The authors would like to thank Alexis M. Wilson and Marisa E. Bertoli for their assistance with filming and preparing the video for this manuscript. This research was supported by the Natural Sciences and Engineering Research Council of Canada (JMK, JRK, IQW), Alberta Innovates-Health Solutions (JMK), and the Canadian Institutes of Health Research (IQW).

<ol>
	<li>Karl, J. M., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Different+evolutionary+origins+for+the+Reach+and+the+Grasp:+an+explanation+for+dual+visuomotor+channels+in+primate+parietofrontal+cortex.">Different evolutionary origins for the Reach and the Grasp: an explanation for dual visuomotor channels in primate parietofrontal cortex.</a> Front Neurol. 4 (208), (2013).</li><li>Whishaw, I. Q., Karl, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+contribution+of+the+reach+and+the+grasp+to+shaping+brain+and+behaviour.">The contribution of the reach and the grasp to shaping brain and behaviour.</a> Can J Exp Psychol. 68 (4), 223-235 (2014).</li><li>Jeannerod, M., Long, J., Badeley, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intersegmental+coordination+during+reaching+at+natural+visual+objects.">Intersegmental coordination during reaching at natural visual objects.</a> Attention and Performance IX. , 153-169 (1981).</li><li>Arbib, M. A., Brooks, V. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perceptual+structures+and+distributed+motor+control.">Perceptual structures and distributed motor control.</a> Handbook of Physiology. 2, 1449-1480 (1981).</li><li>De Bruin, N., Sacrey, L. A., Brown, L. A., Doan, J., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visual+guidance+for+hand+advance+but+not+hand+withdrawal+in+a+reach-to-eat+task+in+adult+humans:+reaching+is+a+composite+movement.">Visual guidance for hand advance but not hand withdrawal in a reach-to-eat task in adult humans: reaching is a composite movement.</a> J Mot Behav. 40 (4), 337-346 (2008).</li><li>Karl, J. M., Sacrey, L. A., Doan, J. B., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hand+shaping+using+hapsis+resembles+visually+guided+hand+shaping.">Hand shaping using hapsis resembles visually guided hand shaping.</a> Exp Brain Res. 219 (1), 59-74 (2012).</li><li>Domell&#246;ff, E., Hopkins, B., Francis, B., R&#246;nnqvist, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+finger+markers+on+the+kinematics+of+reaching+movements+in+young+children+and+adults.">Effects of finger markers on the kinematics of reaching movements in young children and adults.</a> J Appl Biomech. 23 (4), 315-321 (2007).</li><li>Karl, J. M., Sacrey, L. A., Doan, J. B., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oral+hapsis+guides+accurate+hand+preshaping+for+grasping+food+targets+in+the+mouth.">Oral hapsis guides accurate hand preshaping for grasping food targets in the mouth.</a> Exp Brain Res. 221 (2), 223-240 (2012).</li><li>Karl, J. M., Schneider, L. R., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonvisual+learning+of+intrinsic+object+properties+in+a+reaching+task+dissociates+grasp+from+reach.">Nonvisual learning of intrinsic object properties in a reaching task dissociates grasp from reach.</a> Exp Brain Res. 225 (4), 465-477 (2013).</li><li>Hall, L. A., Karl, J. M., Thomas, B. L., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reach+and+Grasp+reconfigurations+reveal+that+proprioception+assists+reaching+and+hapsis+assists+grasping+in+peripheral+vision.">Reach and Grasp reconfigurations reveal that proprioception assists reaching and hapsis assists grasping in peripheral vision.</a> Exp Brain Res. 232 (9), 2807-2819 (2014).</li><li>Karl, J. M., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Haptic+grasping+configurations+in+early+infancy+reveal+different+developmental+profiles+for+visual+guidance+of+the+Reach+versus+the+Grasp.">Haptic grasping configurations in early infancy reveal different developmental profiles for visual guidance of the Reach versus the Grasp.</a> Exp Brain Res. 232 (9), 3301-3316 (2014).</li><li>Whishaw, I. Q., Karl, J. M., Humphrey, N. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissociation+of+the+Reach+and+the+Grasp+in+the+destriate+(V1)+monkey+Helen:+a+new+anatomy+for+the+dual+visuomotor+channel+theory+of+reaching.">Dissociation of the Reach and the Grasp in the destriate (V1) monkey Helen: a new anatomy for the dual visuomotor channel theory of reaching.</a> Exp Brain Res. 234 (8), 2351-2362 (2016).</li><li>Timmann, D., Stelmach, G. E., Bloedel, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grasping+component+alterations+and+limb+transport.">Grasping component alterations and limb transport.</a> Exp Brain Res. 108 (3), 486-492 (1996).</li><li>Saling, M., Mescheriakov, S., Molokanova, E., Stelmach, G. E., Berger, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grip+reorganization+during+wrist+transport:+the+influence+of+an+altered+aperture.">Grip reorganization during wrist transport: the influence of an altered aperture.</a> Exp Brain Res. 108 (3), 493-500 (1996).</li><li>Whishaw, I. Q., Faraji, J., Kuntz, J., Mirza Ahga, B., Patel, M., Metz, G. A. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organization+of+the+reach+and+grasp+in+head-fixed+vs+freely-moving+mice+provides+support+for+multiple+motor+channel+theory+of+neocortical+organization.">Organization of the reach and grasp in head-fixed vs freely-moving mice provides support for multiple motor channel theory of neocortical organization.</a> Exp Brain Res. 235 (6), 1919-1932 (2017).</li></ol>

