The purpose of this study is to better understand the neural correlates of higher-order cognition, both in the healthy brain and in schizophrenia, and to determine how these mechanisms are modulated by transcranial direct current stimulation (tDCS) at frontal and occipital scalp sites. Testing the effects of tDCS at these scalp sites on cognitive task performance will help us understand the roles of the brain regions corresponding to these sites during higher-order cognitive processing (language comprehension, cognitive control, and related attention and memory processes). Behavioral and electrophysiological (EEG) measures will be used to assess cognitive performance. Our overarching hypothesis is that stimulating prefrontal circuits with tDCS can improve cognitive control performance, and ultimately performance on a range of cognitive tasks, as compared to stimulating a different cortical region (occipital cortex) or using sham stimulation. This study is solely intended as basic research in order to understand brain function in healthy individuals and individuals with schizophrenia. This study is not intended to diagnose, cure or treat schizophrenia or any other disease.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
75
In tDCS, saline-soaked electrodes are temporary affixed to the scalp and connected to a battery-powered current generator. A weak (2 mA) constant current is then briefly applied (\~20 minutes) to stimulate the targeted brain area. The targeted brain area is determined by the Study Arm.
Imaging Research Center
Sacramento, California, United States
RECRUITINGBehavioral Cognitive Control Measures on the Stroop Task
Incongruent versus Congruent difference in error rate and reaction time
Time frame: Through study completion, an average of 1 month
EEG Cognitive Control Measures on the Stroop Task
response-locked power in the theta frequency band (4-7 Hz)
Time frame: Through study completion, an average of 1 month
Behavioral Attention Lapse Measures on the Stroop Task
Error Rate on Incorrect Congruent trials (Full Lapses) and Slow-but-Correct Congruent trials (Partial Lapses)
Time frame: Through study completion, an average of 1 month
EEG Attention Lapse Measures on the Stroop Task EEG Attention Lapse Measures on the Stroop Task
Pre-trial power in the alpha frequency band (8-12 Hz)
Time frame: Through study completion, an average of 1 month
Behavioral Cognitive Control Measures on the Change Detection Task Behavioral Cognitive Control Measures on the Change Detection Task
WM storage capacity (k-max)
Time frame: Through study completion, an average of 1 month
EEG Cognitive Control Measures on the Change Detection Task
delay period power in the theta frequency band (4-7 Hz)
Time frame: Through study completion, an average of 1 month
Behavioral Attention Lapse Measures on the Change Detection Task
Attention factor (a); Guess factor (g)
Time frame: Through study completion, an average of 1 month
EEG Attention Lapse Measures on the Change Detection Task
Pre-trial power in the alpha frequency band (8-12 Hz)
Time frame: Through study completion, an average of 1 month
Delivered tDCS Dose to PFC
Estimated electric field in PFC region of interest
Time frame: Through study completion, an average of 1 month
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