RESUMO
Developmental dyslexia is a specific learning disorder with impairments in reading and spelling acquisition. Apart from literacy problems, dyslexics show inefficient speech encoding and deficient novel word learning, with underlying problems in phonological processing and learning. These problems have been suggested to be related to deficient specialization of the left hemisphere for language processing. To examine this possibility, we tracked with magnetoencephalography (MEG) the activation of the bilateral temporal cortices during formation of neural memory traces for new spoken word forms in 7-8-year-old children with high familial dyslexia risk and in controls. The at-risk children improved equally to their peers in overt repetition of recurring new word forms, but were poorer in explicit recognition of the recurring word forms. Both groups showed reduced activation for the recurring word forms 400-1200 ms after word onset in the right auditory cortex, replicating the results of our previous study on typically developing children (Nora et al., 2017, Children show right-lateralized effects of spoken word-form learning. PLoS ONE 12(2): e0171034). However, only the control group consistently showed a similar reduction of activation for recurring word forms in the left temporal areas. The results highlight the importance of left-hemispheric phonological processing for efficient phonological representations and its disruption in dyslexia.
Assuntos
Dislexia/fisiopatologia , Lateralidade Funcional/fisiologia , Memória/fisiologia , Fonética , Fala/fisiologia , Aprendizagem Verbal/fisiologia , Criança , Dislexia/diagnóstico , Feminino , Humanos , Magnetoencefalografia/métodos , Masculino , Leitura , Fatores de RiscoRESUMO
OBJECTIVE: While previous data link the use of postmenopausal hormone therapy to an increased risk for ovarian cancer, little is known about the impact of various progestins, modes or routes of administration of hormone therapy for this risk. In this nationwide study, we compared relations between different estradiol-progestin (EPT) formulations and epithelial ovarian cancer risk. METHODS: All Finnish women over 50 years using EPT for at least 6 months (224 015 women with 602 ovarian cancers) during 1994-2006 were identified from the reimbursement register. The incidence of ovarian cancer in EPT users was compared to that in the age-matched background population by means of observed to expected ratio (standardized incidence ratio, SIR). RESULTS: Ovarian cancer risk was not elevated for EPT use of < 5 years but it was elevated for EPT use of ≥5 years (SIR 1.21, 95% confidence interval (CI) 1.06-1.37). Medroxyprogesterone acetate and norethisterone acetate as components of EPT were associated with similar risks for use for ≥ 5 years (SIR 1.26, 95% CI 0.94-1.64 and SIR 1.42, 95% CI 1.11-1.77, respectively). The risk did not differ between sequential or continuous EPT regimens or between oral or transdermal EPT formulations. The risk elevation for EPT use for ≥ 5 years was seen only for serous (SIR 1.56; 95% CI 1.33-1.80) and mixed cancers (SIR 1.54; 95% CI 1.22-1.91), whereas the risk for mucinous cancer was decreased (SIR 0.47; 95% CI 0.22-0.86). CONCLUSION: The elevated risk of non-mucinous ovarian cancer in users of EPT ≥ 5 years does not depend on progestin type, mode or route of administration of EPT.
Assuntos
Terapia de Reposição de Estrogênios , Neoplasias Císticas, Mucinosas e Serosas/epidemiologia , Neoplasias Ovarianas/epidemiologia , Pós-Menopausa , Idoso , Idoso de 80 Anos ou mais , Intervalos de Confiança , Estradiol/administração & dosagem , Terapia de Reposição de Estrogênios/efeitos adversos , Feminino , Finlândia/epidemiologia , Humanos , Incidência , Acetato de Medroxiprogesterona/administração & dosagem , Pessoa de Meia-Idade , Neoplasias Císticas, Mucinosas e Serosas/induzido quimicamente , Noretindrona/administração & dosagem , Noretindrona/análogos & derivados , Acetato de Noretindrona , Neoplasias Ovarianas/induzido quimicamente , Progestinas/administração & dosagem , Medição de Risco , Fatores de TempoRESUMO
OBJECTIVE: The purpose of the present study was to investigate whether children with reading disabilities (RD) process rise time and pitch changes differently to control children as a function of the interval between two tones. METHODS: Children participated in passive oddball event-related potential (ERP) measurements using paired stimuli. Mismatch negativity (MMN), P3a and late discriminative negativity (LDN) responses to rise time and pitch changes were examined. RESULTS: Control children produced larger responses than children with RD to pitch change in the P3a component but only when the sounds in the pair were close to each other. Compared to children with RD, MMN was smaller and LDN larger in control children in response to rise time change when the sounds in the pair were further apart. The non-overlap in ERP measures between the groups was 40-50%. CONCLUSIONS: Problems in rapid processing of pitch change were reflected in a component associated with attention switching while amplitude envelope processing problems were reflected in components associated with stimulus detection or discrimination. SIGNIFICANCE: Children with RD process both rise time and pitch changes differently from control children thus providing evidence for the nature of amplitude envelope processing and rapid auditory processing deficits in dyslexia.