The authors have no competing financial interests to disclose.

The present paper describes how to use frame-by-frame video analysis to quantify the temporal organization, kinematic structure, and a subset of topographical features of human reach-to-grasp movements. The technique can be used to study typical visually-guided reach-to-grasp movements, but also idiosyncratic reach-to-grasp movements. Such movements are difficult to study using traditional 3D motion tracking systems, but are common in developing infants, participants with altered sensory processing, and patients with sen...

Prehension, the act of reaching to grasp an object, is used for many daily functions including acquiring food items for eating, grooming, manipulating objects, wielding tools, and communicating through gesture and written word. The most prominent theory concerning the neurobehavioral control of prehension, the Dual Visuomotor Channel theory1,2,3,4, proposes that prehension consists of two movements - a reach that transports the hand to the location of the target and a grasp that opens, shapes, and closes the hand to the size and shape of the target. The two movements are mediated by dissociable but interacting neural pathways from visual to motor cortex via the parietal lobe1,2,3,4. Behavioral support for the Dual Visuomotor Channel theory has been ambiguous, largely due to the fact that the reach-to-grasp movement appears as a single seamless act and unfolds with little conscious effort. Nonetheless, prehension is almost always studied in the context of visually-guided prehension in which a healthy participant reaches to grasp a visible target object. Under these circumstances the action does appear as a single movement that unfolds in a predictable and stereotypical fashion. Prior to reach onset the eyes fixate on the target. As the arm extends the digits open, preshape to the size of the object, and subsequently start to close. The eyes disengage from the target just prior to target contact and final grasp of the target follows almost immediately afterwards5. When vision is removed, however, the structure of the movement is fundamentally different. The movement dissociates into its constituent components such that an open-handed reach is first used to locate the target by touching it and then haptic cues associated with target contact guide shaping and closure of the hand to grasp6.
Quantification of the reach-to-grasp movement is most often achieved using a 3 dimensional (3D) motion tracking system. These can include infrared tracking systems, electromagnetic tracking systems, or video based tracking systems. While such systems are effective for acquiring kinematic measures of prehension in healthy adult participants performing stereotypical reach-to-grasp movements towards visible target objects, they do have a number of drawbacks. In addition to being very expensive, these systems require the attachment of sensors or markers onto the arm, hand, and digits of the participant. These are usually attached using medical tape, which can impede tactile feedback from the hand, alter natural motor behavior, and distract participants7. As these systems generally produce numerical output related to different kinematic variables such as acceleration, deceleration, and velocity they are also not ideal for investigating how the hand contacts the target. When using these systems, additional sensors or equipment are required to determine what part of the hand makes contact with the target, where on the target contact occurs, and how the configuration of the hand might change in order to manipulate the target. In addition, infrared tracking systems, which are the most commonly employed, require the use of a specialized camera to track the location of the markers on the hand in 3D space6. This requires a direct line of sight between the camera and the sensors on the hand. As such, any idiosyncrasies in the movement are likely to obscure this line of sight and result in the loss of critical kinematic data. There are, however, a large number of instances in which idiosyncrasies in the reach-to-grasp movement are actually the norm. These include during early development when infants are just learning to reach and grasp for objects; when the target object is not visible and tactile cues must be used to guide the reach and the grasp; when the target object is an odd shape or texture; and when the participant presents with any one of a variety of sensorimotor disorders such as a stroke, Huntington&#39;s disease, Parkinson&#39;s disease, Cerebral Palsy, etc. In all of these cases, the reach-to-grasp movement is neither predictable nor stereotypical, nor is it necessarily guided by vision. Consequently, the capability of 3D motion tracking systems to reliably quantify the temporal and kinematic structure of these movements can be severely limited due to disruptions in sensory feedback from the hand, changes in natural motor behavior, loss of data, and/or difficulties interpreting the idiosyncratic kinematic output from these devices.
The present paper describes a novel technique for quantifying idiosyncratic reach-to-grasp movements in various human populations that is affordable, does not impede sensory feedback from the hand or natural motor behavior, and is reliable but can be flexibly modified to suit a variety of experimental paradigms. The technique involves using multiple high-speed video cameras to record the reach-to-grasp movement from multiple angles. The video is then analyzed offline by progressing through the video frames one at a time and using visual inspection to document key behavioral events that, together, provide a quantified description of the temporal and kinematic organization of the reach-to-grasp movement. The present paper describes a comparative analysis of visually- versus nonvisually-guided reach-to-grasp movements in healthy human adults6,8,9,10 in order to demonstrate the efficacy of the technique; however, modified versions of the technique have also been used to quantify the reach-to-grasp actions of human infants11 and non-human primates12. The comprehensive results of the frame-by-frame video analysis from these studies are among the first to provide behavioral evidence in support of the Dual Visuomotor Channel theory of prehension.

