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1.
Cereb Cortex ; 29(8): 3319-3330, 2019 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-30137241

RESUMO

Autism spectrum disorders (ASDs) are increasingly prevalent neurodevelopmental disorders characterized by sociocommunicative impairments. Growing consensus indicates that neurobehavioral abnormalities require explanation in terms of interconnected networks. Despite theoretical speculations about increased local and reduced distal connectivity, links between local and distal functional connectivity have not been systematically investigated in ASDs. Specifically, it remains open whether hypothesized local overconnectivity may reflect isolated versus overly integrative processing. Resting state functional MRI data from 57 children and adolescents with ASDs and 51 typically developing (TD) participants were included. In regional homogeneity (ReHo) analyses, pericalcarine visual cortex was found be locally overconnected (ASD > TD). Using this region as seed in whole-brain analyses, we observed overconnectivity in distal regions, specifically middle frontal gyri, for an ASD subgroup identified through k-means clustering. While in this subgroup local occipital to distal frontal overconnectivity was associated with greater symptom severity, a second subgroup showed the opposite pattern of connectivity and symptom severity correlations. Our findings suggest that increased local connectivity in ASDs is region-specific and may be partially associated with more integrative long-distance connectivity. Results also highlight the need to test for subtypes, as differential patterns of brain-behavior links were observed in two distinct subgroups of our ASD cohort.


Assuntos
Transtorno Autístico/diagnóstico por imagem , Córtex Pré-Frontal/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem , Adolescente , Transtorno do Espectro Autista/diagnóstico por imagem , Transtorno do Espectro Autista/fisiopatologia , Transtorno Autístico/fisiopatologia , Estudos de Casos e Controles , Criança , Comunicação , Feminino , Lobo Frontal/diagnóstico por imagem , Lobo Frontal/fisiopatologia , Neuroimagem Funcional , Humanos , Imageamento por Ressonância Magnética , Masculino , Vias Neurais/diagnóstico por imagem , Vias Neurais/fisiopatologia , Lobo Occipital/diagnóstico por imagem , Lobo Occipital/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Índice de Gravidade de Doença , Comportamento Social , Comportamento Estereotipado , Córtex Visual/fisiopatologia
2.
Hum Brain Mapp ; 40(8): 2377-2389, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30681228

RESUMO

There is ample evidence of atypical functional connectivity (FC) in autism spectrum disorders (ASDs). However, transient relationships between neural networks cannot be captured by conventional static FC analyses. Dynamic FC (dFC) approaches have been used to identify repeating, transient connectivity patterns ("states"), revealing spatiotemporal network properties not observable in static FC. Recent studies have found atypical dFC in ASDs, but questions remain about the nature of group differences in transient connectivity, and the degree to which states persist or change over time. This study aimed to: (a) describe and relate static and dynamic FC in typical development and ASDs, (b) describe group differences in transient states and compare them with static FC patterns, and (c) examine temporal stability and flexibility between identified states. Resting-state functional magnetic resonance imaging (fMRI) data were collected from 62 ASD and 57 typically developing (TD) children and adolescents. Whole-brain, data-driven regions of interest were derived from group independent component analysis. Sliding window analysis and k-means clustering were used to explore dFC and identify transient states. Across all regions, static overconnnectivity and increased variability over time in ASDs predominated. Furthermore, significant patterns of group differences emerged in two transient states that were not observed in the static FC matrix, with group differences in one state primarily involving sensory and motor networks, and in the other involving higher-order cognition networks. Default mode network segregation was significantly reduced in ASDs in both states. Results highlight that dynamic approaches may reveal more nuanced transient patterns of atypical FC in ASDs.


