RESUMO
The functional architecture of human auditory cortex is still poorly understood compared with that of visual cortex, yet anatomical and electrophysiological studies in non-human primates suggest that the auditory cortex also might be functionally specialized, in a model of parallel and hierarchical organization. In particular, spectral changes such as the formant transitions of speech, or spectral motion (SM) by analogy with visual motion, could be processed in specialized cortical regions. In this study, positron emission tomography (PET) was used to identify which auditory cortical region are involved in SM analysis. We found that a bilateral secondary auditory cortical region, located in the caudal-lateral belt of auditory cortex, was more sensitive to auditory stimuli containing spectral changes than to matched stimuli with a stationary spectral profile. This result suggests that analogies between sensory systems could prove useful in the research into the functional organization of the auditory cortex.
Assuntos
Córtex Auditivo/diagnóstico por imagem , Percepção Auditiva/fisiologia , Estimulação Acústica , Adolescente , Adulto , Córtex Auditivo/fisiologia , Circulação Cerebrovascular/fisiologia , Lateralidade Funcional/fisiologia , Humanos , Masculino , Tálamo/diagnóstico por imagem , Tálamo/fisiologia , Tomografia Computadorizada de EmissãoAssuntos
Depressão/etiologia , Terapia por Estimulação Elétrica/efeitos adversos , Doença de Parkinson/terapia , Doença Aguda , Idoso , Antiparkinsonianos/uso terapêutico , Encéfalo/irrigação sanguínea , Eletrodos Implantados , Feminino , Humanos , Levodopa/uso terapêutico , Doença de Parkinson/tratamento farmacológico , Substância Negra , Núcleos TalâmicosRESUMO
To investigate the role of temporal processing in language lateralization, we monitored asymmetry of cerebral activation in human volunteers using positron emission tomography (PET). Subjects were scanned during passive auditory stimulation with nonverbal sounds containing rapid (40 msec) or extended (200 msec) frequency transitions. Bilateral symmetric activation was observed in the auditory cortex for slow frequency transitions. In contrast, left-biased asymmetry was observed in response to rapid frequency transitions due to reduced response of the right auditory cortex. These results provide direct evidence that auditory processing of rapid acoustic transitions is lateralized in the human brain. Such functional asymmetry in temporal processing is likely to contribute to language lateralization from the lowest levels of cortical processing.