<table><tbody><tr><td>High Speed Video Cameras</td><td>Casio</td><td>http://www.casio-intl.com/asia-mea/en/dc/ex_f1/ or http://www.casio-intl.com/asia-mea/en/dc/ex_100/</td><td>Casio EX-F1 High Speed Camera or Casio EX-100 High Speed Camera used to collect high speed video records</td></tr><tr><td>Adobe Photoshop</td><td>Adobe</td><td>http://www.adobe.com/ca/products/photoshop.html</td><td>Software used to calibrate and measure distances on individual video frames</td></tr><tr><td>Adobe Premiere Pro</td><td>Adobe</td><td>http://www.adobe.com/ca/products/premiere.html?sdid=KKQOM&amp;amp;mv=search&amp;amp;s_kwcid=AL!3085!3!193588412847!e!!g!!adobe%20premiere%20pro&amp;amp;ef_id=WDd17AAABAeTD6-D:20170606160204:s</td><td>Software used to perform Frame-by-Frame Video Analysis</td></tr><tr><td>Height-Adjustable Pedestal</td><td>Sanus</td><td>http://www.sanus.com/en_US/products/speaker-stands/htb3/</td><td>A height adjustable speaker stand with a custom made 9 cm x 9 cm x 9 cm triangular top plate attached to the top with a screw is used as a reaching pedestal</td></tr><tr><td>1 cm Calibration Cube</td><td>Learning Resources (Walmart)</td><td>https://www.walmart.com/ip/Learning-Resources-Centimeter-Cubes-Set-500/24886372</td><td>A 1 cm plastic cube is used to transform distance measures from pixels to centimeters</td></tr><tr><td>Studio Light</td><td>Dot Line</td><td>https://www.bhphotovideo.com/c/product/1035910-REG/dot_line_rs_5620_1600w_led_light.html</td><td>Strong lamp with cool LED light used to illumate the participant and testing area</td></tr><tr><td>3 Dimensional (3D) Sleep Mask</td><td>Kfine</td><td>https://www.amazon.com/Kfine-Sleeping-Contoured-lightweight-Comfortable/dp/B06W5CDY78?th=1</td><td>Used as a blindfold to occlude vision in the No Vision condition</td></tr><tr><td>Orange Slices</td><td>N/A</td><td>N/A</td><td>Orange slices served as the large sized reaching targets</td></tr><tr><td>Donut Balls</td><td>Tim Hortons</td><td>http://www.timhortons.com/ca/en/menu/timbits.php</td><td>Old fashion plain timbits from Tim Hortons served as the medium sized reaching targets</td></tr><tr><td>Blueberries</td><td>N/A</td><td>N/A</td><td>Blueberries served as the small sized reaching targets</td></tr></tbody></table>

frame-by-frame video analysis of idiosyncratic reach-to-grasp movements in humans

