Volume 70, Issue 1, Pages 121-131 (April 2011) Cortical Map Plasticity Improves Learning but Is Not Necessary for Improved Performance  Amanda Reed, Jonathan Riley, Ryan Carraway, Andres Carrasco, Claudia Perez, Vikram Jakkamsetti, Michael P. Kilgard  Neuron  Volume 70, Issue 1, Pages 121-131 (April 2011) DOI: 10.1016/j.neuron.2011.02.038 Copyright © 2011 Elsevier Inc. Terms and Conditions

Figure 1 Repeatedly Pairing NBS with a High-Frequency Tone Significantly Increases the Percent of A1 Neurons that Respond to High-Frequency Tones for 20 Days The methods of inducing and quantifying map plasticity are identical to Kilgard and Merzenich (1998). ∗p < 0.05; ∗∗p < 0.01; all stars indicate statistical results of a t test of whether percent of cortex responding to high tones was significantly different from naive controls. Error bars indicate standard error of the mean (SEM). Solid and dashed lines indicate mean and SEM of the percent of A1 neurons in naive controls that responded to high-frequency tones. Neuron 2011 70, 121-131DOI: (10.1016/j.neuron.2011.02.038) Copyright © 2011 Elsevier Inc. Terms and Conditions

Figure 2 NBS-Induced Plasticity before Tone Discrimination Training Improves Learning (A) Training timeline. Rats did not begin tone frequency discrimination training until after NBS-tone pairing was completed. (B) Mean ± SEM performance of each group on the 1 octave discrimination task during the first 7 days after NBS-tone pairing. (C–E) Mean ± SEM discrimination performance for each group during the first 2 days (Early, dashed lines) and last 2 days (Late, solid lines) of the easy frequency discrimination task. ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001; all stars indicate statistical results of a t test of whether discrimination performance was significantly above chance (d′ = 0). Error bars in all figures indicate SEM. See also Table S1. Neuron 2011 70, 121-131DOI: (10.1016/j.neuron.2011.02.038) Copyright © 2011 Elsevier Inc. Terms and Conditions

Figure 3 NBS-Induced High-Frequency Map Plasticity after Pretraining Transiently Degrades Low-Frequency Discrimination Performance (A) Training timeline for Pretrained Groups of animals. All rats learned to perform the low-frequency discrimination task before NBS pairing began. (B) Discrimination performance in all three groups 3 days before tone exposure and NBS. (C) Discrimination performance in all three groups 3 days after tone exposure and NBS. (D) Discrimination performance in all three groups during the last 3 days at end of discrimination training. (∗), High group performance was significantly different from Control group, p < 0.05. (∗∗), High group performance was significantly different from both Pretrained Control and Pretrained Low group, p < 0.05, significance was determined by a t test comparing performance of the Pretrained High group to the Pretrained Control or Low group for each set of distracters (0.1–1.0 octaves). Error bars in all figures indicate SEM. See also Table S2. Neuron 2011 70, 121-131DOI: (10.1016/j.neuron.2011.02.038) Copyright © 2011 Elsevier Inc. Terms and Conditions

Figure 4 A Brief Period of Training Causes Cortical Map Plasticity, but Longer Periods of Training Renormalize Map Plasticity (A) Map plasticity was quantified by measuring the ratio of the A1 surface area responding to a 2 kHz tone and a 19 kHz tone at 60 dB SPL. Map plasticity developed after discrimination learning, but renormalized after longer periods of training. The asterisk denotes that the map plasticity ratio for the Behavior Alone group was significantly different than naive controls; p < 0.05. See also Figure S1. (B) Timeline of discrimination performance on the 1 octave task for the Behavior Alone group. (C) Timeline of discrimination performance on the 1 octave task for all three Pretrained Groups. Error bars in all figures indicate SEM. Neuron 2011 70, 121-131DOI: (10.1016/j.neuron.2011.02.038) Copyright © 2011 Elsevier Inc. Terms and Conditions

Figure 5 Plasticity Caused by NBS-Tone Pairing Renormalizes with Further Training (A) Map plasticity was quantified in naive controls as well as the three groups of rats that learned the discrimination task after NBS-tone pairing (see Figure 2). Map plasticity developed in the two groups of rats that experienced low-tone discrimination learning (High Group, blue; Control Group, green), but renormalized in the group that experienced NBS-low tone pairing before low-tone discrimination learning (Low Group, red). The x axis corresponds to the days since low-tone training began for the High and Control groups (same as B), and corresponds to the days since NBS began for the low group (same as C). See also Figure S1. (B) Discrimination learning curve for the High and Control groups. (C) Discrimination learning curve for Low Group. There were no differences in discrimination abilities between the Low, High, and Control groups immediately before physiology. Error bars in all figures indicate SEM. Neuron 2011 70, 121-131DOI: (10.1016/j.neuron.2011.02.038) Copyright © 2011 Elsevier Inc. Terms and Conditions