The purpose of this study is to examine how different areas in the brain interact with each other and how using brain imaging and brain stimulation approaches can influence these interactions.
Subcortical strokes affect small vessels deep in the brain, and typically present with motor hemiparesis. The investigator will assess the effects of Transcranial Magnetic Stimulation (TMS) on motor function and examine how different areas in the human brain interact with each other using brain imaging and brain stimulation. The investigator will also evaluate the capacity for noninvasive stimulation to transiently modify brain activity supporting arm movement.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
45
Transcranial Magnetic Stimulation (TMS) will be performed using the Magstim BiStim\^2 paired pulse stimulator to measure transient cortical excitability. Single pulse transcranial magnetic stimulation applied at low frequencies (not greater than 0.25 hertz (Hz)) will be used. The may be repeated at multiple study visits. All five study visits will be completed within four weeks of the initial visit.
Paired associative stimulation (PAS) is a combination of transcranial magnetic stimulation (TMS) and electrical stimulation of the median nerve. 180 paired stimuli are delivered at 0.25 Hz for 12 minutes. Median nerve stimuli at 300% of the perceptual threshold will be applied 25ms prior to transcranial magnetic stimulation delivery over the ipsilesional (stroke) or non-dominant (control) cortex. Transcranial Magnetic Stimulation (TMS) will be performed using the Magstim BiStim\^2 paired pulse stimulator unit and a bipolar bar electrode will be used for median nerve stimulation. This traditional paired associative stimulation may be repeated at multiple study visits. All five study visits will be completed within four weeks of the initial visit.
Emory University
Atlanta, Georgia, United States
Wesley Woods Center
Atlanta, Georgia, United States
Change in Long-term Potentiation-like Plasticity
Long-term potentiation-like plasticity was measured using paired associative stimulation (PAS). PAS consists of repeated peripheral electric stimulation paired with Transcranial Magnetic Stimulation (TMS) applied to the motor cortex at varying interstimulus intervals. Participants received 180 paired stimuli at 0.25 hertz (Hz) for 12 minutes. Impaired long-term potentiation-like plasticity points towards reduced excitatory synaptic connectivity and deficits in sensorimotor integration. Decrease or no change in the amplitudes of motor-evoked potentials (MEPs) indicates impaired long-term potentiation-like plasticity.
Time frame: Baseline, 1 Minute Post-Paired Associative Stimulation
Electroencephalography Recordings at Baseline and 5 MInutes Post-PAS
Electroencephalography (EEG) data were recorded using a 64-channel TMS-compatible electrode cap (Easy Cap). Signals were collected at 2000 hertz (Hz) during pre- and post-transcranial magnetic stimulation epochs (-100ms to 200ms). Up to fifty suprathreshold (120% AMT) transcranial magnetic stimulation pulses were applied to motor cortex while the subject was seated quietly with eyes open. This procedure was conducted bilaterally. Data epochs (-1000 to 4000 ms with respect to TMS delivery) were extracted for subsequent imaginary phase coherence analysis. Post-TMS coherence values between electrodes overlying M1 bilaterally (C3 and C4) were calculated within the beta frequency range (15 to 30 Hz). EEG data values are unit-free that can range from 0 to 1. Higher values represent greater coherence which is thought to indicate stronger connectivity.
Time frame: Baseline, 5 Minutes Post-Paired Associative Stimulation
Abbreviated Wolf Motor Function Test Time
Three items of the Wolf Motor Function Test (WMFT) were used to evaluate functional motor performance. The 3 items were selected based on task difficulty ranging from easiest (hand to table) to most difficult (stack checkers) along with a task of moderate difficulty (lift can). Each task has different control demands and number of actions required to complete successfully. Task performance is timed in seconds, with a maximum time of 120 seconds.
Time frame: Baseline, 10 Minutes Post-Paired Associative Stimulation
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Stimulation of the median nerve will be performed using a bipolar bar electrode affixed to palmar aspect of the forearm proximal to the crease of the wrist bilaterally. Stimuli will be delivered 23ms prior to the transcranial magnetic stimulation (TMS) pulse with 0.1 milliseconds (ms) rectangular pulses at an intensity to evoke a 1 millivolt (mV) response in the abductor pollicis brevis (APB) muscle. This may may be repeated at multiple study visits. All five study visits will be completed within four weeks of the initial visit.