Assuntos
Transtorno do Espectro Autista/fisiopatologia , Encéfalo/fisiopatologia , Conectoma , Rede Nervosa/fisiopatologia , Adolescente , Transtorno do Espectro Autista/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Criança , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/diagnóstico por imagem
3.
Dev Psychobiol ; 60(3): 256-264, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29355936

RESUMO

Assessing language development in the first postnatal year is difficult, as receptive and expressive skills are rudimentary. Although outward manifestations of change are limited, the auditory language system is thought to undergo critical development at this age, as the foundations are laid for the rapid onset of spoken language in the second and third years. We recruited 11 infants, 7 healthy controls (gestational age = 40.69 ± 0.56; range from 40 to 41.43) and preterm babies (gestational age = 28.04 ± 0.95; range from 27.43 to 29.43) who underwent a Magnetic Resonance Imaging study during the first postnatal year (age at scan = 194.18 ± 97.98). We assessed white matter tracts using diffusion-weighted magnetic resonance imaging with probabilistic tractography. Fractional anisotropy was found to be largely mature even at one month, although there was a little further increase during the first postnatal year in both the acoustic radiation and the direct brainstem-Heschl's pathway.


Assuntos
Vias Auditivas/diagnóstico por imagem , Vias Auditivas/crescimento & desenvolvimento , Desenvolvimento Infantil , Imagem de Difusão por Ressonância Magnética/métodos , Recém-Nascido Prematuro , Substância Branca/diagnóstico por imagem , Substância Branca/crescimento & desenvolvimento , Feminino , Humanos , Lactente , Recém-Nascido Prematuro/crescimento & desenvolvimento , Masculino
4.
Neuroimage ; 157: 623-634, 2017 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-28648887

RESUMO

Functional neuroimaging has been used to show that the developing auditory cortex of very young human infants responds, in some way, to sound. However, impoverished stimuli and uncontrolled designs have made it difficult to attribute brain responses to specific auditory features, and thus made it difficult to assess the maturity of feature tuning in auditory cortex. To address this, we used functional magnetic resonance imaging (fMRI) to measure the brain activity evoked by naturalistic sounds (a series of sung lullabies) in two groups of infants (3 and 9 months) and adults. We developed a novel analysis method - inter-subject regression (ISR) - to quantify the similarity of cortical responses between infants and adults, and to decompose components of the response due to different auditory features. We found that the temporal pattern of activity in infant auditory cortex shared similarity with adults. Some of this shared response could be attributed to simple acoustic features, such as frequency, pitch, envelope, but other parts were not, suggesting that even more complex adult-like features are represented in auditory cortex in early infancy.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Desenvolvimento Infantil/fisiologia , Neuroimagem Funcional/métodos , Adulto , Córtex Auditivo/diagnóstico por imagem , Feminino , Humanos , Lactente , Imageamento por Ressonância Magnética , Masculino , Fatores de Tempo
5.
J Pediatr ; 189: 213-217.e1, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28735979

RESUMO

We studied developmental plasticity using functional magnetic resonance imaging (fMRI) in a preterm infant with brain injury on structural MRI. fMRI showed preserved brain function and subsequent neurodevelopment was within the normal range. Multimodal neuroimaging including fMRI can improve understanding of neural plasticity after preterm birth and brain injury.


Assuntos
Lesões Encefálicas/diagnóstico , Encéfalo/patologia , Deficiências do Desenvolvimento/diagnóstico , Imageamento por Ressonância Magnética/métodos , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Masculino
6.
J Cogn Neurosci ; 27(7): 1322-33, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25603030

RESUMO

Auditory cortex is the first cortical region of the human brain to process sounds. However, it has recently been shown that its neurons also fire in the absence of direct sensory input, during memory maintenance and imagery. This has commonly been taken to reflect neural coding of the same acoustic information as during the perception of sound. However, the results of the current study suggest that the type of information encoded in auditory cortex is highly flexible. During perception and memory maintenance, neural activity patterns are stimulus specific, reflecting individual sound properties. Auditory imagery of the same sounds evokes similar overall activity in auditory cortex as perception. However, during imagery abstracted, categorical information is encoded in the neural patterns, particularly when individuals are experiencing more vivid imagery. This highlights the necessity to move beyond traditional "brain mapping" inference in human neuroimaging, which assumes common regional activation implies similar mental representations.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Imaginação/fisiologia , Memória de Curto Prazo/fisiologia , Estimulação Acústica/métodos , Adulto , Mapeamento Encefálico , Feminino , Humanos , Individualidade , Imageamento por Ressonância Magnética , Masculino , Testes Neuropsicológicos , Adulto Jovem
7.
Proc Natl Acad Sci U S A ; 108(31): 12961-6, 2011 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-21768383

