RESUMEN
BACKGROUND: Being born with very low birth weight (VLBW; birth weight (BW) ≤1500 g) is associated with increased risk of maldevelopment of the immature brain which may affect neurological functioning. Deficits in attention and executive function problems have been reported in VLBW survivors compared with healthy subjects. AIMS: The aim of this study was to evaluate attention and executive functions and to relate the clinical test results to cortical morphometry findings in VLBW young adults compared with term-born controls. STUDY DESIGN: Prospective follow-up study of three year cohorts of VLBW and control children from birth to adulthood. OUTCOME MEASURES: A comprehensive neuropsychological test battery was administered to 55 VLBW subjects born preterm (mean BW: 1217 g) and 81 term-born controls (mean BW: 3707 g) at age 19-20. Cerebral MRI was successfully obtained in 46 VLBW subjects and 61 controls. The FreeSurfer software package was applied for the cortical analyses based on T1-weighted MRI images. RESULTS: The VLBW group obtained inferior scores on 15 of the 29 neuropsychological measures assessing attention and executive function and on both the attention and executive function domain scores. We found positive correlations between the executive function domain score and cortical surface area, especially in the antero-medial frontal and the temporal lobes of the brain in the VLBW group. CONCLUSION: Young adults born with VLBW show deficits in attention and executive function compared with controls. The executive problems were related to smaller cortical surface area in brain regions known to be involved in higher order cognitive functioning.
Asunto(s)
Desarrollo del Adolescente , Función Ejecutiva , Lóbulo Frontal/crecimiento & desarrollo , Recién Nacido de muy Bajo Peso/crecimiento & desarrollo , Lóbulo Temporal/crecimiento & desarrollo , Adolescente , Atención , Estudios de Casos y Controles , Desarrollo Infantil , Femenino , Lóbulo Frontal/fisiología , Humanos , Recién Nacido , Masculino , Lóbulo Temporal/fisiología , Adulto JovenRESUMEN
BACKGROUND: While recent genome-wide association studies have identified several new bipolar disorder (BD) risk variants, structural imaging studies have reported enlarged ventricles and volumetric reductions among the most consistent findings. We investigated whether these genetic risk variants could explain some of the structural brain abnormalities in BD. METHODS: In a sample of 517 individuals (N=121 BD cases, 116 SZ cases, 61 other psychosis cases and 219 healthy controls), we tested the potential association between nine SNPs in the genes CACNA1C, ANK3, ODZ4 and SYNE1 and eight brain structural measures found to be altered in BD, and if these were specifically affecting the BD sample. We also assessed the polygenic effect of all these 9 SNPs on the brain phenotypes. RESULTS: Our most significant result was an association between the risk allele A in CACNA1C SNP rs4775913 and decreased cerebellar volume (pnom.=0.0075) in the total sample, which did not remain significant after multiple testing correction (pthreshold<0.0064). There was no evidence for diagnostic specificity for this association in the BD group. Further, no polygenic effect of these 9 SNPs was observed. LIMITATIONS: Low statistical power might increase our type II error rate. CONCLUSIONS: The present findings indicate that these risk SNPs do not explain a large proportion of the structural brain alterations in BD. Thus, these genes which are all related to neuronal functions must be involved in other pathophysiological aspects of BD development.
Asunto(s)
Trastorno Bipolar/genética , Encéfalo/patología , Carácter Cuantitativo Heredable , Adulto , Alelos , Trastorno Bipolar/patología , Encéfalo/anatomía & histología , Estudios de Casos y Controles , Femenino , Estudios de Asociación Genética , Humanos , Imagen por Resonancia Magnética , Masculino , Neuroimagen , Fenotipo , Polimorfismo de Nucleótido SimpleRESUMEN
PURPOSE: In order to examine auditory lateralization of prelexical speech processing, a dichotic listening task was performed with concurrent EEG measurement. METHODS: Subjects were tested with dichotic pairs of six consonant-vowel (CV) syllables that initially started with a voiced (/ba/, /da/, /ga/) or a voiceless stop consonant (/pa/, /ta/, /ka/). Electrophysiological correlates were analyzed by a low resolution electromagnetic tomography (LORETA) approach to estimate the sources of N1 event-related potentials (ERP) in the 3D brain. RESULTS: Behavioral and electrophysiological measures revealed different ear advantages and ERP amplitude measures for voiced and voiceless syllables. Fronto-central N1 amplitudes were larger for syllables with voiced than voiceless initial consonants. LORETA source estimates revealed a lateralization effect, with stronger leftward lateralization for voiced than voiceless CV syllables. CONCLUSIONS: The present study demonstrates that auditory lateralization is affected by temporal cues in CV syllables. The lateralization effect suggests that functional hemispheric differences exist at an early prelexical level of speech processing.
