Dear Users
This week I will give a talk based on an article that is currently "in
press" in NeuroImage. The article is about using magnetoencephalography
to investigate the spatiotemporal representation of changes in pitch
over time (frequency modulation).
YNiC seminars take place from 4-5 pm in YNiC open plan.
Everyone is welcome to attend.
Best wishes
Rebecca
Citation: Rebecca E. Millman, Garreth Prendergast, Padriag T. Kitterick,
Will P. Woods and Gary G. R. Green. (2010). Spatiotemporal
reconstruction of the auditory steady-state response to frequency
modulation using magnetoencephalography. NeuroImage 49, 745-758.
Abstract:
The aim of this study was to investigate the mechanisms involved in the
perception of perceptually salient frequency modulation (FM) using
auditory steady-state responses (ASSRs) measured with
magnetoencephalography (MEG). Previous MEG studies using
frequency-modulated amplitude modulation as stimuli (Luo et al., 2006,
2007) suggested that a phase modulation encoding mechanism exists for
low (< 5 Hz) FM modulation frequencies but additional amplitude
modulation encoding is required for faster FM modulation frequencies. In
this study single-cycle sinusoidal FM stimuli were used to generate the
ASSR. The stimulus was either an unmodulated 1-kHz sinusoid or a 1-kHz
sinusoid that was frequency-modulated with a repetition rate of 4, 8, or
12 Hz. The fast Fourier transform (FFT) of each MEG channel was
calculated to obtain the phase and magnitude of the ASSR in sensor-space
and multivariate Hotelling's /T/^2 statistics were used to determine the
statistical significance of ASSRs. MEG beamformer analyses were used to
localise the ASSR sources. Virtual electrode analyses were used to
reconstruct the time series at each source. FFTs of the virtual
electrode time series were calculated to obtain the amplitude and phase
characteristics of each source identified in the beamforming analyses.
Multivariate Hotelling's /T/^2 statistics were used to determine the
statistical significance of these reconstructed ASSRs. The results
suggest that the ability of auditory cortex to phase-lock to FM is
dependent on the FM pulse rate and that the ASSR to FM is lateralised to
the right hemisphere.
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