The temporal frequency tuning of human visual cortex investigated using synthetic aperture magnetometry

Fawcett, Ian P.; Barnes, Gareth R.; Hillebrand, Arjan and Singh, Krish D. (2004). The temporal frequency tuning of human visual cortex investigated using synthetic aperture magnetometry. Neuroimage, 21 (4), pp. 1542-1553.


Using synthetic aperture magnetometry (SAM) analyses of magnetoencephalographic (MEG) data, we investigated the variation in cortical response magnitude and frequency as a function of stimulus temporal frequency. In two separate experiments, a reversing checkerboard stimulus was used in the right or left lower visual field at frequencies from 0 to 21 Hz. Average temporal frequency tuning curves were constructed for regions-of-interest located within medial visual cortex and V5/MT. In medial visual cortex, it was found that both the frequency and magnitude of the steady-state response varied as a function of the stimulus frequency, with multiple harmonics of the stimulus frequency being found in the response. The maximum fundamental response was found at a stimulus frequency of 8 Hz, whilst the maximum broadband response occurred at 4 Hz. In contrast, the magnitude and frequency content of the evoked onset response showed no dependency on stimulus frequency. Whilst medial visual cortex showed a power increase during stimulation, extra-striate areas such as V5/MT exhibited a bilateral event-related desynchronisation (ERD). The frequency content of this ERD did not depend on the stimulus frequency but was a broadband power reduction across the 5-20 Hz frequency range. The magnitude of this ERD within V5/MT was strongly low-pass tuned for stimulus frequency, and showed only a moderate preference for stimuli in the contralateral visual field.

Publication DOI:
Divisions: Life & Health Sciences > Psychology
Life & Health Sciences > Optometry
Uncontrolled Keywords: ERD,MEG,stimulus frequency,Cognitive Neuroscience,Neurology
Published Date: 2004-04


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