Maximizing the Impact of Neuroplasticity Using Transcranial Electrical Stimulation Study 1

Study Summary

Non-invasive neuromodulation, such as transcranial direct current stimulation ( tDCS) , is emerging as an important therapeutic tool with documented effects on brain circuitry, yet little is understood about h ow it changes cognition. In particular, tDCS may have a critical role to play in generalization, that is how training in one domain generalizes to unlearned or unpracticed domains. This problem has resonance for disorders with cognitive deficits, such as schizophrenia. Understanding how tDCS affects brain circuity is critical to the design and application of effective interventions, especially if the effects are different for healthy vs. psychiatric populations. In previous research, one clue to the mechanism underlying increased learning and generalization with tDCS was provided by neuroimaging data from subjects with schizophrenia undergoing cognitive training where increases in thalamocortical (prefrontal) functional connectivity (FC) predicted greater generalization. The premise of this proposal is that increases in thalamocortical FC are associated with the generalization of cognitive training, and tDCS facilitates these increases. The overarching goals of this proposal are to deploy neuroimaging and cognitive testing to understand how tDCS with cognitive training affect thalamocortical circuitry in individuals with and without psychosis and to examine variability in response within both groups. Study 1 will compare right prefrontal, left prefrontal and sham tDCS during concurrent cognitive training over 12 weeks in 90 healthy controls. Study 2 (NCT03896438) will be similar in all aspects but will examine 90 patients with schizophrenia or schizoaffective disorder and include clinical assessments. Results of the study will provide crucial information about location of stimulation, length of treatment, modeled dosage, trajectory and durability needed to guide future research and interventions for cognitive impairments.

Primary Outcome

Most participants completed MRI sessions on a 3T scanner located in the Center for Magnetic Resonance Research (CMRR) at the University of Minnesota. FC measures how different brain regions change in activation together. We characterized FC using global connectivity from graph theory analysis. We extracted the fMRI time courses from 454 parcellations defined by the 400 S4 Schaefer Atlas (Schaefer et al., 2018) combined with the Melbourne Subcortex Atlas (Tian et al., 2020). We computed the absol

Interventions

• DEVICE Transcranial direct current stimulation (tDCS)