Prehension, the act of reaching to grasp an object, is central to the human experience. We use it to feed ourselves, groom ourselves, and manipulate objects and tools in our environment. Such behaviors are impaired by many sensorimotor disorders, yet our current understanding of their neural control is far from complete. Current technologies for investigating human reach-to-grasp movements often utilize motion tracking systems that can be expensive, require the attachment of markers or sensors to the hands, impede natural movement and sensory feedback, and provide kinematic output that can be difficult to interpret. While generally effective for studying the stereotypical reach-to-grasp movements of healthy sighted adults, many of these technologies face additional limitations when attempting to study the unpredictable and idiosyncratic reach-to-grasp movements of young infants, unsighted adults, and patients with neurological disorders. Thus, we present a novel, inexpensive, and highly reliable yet flexible protocol for quantifying the temporal and kinematic structure of idiosyncratic reach-to-grasp movements in humans. High speed video cameras capture multiple views of the reach-to-grasp movement. Frame-by-frame video analysis is then used to document the timing and magnitude of pre-defined behavioral events such as movement start, collection, maximum height, peak aperture, first contact, and final grasp. The temporal structure of the movement is reconstructed by documenting the relative frame number of each event while the kinematic structure of the hand is quantified using the ruler or measure function in photo editing software to calibrate 2 dimensional linear distances between two body parts or between a body part and the target. Frame-by-frame video analysis can provide a quantitative and comprehensive description of idiosyncratic reach-to-grasp movements and will enable researchers to expand their area of investigation to include a greater range of naturalistic prehensile behaviors, guided by a wider variety of sensory modalities, in both healthy and clinical populations.

This section provides examples of the results that can be obtained when using frame-by-frame video analysis to investigate idiosyncratic reach-to-grasp movements under nonvisual sensory guidance. The primary finding is that when participants can use vision to preemptively identify both the extrinsic (location/orientation) and intrinsic (size/shape) properties of a target object they integrate the reach and the grasp into a single seamless prehensile act in which they preshape the hand to ...

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Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans

This protocol describes how to use frame-by-frame video analysis to quantify idiosyncratic reach-to-grasp movements in humans. A comparative analysis of reaching in sighted versus unsighted healthy adults is used to demonstrate the technique, but the method can also be applied to the study of developmental and clinical populations.

Prehension, the act of reaching to grasp an object, is central to the human experience. We use it to feed ourselves, groom ourselves, and manipulate ...

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8.3K Views.  Thompson Rivers University. This protocol describes how to use frame-by-frame video analysis to quantify idiosyncratic reach-to-grasp movements in humans. A comparative analysis of reaching in sighted versus unsighted healthy adults is used to demonstrate the technique, but the method can also be applied to the study of developmental and clinical populations.

Video: Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans

Corticospinal Excitability Modulation During Action Observation

This study used the transcranial magnetic stimulation/motor evoked potential (TMS/MEP) technique to pinpoint when the automatic tendency to mirror someone else's action becomes anticipatory simulation of a complementary act. TMS was delivered to the left primary motor cortex corresponding to the hand to induce the highest level of MEP activity from the abductor digiti minimi (ADM; the muscle serving little finger abduction) as well as the first dorsal interosseus (FDI; the muscle serving index finger flexion/extension) muscles. A neuronavigation system was used to maintain the position of the TMS coil, and electromyographic (EMG) activity was recorded from the right ADM and FDI muscles. Producing original data with regard to motor resonance, the combined TMS/MEP technique has taken research on the perception-action coupling mechanism a step further. Specifically, it has answered the questions of how and when observing another person's actions produces motor facilitation in an onlooker's corresponding muscles and in what way corticospinal excitability is modulated in social contexts.

Single-pulse transcranial magnetic stimulation over the primary motor cortex, neuronavigation, and registration of electromyographic activity of hand muscles were used in this study to explore corticospinal excitability while participants were observing action sequences.

This study used the transcranial magnetic stimulation/motor evoked potential (TMS/MEP) technique to pinpoint when the automatic tendency to mirror someone ...