RESUMO

Philosophers and scientists have puzzled for millennia over how perceptual information is stored in short-term memory. Some have suggested that early sensory representations are involved, but their precise role has remained unclear. The current study asks whether auditory cortex shows sustained frequency-specific activation while sounds are maintained in short-term memory using high-resolution functional MRI (fMRI). Investigating short-term memory representations within regions of human auditory cortex with fMRI has been difficult because of their small size and high anatomical variability between subjects. However, we overcame these constraints by using multivoxel pattern analysis. It clearly revealed frequency-specific activity during the encoding phase of a change detection task, and the degree of this frequency-specific activation was positively related to performance in the task. Although the sounds had to be maintained in memory, activity in auditory cortex was significantly suppressed. Strikingly, patterns of activity in this maintenance period correlated negatively with the patterns evoked by the same frequencies during encoding. Furthermore, individuals who used a rehearsal strategy to remember the sounds showed reduced frequency-specific suppression during the maintenance period. Although negative activations are often disregarded in fMRI research, our findings imply that decreases in blood oxygenation level-dependent response carry important stimulus-specific information and can be related to cognitive processes. We hypothesize that, during auditory change detection, frequency-specific suppression protects short-term memory representations from being overwritten by inhibiting the encoding of interfering sounds.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Memória de Curto Prazo/fisiologia , Estimulação Acústica , Adulto , Análise de Variância , Córtex Auditivo/anatomia & histologia , Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Desempenho Psicomotor/fisiologia , Análise e Desempenho de Tarefas , Adulto Jovem
8.
Cortex ; 171: 423-434, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-38109835

RESUMO

The absence of speech is a clinical phenotype seen across neurodevelopmental syndromes, offering insights for neural language models. We present a case of bilateral perisylvian polymicrogyria (BPP) and complete absence of speech with considerable language comprehension and production difficulties. We extensively characterized the auditory speech perception and production circuitry by employing a multimodal neuroimaging approach. Results showed extensive cortical thickening in motor and auditory-language regions. The auditory cortex lacked sensitivity to speech stimuli despite relatively preserved thalamic projections yet had no intrinsic functional organization. Subcortical structures implicated in early stages of processing exhibited heightened sensitivity to speech. The arcuate fasciculus, a suggested marker of language in BPP, showed similar volume and integrity to a healthy control. The frontal aslant tract, linked to oromotor function, was partially reconstructed. These findings highlight the importance of assessing the auditory cortex beyond speech production structures to understand absent speech in BPP. Despite profound cortical alterations, the intrinsic motor network and motor-speech pathways remained largely intact. This case underscores the need for comprehensive phenotyping using multiple MRI modalities to uncover causes of severe disruption in language development.


Assuntos
Anormalidades Múltiplas , Córtex Auditivo , Deficiência Intelectual , Malformações do Desenvolvimento Cortical , Polimicrogiria , Percepção da Fala , Humanos , Córtex Auditivo/fisiologia , Fala/fisiologia , Percepção da Fala/fisiologia , Imageamento por Ressonância Magnética/métodos , Fenótipo
9.
Brain Behav ; 14(6): e3594, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38849980

RESUMO

INTRODUCTION: In vivo myeloarchitectonic mapping based on Magnetic Resonance Imaging (MRI) provides a unique view of gray matter myelin content and offers information complementary to other morphological indices commonly employed in studies of autism spectrum disorder (ASD). The current study sought to determine if intracortical myelin content (MC) and its age-related trajectories differ between middle aged to older adults with ASD and age-matched typical comparison participants. METHODS: Data from 30 individuals with ASD and 36 age-matched typical comparison participants aged 40-70 years were analyzed. Given substantial heterogeneity in both etiology and outcomes in ASD, we utilized both group-level and subject-level analysis approaches to test for signs of atypical intracortical MC as estimated by T1w/T2w ratio. RESULTS: Group-level analyses showed no significant differences in average T1w/T2w ratio or its associations with age between groups, but revealed significant positive main effects of age bilaterally, with T1w/T2w ratio increasing with age across much of the cortex. In subject-level analyses, participants were classified into subgroups based on presence or absence of clusters of aberrant T1w/T2w ratio, and lower neuropsychological function was observed in the ASD subgroup with atypically high T1w/T2w ratio in spatially heterogeneous cortical regions. These differences were observed across several neuropsychological domains, including overall intellectual functioning, processing speed, and aspects of executive function. CONCLUSIONS: The group-level and subject-level approaches employed here demonstrate the value of examining inter-individual variability and provide important preliminary insights into relationships between brain structure and cognition in the second half of the lifespan in ASD, suggesting shared factors contributing to atypical intracortical myelin content and poorer cognitive outcomes for a subset of middle aged to older autistic adults. These atypicalities likely reflect diverse histories of neurodevelopmental deficits, and possible compensatory changes, compounded by processes of aging, and may serve as useful markers of vulnerability to further cognitive decline in older adults with ASD.


