Figure 6. Orientation-shifted stimulus pairs elicit exaggerated potentiation compared to phase-shifted pairs.

A) Diagram of a modified visual stimulation protocol combining attributes of the SRP and sequence protocols. Each mouse (N = 6) views two pairs of stimuli across interleaved blocks. The pairs of stimuli are either phase- or orientation-shifted (labeled ‘SRP’ and ‘Sequence’, respectively). All other stimulation properties are identical across the two conditions. B) Average VEP waveforms for the SRP and sequence stimulus pairs, with ticks denoting the onset of phase reversed (flip and flop) and orientation-shifted (A and B) images. C) Comparing VEP magnitudes elicited by the second stimulus in each pair (‘flop’ vs. ‘B’) indicates that potentiation over days is exaggerated for the orientation-shifted compared to phase-shifted stimulus (two-way RM ANOVA, Stimulus by Day interaction, F_3,15 = 4.81, p = 0.015; Sidak’s posthoc comparisons of SRP and sequence VEPs on d1, p = 0.92; d2, p = 0.0036; d3, p = 0.050; d4, p = 0.011). We conclude that in addition to potentiation driven by familiarity with the identity of each oriented grating, during familiar visual sequences the brain predictively modulates responses to each cued stimulus, further enhancing VEP magnitude. * < 0.05, ** < 0.01, n.s. non-significant.