Fig. 9.

Temporal evolution of laminar activation. A: initial transient spiking (solid lines) and current source density sink (SiCSD; dashed lines) responses to the first (Init.; black) and fourth (Rep.; red) stimulus presentations for the granular and supragranular laminar compartments. Each response was averaged across all sessions (N = 61) and both monkeys. Responses were normalized between the baseline and maximum response for comparison. B: subtractive analysis between conditions where the response to the fourth presentation (P₄) is subtracted from first (P₁) for each data type-compartment combination. Color denotes laminar compartment (blue, supragranular; purple, granular), and lines denote spiking (solid) or SiCSD (dashed). Red drop lines show when the difference between conditions becomes significant through a t-test at each data point with a P value <0.001 for more than 10 consecutive samples. Supragranular SiCSD differences precede spiking differences in both laminar compartments, and granular SiCSD does not become significantly different until after spiking has already been suppressed.