Intensity-Dependent Changes in Quantified Resting Cerebral Perfusion With Multiple Sessions of Transcranial DC...

Area of Science:

• Neuroscience
• Medical Imaging
• Neuromodulation

Background:

• Transcranial direct current stimulation (tDCS) influences behavior, but its neural mechanisms, especially with repeated sessions, are unclear.
• Understanding cerebral blood flow (CBF) changes is crucial for elucidating tDCS effects.

Purpose of the Study:

• To investigate the impact of tDCS intensity and repetition on cerebral perfusion (CBF).
• To explore the neural underpinnings of tDCS-induced behavioral changes.

Main Methods:

• 47 subjects received 1-mA or 2-mA tDCS on the left prefrontal cortex for three consecutive days.
• Resting CBF was measured using arterial spin labeling MRI before and after stimulation.
• A sham stimulation group served as a control.

Main Results:

• Sham stimulation led to widespread decreased CBF.
• 2-mA tDCS showed minimal CBF decrease, with increased CBF in regions like the locus coeruleus (LC).
• 1-mA tDCS initially decreased CBF, but later scans showed increased CBF, suggesting persistent and cumulative neural effects.

Conclusions:

• Higher intensity tDCS (2-mA) positively impacts CBF, potentially via the noradrenergic system, explaining behavioral enhancements.
• Repeated tDCS demonstrates cumulative effects, with neural impacts persisting for at least 24 hours.