Effect of sodium valproate on neuromagnetic responses to chromatic flicker: Implication for photosensitivity

Katsumi Watanabe*, R. Sayres, S. Shimojo, T. Imada, K. Nihei

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


The effect of oral administration of sodium valproate in normal subjects was evaluated using whole-scalp magnetoencephalography, with results compared to the effect of sodium valproate in photosensitive children. Neuromagnetic responses to 10 Hz equiluminant red-green and red-blue flicker were measured before and after 5 days of sodium valproate administration. For the red-green flicker, relative power spectra at the stimulus frequency (10 Hz) were attenuated with medication in most brain regions. However, for the red-blue flicker, the 10-Hz power in the occipital region was enhanced with medication, while it was reduced in other regions. These results qualitatively resembled those in photosensitive children. The present findings suggest that (1) combinational chromatic sensitivity can be a critical factor for cortical excitability, that (2) the effect of sodium valproate is qualitatively similar in normal and photosensitive subjects, and that (3) the effect of sodium valproate on cortical excitability is not simply to suppress the stimulus-synchronized occipital activity, but rather to inhibit the spread of cortical activity from the occipital region to other regions.

Original languageEnglish
JournalNeurology and Clinical Neurophysiology
Publication statusPublished - 2004 Jan 1
Externally publishedYes


  • Color
  • Epilepsy
  • Flicker
  • Magnetoencephalography
  • Photosensitive

ASJC Scopus subject areas

  • Neuroscience(all)


Dive into the research topics of 'Effect of sodium valproate on neuromagnetic responses to chromatic flicker: Implication for photosensitivity'. Together they form a unique fingerprint.

Cite this