Fig. 2: Evidence of state-dependent encoding during handwriting.
From: Human motor cortex encodes complex handwriting through a sequence of stable neural states
a, Reliability and tuning property of neurons (n = 2,850 neurons across 20 sessions). The reliability of the response to each character is characterized using the Fisher’s discriminant value (FD) across characters (the 30 within each session), while the tuning property is characterized using the R2 of the directional tuning model. Neurons with reliable tuning but cannot be explained by the directional tuning model are referred to as complex-tuning neurons (n = 115, R2 < 0.1 and FD ≥ 1.4), and neurons conformed to the directional tuning model are referred to as simple-tuning neurons (n = 64, R2 ≥ 0.1 and FD ≥ 1.4). b,c, Responses of exemplary complex-tuning neurons during handwriting, including the tuning curves (solid line, mean over 90 trials; shaded area, s.d.) and the neural firing rate overlaid on the character trajectory. b, An exemplary neuron that shows diverged responses to the same downward movement in two characters. c, An exemplary neuron that responds to multiple movement directions but does not consistently respond to any direction. d, Responses of exemplary simple-tuning neurons during handwriting, including the tuning curves (solid line, mean over 90 trials; shaded area, s.d.) and the neural firing rate overlaid on the character trajectory. The neuron responds to the downward direction during writing, while it responds to some fragments but not others, although the fragments contain similar trajectories Source data.
