Supplementary Figure 2: Population effects are also observed in single neurons
From: Frequency-specific hippocampal-prefrontal interactions during associative learning
(a) Rasters showing spike times for an exemplary PFC neuron on trials in which the monkey is cued to recall associate object A1 (top panel, gray) or A2 (bottom, red). Within each panel, learning trials progress from bottom to top. (b) Spike density functions (computed with 75 ms Hann window) summarizing the PFC neuron’s firing rate when recalling associate A1 (gray) or A2 (red) within the early, middle, and late learning stages (light-to-dark colors). Its activity is stronger when associate A2 is recalled, and this preference increases with learning, reflecting population-level PFC signals for learned associations. (c) Rasters showing spike times for an exemplary hippocampal neuron following correct (top panel, green) and incorrect (bottom, brown) trials. Within each panel, learning trials progress from bottom to top. (d) Spike density functions showing the HPC neuron’s firing rate for correct (green) and incorrect (brown) trials within the early, middle, and late learning stages (light-to-dark colors). Its activity is stronger following incorrect trials, but this preference diminishes with learning, reflecting the robust population-level HPC outcome signals and their shift from error-preferring toward correct-preferring bias with learning.
