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. Author manuscript; available in PMC: 2010 Mar 12.
Published in final edited form as: J Neurosurg. 2009 Jun;110(6):1304–1316. doi: 10.3171/2008.10.JNS08466

Fig. 3.

Fig. 3

A single unit in the SMA proper (Case 2) related to multiple kinematic parameters: speed, direction, magnitude of the acceleration vector, and position in the x direction. The firing rate increases with speed (A) and x position (D), but decreases with acceleration (C). Movement to the right gains higher firing rates (B), which is consistent with an increase in firing rate along the positive x axis (D). The effective field in Cartesian velocity space (E) demonstrates the interaction between speed and direction: high firing rates are obtained at high speeds, but only when moving in the “right” direction. The gradual increase in firing rate with increase in speed is best viewed in polar coordinates (F) on the second row (that is, only for movement in the “right” direction).