Figure 6.

Lateral habenula activity related to positive information prediction errors evoked by delivery of reward information. (a) Average activity of information-predictive neurons on trials when informative cues were presented (left) resembled the theoretical combined inverted IPE+cRPE signal (right; model uses the same conventions as in Fig. 4). Activity is shown in response to the onset of the informative cues (right) for trials when the information probability was 100% (red, ‘predictable info’) or 50% (purple, ‘unpredicted info’) and when the informative cue indicated a big reward (solid lines) or small reward (dashed lines). This population had strong excitation or inhibition encoding cRPEs, and also had a lower firing rate on ‘unpredicted info’ than ‘predictable info’ trials (inset: difference in firing rate between ‘unpredicted info’ and ‘predictable info’, calculated separately for small-reward, big-reward, and all trials; error bars are ± 1 SE; */** for P < 0.05/0.01, signed-rank test). (b) Activity difference related to information probability (purple, unpredicted info – predictable info) and cued reward value (gray, big reward – small reward). Shaded area indicates ± 1 SE. (c) Single-neuron indexes for coding positive IPEs in response to the informative cues. Same format as Fig. 3d,e, but showing the subpopulation of information-predictive neurons. (d) Neurons with strong coding of positive IPEs evoked by the informative cues (y-axis) also tended to have strong coding of positive IPEs evoked by the targets (middle) and negative IPEs evoked by the random cues (left) and targets (right). Same format as Fig. 3f.