Adaptation-induced plasticity of orientation tuning in two V1 neuron pairs. Orientation tuning curves of neuron pairs responding to drifting gratings were recorded in area 17. Curves were centered in relation to the preferred orientation of one cell of the pair in the control condition. Spontaneous activity was subtracted. Arrows indicate the adapting orientation that was presented continuously for 12 minutes. Inter-electrode distance was 400 microns for both pairs. Color code – blue: control, red: adaptation, green: 60 minutes later (error bars denote SEM). (A) Example of an adaptation-induced shift of 18.5° to the right for the cell GM1-x1 and a small shift of 4.5° in the same direction for the other cell GM1-y1. (B) Another example of a 21.9° shift to the left for the cell GE3-y1, but only a very small effect of 1.7° for the other cell of the pair, GE3-x1. (C and D) Respective waveforms for the 2 neuron pairs presented in A and B. The waveforms are similar across conditions, indicating the stability of a cell's activity and discrimination. The S/N ratios were 3.2 and 4.0 for neurons presented in C while S/N ratios of neurons in D were 3.1 and 2.6, respectively. (E and F) The absolute difference of preferred orientation between cells across experimental conditions (A: increase from 0° to 14° after adaptation; B: decrease from 22° to 1.2°). The original preferred orientation difference recovered within 60 min.