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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 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 ± 45° 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 ± 20°) 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.
Goal-directed reaching is a fundamental motor behavior that allows humans to interact with and manipulate the external environment. The study of reaching in the fields of motor physiology, psychology, and neuroscience has produced rich and extensive literature that includes a variety of methodologies. Early studies of reaching used direct neural recordings in non-human primates to investigate neural activity at the level of single neurons1,2. More recent studies have investigated reaching using behavioral paradigms that employ sensorimotor adaptation to explore the nature of motor learning and control
All methods detailed here were performed in compliance with IRB protocol and approval (University of Oregon IRB protocol number 10182017.017). Informed consent was obtained from all subjects.
1. Reaching apparatus
Successful execution of the described methods includes the recording of tablet data, EMG traces, and reliable elicitation of MEPs. An experiment was completed that included 270 test trials with TMS delivered on 4/5 of the trials (216 trials).
Data were collected from 16 participants (eight females; eight males) aged 25 ± 10 years, all of whom self-reported as right-handed. We assessed the effectiveness of the visual perturbation on behavioral performance by deriving a learning function fo.......
The methods outlined above offer a novel approach to studying motor preparation in the context of reaching behaviors. Although reaching represents a popular model task in the study of motor control and learning, there is a need for precisely evaluating the CS dynamics associated with reaching behavior. TMS offers a noninvasive, temporally precise method of capturing CS activity at discrete time points during reaching. The approach described here combines two independent subfields-TMS and reaching-into a .......
This research was made possible in part by the generous funding of the Knight Campus Undergraduate Scholars program and the Phil and Penny Knight Foundation
....Name | Company | Catalog Number | Comments |
2-Port Native PCI Express | StarTech.com | RS232 Card with 16950 UART | Must be compatible with desktop computer |
Adjustable 80-20 aluminum frame | any | ||
Alcohol prep pads | any | EMG preparation | |
Bagnoli Bipolar Electrodes | Delsys | DE 2.1 | |
Bagnoli Reference Electrode | Delsys | USX2000 | 2” (5cm) Round |
Bagnoli-8 EMG System | Delsys | ||
Chair | any | ||
Computer monitor for EMG/TMS | n/a | ||
Desk | any | ||
Desktop Computer | Dell | xps 8930 | RAM: 16 GB, Storage: 1TB, Graphics: 1060 6GB |
EMG electrodes | Delsys | Sensor Adhesive Interface | |
Fine grain sandpaper | any | EMG preparation | |
Graphics tablet | Wacom | Intuos-4 XL | |
Handle of paint roller | any | to be used as stylus handle, hollowed out center must be large enough for stylus to sit securely inside | |
Medical tape | any | To secure EMG electrodes | |
PCI-6220 card DAQ | National Instruments | To interface EMG system | |
Photodiode Sensor | Vishay | BPW21R | To record timing of task events into EMG trace. |
Rear TMS port | Magstim | Included with TMS machine | |
Right-handed polyethylene glove | any | Cut out thumb and index finger of glove to expose FDI muscle | |
Sensory Adhesive Interface, 2-slot | Delsys | SC-F01 | |
Stylus | Wacom | Intuos-4 grip pen | |
Tablet-to-Computer USB cable | any | Included in Tablet purchase | |
Task Monitor | Asus | VG248 | |
TMS coil | Magstim | D70 Remote Coil | 7cm diameter, figure-of-eight coil |
TMS machine | Magstim | 200-2 | |
TMS-to-Computer DB9 cable | any | Connects to PCIe Serial Card | |
Velcro | any | To be placed on glove and stylus handle |
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ISSN 1940-087X
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