Attentional modulation of oscillatory activity in human visual cortex

Noriko Yamagishi*, Daniel E. Callan, Naokazu Goda, Stephen J. Anderson, Yoshikazu Yoshida, Mitsuo Kawato

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The effects of attentional modulation on activity within the human visual cortex were investigated using magnetoencephalography. Chromatic sinusoidal stimuli were used to evoke activity from the occipital cortex, with attention directed either toward or away from the stimulus using a bar-orientation judgment task. For five observers, global magnetic field power was plotted as a function of time from stimulus onset. The major peak of each function occurred at about 120 ms latency and was well modeled by a current dipole near the calcarine sulcus. Independent component analysis (ICA) on the non-averaged data for each observer also revealed one component of calcarine origin, the location of which matched that of the dipolar source determined from the averaged data. For two observers, ICA revealed a second component near the parieto-occipital sulcus. Although no effects of attention were evident using standard averaging procedures, time-varying spectral analyses of single trials revealed that the main effect of attention was to alter the level of oscillatory activity. Most notably, a sustained increase in alpha-band (7-12 Hz) activity of both calcarine and parieto-occipital origin was evident. In addition, calcarine activity in the range of 13-21 Hz was enhanced, while calcarine activity in the range of 5-6 Hz was reduced. Our results are consistent with the hypothesis that attentional modulation affects neural processing within the calcarine and parieto-occipital cortex by altering the amplitude of alpha-band activity and other natural brain rhythms. © 2003 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)98-113
Number of pages16
Issue number1
Publication statusPublished - Sept 2003


  • alpha rhythm
  • area V1
  • attention
  • MEG
  • rhythmic activity
  • vision


Dive into the research topics of 'Attentional modulation of oscillatory activity in human visual cortex'. Together they form a unique fingerprint.

Cite this