EMDR FORUM ARCHIVE, 2000
Eye Movements vs. Fixed Eye Conditions
Ulrich Lanius, Ph.D. · 10/20/02 at 6:41 ET
One of the great problems in looking into whether eye movements are an effective ingrediant of EMDR is that a fixed eye condition is not a good control. Corbettta et al. (1998) found about a 70% overlap between eye movements and eye fixation with regard to areas of brain activation. That is, both eye movements and eye fixation increase frontal, parietal, and temporal activity in the brain. Martinez-Conde et al. (2002) provide a possible underlying mechanism for Corbetta's findings. That is, they report that when images are stabilized on the retina, visual perception fades. However, this does not occur during voluntary visual fixation due to constantly occurring small eye movements, including microsaccades, that prevent this fading. Given copious evidence that PTSD results in frontal hypfunction of the brain, it makes at least theoretical sense that increasing brain activity through external stimulation may be helpful in treating trauma related syndromes. To show the effectiveness of such stimulation in treatment studies is clearly a challenge, given that eye fixation does not appear to be good control condition. Corbetta M, Akbudak E, Conturo TE, Snyder AZ, Ollinger JM, Drury HA, Linenweber MR, Petersen SE, Raichle ME, Van Essen DC, Shulman GL (1998). A common network of functional areas for attention and eye movements. Neuron, 21: 761-73. Martinez-Conde S, Macknik SL , Hubel DH (2002). The function of bursts of spikes during visual fixation in the awake primate lateral geniculate nucleus and primary visual cortex. Proc. Natl. Acad. Sci., 99: 13920-13925.
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