Fig. 2: Hand position specific firing in PMd cell is not a byproduct of known tuning properties.

A Firing rate as a function of hand-direction, hand-speed, and food-location in three exemplary cells, respectively. The upper row, firing rate as a function of hand moving direction, followed by the distribution of preferred direction of hand direction-tuned cells (n = 144). The middle row, firing rate as a function of hand moving speed, followed by the distribution of speed score of hand speed-tuned cells (n = 192). The bottom row, color-coded spatial rate maps for food location, followed by the distribution of SI of all food location-tuned cells (n = 18). Dark blue indicates the minimal firing rate within the map, and dark red indicates the maximal firing rate within the map. B Population summary of cells tuned to hand position, hand moving direction, speed, or food location. C Scatter plot showing hand-position/speed-direction indexes and hand-position/food-location indexes of the 132 hand position-tuned cells which met the SI criterion. During the reconstruction analysis, we obtained two normalized reconstruction errors based on two opposing hypotheses and subsequently, the ratio of these errors yields the hand-position index. We identified cells with higher hand-position index ( > 1) as primary hand position-tuned cells whose hand position tunings could not be explained by pure other tunings (n = 50, blue dots). The vertical dotted line and the horizontal dotted line indicate the identity hand-position index. Source data is provided as a Source Data file.