Assuntos
Variação Contingente Negativa/fisiologia , Dislexia/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Discriminação da Altura Tonal/fisiologia , Tempo de Reação/fisiologia , Estimulação Acústica/métodos , Mapeamento Encefálico , Criança , Eletroencefalografia , Feminino , Humanos , Masculino , Análise Multivariada , Testes Neuropsicológicos , Leitura , Fatores de TempoRESUMO
OBJECTIVE: The effects of within stimulus presentation rate and rise time on basic auditory processing were investigated in children with reading disabilities and typically reading children. METHODS: Children with reading disabilities (RD; N=19) and control children (N=20) were studied using event-related potentials (ERPs). Paired stimuli were used with two different within-pair-intervals (WPI; 10 and 255 ms) and two different rise times (10 and 130 ms). Each stimulus was presented with equal probability and long between-pair inter-stimulus intervals (1-5s). The study focused on N1 and P2 components. RESULTS: The P2 responses to the first tone in the pair showed differences between children with RD and control children. Also, children with RD had larger N1 response than control children to stimuli with short WPI and long rise time. CONCLUSIONS: These results provide evidence for basic auditory processing abnormalities in children with RD. This processing difference could be related to extraction of stimulus features from sounds or to attentional mechanisms. SIGNIFICANCE: Our results show support for behavioral findings that children with RD and control children process rise times differently. More than half of children with RD showed atypical auditory processing.
Assuntos
Dislexia/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Estimulação Acústica , Análise de Variância , Atenção , Percepção Auditiva/fisiologia , Criança , Eletroencefalografia , Feminino , Lateralidade Funcional/fisiologia , Humanos , Testes de Inteligência , Masculino , Testes Neuropsicológicos , Análise de Componente Principal , LeituraRESUMO
Developmental dyslexia is a distinct learning disability with unexpected difficulty in learning to read despite adequate intelligence, education, and environment, and normal senses. The genetic aetiology of dyslexia is heterogeneous and loci on chromosomes 2, 3, 6, 15, and 18 have been repeatedly linked to it. We have conducted a genome scan with 376 markers in 11 families with 38 dyslexic subjects ascertained in Finland. Linkage of dyslexia to the vicinity of DYX3 on 2p was confirmed with a non-parametric linkage (NPL) score of 2.55 and a lod score of 3.01 for a dominant model, and a novel locus on 7q32 close to the SPCH1 locus was suggested with an NPL score of 2.77. The SPCH1 locus has previously been linked with a severe speech and language disorder and autism, and a mutation in exon 14 of the FOXP2 gene on 7q32 has been identified in one large pedigree. Because the language disorder associated with the SPCH1 locus has some overlap with the language deficits observed in dyslexia, we sequenced the coding region of FOXP2 as a candidate gene for our observed linkage in six dyslexic subjects. No mutations were identified. We conclude that DYX3 appears to be important for dyslexia susceptibility in many Finnish families, and a suggested linkage of dyslexia to chromosome 7q32 will need verification in other data sets.
Assuntos
Mapeamento Cromossômico , Cromossomos Humanos Par 2/genética , Cromossomos Humanos Par 7/genética , Dislexia/genética , Fatores de Transcrição , Análise Mutacional de DNA , Feminino , Finlândia , Fatores de Transcrição Forkhead , Genoma Humano , Genótipo , Humanos , Escore Lod , Masculino , Linhagem , Proteínas Repressoras/genéticaRESUMO
Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia or compensated dyslexia and a control group performed a detection task with sound pairs of different rise times. Results showed that the participants with dyslexia differed from the control group in rise time detection and a correlation was found between rise time detection and reading and phonological skills. A subgroup of participants with lower sensitivity to rise time detection characterized by low accuracy in syllable-level phonological skills was found within the dyslexic group. Short stimuli containing only one rise time produced associations with phonological skills and reading, even in a language where the perception of rise time contrasts are not crucial for the signaling of phonemic contrast.
