tDCS and Aphasia Treatment

Aphasia, commonly defined as impairment or loss of language functions, is a frequent and
often chronic consequence of stroke, with detrimental effects on patient autonomy and
health-related quality of life (HRQOL). Although beneficial in some cases, the effectiveness
of behavioral therapy is often limited, and therefore new complementary treatments must be
developed in order to improve rehabilitation of post-stroke aphasia.

In most individuals, language areas in the brain are localized in the left hemisphere. After
stroke, there is evidence that the brain reorganizes such that either areas close to damaged
language areas in the Left Hemisphere, or anatomically similar areas in the Right
Hemisphere, are recruited to perform language tasks.

Recently, studies have begun to examine the effects of non-invasive brain stimulation on
aphasia rehabilitation. One such technique is transcranial direct current stimulation
(tDCS), which involves administering weak electrical currents through surface electrodes on
the scalp. The effects can either stimulate an area, or inhibit an area of the brain. The
main hypothesis is that stimulating language areas in the Left Hemisphere in conjunction
with speech language therapy will facilitate reorganization of language-relevant areas of
the brain, and improve expression.

The proposed study will compare the effects of transcranial direct current stimulation
(tDCS) activating language centers in the Left Hemisphere and sham tDCS, in right-handed
individuals with chronic post-stroke aphasia. This study will provide information on the
effects of tDCS, in conjunction with speech-language therapy, on aphasia rehabilitation.

Inclusion Criteria: single left hemisphere stroke, more than three months post stroke,
right handed, no other medical problems, ages 18-100 -

Exclusion Criteria: more than one stroke, less than three months post stroke, other
medical problems, pacemaker or other electronic implant (e.g. hip replacement), pregnancy