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. 2020 Mar 13;9:e51972. doi: 10.7554/eLife.51972

Figure 6. Skewness of peri-SWR hippocampal MUA informs neocortical activation latency relative to SWRs.

(A) (i) Distribution of hippocampal MUA AI values for a representative animal. Dashed lines (Q1 and Q3) indicate the first and third quartiles. The SWRs for which the associated hippocampal MUA AI values are less than Q1 and greater than Q3 are called HPC QR1 and QR4, respectively. HPC QR2-3 consists of all other SWRs. (ii) Distribution of the proportion of SWRs in each animal for which the sign of both RSC and hippocampal MUA AI values match, as an indication of how well hippocampal MUA can inform whether RSC activity precedes or follows SWRs. The horizontal red line indicates the median of all proportion values in n = 14 animals (significantly above the chance level of 50%; two-sided Wilcoxon signed rank test p=1.220703125 × 10–4). (iii) Correlation between the RSC and hippocampal MUA AI values pooled across all animals (14 animals) is low but significant (n = 11725 SWRs across all animals; two-sided t-test p<10−15). (iv) Example plots of mean peri-SWR RSC glutamate activity associated with HPC QR1 (blue) and QR4 (red). (v) Time course of exemplar mean peri-SWR HPC MUA traces associated with SWRs in HPC QR1 (blue) and Q4 (red). Notice that both HPC MUA activity (v) and RSC glutamate activity (iv) are negatively skewed (negative AI) for HPC QR1, and the converse is true for HPC QR4. (B) Mean neocortical voltage activity centered on SWR centers associated with HPC QR1, QR2-3, and QR4 in a representative animal. Note the relative temporal shift in activity across three quartile ranges. This figure has two figure supplement.

Figure 6.

Figure 6—figure supplement 1. Whether retrosplenial cortex activation precedes or follows SWRs is correlated by skewness peri-SWR hippocampal MUA.

Figure 6—figure supplement 1.

(A) Representative mean peri-SWR RSC activity (red traces) and hippocampal MUA (blue traces) calculated for hippocampal SWRs in HPC QR1, QR2-3, and QR4 defined in Figure 6A i. Notice that skewness of RSC activity and hippocampal MUA matches in each plot. (B) (i–ii) Group data (n = 14) representing the peak timestamps (i) and AI values (ii) calculated from mean peri-SWR RSC traces (red traces in panel A). Both graphs show that mean peri-SWR activation tends to precede and follow the SWRs in HPC QR1 and QR4, respectively. Bar graphs represent mean ± SEM.; **p<0.01, ***p<0.001, one-sided paired t-test.
Figure 6—figure supplement 2. The correspondence between neocortical activation latency relative to SWRs and skewness of peri-SWR hippocampal MUA is similar under sleep/urethane anesthesia and VSD/iGluSnFR imaging conditions.

Figure 6—figure supplement 2.

(A) There is no statistically significant difference in the proportion of RSC and HPC MUA AI values with the same sign in VSD versus iGluSnFR (i) nor sleep versus urethane (ii) conditions. (B) The correlation coefficients between RSC and HPC MUA AI values are statistically significant across all four conditions and are close to each other.