Assuntos
Dislexia/fisiopatologia , Percepção Sonora , Estimulação Acústica , Adulto , Escrita Manual , Humanos , Reconhecimento Visual de Modelos , Fonética , Tempo de Reação , LeituraRESUMO
Previous studies have demonstrated that motor activity during sleep is lateralized to the nondominant hand. There are two basic theories concerning this phenomenon: 1) The nondominant hemisphere is nonspecifically more alert or responsive than the dominant one, and 2) the lateralization to the nondominant side is task specific, reflecting the spatially oriented mode of information processing that is responsible for movements during sleep. We examined the motor responses to auditory stimuli during waking and sleep of 10 right-handed healthy subjects, who were instructed to switch off a tone stimulus by pressing a transducer that was attached to each hand. Sleep stage scoring was performed according to Rechtschaffen and Kales's criteria. During wakefulness and in all stages of sleep, with and without alpha activity occurring after stimulus onset, the dominant hand was used more, but during nonrapid eye movement S1 sleep the difference was not statistically significant. When alpha activity was present in the electroencephalogram after stimulus onset, the responses were significantly more lateralized to the right hand than when there was no alpha activity. During an actimetric home recording of both wrists of the subjects, there was an excess of left-sided movements during sleep as compared to waking. The results do not support the idea that the right hemisphere is generally more responsive than the left during sleep. They are, however, in accordance with the hypothesis that spatial information processing is a crucial factor in the nondominant lateralization of spontaneous sleep movements.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Nível de Alerta/fisiologia , Dominância Cerebral/fisiologia , Atividade Motora/fisiologia , Privação do Sono/fisiologia , Fases do Sono/fisiologia , Estimulação Acústica , Adolescente , Adulto , Atenção/fisiologia , Córtex Cerebral/fisiologia , Feminino , Lateralidade Funcional/fisiologia , Humanos , Masculino , Desempenho Psicomotor/fisiologia , Sono REM/fisiologia , Vigília/fisiologiaRESUMO
We investigated the relationship between hemodynamic and other autonomically mediated responses to experimentally induced mental stress and the parameters of the insulin resistance syndrome (IRS) in 48 healthy adolescent boys. Mental stress was induced with mental arithmetic and the Stroop Color-Word Test. Heart rate (HR), finger blood volume (FBV), and skin conductance level (SCL) were recorded continuously during task performance. IRS parameters measured were serum insulin, high-density lipoprotein (HDL) cholesterol, serum triglyceride (TG), systolic blood pressure (SBP), subscapular skinfold (SSF), and subscapular to triceps skinfold ratio (STR). The results indicated that a high level and an increasing linear trend of HR and FBV during task performance were related, independently of each other and of body mass index (BMI), to a high insulin concentration. An increasing linear trend of HR during mental stress was also related to high SSFs independently of MI. In addition, a high SCL during task performance was associated with high TG levels, SSFs, and STRs. It is discussed whether stress-induced sympathetic overactivity might contribute to the development of the IRS.
Assuntos
Sistema Nervoso Autônomo/fisiopatologia , Resistência à Insulina , Estresse Psicológico/fisiopatologia , Adolescente , Antropometria , Estudos de Coortes , Feminino , Humanos , Masculino , Estudos ProspectivosRESUMO
In order to study the event-related potential correlates of human ability to detect temporal changes within a continuous sound a sound consisting of two alternating pitches of the same constant duration, with infrequent shortenings of one of the tones, was presented to the subjects. The infrequent shortenings were found to elicit a negative component of the auditory event related potential, called the mismatch negativity (MMN). The experimental parameters were chosen to produce a MMN with a minimal contamination of N1, the main negative deflection of an evoked response with the same latency range as MMN and with a short experimental time. The duration of the whole experiment with three different deviant tones was only 11 min. The fast experiment is useful for subjects, for whom a long experiment may be too demanding (infants or patients).
