To compare the capacities of preterms to those observed...
Article
Full-text available
Objective: High Density electroencephalography (HD EEG) is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons to...
Data
Transient change in Global Time-Frequency Representation (GTFR) in different scaling factors (800, 400, and 200%).
Data
Impact of varying slow wave amplitude on time-frequency analysis. (A) Simulated IES dipole in the right central sulcus, Locations, orientations. (B) Simulated IES with increasing slow wave amplitudes (0, 5, 10, 15, 20 nAm). (C) The simulated scalp IES in average reference format. The solid lines indicate the signal + noise wave forms generated by t...
Article
Full-text available
Objective: Interictal epileptic spikes (IESs), apart from being a key marker of epileptic neuronal networks, constitute a nice model of the widespread endogenous phenomenon of neuronal hypersynchronization. Many questions concerning the mechanisms that drive neurons to hypersynchronize remain unresolved, but synaptic as well as nonsynaptic events...
Article
Full-text available
Temporal theta slow-wave activity (TTA-SW) in premature infants is a specific signature of the early development of temporal networks, as it is observed at the turning point between non-sensory driven spontaneous local processing and cortical network functioning. The role in development and the precise location of TTA-SW remain unknown. Previous st...
Article
28th International Symposium on Cerebral Blood Flow, Metabolism and Function / 13th International Conference on Quantification of Brain Function with PET, Int Soc Cerebral Blood Flow & Metab, Berlin, GERMANY, APR 01-04, 2017
Article
18th World Congress of Psychophysiology of the International Organization of Psychophysiology (IOP), Havana, CUBA, AUG 31-SEP 04, 2016
Article
Full-text available
During the last trimester of human gestation, neurons reach their final destination and establish long- and short-distance connections. Due to the difficulties obtaining functional data at this age, the characteristics of the functional architecture at the onset of sensory thalamocortical connectivity in humans remain largely unknown. In particular...
Article
Full-text available
In this study, we investigated changes in functional connectivity (FC) of the brain networks in patients with benign epilepsy with centrotemporal spikes (BECTS) compared to healthy controls using high-density EEG data collected under eyes-closed resting state condition. EEG source reconstruction was performed with exact Low Resolution Electromagnet...
Article
Objectives There is increasing evidence that epilepsy might alter the brain connectivities. We investigated the changes in the brain connectivity in children with benign childhood epilepsy with centro-temporal spikes. Methods High density EEG data recorded from 8 patients and age-matched 9 controls with eyes closed. For controls five segments and...
Article
Full-text available
The propagation of laser light in human tissues is an important issue in functional optical imaging. We modeled the thermal effect of different laser powers with various spot sizes and different head tissue characteristics on neonatal and adult quasirealistic head models. The photothermal effect of near-infrared laser (800 nm) was investigated by n...
Conference Paper
Multimodal coregistration (fNIRS-EEG)offer unique opportunities for studying cerebral responses of preemies.In IntraVentricular Hemorrhage, it revealed weaker hemodynamic response which can provide early diagnosis of neurovascular coupling impairment