Extended Data Fig. 6: MTL and non-MTL recordings and item-specific information revealed by stimulus–neural association analysis.

(a) To minimize the involvement of recording neocortical sites that account for only a small amount of variance in the retained STM content, we performed a feature selection procedure based on an omnibus F test. Specifically, for each participant, we identified the top 50% of the stimulus-sensitive cortical electrodes based on a one-way ANOVA on the delay-period high-frequency (70–150 Hz) activity across 9 colors. These non-MTL cortical electrodes (excluding electrodes in the hippocampus-amygdala complex, perirhinal/entorhinal cortices, and parahippocampus areas) are marked in light blue in a reconstructed brain surface in the MNI brain. The omnibus nature of this analysis does not impose any assumptions regarding specific stimulus tuning or the spatial distribution of these relevant cortical recording sites, and hence can help detect STM content retained in distributed cortical areas^25,32,33 (also see Discussion). We then performed a similar stimulus–neural association analysis outlined in Fig. 2 based on these non-MTL signals. We find that these neocortical recording sites retain significant STM information about the cued item throughout the delay period. (b) MTL electrodes in the hippocampus and perirhinal/entorhinal cortices across participants are marked in orange on a reconstructed brain surface in the MNI brain. Stimulus–neural association findings from the MTL electrodes are reproduced from Fig. 2. (c) We directly compared the item-specific information in the MTL and non-MTL recording sites. STM information contained within the activity of the distributed non-MTL neocortical areas is sustained throughout the delay period, especially after the offset of item-specific information in the MTL during the mid-delay period. While these results suggest that STM information can sustain throughout the delay period in a distributed cortical network, these findings do not imply that STM depends on sustained neural activation²⁵. Significant timepoints after cluster-based correction for multiple comparisons at the 0.05 level are marked in yellow.