Assuntos
Transtorno do Espectro Autista , Imageamento por Ressonância Magnética , Bainha de Mielina , Humanos , Masculino , Feminino , Idoso , Pessoa de Meia-Idade , Bainha de Mielina/patologia , Transtorno do Espectro Autista/diagnóstico por imagem , Transtorno do Espectro Autista/fisiopatologia , Transtorno do Espectro Autista/metabolismo , Transtorno do Espectro Autista/patologia , Adulto , Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/patologia , Córtex Cerebral/fisiopatologia , Testes Neuropsicológicos , Envelhecimento/fisiologia , Envelhecimento/patologia
10.
Hum Brain Mapp ; 33(2): 387-97, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21391273

RESUMO

A key challenge of object recognition is achieving a balance between selectivity for relevant features and invariance to irrelevant ones. Computational and cognitive models predict that optimal selectivity for features will differ by object, and here we investigate whether this is reflected in visual representations in the human ventral stream. We describe a new real-time neuroimaging method, dynamically adaptive imaging (DAI), that enabled measurement of neural selectivity along multiple feature dimensions in the neighborhood of single referent objects. The neural response evoked by a referent was compared to that evoked by 91 naturalistic objects using multi-voxel pattern analysis. Iteratively, the objects evoking the most similar responses were selected and presented again, to converge upon a subset that characterizes the referent's "neural neighborhood." This was used to derive the feature selectivity of the response. For three different referents, we found strikingly different selectivity, both in individual features and in the balance of tuning to sensory versus semantic features. Additional analyses placed a lower bound on the number of distinct activation patterns present. The results suggest that either the degree of specificity available for object representation in the ventral stream varies by class, or that different objects evoke different processing strategies.


Assuntos
Reconhecimento Visual de Modelos/fisiologia , Percepção Visual/fisiologia , Adulto , Mapeamento Encefálico , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Neuroimagem , Semântica
11.
Brain Connect ; 12(3): 234-245, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34102876

RESUMO

Background/Introduction: Autism spectrum disorder (ASD) is characterized by atypical functional connectivity (FC) within and between distributed brain networks. However, FC findings have often been inconsistent, possibly due to a focus on static FC rather than brain dynamics. Lagged connectivity analyses aim at evaluating temporal latency, and presumably neural propagation, between regions. This approach may, therefore, reveal a more detailed picture of network organization in ASD than traditional FC methods. Methods: The current study evaluated whole-brain lag patterns in adolescents with ASD (n = 28) and their typically developing peers (n = 22). Functional magnetic resonance imaging data were collected during rest and during a lexico-semantic decision task. Optimal lag was calculated for each pair of regions of interest by using cross-covariance, and mean latency projections were calculated for each region. Results: Latency projections did not regionally differ between groups, with the same regions emerging among the "earliest" and "latest." Although many of the longest absolute latencies were preserved across resting-state and task conditions, lag patterns overall were affected by condition, as many regions shifted toward zero-lag during task performance. Lag structure was also strongly associated with literature-derived estimates of arterial transit time. Discussion: Results suggest that lag patterns are broadly typical in ASD but undergo changes during task performance. Moreover, lag patterns appear to reflect a combination of neural and vascular sources, which should be carefully considered when interpreting lagged FC. Impact statement Altered brain dynamics have been proposed in autism spectrum disorder (ASD). Lagged functional connectivity analysis uses cross-correlation between functional magnetic resonance imaging (fMRI) time series to determine regional latency. Few studies have examined blood oxygen level-dependent (BOLD) lag in ASD, and findings have been inconsistent. Using multi-echo fMRI data with improved artifact detection and removal, we find differences in lag structure between task and rest states, but not between adolescents with ASD and typically developing peers. Additional analyses exploring links with arterial transit time, however, highlight the impact of vascular organization on BOLD lag patterns and its potential to confound measures of neural dynamics.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Adolescente , Transtorno do Espectro Autista/diagnóstico por imagem , Transtorno Autístico/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico/métodos , Humanos , Imageamento por Ressonância Magnética/métodos , Vias Neurais , Saturação de Oxigênio , Descanso
12.
Cortex ; 153: 110-125, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35640320