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are deliberately planned, while others spontaneously occur below conscious awareness. The deliberate component of this dichotomy has been studied extensively in several contexts, while the spontaneous component remains largely under-explored. Moreover, how perceptual processes modulate these movement classes is still unclear. In particular, a currently debated issue is whether the visuomotor system is governed by the spatial percept produced by a visual illusion or whether it is not affected by the illusion and is governed instead by the veridical percept. Bistable percepts such as 3D depth inversion illusions (DIIs) provide an excellent context to study such interactions and balance, particularly when used in combination with reach-to-grasp movements. In this study, a methodology is developed that uses a DII to clarify the role of top-down processes on motor action, particularly exploring how reaches toward a target on a DII are affected in both deliberate and spontaneous movement domains.

It is unclear how top-down signals from the ventral visual stream affect movement. We developed a paradigm to test motor behavior towards a target on a 3D depth inversion illusion. Significant differences are reported in both deliberate, goal-directed movements and automatic actions under illusory and veridical viewing conditions.

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are ...

Investigating Motor Skill Learning Processes with a Robotic Manipulandum

Skilled reaching tasks are commonly used in studies of motor skill learning and motor function under healthy and pathological conditions, but can be time-intensive and ambiguous to quantify beyond simple success rates. Here, we describe the training procedure for reach-and-pull tasks with ETH Pattus, a robotic platform for automated forelimb reaching training that records pulling and hand rotation movements in rats. Kinematic quantification of the performed pulling attempts reveals the presence of distinct temporal profiles of movement parameters such as pulling velocity, spatial variability of the pulling trajectory, deviation from midline, as well as pulling success. We show how minor adjustments in the training paradigm result in alterations in these parameters, revealing their relation to task difficulty, general motor function or skilled task execution. Combined with electrophysiological, pharmacological and optogenetic techniques, this paradigm can be used to explore the mechanisms underlying motor learning and memory formation, as well as loss and recovery of function (e.g. after stroke).

A paradigm is presented for training and analysis of an automated skilled reaching task in rats. Analysis of pulling attempts reveals distinct subprocesses of motor learning.

Skilled reaching tasks are commonly used in studies of motor skill learning and motor function under healthy and pathological conditions, but can be ...

The Structure of Skilled Forelimb Reaching in the Rat: A Movement Rating Scale

Skilled reaching for food is an evolutionary ancient act and is displayed by many animal species, including those in the sister clades of rodents and primates. The video describes a test situation that allows filming of repeated acts of reaching for food by the rat that has been mildly food deprived. A rat is trained to reach through a slot in a holding box for food pellet that it grasps and then places in its mouth for eating. Reaching is accomplished in the main by proximally driven movements of the limb but distal limb movements are used for pronating the paw, grasping the food, and releasing the food into the mouth. Each reach is divided into at least 10 movements of the forelimb and the reaching act is facilitated by postural adjustments. Each of the movements is described and examples of the movements are given from a number of viewing perspectives. By rating each movement element on a 3-point scale, the reach can be quantified. A number of studies have demonstrated that the movement elements are altered by motor system damage, including damage to the motor cortex, basal ganglia, brainstem, and spinal cord. The movements are also altered in neurological conditions that can be modeled in the rat, including Parkinson's disease and Huntington's disease. Thus, the rating scale is useful for quantifying motor impairments and the effectiveness of neural restoration and rehabilitation. Because the reaching act for the rat is very similar to that displayed by humans and nonhuman primates, the scale can be used for comparative purposes. from a number of viewing perspectives. By rating each movement element on a 3-point scale, the reach can be quantified. A number of studies have demonstrated that the movement elements are altered by motor system damage, including damage to the motor cortex, basal ganglia, brainstem, and spinal cord. The movements are also altered in neurological conditions that can be modeled in the rat, including Parkinson's disease and Huntington's disease. Thus, the rating scale is useful for quantifying motor impairments and the effectiveness of neural restoration and rehabilitation.

Experiments on animals were performed in accordance with the guidelines and regulations set forth by the University of Lethbridge Animal Care Committee in accordance with the regulations of the Canadian Council on Animal Care.

The skilled reaching scale divides the movement by a forelimb in a reach for food act into composite elements each of which are evaluated with a three-point scale. The rating scale is described for a normal rat and can be applied toward evaluating neurological motor disorders.

