Hybrid dedicated and distributed coding in PMd/M1 provides separation and interaction of bilateral arm signals
Fig 5
Neural activity is progressively consolidated within arm-specific subpopulations.
(A) Modulation for the preferred arm plotted against arm preference, for all units in each brain area and task phase. Log-linear best fit lines are displayed in red. Inset figures belong to Monkey W. (B) Slopes of regression lines fit to data from (A), independently for ipsi- and contra-preferring sub-populations. Mean +/- bootstrapped 95% confidence interval. (C-E) For the Move phase in monkey O, cumulative modulation plotted against arm preference, i.e. each point indicates the proportion of modulation accounted for by all units with arm preference values to the left of the indexed position. Positive values on the x-axis indicate contra-preferring, and negative values indicate ipsi-preferring. Shaded error bars indicate bootstrapped standard error. See S2 Fig for cumulative modulation plots for both animals in each phase. (C) The full spectrum of arm preferences is shown. Shaded backgrounds indicate three partitions: Contra-dedicated [0.4, 1] and Ipsi-dedicated [-1, -0.4] in white, and Neutral [-0.3, 0.3] in grey. (D) Cumulative modulation within contra-dedicated regime. (E) Same as (D), but ipsi-dedicated. Note inverted axis. (F) The proportion of modulation within each partition from (C) during ipsi- or contralateral movements. Note that the total modulation is significantly lower for ipsilateral movements, particularly for Monkey W, and these data are only displayed as proportions. Mean +/- bootstrapped 95% confidence interval.