Figure 4. Single site and long-latency stimulation increase the functional connectivity between M1 and S1.

(A) Experimental protocol. Conditioning stimulation was interrupted by periodic connectivity measurements including passive recording and active testing. Either one or two non-interfering lasers were used. (B) Examples of changes in SERR across the recording array in monkey G. Red circles show initial connectivity and white circles show connectivity after 50 min. of conditioning. (C) Summary of SERR changes across all experiments. Each symbol represents the connectivity averaged over all secondary channels for one experiment. Filled markers show significant changes (paired t-test; p<0.05, the p-values for each experiment are listed in the supplementary spreadsheet). (D) Changes in SERR when stimulating in either S1 or M1 in comparison to control. Error bars represent standard error and asterisks show significant changes (paired t-test; Control: p=0.8, laser in S1: p=0.01, laser in M1: p=1.6e-04). (E) Examples of changes in theta (4–8 Hz) coherence across the recording array. (F) Summary of theta coherence changes across all experiments. Each marker represents the connectivity averaged over all channels for one experiment. Filled markers show significant changes (paired t-test; p<0.05, the p-values for each experiment are listed in the supplementary spreadsheet). (G) Change in coherence across different frequency bands in comparison to controls. Asterisk show significant difference between the two groups (unpaired t-test, Bonferroni corrected; p<0.05, the p-values are listed in the supplementary spreadsheet). (H) Linear relationship between SERR and coherence across different frequencies for pre-stim, post-stim and the change in both measures. Summary data showing the mean and standard error (shaded region) of regression slope and r² as a function of coherence frequency (see the example regression for the theta-band in Figure 3B).

Figure 4—figure supplement 1. Linear relationship between SERR and coherence across different frequencies for control sessions.

Replication of Figure 4H for control (no stimulation) sessions. Each line shows the mean and standard error (shaded region) of regression slope and r² as a function of the coherence frequency.

Figure 4—figure supplement 2. Change in power following stimulation.

Change in power from pre- to post-conditioning across monkeys and non-interference experiments. Bars reflect standard errors around the mean change in power in each 4 Hz frequency band. (A) Average change in power across secondary recording sites normalized to the change in power at the stimulation site. (B) Average change in power across secondary recording sites. (C) Average change in power at the stimulation site.