RESUMO

Individuals with autism spectrum disorder (ASD) frequently present with impairments in motor skills (e.g., limb coordination, handwriting and balance), which are observed across the lifespan but remain largely untreated. Many adults with ASD may thus experience adverse motor outcomes in aging, when physical decline naturally occurs. The 'hand knob' of the sensorimotor cortex is an area that is critical for motor control of the fingers and hands. However, this region has received little attention in ASD research, especially in adults after midlife. The hand knob area of the precentral (PrChand) and postcentral (PoChand) gyri was semi-manually delineated in 49 right-handed adults (25 ASD, 24 typical comparison [TC] participants, aged 41-70 years). Using multimodal (T1-weighted, diffusion-weighted, and resting-state functional) MRI, we examined the morphology, ipsilateral connectivity and laterality of these regions. We also explored correlations between hand knob measures with motor skills and autism symptoms, and between structural and functional connectivity measures. Bayesian analyses indicated moderate evidence of group effects with greater right PrChand volume and reduced leftward laterality of PrChand and PoChand volume in the ASD relative to TC group. Furthermore, the right PoC-PrChand u-fibers showed increased mean diffusivity in the ASD group. In the ASD group, right u-fiber volume positively correlated with corresponding functional connectivity but did not survive multiple comparisons correction. Correlations of hand knob measures and behavior were observed in the ASD group but did not survive multiple comparisons correction. Our findings suggest that morphological laterality and u-fiber connectivity of the sensorimotor network, putatively involved in hand motor/premotor function, may be diminished in middle-aged adults with ASD, perhaps rendering them more vulnerable to motor decline in old age. The altered morphology may relate to atypical functional motor asymmetries found in ASD earlier in life, possibly reflecting altered functional asymmetries over time.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Substância Branca , Adulto , Teorema de Bayes , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade
13.
Brain Connect ; 10(1): 18-28, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31884804

RESUMO

Autism spectrum disorders (ASDs) have been linked to atypical communication among distributed brain networks. However, despite decades of research, the exact nature of these differences between typically developing (TD) individuals and those with ASDs remains unclear. ASDs have been widely studied using resting-state neuroimaging methods, including both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). However, little is known about how fMRI and EEG measures of spontaneous brain activity are related in ASDs. In the present study, two cohorts of children and adolescents underwent resting-state EEG (n = 38 per group) or fMRI (n = 66 ASD, 57 TD), with a subset of individuals in both the EEG and fMRI cohorts (n = 17 per group). In the EEG cohort, parieto-occipital EEG alpha power was found to be reduced in ASDs. In the fMRI cohort, blood oxygen level-dependent (BOLD) power was regionally increased in right temporal regions and there was widespread overconnectivity between the thalamus and cortical regions in the ASD group relative to the TD group. Finally, multimodal analyses indicated that while TD children showed consistently positive relationships between EEG alpha power and regional BOLD power, these associations were weak or negative in ASDs. These findings suggest atypical links between alpha rhythms and regional BOLD activity in ASDs, possibly implicating neural substrates and processes that coordinate thalamocortical regulation of the alpha rhythm.