Assuntos
Encéfalo/fisiologia , Potenciais Evocados Auditivos/fisiologia , Estimulação Acústica , Adulto , Discriminação Psicológica , Eletroencefalografia , Humanos , Som , Fatores de TempoRESUMO
Potential use of different auditory evoked brain responses for determining cerebral lateralization of speech function was evaluated. Cortical magnetic fields elicited by plosive syllables or complex non-speech sounds analogous to them were recorded with 122-channel magnetometer. We estimated parameters of magnetic P1, N1 and P2 responses to both stimuli in the two hemispheres and found no hemispheric asymmetry for any of the responses. No correlation between the right-ear advantage, determined with dichotic listening test, and any of asymmetry indexes, calculated for the speech-elicited responses, was observed. These results suggest that P1, N1 and P2 responses to speech signals do not indicate lateralization of speech function in the brain. The results are discussed in relation to previous studies suggesting that the mismatch negativity (MMN) seems to be the only early auditory cortex response sensitive to the lateralization of speech function.
Assuntos
Córtex Auditivo/fisiologia , Campos Eletromagnéticos , Potenciais Evocados/fisiologia , Lateralidade Funcional/fisiologia , Percepção da Fala/fisiologia , Adolescente , Adulto , Córtex Auditivo/anatomia & histologia , Feminino , Humanos , Masculino , Tempo de Reação/fisiologiaRESUMO
Infants born to families with a background of developmental dyslexia have an increased risk of becoming dyslexic. In our previous study no major group or stimulus effects in the event-related potentials (ERPs) of at-risk and control infants were found until the age of 6 months. However, in the current study, when we made the stimulus presentation rate slower, the ERPs to the short deviant /ka/ were different from those to the long standard /kaa/ stimulus already in newborns. In addition, clear group differences in the ERPs were found. The results demonstrate that infants born with a high familial risk for dyslexia process speech/auditory stimulus durations differently from control infants at birth.
Assuntos
Dislexia/genética , Estimulação Acústica/métodos , Córtex Cerebral/fisiopatologia , Potenciais Somatossensoriais Evocados/fisiologia , Humanos , Lactente , Recém-Nascido , Fonética , Valores de Referência , Fatores de Risco , Fatores de TempoRESUMO
We studied the brain's reactions to deviations in the duration of a stop consonant using event-related potentials in an oddball paradigm. A naturally produced nonsense word was used as a frequent standard stimulus which differed from two infrequently presented deviant stimuli only by the duration of the silence period inside the stop, making the consonant sound longer. Evoked responses to the deviant stimuli showed sharply rising negativity after the unexpected prolongation of the silence and a later negativity, the duration of which was related to the timing of the beginning of the second part of the deviant sound. This later negativity is, at least partly, elicited by a mismatch process to the omission of a sound at the expected latency.
Assuntos
Encéfalo/fisiologia , Potenciais Evocados Auditivos/fisiologia , Fala , Estimulação Acústica , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Fatores de TempoRESUMO
We studied auditory event-related potentials (ERP) in newborns and 6-month-old infants, about half of whom had a familial risk for dyslexia. Syllables varying in vowel duration were presented in an oddball paradigm, in which ERPs to deviating stimuli are assumed to reflect automatic change detection in the brain. The ERPs of newborns had slow positive deflections typical of their age, but significant stimulus and group effects were found only by the age of 6 months. In both groups, the responses to the deviant /ka/ were more positive than those to the standard /kaa/ stimuli, contrary to the findings of adult ERPs to duration changes. The results also suggested differences in brain activation pattern between the groups.
Assuntos
Envelhecimento/fisiologia , Córtex Cerebral/fisiologia , Dislexia/genética , Potenciais Evocados Auditivos/fisiologia , Estimulação Acústica/métodos , Humanos , Lactente , Recém-Nascido , Fonética , Valores de Referência , Fatores de RiscoRESUMO
Comparisons of the developmental pathways of the first 5 years of life for children with (N = 107) and without (N = 93) familial risk for dyslexia observed in the Jyväskylä Longitudinal study of Dyslexia are reviewed. The earliest differences between groups were found at the ages of a few days and at 6 months in brain event-related potential responses to speech sounds and in head-turn responses (at 6 months), conditioned to reflect categorical perception of speech stimuli. The development of vocalization and motor behavior, based on parental report of the time of reaching significant milestones, or the growth of vocabulary (using the MacArthur Communicative Development Inventories) failed to reveal differences before age 2. Similarly, no group differences were found in cognitive and language development assessed by the Bayley Scales of Infant Development and the Reynell Developmental Language Scales before age 2.5. The earliest language measure that showed lower scores among the at-risk group was maximum sentence length at age 2. Early gross motor development had higher correlation to later language skills among the at-risk group rather than the control children. The most consistent predictor of differential development between groups was the onset of talking. Children who were identified as late talkers at age 2 were still delayed at the age 3.5 in most features of language-related skills-but only if they belonged to the group at familial risk for dyslexia. Several phonological and naming measures known to correlate with reading from preschool age differentiated the groups consistently from age 3.5. Our findings imply that a marked proportion of children at familial risk for dyslexia follow atypical neurodevelopmental paths. The signs listed previously comprise a pool of candidates for early predictors and precursors of dyslexia, which await validation.
