Fig. 2.

Architecture of eye-hand coordination. A–C: schematics of the 3 different architectures that generate coordinated eye-hand movements. [Adapted from Gopal et al. (2015).] A possible architecture is schematized with a separate visual stage (purple squares), where the targets get encoded, and a motor planning stage (pink circles). Thick red (eye) and dashed blue (hand) traces represent separate stochastic signals that are integrated over time to reach a threshold indicated by the dashed black line. Each movement is executed as soon as the respective accumulator reaches threshold. A: an independent model in which eye and hand effectors have completely distinct and separate visual and motor planning stages but are passively coordinated by the common target. B: an interactive model comprising independent eye and hand networks that interact (black arrows) at the level of motor preparation. C: a common command model, which is thought to have a common visual and motor planning stage. The dashed red-blue trace represents the common stochastic sensory signal that is integrated over time to reach threshold. Saccades are executed as soon as the common signal reaches threshold, whereas hand movements are executed after a temporal delay with Gaussian jitter (green).