Skilled reaching for food is an evolutionary ancient act and is displayed by many animal species, including those in the sister clades of rodents and ...

Biology

Design and Use of an Apparatus for Presenting Graspable Objects in 3D Workspace

Reaching and grasping are highly-coupled movements, and their underlying neural dynamics have been widely studied in the last decade. To distinguish reaching and grasping encodings, it is essential to present different object identities independent of their positions. Presented here is the design of an automatic apparatus that is assembled with a turning table and three-dimensional (3D) translational device to achieve this goal. The turning table switches different objects corresponding to different grip types while the 3D translational device transports the turning table in 3D space. Both are driven independently by motors so that the target position and object are combined arbitrarily. Meanwhile, wrist trajectory and grip types are recorded via the motion capture system and touch sensors, respectively. Furthermore, representative results that demonstrate successfully trained monkey using this system are described. It is expected that this apparatus will facilitate researchers to study kinematics, neural principles, and brain-machine interfaces related to upper limb function.

Presented here is a protocol to build an automatic apparatus that guides a monkey to perform the flexible reach-to-grasp task. The apparatus combines a 3D translational device and turning table to present multiple objects in an arbitrary position in 3D space.

Reaching and grasping are highly-coupled movements, and their underlying neural dynamics have been widely studied in the last decade. To distinguish ...

Automated Rat Single-Pellet Reaching with 3-Dimensional Reconstruction of Paw and Digit Trajectories

Rodent skilled reaching is commonly used to study dexterous skills, but requires significant time and effort to implement the task and analyze the behavior. Several automated versions of skilled reaching have been developed recently. Here, we describe a version that automatically presents pellets to rats while recording high-definition video from multiple angles at high frame rates (300 fps). The paw and individual digits are tracked with DeepLabCut, a machine learning algorithm for markerless pose estimation. This system can also be synchronized with physiological recordings, or be used to trigger physiologic interventions (e.g., electrical or optical stimulation).

Rodent skilled reaching is commonly used to study dexterous skills, but requires significant time and effort to implement the task and analyze the behavior. We describe an automated version of skilled reaching with motion tracking and three-dimensional reconstruction of reach trajectories.

Rodent skilled reaching is commonly used to study dexterous skills, but requires significant time and effort to implement the task and analyze the ...

Estimation of Contact Regions Between Hands and Objects During Human Multi-Digit Grasping

To grasp an object successfully, we must select appropriate contact regions for our hands on the surface of the object. However, identifying such regions is challenging. This paper describes a workflow to estimate the contact regions from marker-based tracking data. Participants grasp real objects, while we track the 3D position of both the objects and the hand, including the fingers' joints. We first determine the joint Euler angles from a selection of tracked markers positioned on the back of the hand. Then, we use state-of-the-art hand mesh reconstruction algorithms to generate a mesh model of the participant's hand in the current pose and the 3D position. 
Using objects that were either 3D printed or 3D scanned-and are, thus, available as both real objects and mesh data-allows the hand and object meshes to be co-registered. In turn, this allows the estimation of approximate contact regions by calculating the intersections between the hand mesh and the co-registered 3D object mesh. The method may be used to estimate where and how humans grasp objects under a variety of conditions. Therefore, the method could be of interest to researchers studying visual and haptic perception, motor control, human-computer interaction in virtual and augmented reality, and robotics.

When we grasp an object, multiple regions of the fingers and hand typically make contact with the object's surface. Reconstructing such contact regions is challenging. Here, we present a method for approximately estimating the contact regions by combining marker-based motion capture with existing deep learning-based hand mesh reconstruction.

To grasp an object successfully, we must select appropriate contact regions for our hands on the surface of the object. However, identifying such regions ...

