Journal: bioRxiv

Article Title: Reinforcement-Based Processes Actively Regulate Motor Exploration Along Redundant Solution Manifolds

doi: 10.1101/2023.02.08.527668

Figure Lengend Snippet: A) Participants grasped the handle of a robotic manipulandum. A semi-silvered mirror projected images (start position, target) from an LCD screen and occluded vision of the hand. Participants were instructed to reach from the start position (white circle) and attempt to stop their hand inside a virtually displayed target (white rectangle). For all experiments, participants were informed that they would receive positive reinforcement feedback (pleasant sound, target expands, small monetary gain; represented with the sound icons) if they successfully stopped within the target. B) Experiment 1 examined the role of reinforcement feedback on exploratory sensorimotor behaviour. In separate blocks of trials, participants reached either to a long-rectangular target that promoted exploration along the movement extent (task-redundant, light blue) or a short-rectangular target (task-relevant, light orange) that discouraged exploration. Participants received positive reinforcement feedback if they stopped within the virtually displayed target. C) In Experiment 2 , our goal was to control for the size of the virtually displayed target and to replicate the results of the first experiment. Participants always observed a short-rectangular target (solid grey outline) and received reinforcement feedback when their hand stopped within the reward zone (dashed grey outline). Critically, and unbeknownst to participants, in one condition there was a long-rectangular reward zone (task-redundant, dark blue) that promoted exploration. In the second condition, the reward zone matched the virtually displayed short rectangular target (task-relevant, dark red). D) In Experiment 3 we manipulated the probability of reinforcement feedback while controlling for both the size of the virtually displayed target and the unseen reward zone. Participants were shown the same long rectangular target (dark grey outline) and probabilistically received positive reinforcement feedback when their hand stopped within the reward zone (grey dashed outline). There was an 80% probability (purple) and a 20% probability (pink) that participants would receive positive reinforcement feedback in either condition.

Article Snippet: Participants grasped the handle of a robotic manipulandum ( , KINARM, BKIN Technologies, Kingston, ON, Canada) and made reaching movements in the horizontal plane.

Techniques:

Journal: PLoS Computational Biology

Article Title: The decay of motor adaptation to novel movement dynamics reveals an asymmetry in the stability of motion state-dependent learning

doi: 10.1371/journal.pcbi.1005492

Figure Lengend Snippet: (A) Experimental setup. Subjects made reaching movements from mid-line in both forward (90°) and backward (270°) directions, using a robotic manipulandum. The location of the hand was represented by a filled yellow circle, while the view of arm was occluded. (B) Trial Types. Null movements (grey arrows) were made in the absence of the any force from the robot. During force-field trial movements, the robot applied forces that were dependent on a single or combination of motion kinematics. During velocity-dependent force-field movements the manipulandum applied lateral forces that scaled with movement velocity (black arrows). For position-dependent movements, the lateral force scaled with hand position with respect to the start position. Lastly, for both unbiased and position biased combination force-field movements the lateral force scaled with both hand position and velocity. During error-clamp movements the manipulandum constrained the movement trajectory between the two targets by countering any lateral motions. (C) Experimental Paradigm. Subjects first completed a baseline period, during which they experienced null movements with sparse instances of error-clamp movements (blue bars). The 1 st transition period, contained an initial period of null movements, followed by the abrupt application of the force-field. The adaptation period contained only force-field and error-clamp trials. Finally, the 2 nd transition period started with force-field movements followed by only error-clamp trials (thick blue bar). The frequency of error clamp trials increased during the two transition periods.

Article Snippet: The subjects were instructed to move a cursor between two targets located on a screen in the sagittal axis of their body while grasping a robot manipulandum (KINARM End-Point Lab, ).

