Efficacy of Low-frequency rTMS in Aphasia

In a randomized controlled trial, efficacy of low-frequency, inhibitory rTMS will be examined in rehabilitation of acquired aphasia. Two cortical sites will be targeted: Right-hemispheric homologues of Broca's and Wernicke's areas.

In addition to cognitive screening prior to onset of rTMS, language assessments will be conducted before, during and after the intervention. An eyetracking-while-listening experiment will also be conducted before and after the intervention to investigate morphosyntactic processing.

Efficacy of low-frequency (1hz), inhibitory rTMS will be examined in rehabilitation of acquired aphasia. Two cortical sites will be targeted: Right-hemispheric homologues of Broca's and Wernicke's areas. In other words, right frontal and right temporal sites will be targeted.

In addition to cognitive screening prior to onset of rTMS, language assessments will be conducted before, during and after the intervention. The language assessment will be conducted using the Turkish Aphasia Language Assessment Test (ADD) and sets of pictures used to assess naming performance. ADD will be carried out before and after the intervention. Six picture sets will be used, one at baseline, four on different days during the intervention, and the last one immediately after the last day of the intervention. Cognitive screening will be conducted at baseline using the digit span test and Raven's colored progressive matrices. In addition, a pre- and post-treatment eyetracking-while-listening experiment will be conducted to investigate morphosyntactic processing in Turkish and to examine whether the two brain stimulation interventions differentially affect online (dynamic, time-dependent) measures of morphosyntactic processing. The eyetracking paradigm will request the participants to listen to Turkish sentences varying in morphosyntactic complexity (canonical versus noncanonical sentences) and to look at the picture (out of two pictures presented on the screen) corresponding to the sentence they are listening to.

Eligibility Criteria:
Inclusion Criteria:

* Right-handedness,
* Normal or corrected-to-normal vision and hearing,
* Aphasia following cerebrovascular accident,
* Cerebrovascular accident at least 6 months prior to enrolment in the study,
* Satisfying current TMS safety guidelines (Rossi et al. 2009, 2021), which are:
* No previous history of epilepsy,
* No implant (e.g., cochlear implant) or stimulator (e.g., deep brain stimulation) in the head which may interact with the magnetic field,
* No use of central nervous system active drugs that lower seizure threshold (as listed in the aforementioned guidelines)

Exclusion Criteria:

* Left-handedness, ambidexterity,
* Impaired and uncorrected vision or hearing,
* No aphasia symptoms following cerebrovascular accident,
* Time since cerebrovascular accident less than 6 months,
* Violating current TMS safety guidelines (Rossi et al. 2009, 2021). In other words:
* Having a previous history of epilepsy,
* Having an implant (e.g., cochlear implant) or stimulator (e.g., deep brain stimulation) in the head which may interact with the magnetic field,
* Taking central nervous system active drugs that lower seizure threshold (as listed in the aforementioned guidelines)