Asunto(s)
Percepción Auditiva/fisiología , Lateralidad Funcional/fisiología , Percepción del Habla/fisiología , Estimulación Acústica , Adulto , Atención/fisiología , Mapeo Encefálico , Señales (Psicología) , Interpretación Estadística de Datos , Electroencefalografía , Campos Electromagnéticos , Femenino , Humanos , Masculino , Plasticidad Neuronal/fisiología , Desempeño Psicomotor/fisiología , Reclutamiento Neurofisiológico/fisiologíaRESUMEN
The present study used functional and structural MRI to investigate differences in neuronal substrates underlying shifts of attention in young and old subjects, studied with dichotic listening. Two different consonant-vowel syllables were presented and the subjects were instructed to attend to and report from either the left or right ear stimulus. Typically, a right-ear advantage is observed when attending to the right-ear stimulus, and a left-ear advantage when attending to the left-ear stimulus. The behavioral results showed that the old group had difficulties with attentional modulation of the right-ear advantage in the attend left condition. This is interpreted as a failure of an important aspect of attentional control; the top-down biasing of attention for selection of task-relevant stimulus. The fMRI results showed that an area in the left middle frontal gyrus was more activated in the young group compared to the old group in the attend left condition. The structural MRI data showed reduced gray matter density of the same area in the old group. Based on these converging findings, we suggest that the left middle frontal gyrus plays an important role in top-down biasing of selecting task-relevant stimuli, and to inhibit processing of task-irrelevant stimuli. To our knowledge, this is one of the first studies addressing the question on how age-related changes in attentional processing is reflected in both functional and structural differences in the brain.
Asunto(s)
Envejecimiento/fisiología , Mapeo Encefálico/métodos , Encéfalo/fisiología , Imagen por Resonancia Magnética/métodos , Adulto , Encéfalo/crecimiento & desarrollo , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
The aim of the present study was to investigate differences in brain activation in a family with SLI as compared to intact individuals with normally developed language during processing of language stimuli. Functional magnetic resonance imaging (fMRI) was used to monitor changes in neuronal activation in temporal and frontal lobe areas in 5 Finnish family members with specific language impairment (SLI) and 6 individuals in an intact control group. Magnetic resonance (MR) image acquisitions were made while the participants listened to series of isolated vowel sounds, pseudowords, and real words. The stimuli were digitized single Finnish vowel sounds, 3-phoneme pseudowords, and 3- and 4-phoneme real words. MR scanning was made with a 1.5 T Siemens Vision Plus scanner, and the auditory stimuli were presented according to an event-related fMRI design. The results showed significant differences between the family with SLI and the intact control group with regard to brain activation in areas in the temporal and frontal lobes. Temporal lobe activation differences were most pronounced in the middle temporal gyrus bordering the superior temporal sulcus. The control participants also activated an area in the inferior frontal lobe in BA 44. It is concluded that individuals with SLI showed reduced activation in brain areas that are critical for speech processing and phonological awareness. The present functional brain imaging data fit well with other recent imaging data that also showed structural abnormalities in the same and neighboring areas.
Asunto(s)
Familia , Lóbulo Frontal/fisiología , Trastornos del Lenguaje/fisiopatología , Imagen por Resonancia Magnética , Percepción del Habla/fisiología , Lóbulo Temporal/fisiología , Estimulación Acústica , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Niño , Análisis por Conglomerados , Femenino , Lóbulo Frontal/patología , Humanos , Trastornos del Lenguaje/genética , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Linaje , Lóbulo Temporal/patologíaRESUMEN
The present study used fMRI to investigate the relationship between stimulus presentation mode and attentional instruction in a free-report dichotic listening (DL) task with consonant-vowel (CV) syllables. Binaural and dichotic CV syllables were randomly presented to the subjects during four different instructional conditions: a passive listening instruction and three active instructions where subjects listened to both ears, right ear and left ear, respectively. The results showed that dichotic presentations activated areas in the superior temporal gyrus, middle and inferior frontal gyrus and the cingulate cortex to a larger extent than binaural presentations. Moreover, the results showed that increase of activation in these areas was differentially dependent on presentation mode and attentional instruction. Thus, it seems that speech perception, as studied with the DL procedure, involves a cortical network extending beyond primary speech perception areas in the brain, also including prefrontal cortex.
Asunto(s)
Pruebas de Audición Dicótica , Imagen por Resonancia Magnética , Corteza Prefrontal/fisiología , Percepción del Habla/fisiología , Adulto , Atención/fisiología , Vías Auditivas/fisiología , Mapeo Encefálico , Femenino , Lóbulo Frontal/fisiología , Giro del Cíngulo/fisiología , Humanos , Masculino , Red Nerviosa/fisiología , Fonética , Semántica , Lóbulo Temporal/fisiologíaRESUMEN
Focusing of attention to a specific speech source plays an important role in everyday speech perception. However, little is known of the neuronal substrates of focused attention in speech perception. Thus, the present study investigated the effects on neuronal activation of directed attention to auditory stimuli that differed in semantic content. Using an event-related fMRI protocol, single vowels, three-phoneme pseudowords and three- and four-phoneme real nouns and words were randomly presented to the subjects during four different instructional conditions. One condition was passive listening without any specific instructions of focusing of attention. The other conditions were attention focused on either the vowels, the pseudowords or the words. Thus, the acoustic stimulation was constant across conditions. The subjects were 13 healthy adults. Functional MRI was performed with a 1.5 T scanner, using an event-related design. During passive listening, there were significant activations bilaterally in the superior temporal gyrus. Instruction to attend to the pseudowords caused activation in middle temporal lobe areas, extending more anterior compared to the activations seen during passive listening. Instruction to attend to the vowel sounds caused an increase in activation in the superior/medial temporal lobe, with a leftward asymmetry. Instruction to attend to the words caused a leftward asymmetry, particularly in the middle and superior temporal gyri. It is concluded that attention plays a modulatory role in neuronal activation to speech sounds, producing specific activations to specific stimulus categories that may act to facilitate speech perception.