Figure 2.

a) From Schoups et al., 2001 (their figure 3a). Slope of the tuning curve for neurons tuned to orientations 0-50 degrees offset from the trained orientation. The solid red line represents trained neurons and the dashed blue line represents untrained neurons. There is a significant increase in the slope of the tuning curve for trained neurons tuned 12-20 degrees away from the trained orientation, indicating that these neurons were the most informative for accurately discriminating the trained stimulus. (Reprinted with permission from Macmillan Publishers Ltd: Nature, Schoups, A., Vogels, R., Qian, N., & Orban, G. (2001). Practising orientation identification improves orientation coding in V1 neurons. Nature. 412, 549-553., Copyright 2001). b) From Yang & Maunsell, 2004 (their figure 6). Normalized population tuning curve for trained (black curve) and untrained (gray curve) populations, where 0 degrees represents the preferred orientation of a given neuron. There is a significant decrease in bandwidth and increase in amplitude for the trained populations compared to untrained populations, indicating a gain enhancement of those populations that optimally discriminate the trained stimulus. (Reproduced with permission of Society for Neuroscience: Yang, T. & Maunsell, J.H.R. (2004). The effect of perceptual learning on neuronal responses in monkey visual area V4. The Journal of Neuroscience. 24, 1617-1626., Copyright 2004.)