Assuntos
Deficiências do Desenvolvimento/genética , Dislexia/genética , Criança , Pré-Escolar , Deficiências do Desenvolvimento/diagnóstico , Dislexia/diagnóstico , Predisposição Genética para Doença/genética , Humanos , Lactente , Recém-Nascido , Transtornos do Desenvolvimento da Linguagem/diagnóstico , Transtornos do Desenvolvimento da Linguagem/genética , Estudos Longitudinais , RiscoRESUMO
Posture control during aiming over a period of 7.5 s preceding the shot was studied among national top-level rifle shooters as well as among national level shooters and amateurs familiar with rifle shooting. Movement of the center of forces (COF) was analyzed in terms of the speed and amplitude of the movement. These calculations were carried out in 1.5 s windows, the first window beginning 7.5 s and ending at 6.0 s prior the shot. The last window ended at the trigger pull. Posture control data differentiated the studied groups according to their level in competitive shooting. The male top-level shooters could stabilize their posture significantly better than female top-level or male national level shooters, who were, in turn, much more stable than naive shooters. The experienced shooters were able to stabilize their posture even better during the last seconds preceding the shot, whereas in naive shooters there were no significant differences when the successive windows were compared with each other. When a comparison was made between the best and worst 20 shots of each subject, a significant difference in balance parameters was only observed among the naive shooters, who showed more pronounced movement of the COF in the less successful trials. Among the highly trained top-level shooters a miss in whole-body posture stabilization apparently seldom is a reason for a poor result.
Assuntos
Armas de Fogo , Destreza Motora , Postura , Adulto , Análise de Variância , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Destreza Motora/fisiologia , Movimento , Equilíbrio Postural/fisiologia , Postura/fisiologia , Fatores Sexuais , Processamento de Sinais Assistido por Computador , Esportes/fisiologia , Fatores de TempoRESUMO
Dichotic listening has been used for assessing asymmetries in processing auditory stimuli. It is known that there is better recognition of dichotic stimuli in the right ear with verbal stimuli (right ear advantage, REA) by the majority of the subjects. We were interested in the psychophysiological correlates of ear advantage as it is manifested in event-related potentials (ERP). We compared ERPs to monaural and dichotic syllables in stable REA and LEA subjects. The most consistent finding was that REA subjects show larger positive ERP deflections over the left hemisphere (maximal at T5) and LEA subjects over the right hemisphere (maximal at T6) both at the latency range of 320-340 msec. Thus, brain event-related potentials support the contention that the REA and LEA reflect differential activation of the left and right hemispheres, respectively.
Assuntos
Encéfalo/fisiologia , Potenciais Evocados Auditivos/fisiologia , Lateralidade Funcional/fisiologia , Percepção da Fala/fisiologia , Estimulação Acústica , Adulto , Percepção Auditiva , Testes com Listas de Dissílabos , Dominância Cerebral/fisiologia , Feminino , Humanos , Idioma , Masculino , ProibitinasRESUMO
The purposes of this study were to investigate (a) whether children in families with a positive history of dyslexia were more likely to show delays in language development than children without family risk and (b) whether a delayed onset of expressive language (late talking) predicted later language development. We analyzed the language development of 200 children longitudinally at 14, 24, 30, and 42 months and assessed their symbolic play at 14 months. Half of the children (N = 106) were from families with a history of dyslexia (the Dyslexia Risk [DR] group), and other children served as age-matched controls. Parental reports and structured tests were used to assess children's receptive and expressive language and symbolic play. No differences emerged between the two groups in receptive language, symbolic play, or on the Bayley MDI. The groups, however, diverged in expressive language measures. The maximum sentence length at 2 years and object naming and inflectional morphology skills at 3.5 years were higher for the control group than for the DR group. Reynell receptive score at 2.5 years provided the greatest unique contribution to the prediction of the children's receptive and expressive language. Children's risk status did not contribute to receptive language, but provided a significant contribution to their expressive language at 3.5 years, even after the variance associated with parental education and children's previous language skills was controlled. Late talkers in the DR group differed from the other members of the DR group in both receptive and expressive language at 3.5 years, although in the control group children with a late-talking history performed at age-level expectations. The findings suggest that children with a familial risk for dyslexia and with a history of late talking are at higher risk for delays in language acquisition than children without the familial risk for dyslexia.
