Stimulus response potentiation is absent in aged mice. A, SRP was induced in mouse visual cortex by repeated presentations of sinusoidal gratings. Three-month-old mice (orange squares) exhibited large and sustained potentiation of binocular VEPs over many days of exposure to the same stimulus orientation (Day 5 = 2.2 ± 0.32-fold increase over Day 1; paired t test p = 0.0068, n = 5). Six-month-old mice (red triangles) exhibited less potentiation on average per day than 3-month-old mice but still exhibited significant SRP (Day 5 = 1.6 ± 0.19-fold increase over Day 1; paired t test p = 0.00035, n = 10) and 9-month-old mice (blue circles) did not exhibit any statistically significant potentiation (Day 5 = 1.08 ± 0.32-fold increase over Day 1; paired t test p = 0.675, n = 5). B, Binocular VEPs were recorded at different frequencies of sinusoidal gratings or with different contrast percentages. No differences were observed between the groups (F_(2,26) = 0.623, p = 0.542; repeated-measures MANOVA). Error bars represent ± SEM. Inset, Average VEP waveforms for each age group as contrast was increased.