Table 1. The image features that are most provocative in photosensitive epilepsy (expressed as photo-paroxysmal responses (PPR) in the EEG), are also the most likely to induce large gamma oscillations.

When image properties vary according to the exemplars (changes in size, contrast, number of orientations, luminance/chromatic, spatial frequency, sine wave to square wave, adding noise) the number of PPR in photosensitive patients change in the same way as the amplitude of the gamma oscillations. Multiunit activity and the fMRI BOLD response change in a different manner. The direction of the arrows indicates increases or decreases, and a desaturated arrow indicates variable evidence. For gamma oscillations, spiking activity and BOLD responses, we assess an increase or decrease as the change in response of the neural population representing the stimulus center, not the signal pooled over all of visual cortex. Additional notes are provided in the Supplemental Table S1. This table includes spatial stimulus features from which the effects on provocativeness in epilepsy, induced gamma oscillations and firing rates have been described (see the Supplemental Table S1 and Table S2 for some additional stimulus features).

Stimulus characteristic	Stimuli exemplars	I. Stimulus provocativeness in photosensitive epilepsy	II. Gamma oscillation in V1/V2	III. Spiking activity in V1/V2	IV. BOLD in V1/V2
1. Size
2. Contrast
3. Number of orientations
4. Luminance→ chromatic				--
5. Spatial frequency low to middle (1-4cpd)
6. Spatial frequency middle (l-4cpd) to high
7. Sinusoidal → square wave		--	--		--
8. Increasing noise