Figure 5.

Preference of motor cortex and PPC neurons for contralateral or ipsilateral forelimb movements. A, Functional spike activity of RS and FS subtypes of M1, M2, and PPC neurons for contralateral and ipsilateral forelimb movements. Each row shows normalized Gaussian-filtered PETH of a single neuron [aligned with the pedal release onset at 0 s (vertical line); σ = 12.5 ms for spikes in 0.05 ms bins] during contralateral and ipsilateral release trials. The task-related neurons were sorted by the order of peak time (early to late). B, Distributions for the contralateral (abscissa) and ipsilateral (ordinate) release trials in peak activity of go-type neurons and in sustained activity of hold-type neurons in M1, M2, and PPC. Light triangles and dark circles represent individual RS and FS neurons, respectively. C, Cumulative distributions (left) and averages (right) of the laterality index of go-type activity for the RS (top) and FS (bottom) subtypes of M1, M2, and PPC neurons. Its positive and negative values indicate preference for contralateral and ipsilateral forelimb movements, respectively. Error bars indicate SEM. D, Cumulative distributions (left) and averages (right) of the AUC in ROC analysis between contralateral and ipsilateral trials of go-type activity for the RS (top) and FS (bottom) subtypes of M1, M2, and PPC neurons. See Materials and Methods for details. *p < 0.05, **p < 0.01, ***p < 0.001, post hoc Scheffe's test.