Stroke is a leading cause of disability with many patients suffering chronic motor function impairments that affect their day-to-day activities. The goal of this proposal is to provide a first assessment of the feasibility and efficacy of an innovative non-invasive brain stimulation system, kTMP, in the treatment of motor impairment following stroke.

The goal of this study is to test the feasibility of a novel first-in-class non-invasive approach to enhance motor function in stroke patients. This study has a crossover design comparing low-frequency (3 Hz) versus beta-frequency (13-30 Hz) amplitude modulation in kTMP on upper extremity kinematics in chronic stroke patients. The kilohertz Transcranial Magnetic Perturbation (kTMP) device allows the investigators to target frequency-specific neural activity non-invasively - with no patient discomfort - at and beyond stimulation intensities associated with enhanced recovery from stroke (up to 8 V/m), something that is not possible to achieve with existing NIBS methods.

The trial also aims to assess the short-term effects of kTMP on reach-to-grasp kinematics. kTMP stimulation is targeted to the motor hotspot for eliciting motor evoked potentials (MEPs) within motor cortex to evaluate short term changes in motor performance.

Inclusion Criteria:

1. Adults aged 18-80 years who have a history of a unilateral stroke ≥ 12 m prior to enrollment.
2. Fugl-Meyer Assessment: Upper Extremity (FMA UE) score 20-55.
3. Ability to communicate, understand, and give appropriate consent. Participants can follow two-step commands.
4. Motor evoked potentials in a hand muscle when stimulating ipsilesional cortex with suprathreshold single-pulse TMS (MEP positive).

Exclusion Criteria:

1. Participants with moderate or severe cognitive impairment (MoCA < 18).
2. Participants with sensory deficits FMA-S ≥ 6/12 (with proprioception ≥ 2/4).
3. Language impairment or behavioral disorder that interferes with their ability to adhere to the protocol or to provide informed consent.
4. Individuals who have a serious uncontrolled medical condition, including but not limited to severe cardiovascular and cardiopulmonary disease.
5. Pregnancy or plans to become pregnant during the study period.
6. Botulinum toxin injections of the affected upper extremity within 3 months prior to onset of study assessments/testing through the last visit.
7. Severe spasticity of the affected upper limb (Modified Ashworth ≥ 3).
8. Absolute contraindications related to non-invasive brain stimulation, including:

History of seizures in the last 12 months while taking anti-epilepsy medication Presence of any metal implants in the head (excluding the mouth), such as cortical stimulators and DBS, clips, coils, shunts, stents or skull plates, cochlear implants Permanent eye liner or head tattoos Implanted electronics such as pacemakers, defibrillators, intrathecal baclofen pumps or vagus nerve stimulator History of experiencing a serious adverse event during a previous transcranial magnetic stimulation (TMS) session