Figure 5.
The Hybrid Bidirectional Bridging Approach Is Effective When a Neuronal Assembly Must be Replaced
(A and B) (A) Schematic of the experimental protocols. We recorded 20 min of spontaneous activity (S1) followed by laser ablation. The gray-shaded area indicates 20 min of no recording during ablation. Dots represent 2 h of no recording after the lesion to obtain stable activity in both modules and to test different stimulation channels. Then, we recorded 20 min of SPL activity (SPL3) followed by 20 min of a hybrid bidirectional bridging (HBB) protocol and another 20 min of spontaneous activity (SPL4). (B1) Top, 20-s-long raster plot depicting the BNN bursting activity involving both modules before lesion. Bottom, activity of SNN uncorrelated with the BNN. The networks are not linked. (B2) Top, 20-s-long raster plot after lesion showing uncorrelated bursting activity on BNN modules 1 and 2. Bottom, same as that in B1. (B3) Twenty-second-long raster plot during HBB depicting two hybrid events. The first event on the left was an NB detected on module 1 of the BNN. The detection resulted in a stimulation pulse delivered to 10 excitatory neurons of the SNN (blue line, bottom). An NB on the SNN was detected 18 ms after the stimulation and triggered the delivery of a stimulation pulse to module 1 of the BNN (gray line, top). (B4) Twenty-second-long raster plot depicting the uncorrelated activity of BNN modules (top) and SNN network (bottom).
(C–E) (C) MFR during the four experimental phases was stable (color code as in panel A: S1: light blue dot; SPL3, SPL4: dark gray dots; HBB: red dot). No significant difference was found (one-way repeated measures analysis of variance. p < 0.001, DF = 3, F = 3,16; Bonferroni test: all comparisons with p > 0.05). (D1) CC function during the four experimental phases. Color code the same as that in panel A. Note that during BB, the cross-correlation function (red) recovers even if not completely with respect to the initial profile (light blue). (D2) CC area was highly reduced during the post-lesion phases. The CC area partially recovered during the BB protocol and collapsed again when stimulation was switched off (one-way repeated measures analysis of variance. p < 0.001, DF = 3; F = 70,448; S1 vs SPL3: p = 5.80E-10; S1 vs SPL4 p = 2.72 × 10−9; S1 vs HBB: p = 9.16 × 10−4; HBB vs SPL3 p = 1.16 × 10−7; HBB vs SPL4 p = 1.02 × 10−6; SPL4 vs SPL3 p = 0.73643). (E1) NBR did not change during HBB with respect to the S1 phase (one-way repeated measures analysis of variance. p = 0.005, DF = 3; F = 6,069; S1 vs SPL3 p = 0.02482; S1 vs SPL4 p = 1; S1 vs HBB p = 1; HBB vs SPL3 p = 0.01022; HBB vs SPL4 p = 1; SPL4 vs SPL3 p = 0.00674). (E2) Probability of a single-module NB (Prob smNB) was close to one after the lesion. During the HBB protocol, the probability was similar to that in the pre-lesion condition (one-way repeated measures analysis of variance. p < 0.001, DF = 3; F = 453,439; S1 vs SPL3 p = 4.96 × 10−13; S1 vs SPL4 p = 1.03 × 10−12; S1 vs HBB p = 0.22606; HBB vs SPL3 p = 1.94 × 10−12; HBB vs SPL4 p = 4.30 × 10−12; SPL4 vs SPL3 p = 1). Data in the plots is reported as mean ± standard error of the mean.