Assuntos
Transtorno do Espectro Autista/diagnóstico por imagem , Transtorno do Espectro Autista/fisiopatologia , Adolescente , Ritmo alfa/fisiologia , Transtorno do Espectro Autista/metabolismo , Transtorno Autístico/diagnóstico por imagem , Transtorno Autístico/fisiopatologia , Encéfalo/fisiopatologia , Mapeamento Encefálico/métodos , Criança , Eletroencefalografia/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Tálamo/fisiopatologia
14.
Artigo em Inglês | MEDLINE | ID: mdl-30343132

RESUMO

BACKGROUND: Functional magnetic resonance imaging research on autism spectrum disorders (ASDs) has been largely limited to individuals with near-average intelligence. Although cognitive impairment is common in ASDs, functional network connectivity in this population remains poorly understood. Specifically, it remains unknown whether lower-functioning individuals exhibit exacerbated connectivity abnormalities similar to those previously detected in higher-functioning samples or specific divergent patterns of connectivity. METHODS: Resting-state functional magnetic resonance imaging data from 88 children (44 ASD, 44 typically developing; average age: 11 years) were included. Based on IQ, individuals with ASDs were assigned to either a lower-functioning group (mean IQ = 77 ± 6) or a higher-functioning group (mean IQ = 123 ± 8). Two typically developing comparison groups were matched to these groups on head motion, handedness, and age. Seeds in the medial prefrontal cortex, posterior cingulate cortex, posterior superior temporal sulcus, insula, and amygdala were used to contrast whole-brain functional connectivity across groups. RESULTS: Lower-functioning ASD participants (compared with higher-functioning ASD participants) showed significant underconnectivity within the default mode network and the ventral visual stream. Higher-functioning ASD participants (compared with matched typically developing participants) showed significantly decreased anticorrelations among default mode, salience, and task-positive regions. Effect sizes of detected differences were large (Cohen's d > 1.46). CONCLUSIONS: Lower- and higher-functioning individuals with ASDs demonstrated distinct patterns of atypical connectivity. Findings suggest a gross pattern of predominantly reduced network integration in lower-functioning ASDs (affecting default mode and visual networks) and predominantly reduced network segregation in higher-functioning ASDs. Results indicate the need for stratification by general functional level in studies of functional connectivity in ASDs.


Assuntos
Transtorno do Espectro Autista/fisiopatologia , Transtorno do Espectro Autista/psicologia , Encéfalo/fisiopatologia , Inteligência , Adolescente , Criança , Feminino , Humanos , Testes de Inteligência , Masculino , Vias Neurais/fisiopatologia , Índice de Gravidade de Doença
15.
Dev Cogn Neurosci ; 33: 194-205, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29158073

RESUMO

Functional MRI (fMRI) in infants is rapidly growing and providing fundamental insights into the origins of brain functions. Comparing brain development at different ages is particularly powerful, but there are a number of methodological challenges that must be addressed if confounds are to be avoided. With development, brains change in composition in a way that alters their tissue contrast, and in size, shape, and gyrification, requiring careful image processing strategies and age-specific standard templates. The hemodynamic response and other aspects of physiology change with age, requiring careful paradigm design and analysis methods. Infants move more, particularly around the second year of age, and move in a different way to adults. This movement can lead to distortion in fMRI images, and requires tailored techniques during acquisition and post-processing. Infants have different sleep patterns, and their sensory periphery is changing macroscopically and in its neural pathways. Finally, once data have been acquired and analyzed, there are important considerations during mapping of brain processes and cognitive functions across age groups. In summary, new methods are critical to the comparison across age groups, and key to maximizing the rate at which infant fMRI can provide insight into the fascinating questions about the origin of cognition.


Assuntos
Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Imageamento por Ressonância Magnética/métodos , Fatores Etários , Feminino , Humanos , Lactente , Recém-Nascido , Masculino
16.
J Am Acad Child Adolesc Psychiatry ; 57(10): 764-774.e3, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30274651

