Treating Primary Progressive Aphasia (PPA) Using High-definition tDCS

High definition transcranial direct current stimulation (HD-tDCS) involves the application of low-intensity current through electrodes placed on the scalp. It is believed to elicit brain effects by producing incremental shifts in the resting membrane potential of large numbers of neurons, which alters neuronal firing rates and thus modulates patterns of brain activity in potentially behaviorally-relevant ways. HD-tDCS differs from conventional transcranial direct current stimulation (tDCS) because it employed smaller electrodes configured in such a way as to deliver more focal stimulation of the brain.

Modified constraint-induced language therapy (mCILT) is a behavioral language therapy that invokes use-dependent learning in communicative interactions by requiring spoken output and restricting use of alternative forms of communication, such as gestures, as a substitute for spoken output. Other key elements of CILT include massed practice of goal-directed speech and shaping of desired responses by increasing response demands as participants improve. MCILT differs from traditional constraint-induced language therapy (CILT) in three ways: 1) it will be done as an individual therapy with the examiner in the role of a communication partner; 2) treatment will be delivered in short sessions (1 hour rather than a more typical 3-4 hour session); 3) targeting nouns + semantically related verbs to generate noun + verb phrases in treatment, a modification that may be better suited to addressing syntactic structure.