TMS is a non-invasive brain stimulation technique, which can be used to change the activity of a person's brain cells without needles or surgery. In this study, the invesigators are interested in the brain's ability to adapt (also called "neuroplasticity") and regain language functioning after a stroke-specifically, they want to determine whether how a person's brain responds to TMS in the short term can be used to predict how well they will recover language abilities in the long term.
Aphasia is an impairment of language that may occur after a stroke (or other brain injuries). A person with aphasia may experience difficulties speaking, understanding speech, reading, writing, or any combination of these symptoms. Despite advances in understanding of language systems and functional neuroplasticity after brain injury, accurate predictors of aphasia recovery after stroke remain elusive. In order to better understand, predict, and enhance language improvement after stroke, there is a critical need to develop tools that can assess the influence of neuroplasticity on recovery. Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation tool that has been used to predict the brain's neuroplastic capacity by assessing physiological responses observed immediately following administration of TMS. Additionally, difference in the physiological response to TMS have been shown to be affected by polymorphism in the gene coding for brain derived neurotrophic factor (BDNF). The current project explores the idea that because neural mechanisms of plasticity are essential determinants of both recovery after brain injury and physiologic response to TMS, magnetic brain stimulation could be employed as an indicator of the capacity for clinically relevant neuroplasticity, and potentially as a predictor of recovery from post-stroke deficits such as aphasia The goals of this protocol are to 1) explore the utility of theta burst stimulation (TBS), a type of transcranial magnetic stimulation (TMS), as a tool for assessing neuroplasticity in the language system in patients with aphasia due to stroke, 2) and to assess the utility of TBS as a biomarker and predictor of functional recovery in patients with aphasia. This protocol will encompass two separate but related experiments. In the first experiment, the investigators will apply TBS to brain regions that control language functions in aphasic patients in order to determine whether we can induce a transient improvement in naming ability. They will use a statistical model they have developed to categorize patients as either having High Plasticity or Low Plasticity. The investigators will determine whether this distinction predicts which patients are likely to have greater TBS-induced changes in language performance. In the second experiment, in the same patients, the investigators will apply TBS to the motor cortex to elicit changes in motor evoked potentials (MEPs). Using the same model to form matched groups, we predict that MEPs will be more attenuated in High Plasticity groups compared to the Low Plasticity group.
Study Type
OBSERVATIONAL
Enrollment
41
TMS is a form of non-invasive brain stimulation which uses magnetic pulses to stimulate regions of the brain from outside the head, on the scalp. Specifically, TMS is performed with a copper-and-plastic coil that emits a magnetic field, which can affect brain cells in specific locations. In this study, researchers will also use a form of TMS called theta-burst stimulation (TBS), where TMS pulses are delivered rapidly over time.
University of Pennsylvania
Philadelphia, Pennsylvania, United States
Transient TBS-induced changes in motor evoked potentials (MEPs)
Single-Pulse TMS will be used to measure MEPs prior to and after stimulation. When measuring MEPs, single pulses of TMS will be administered at approximately 120% of motor threshold, and with a minimum interstimulus interval of 5 seconds. Mean MEP amplitudes will be calculated by averaging the MEP amplitudes generated by 20 pulses. MEP measures will be obtained three times in order to establish a stable baseline. This procedure will be followed by TBS delivered to the optimal site in the motor cortex. TBS will be applied to the region of the primary motor cortex (M1) representing the hand. After TBS, MEPs will be acquired, at 0-, 10-, 20-, 30-, 40-, and 60-min post-stimulation.
Time frame: Up to 2 week
Transient TBS-induced changes in language performance
Participants will be asked to perform a 40-item picture naming task pre/post TBS stimulation. Stimulation will occur at language cortex and vertex (order will be counterbalanced). Transient changes in naming abilities will be measured directly by assessing naming performance.
Time frame: Up to 4 weeks
Safety and Tolerability of TBS in patient with aphasia
We will collect the number of patients with TMS-related adverse events.
Time frame: Through study completion
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