RESUMO

OBJECTIVE: Converging evidence indicates that brain abnormalities in autism spectrum disorders (ASDs) involve atypical network connectivity. Given the central role of social deficits in the ASD phenotype, this investigation examined functional connectivity of the amygdala-a brain structure critically involved in processing of social information-in children and adolescents with ASDs, as well as age-dependent changes and links with clinical symptoms. METHOD: Resting-state functional magnetic resonance imaging (rs-fMRI) data from 55 participants with ASDs and 50 typically developing (TD) controls, aged 7 to 17 years, were included. Groups were matched for age, gender, IQ, and head motion. Functional connectivity MRI (fcMRI) analysis was applied to examine intrinsic functional connectivity (iFC) of the amygdala, including cross-sectional tests of age-related changes. RESULTS: Direct between-group comparisons revealed reduced functional connectivity between bilateral amygdalae and left inferior occipital cortex, accompanied by greater connectivity between right amygdala and right sensorimotor cortex in the ASD group. This atypical pattern of amygdala connectivity was associated with decreased symptom severity and better overall functioning, as specifically seen in an ASD subgroup with the most atypical amygdala iFC but the least impaired social functioning. Age-related strengthening of amygdala-prefrontal connectivity, as observed in the TD group, was not detected in children with ASDs. CONCLUSION: Findings support aberrant network sculpting in ASDs, specifically atypical integration between amygdala and primary sensorimotor circuits. Paradoxical links between atypical iFC and behavioral measures suggest that abnormal amygdala functional connections may be compensatory in some individuals with ASDs.


Assuntos
Tonsila do Cerebelo/fisiopatologia , Transtorno Autístico/fisiopatologia , Conectoma , Rede Nervosa/fisiopatologia , Índice de Gravidade de Doença , Adolescente , Córtex Cerebral/fisiopatologia , Estudos Transversais , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino
17.
Hear Res ; 366: 75-81, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30029804

RESUMO

From their second year, infants typically begin to show rapid acquisition of receptive and expressive language. Here, we ask why these language skills do not begin to develop earlier. One evolutionary hypothesis is that infants are born when many brains systems are immature and not yet functioning, including those critical to language, because human infants have large have a large head and their mother's pelvis size is limited, necessitating an early birth. An alternative proposal, inspired by discoveries in machine learning, is that the language systems are mature enough to function but need auditory experience to develop effective representations of speech, before the language functions that manifest in behaviour can emerge. Growing evidence, in particular from neuroimaging, is supporting this latter hypothesis. We have previously shown with magnetic resonance imaging (MRI) that the acoustic radiation, carrying rich information to auditory cortex, is largely mature by 1 month, and using functional MRI (fMRI) that auditory cortex is processing many complex features of natural sounds by 3 months. However, speech perception relies upon a network of regions beyond auditory cortex, and it is not established if this network is mature. Here we measure the maturity of the speech network using functional connectivity with fMRI in infants at 3 months (N = 6) and 9 months (N = 7), and in an adult comparison group (N = 15). We find that functional connectivity in speech networks is mature at 3 months, suggesting that the delay in the onset of language is not due to brain immaturity but rather to the time needed to develop representations through experience. Future avenues for the study of language development are proposed, and the implications for clinical care and infant education are discussed.


Assuntos
Desenvolvimento da Linguagem , Adulto , Fatores Etários , Córtex Auditivo/diagnóstico por imagem , Córtex Auditivo/crescimento & desenvolvimento , Córtex Auditivo/fisiologia , Vias Auditivas/diagnóstico por imagem , Vias Auditivas/crescimento & desenvolvimento , Vias Auditivas/fisiologia , Conectoma , Feminino , Neuroimagem Funcional , Humanos , Lactente , Imageamento por Ressonância Magnética , Masculino , Modelos Neurológicos , Modelos Psicológicos , Percepção da Fala/fisiologia , Adulto Jovem
18.
Dev Cogn Neurosci ; 29: 117-126, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28223033

RESUMO

Autism spectrum disorder (ASD) is a complex and prevalent neurodevelopmental disorder characterized by social and communicative deficits, as well as repetitive behaviors and atypical sensitivity to sensory stimulation. Alterations in network connectivity are widely recognized, but their interplay with social and sensory symptoms remains largely unclear. Here, functional magnetic resonance imaging and diagnostic and behavioral assessments were used in a cohort of children and adolescents with ASD (n=40) and matched typically developing (TD, n=38) controls to examine the relation between auditory processing, interhemispheric and thalamocortical network connectivity, and social-behavioral symptom severity. We found that atypical processing of sounds was related to social, cognitive, and communicative impairments. Additionally, severity of sensory processing deficits and lower verbal IQ were related to reduced interhemispheric connectivity of auditory cortices in ASD. Increased connectivity between the thalamus and auditory cortex in ASD, however, was associated with reduced cognitive and behavioral symptomatology, suggesting that thalamocortical overconnectivity might reflect a compensatory mechanism in ASD. These findings provide novel evidence for links between auditory sensory deficits and impairments in social interaction and communication.