Techniques:

Journal: iScience

Article Title: Post-surgical wireless monitoring of arterial health progression

doi: 10.1016/j.isci.2021.103079

Figure Lengend Snippet: In vitro demonstrations indicate strong capability to monitor arterial pulsations and arterial blockage progression (A) Photograph of the experiment setup with the pulsatile negative air flow simulation to mimic arterial pulsatile behavior. The interdigitated fringe-field capacitive sensor is wrapped around a polyolefin tube with either a 5- or 6-mm diameter that is closed at one end and connected to the air pump at the other. (B) Relative capacitance change of the wired sensor wrapped like a cuff around the artificial artery. The sensor distinguishes between different physiological pulse rates (45, 60, and 80 bpm) when wrapped around the 6-mm tube (top). This capability is consistent for a 5-mm artery even with the addition of a 1-lb layer of artificial fat, skin, and muscle (Syndaver) on top of the construct to better mimic implantation (bottom). (C) Photograph of the experiment setup with a continuous water flow in a closed circular loop. The interdigitated fringe-field capacitive sensor is wrapped around an artificial artery (Syndaver) with an inner diameter of 2–7 mm. The sensor is wrapped around the artery like a cuff and 1-lb of artificial fat, skin, and muscle is applied on top to mimic for similar additional pressures in vivo. The blockage is incorporated by wrapping a thick rubber string around the artificial artery at different diameters. (D) The sensor responds to blockages 10 cm downstream of the sensor when wrapped around a 2-mm inner diameter artificial artery to mimic a radial artery. The red-filled circle indicates a blocked artery while the circle with non-filled circle indicates normal flow. (E) The sensor responds to progression of arterial blockages at 0%, 44%, 75%, and 100% reduction in arterial area when wrapped around a 4-mm inner diameter artificial artery to mimic a coronary artery. The extent of blockage is represented by the extent to which blue circles (to represent an artery) are blue filled. (F) When wrapped around a 6-mm inner diameter artificial artery to mimic the carotid artery, the sensor demonstrates capability to detect extent of arterial blockage for partial and full blockages up to at least 10-cm downstream of the sensor. Extent of blockage is indicated by extent of red filling of the circles to represent arteries. Data are represented as mean change. (G) The sensor is able to detect blockages upstream of the sensor, here wrapped around a 4-mm inner diameter artificial artery. Capacitance decreases with application of a blockage to indicate the pressure decrease from elimination of flow. (H) When wrapped around a 7-mm inner diameter artificial artery to mimic the femoral artery, the sensor demonstrates capability to detect extent of arterial blockage for blockages at different distance upstream of the sensor. The sign of the relative capacitance change is dependent on the distance from the partial blockage due to high-frequency oscillations in flow and pressure. Extent of blockage is indicated by extent of red filling of the circles to represent arteries. Data are represented as mean change. (I) Photograph of the experiment setup with continuous water flow in a closed circular circuit, similar to (C) with the addition of a robotic gripper (Lynxmotion Little Grip Kit, Robotshop). The gripper was used to introduce pulsations at a rate of 60 bpm with a change in arterial area of 10–15%. (J) When wrapped around a 6-mm inner diameter artificial artery, the sensor distinguishes between pulses and progression of blockages for a partial blockage 1-cm upstream of the sensor. (K) When 1-lb of artificial fat, skin, and muscle is applied to the sensor wrapped around a 6-mm inner diameter artificial artery, it still maintains capability to distinguish between pulsations and progression of blockages, here shown for a partial blockage 2-cm downstream of the sensor.

Article Snippet: Data are represented as mean change. (I) Photograph of the experiment setup with continuous water flow in a closed circular circuit, similar to (C) with the addition of a robotic gripper (Lynxmotion Little Grip Kit, Robotshop).

Techniques: In Vitro, Construct, In Vivo, Introduce

Journal: iScience

Article Title: Post-surgical wireless monitoring of arterial health progression

doi: 10.1016/j.isci.2021.103079

Figure Lengend Snippet:

Article Snippet: Data are represented as mean change. (I) Photograph of the experiment setup with continuous water flow in a closed circular circuit, similar to (C) with the addition of a robotic gripper (Lynxmotion Little Grip Kit, Robotshop).

Techniques: Recombinant, Software