PMC6220062_01
Experimental design. (A) Images of the four objects selected to represent different levels of required grasp force. (B) Task presentation and timing of the attempted grasp and object observation trials. (C) Object transport trial example. For this task, the name of one of the four objects was played at the start of the trial and the subject was then asked to attempt to use the virtual arm to grasp and transport the virtual object with the appropriate amount of force. Five position targets were used including a center target and four others approximately 20 cm above, below, left, and right of center.
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F1
He had two 4 x 4 mm, 88-channel microelectrode arrays (Blackrock Microsystems, Salt Lake City, UT, United States) implanted in the hand and arm area of M1 in the left hemisphere (Locations shown in Figure 1C of). The subject was asked to watch a television screen where images of four different objects were presented: a large marshmallow, a tomato, an orange, and a can of soup (Figure 1A). For all trials, the target object was shown for 4 s, followed by 4 s of rest during which a fixation cross was displayed before the next trial started (Figure 1B). At the start of each trial, one of the four objects (Figure 1A) was spoken as a computer-generated audio cue. Next, a red ellipsoid appeared at a target position (Figure 1C). To determine whether implicit grasp force was represented in M1 during attempted grasp and object observation, we performed naive Bayes classification on 1 s of neural data starting 2 s after the start of the trial (Figure 1B).