The Impact of Motor Task Conditions on Goal-Directed Arm Reaching Kinematics and Trunk Compensation in Chronic Stroke Survivors

Trunk compensation is the most common movement strategy to substitute for upper extremity (UE) motor deficits in chronic stroke survivors. There is a lack of evidence examining how task conditions impact trunk compensation and goal-directed arm reaching kinematics. This protocol aims to investigate the impact of task conditions, including task difficulty and complexity, on goal-directed arm reaching kinematics. Two non-disabled young adults and two chronic stroke survivors with mild UE motor impairment were recruited for testing the protocol. Each participant performed goal-directed arm reaches with four different task conditions (2 task difficulties [large vs. small targets] X 2 task complexities [pointing vs. picking up]). The task goal was to reach and point at a target or pick up an object located 20 cm in front of the home position as quickly as possible with a stylus or a pair of chopsticks, respectively, in response to an auditory cue. Participants performed ten reaches per task condition. A 3-dimensional motion capture camera system was used to record trunk and arm kinematics. Representative results showed that there was a significant increase in movement duration, movement jerkiness, and trunk compensation as a function of task complexity, but not task difficulty in all participants. Chronic stroke survivors showed significantly slower, jerkier, and more feedback-dependent arm reaches and significantly more compensatory trunk movements than non-disabled adults. Our representative results support that this protocol can be used to investigate the impact of task conditions on motor control strategies in chronic stroke survivors with mild UE motor impairment.

This protocol is intended to investigate the impact of task conditions on movement strategies in chronic stroke survivors. Further, this protocol can be used to examine if a restriction in elbow extension induced by neuromuscular electrical stimulation causes trunk compensation during goal-directed arm reaches in non-disabled adults.

Trunk compensation is the most common movement strategy to substitute for upper extremity (UE) motor deficits in chronic stroke survivors. There is a lack ...

Neuroscience

In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

Fine motor skills are essential in everyday life and can be compromised in several nervous system disorders. The acquisition and performance of these tasks require sensory-motor integration and involve precise control of bilateral brain circuits. Implementing unimanual behavioral paradigms in animal models will improve the understanding of the contribution of brain structures, like the striatum, to complex motor behavior as it allows manipulation and recording of neural activity of specific nuclei in control conditions and disease during the performance of the task. 
Since its creation, optogenetics has been a dominant tool for interrogating the brain by enabling selective and targeted activation or inhibition of neuronal populations. The combination of optogenetics with behavioral assays sheds light on the underlying mechanisms of specific brain functions. Wireless head-mounted systems with miniaturized light-emitting diodes (LEDs) allow remote optogenetic control in an entirely free-moving animal. This avoids the limitations of a wired system being less restrictive for animals' behavior without compromising light emission efficiency. The current protocol combines a wireless optogenetics approach with high-speed videography in a unimanual dexterity task to dissect the contribution of specific neuronal populations to fine motor behavior.

In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

The present protocol describes how to use wireless optogenetics combined with high-speed videography in a single pellet reach-to-grasp task to characterize the neural circuits involved in the performance of skilled motor behavior in freely moving mice.

Fine motor skills are essential in everyday life and can be compromised in several nervous system disorders. The acquisition and performance of these ...

Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior

Reaching is a widely studied behavior in motor physiology and neuroscience research. While reaching has been examined using a variety of behavioral manipulations, there remain significant gaps in the understanding of the neural processes involved in reach planning, execution, and control. The novel approach described here combines a two-dimensional reaching task with transcranial magnetic stimulation (TMS) and concurrent electromyography (EMG) recording from multiple muscles. This method allows for the noninvasive detection of corticospinal activity at precise time points during the unfolding of reaching movements. The example task code includes a delayed response reaching task with two possible targets displayed &#177; 45&#176; off the midline. Single pulse TMS is delivered on the majority of task trials, either at the onset of the preparatory cue (baseline) or 100 ms prior to the imperative cue (delay). This sample design is suitable for investigating changes in corticospinal excitability during reach preparation. The sample code also includes a visuomotor perturbation (i.e., cursor rotation of &#177; 20&#176;) to investigate the effects of adaptation on corticospinal excitability during reach preparation. The task parameters and TMS delivery can be adjusted to address specific hypotheses about the state of the motor system during reaching behavior. In the initial implementation, motor evoked potentials (MEPs) were successfully elicited on 83% of TMS trials, and reach trajectories were recorded on all trials.

Reaching is a fundamental skill that allows humans to interact with the environment. Several studies have aimed to characterize reaching behavior using a variety of methodologies. This paper offers an open-source application of transcranial magnetic stimulation to assess the state of corticospinal excitability in humans during reaching task performance.

Reaching is a widely studied behavior in motor physiology and neuroscience research. While reaching has been examined using a variety of behavioral ...

Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans

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In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior