TMS as a Biological Marker of Neuroplasticity
Condition: Stroke; Aphasia
MeSH terms: Aphasia
Study type: Observational

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Transcranial Magnetic Stimulation
Intervention type(s): Device
Intervention description(s): 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.
Other intervention name(s): TMS
Observational model: Case-Only
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Individuals who have had one or more strokes and are now experiencing the symptoms of
        aphasia. Aphasia is a communication disorder which may result in difficulties
        speaking,understanding speech, or both.
      
Biospecimen description: 
      The investigators are asking participants to provide a saliva sample which will later be
      genotyped for the BDNF protein.

      Saliva samples are optional.
    
Keywords: Transcranial Magnetic Stimulation (TMS)