Evidence of physiological changes associated with single-session pre-frontal tDCS: a pilot study

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique.
• tDCS has shown promise in enhancing attention and reducing post-stroke fatigue.
• Limited physiological data exists to corroborate behavioral improvements from tDCS in post-stroke populations.

Purpose of the Study:

• To investigate the physiological effects of a single tDCS session on attention and fatigue in individuals with post-stroke aphasia.
• To determine if tDCS can improve attention and fatigue as measured by electroencephalography (EEG) and pupillometry.

Main Methods:

• Ten participants with post-stroke aphasia underwent two sessions: one with active tDCS and one with sham tDCS, with a washout period in between.
• Sessions included a sustained attention task with simultaneous EEG and pupillometry.
• Participants completed the attention task again after tDCS/sham stimulation.

Main Results:

• No significant differences were found in behavioral reaction times or EEG-measured attention states between active and sham tDCS conditions.
• Pupil dilation was significantly greater after active tDCS compared to pre-training conditions, suggesting locus coeruleus-norepinephrine pathway activation.
• Active tDCS significantly mitigated the increase in task-based fatigue compared to sham tDCS.

Conclusions:

• A single tDCS session did not directly enhance attention, as indicated by behavioral and EEG measures.
• Physiological changes (pupil dilation) suggest activation of the LC-NE pathway.
• tDCS effectively mitigated task-based fatigue in individuals with post-stroke aphasia.