Fig. 5: Sequential activation after pre-activation could guide stimulus-driven pattern completion.
From: Distinct neuronal populations in the human brain combine content and context
a, Schematic model of stimulus–context storage. Activation of entorhinal cortical (EC) MS (red) and hippocampal (H) MC neurons (green) during trial events. Specific context neurons in the hippocampus respond to particular questions (coloured circles) and are reactivated during picture presentations (top left). Picture presentations elicit responses in selected stimulus neurons (numbers), whose activity predicts context neuron firing after approximately 40 ms (Fig. 4), strengthening connections encoding stimulus–context associations. Question response strengths predict context neuron activity and excitability (yellow triangles) during subsequent picture presentations (panels b,d; Extended Data Fig. 10a–c; lower left). Pre-activation by preferred contexts guides stimulus-driven pattern completion in hippocampal context neurons (right; dashed yellow line; panels d–f). b, Scatter plot of mean z-values for the five contextual questions during question versus picture presentations, computed per MC neuron and patient (5 questions × 16 patients, green stars in panel b and grey stars in panel c). Pearson correlations are visualized by regression lines. Question-evoked responses predict picture responses (r = 0.46, P = 2.07 × 10−5). c, As in panel b, but baseline versus picture presentations showing no correlation (r = 0.03, P = 0.78). d, Shift-corrected cross-correlations of EC-MS and H-MC during picture presentations after a preferred (maximum response, green) versus a non-preferred context (grey). The red horizontal lines indicate significant differences (P < 0.01, two-sided cluster permutation test). Data are mean ± s.e.m. (solid lines and shaded areas, respectively) with the dashed line indicating zero. MS firing predicts MC firing more strongly in preferred contexts. n = 40 neurons. e, Context SVM-decoding accuracy of H-MC trained with question and decoded with picture activity time locked (0–100 ms) to EC-MS firing (6 sessions: P = 0.031; 40 neuron pairs: P = 5.794 × 10−4; two-sided Wilcoxon signed-rank test). f, Context SVM decoding of H-MC distinguishing whether preferred (red) versus non-preferred (blue) pictures of the corresponding EC-MS were presented (6 sessions: P = 0.0156; 40 neuron pairs: P = 0.0338; one-sided Wilcoxon signed-rank test). For the boxplots (e,f), quantile 1, median, quantile 3 and whiskers (points within ±1.5× the interquartile range) are shown; dashed lines indicate chance. *P < 0.05.