Cortico-cortical Paired Associative Stimulation (CC-PAS) is a combination of TMS and electrical stimulation of the median nerve. 180 paired stimuli are delivered at 0.25 Hz for 12 minutes. The interstimulus interval will range from 5-15 ms depending on site of stimulation.TMS will be performed using the Magstim BiStim\^2 paired pulse stimulator unit and a bipolar bar electrode will be used for median nerve stimulation. This CC-PAS may be repeated at multiple study visits. All five study visits will be completed within four weeks of the initial visit.
The sham PAS is a combination of TMS and electrical stimulation of the median nerve. The coil is rotated and separated from the head with a plastic spacer to ensure indirect contact with the head.180 paired stimuli are delivered at 0.25 Hz for 12 minutes. TMS will be performed using the Magstim BiStim\^2 paired pulse stimulator unit and a bipolar bar electrode will be used for median nerve stimulation. This sham paired associative stimulation may be repeated at multiple study visits. All five study visits will be completed within four weeks of the initial visit.
Wolf Motor Function Test
The arm function in subjects in the subcortical stroke group was evaluated by the Wolf Motor Function Test (WMFT). The test consists of timed and functional tasks and has 17 items. It is composed of 3 parts: Time, functional ability and strength and includes 15 function-based tasks and 2 strength based tasks. Items 1-6 involve timed functional tasks, items 7-14 are measures of strength, and the remaining 9 items consist of analyzing movement quality when completing various tasks. The examiner will test the less affected upper extremity followed by the most affected side. Scores are based on time taken to complete each task. The median time to complete all tasks will be be used to evaluate motor function. Larger values indicate greater upper extremity motor dysfunction.
Time frame: Baseline
Abbreviated Wolf Motor Function Test Time
Three items of the WMFT were used to evaluate functional motor performance. The 3 items were selected based on task difficulty ranging from easiest (hand to table) to most difficult (stack checkers) along with a task of moderate difficulty (lift can). Each task has different control demands and number of actions required to complete successfully. Task performance will be timed, with a maximum time of 120 seconds.
Time frame: 30 minutes post-Paired Associative Stimulation, 24 hours post-Paired Associative Stimulation
Long-term Potentiation-like Plasticity
Long-term potentiation-like plasticity was measured using paired associative stimulation (PAS). PAS consists of repeated peripheral electric stimulation paired with Transcranial Magnetic Stimulation (TMS) applied to the motor cortex at varying interstimulus intervals. Participants receive 180 paired stimuli at 0.25 Hz for 12 minutes. Impaired long-term potentiation-like plasticity points towards reduced excitatory synaptic connectivity and deficits in sensorimotor integration. Decrease or no change in the amplitudes of motor-evoked potentials (MEPs) indicates impaired long-term potentiation-like plasticity.
Time frame: 30 minutes post-Paired Associative Stimulation, 24 hours post-Paired Associative Stimulation
Electroencephalography Recordings at 30 Minutes and 24 Hours Post-PAS
Electroencephalography (EEG) data were recorded using a 64-channel TMS-compatible electrode cap (Easy Cap). Signals were collected at 2000 hertz (Hz) during pre- and post-transcranial magnetic stimulation epochs (-100ms to 200ms). Up to fifty suprathreshold (120% AMT) transcranial magnetic stimulation pulses were applied to motor cortex while the subject was seated quietly with eyes open. This procedure was conducted bilaterally. Data epochs (-1000 to 4000 ms with respect to TMS delivery) were extracted for subsequent imaginary phase coherence analysis. Post-TMS coherence values between electrodes overlying M1 bilaterally (C3 and C4) were calculated within the beta frequency range (15 to 30 Hz). EEG data values are unit-free that can range from 0 to 1. Higher values represent greater coherence which is thought to indicate stronger connectivity.
Time frame: 30 minutes post-Paired Associative Stimulation, 24 hours post-Paired Associative Stimulation
Serial Reaction Time Task (SRTT) Performance
The SRTT involves pressing a key that corresponds to a target square positioned on a screen in front of the participant as quickly and accurately as possible. The response time for repeated and random sequences evaluate SRTT performance and skill is measured as the difference in response times between repeated and random sequences. Lower response times indicate better performance and a larger positive difference in response times represents greater sequence-specific skill. Negative values represent better performance on random sequences compared to repeated sequences.
Time frame: Baseline, 10 minutes post-PAS, 30 minutes post-PAS, and 24 hours post-PAS