There have been several attempts to use the neuromagnetic response to the onset of a tonal sound (N100m) to study pitch processing in auditory cortex. Unfortunately, a large proportion of the N100m is simply a response to the onset of sound energy, independent of whether the sound produces a pitch. The current study describes a novel stimulus paradigm designed to circumvent the energy-onset response and thereby isolate the response of those neural elements specifically involved in pitch processing. The temporal resolution of magnetoencephalography enables us to show that the latency and amplitude of this pitch-onset response (POR) vary with the pitch and pitch strength of the tone. The spatial resolution is sufficient to show that its source lies somewhat anterior and inferior to that of the N100m, probably in the medial part of Heschl's gyrus.
Playing a musical instrument is associated with numerous neural processes that continuously modify the human brain and may facilitate characteristic auditory skills. In a longitudinal study, we investigated the auditory and neural plasticity of musical learning in 111 young children (aged 7-9 y) as a function of the intensity of instrumental practice and musical aptitude. Because of the frequent co-occurrence of central auditory processing disorders and attentional deficits, we also tested 21 children with attention deficit (
Dyslexia, attention deficit hyperactivity disorder (ADHD), and attention deficit disorder (ADD) show distinct clinical profiles that may include auditory and language-related impairments. Currently, an objective brain-based diagnosis of these developmental disorders is still unavailable. We investigated the neuro-auditory systems of dyslexic, ADHD, ADD, and age-matched control children (N = 147) using neuroimaging, magnetencephalography and psychoacoustics. All disorder subgroups exhibited an oversized left planum temporale and an abnormal interhemispheric asynchrony (10–40 ms) of the primary auditory evoked P1-response. Considering right auditory cortex morphology, bilateral P1 source waveform shapes, and auditory performance, the three disorder subgroups could be reliably differentiated with outstanding accuracies of 89–98%. We therefore for the first time provide differential biomarkers for a brain-based diagnosis of dyslexia, ADHD, and ADD. The method allowed not only allowed for clear discrimination between two subtypes of attentional disorders (ADHD and ADD), a topic controversially discussed for decades in the scientific community, but also revealed the potential for objectively identifying comorbid cases. Noteworthy, in children playing a musical instrument, after three and a half years of training the observed interhemispheric asynchronies were reduced by about 2/3, thus suggesting a strong beneficial influence of music experience on brain development. These findings might have far-reaching implications for both research and practice and enable a profound understanding of the brain-related etiology, diagnosis, and musically based therapy of common auditory-related developmental disorders and learning disabilities.
The supratemporal sources of the earliest auditory cortical responses (20-80 ms) were identified using simultaneously recorded electroencephalographic (EEG) and magnetoencephalographic (MEG) data. Both hemispheres of six subjects were recorded two or three times in different sessions in response to 8000 right-ear 1 kHz pure tones stimuli. Four components were identified: Pa (28 ms), Nb (40 ms), and two subcomponents of the Pb complex, termed Pb1 (52 ms) and Pb2 (74 ms). Based on MEG data, the corresponding sources were localized on the anatomy using individual realistic head models: Pa in the medial portion of Heschl's gyri (H1/H2); Nb/Pb1 in the lateral aspect of the supratemporal gyrus (STG); and Pb2 in the antero-lateral portion of Heschl's gyri. All sources were oriented antero-superiorly. This pattern was clearest in the contralateral hemisphere, where these three activities could be statistically dissociated. Results agree with previous invasive human intracerebral recordings, with animal studies reporting secondary areas involved in the generation of middle latency auditory-evoked components, and with positron emission tomography and functional magnetic resonance imaging studies often reporting these three active areas although without temporal information. The early STG activity may be attributed to parallel thalamo-cortical connections, or to cortico-cortical connections between the primary auditory cortex and the STG, as recently described in humans.
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