Assuntos
Dislexia/genética , Desenvolvimento da Linguagem , Jogos e Brinquedos , Simbolismo , Dislexia/epidemiologia , HumanosRESUMO
A random sample of 91 preschool children was assessed prior to receiving formal reading instruction. Verbal and nonverbal measures were used as predictors for the time of instruction required to accurately decode pseudowords in the highly orthographically regular Finnish language. After 2 years, participants were divided into four groups depending on the duration of instruction they had required to reach 90 % accuracy in their reading of pseudowords. Participants were classified as precocious decoders (PD), who could read at school entry; early decoders (ED), who learned to read within the first 4 months of Grade 1; ordinary decoders (OD), who learned to read within 9 months; and late decoders (LD), who failed to reach the criterion after 18 months of reading instruction at Grade 2. Phonological awareness played a significant role only in differentiating PD from ED and OD. However, phonological awareness failed to predict the delayed learning process of LD. LD differed from all other groups in visual analogical reasoning in an analysis not containing phonological awareness measures. Letter knowledge and visual analogical reasoning explained above 90% of the PD-LD difference. Preschool composite (objects, colors, and digits) naming speed measures best predicted reading fluency at the end of Grade 2. The supportive role of orthographic knowledge in phonological awareness, the role of visual analogical reasoning, and the inability of phonological measures to discriminate late decoders are discussed.
Assuntos
Dislexia/diagnóstico , Escolaridade , Idioma , Fonética , Leitura , Criança , Pré-Escolar , Feminino , Finlândia , Seguimentos , Humanos , MasculinoRESUMO
We measured event-related potentials (ERPs) to synthetic consonant-vowel syllables (/ba/, /da/, /ga/) from 26 newborns with familial risk for dyslexia and 23 control infants participating in the Jyväskylä Longitudinal Study of Dyslexia. The syllables were presented with equal probability and with interstimulus intervals ranging from 3,010 to 7,285 ms. Analyses of averaged ERPs from the latencies identified on the basis of principal component analysis (PCA) revealed significant group differences in stop-consonant processing in several latency ranges. At the latencies of 50-170 ms and 540-630 ms, the responses to /ga/ were larger and more positive than those to /ba/ and /da/ in the right hemisphere in the at-risk group. Between 740 and 940 ms, the responses to /ba/ and /da/ differed between anterior and posterior electrode sites in the control group. These results indicate that the cortical electric activation evoked by speech elements differs between children with and without risk for dyslexia even immediately after birth. Group-related effects at early and late latency ranges of ERPs suggest differences both in the early sound processing based on activation of afferent elements and in later phases of syllable encoding.
Assuntos
Transtornos da Percepção Auditiva/genética , Dislexia/genética , Potenciais Evocados Auditivos/genética , Fonética , Percepção da Fala/fisiologia , Transtornos da Percepção Auditiva/fisiopatologia , Córtex Cerebral/fisiopatologia , Dominância Cerebral/genética , Dominância Cerebral/fisiologia , Dislexia/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Feminino , Humanos , Recém-Nascido , Masculino , Análise de Componente Principal , Tempo de Reação/genética , Tempo de Reação/fisiologia , Medição de Risco/estatística & dados numéricosRESUMO
Although behavioral evidence provides support for the notion that attention deficit-hyperactivity disorder (ADHD) is related to central nervous system dysfunction, there is little direct evidence to reveal which neurometabolic systems or brain structures are involved. Recent magnetic resonance imaging (MRI) studies suggest that, compared to nondisabled controls, ADHD children may have a smaller right frontal region. Morphometric analysis of MRI scans was used in this exploratory study to determine whether correlated regional variation might exist in the corpus callosum of children with ADHD. While all MRI scans were judged to be clinically normal, morphometric analysis revealed that, compared to nondisabled controls, ADHD children had a smaller corpus callosum, particularly in the region of the genu and splenium, and in the area just anterior to the splenium. Interhemispheric fibers in these regions interconnect the left and right frontal, occipital, parietal, and posterior temporal regions. These results suggest that subtle differences may exist in the brains of children with ADHD and that deviations in normal corticogenesis may underlie the behavioral manifestations of this disorder.