Assuntos
Córtex Auditivo/fisiopatologia , Percepção Auditiva , Transtorno do Espectro Autista/fisiopatologia , Transtorno do Espectro Autista/psicologia , Comportamento Social , Tálamo/fisiopatologia , Adolescente , Transtorno do Espectro Autista/diagnóstico , Criança , Estudos de Coortes , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino
19.
Dev Neurobiol ; 78(5): 456-473, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29266810

RESUMO

Atypical functional connectivity has been implicated in autism spectrum disorders (ASDs). However, the literature to date has been largely inconsistent, with mixed and conflicting reports of hypo- and hyper-connectivity. These discrepancies are partly due to differences between various neuroimaging modalities. Functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and magnetoencephalography (MEG) measure distinct indices of functional connectivity (e.g., blood-oxygenation level-dependent [BOLD] signal vs. electrical activity). Furthermore, each method has unique benefits and disadvantages with respect to spatial and temporal resolution, vulnerability to specific artifacts, and practical implementation. Thus far, functional connectivity research on ASDs has remained almost exclusively unimodal; therefore, interpreting findings across modalities remains a challenge. Multimodal integration of fMRI, EEG, and MEG data is critical in resolving discrepancies in the literature, and working toward a unifying framework for interpreting past and future findings. This review aims to provide a theoretical foundation for future multimodal research on ASDs. First, we will discuss the merits and shortcomings of several popular theories in ASD functional connectivity research, using examples from the literature to date. Next, the neurophysiological relationships between imaging modalities, including their relationship with invasive neural recordings, will be reviewed. Finally, methodological approaches to multimodal data integration will be presented, and their future application to ASDs will be discussed. Analyses relating transient patterns of neural activity ("states") are particularly promising. This strategy provides a comparable measure across modalities, captures complex spatiotemporal patterns, and is a natural extension of recent dynamic fMRI research in ASDs. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 456-473, 2018.


Assuntos
Transtorno do Espectro Autista/diagnóstico por imagem , Transtorno do Espectro Autista/fisiopatologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Imagem Multimodal/métodos , Animais , Humanos , Vias Neurais/diagnóstico por imagem , Vias Neurais/fisiopatologia
20.
Neuroimage Clin ; 18: 399-406, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29487797

RESUMO

Objective: Functional connectivity magnetic resonance imaging (fcMRI) of neonates with perinatal brain injury could improve prediction of motor impairment before symptoms manifest, and establish how early brain organization relates to subsequent development. This cohort study is the first to describe and quantitatively assess functional brain networks and their relation to later motor skills in neonates with a diverse range of perinatal brain injuries. Methods: Infants (n = 65, included in final analyses: n = 53) were recruited from the neonatal intensive care unit (NICU) and were stratified based on their age at birth (premature vs. term), and on whether neuropathology was diagnosed from structural MRI. Functional brain networks and a measure of disruption to functional connectivity were obtained from 14 min of fcMRI acquired during natural sleep at term-equivalent age. Results: Disruption to connectivity of the somatomotor and frontoparietal executive networks predicted motor impairment at 4 and 8 months. This disruption in functional connectivity was not found to be driven by differences between clinical groups, or by any of the specific measures we captured to describe the clinical course. Conclusion: fcMRI was predictive over and above other clinical measures available at discharge from the NICU, including structural MRI. Motor learning was affected by disruption to somatomotor networks, but also frontoparietal executive networks, which supports the functional importance of these networks in early development. Disruption to these two networks might be best addressed by distinct intervention strategies.


Assuntos
Lesões Encefálicas/complicações , Encéfalo/diagnóstico por imagem , Transtornos das Habilidades Motoras/etiologia , Vias Neurais/diagnóstico por imagem , Transtornos do Neurodesenvolvimento/etiologia , Fatores Etários , Criança , Estudos de Coortes , Feminino , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Imageamento por Ressonância Magnética , Masculino , Transtornos das Habilidades Motoras/patologia , Transtornos do Neurodesenvolvimento/diagnóstico por imagem , Transtornos do Neurodesenvolvimento/patologia
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