Effect of Anodal Direct-Current Stimulation on Cortical Hemodynamic Responses With Laser-Speckle Contrast Imaging

Abstract

Transcranial direct-current stimulation (DCS) offers a method for noninvasive neuromodulation usable in basic and clinical human neuroscience. Laser-speckle contrast imaging (LSCI), a powerful, low-cost method for obtaining images of dynamic systems, can detect regional blood-flow distributions with high spatial and temporal resolutions. Here, we used LSCI for measuring DCS-induced cerebral blood flow in real-time. Results showed that the change-rate of cerebral blood flow could reach approximately 10.1 ± 5.1% by DCS, indicating that DCS can increase cerebral blood flow and alter cortical hemodynamic responses. Thus, DCS shows potential for the clinical treatment and rehabilitation of ischemic strokes.

Laser speckle contrast imaging for blood flow monitoring in predicting outcomes after cerebral ischemia-reperfusion injury in mice

“…LSCI, which can image the velocity distribution of blood flow in real time with high temporal and spatial resolution, has incomparable advantages [12]. In this study, the changes in cerebral cortical blood flow during CIRI in mice were observed by LSCI, which verified the convenience and feasibility of LSCI for monitoring cerebral blood flow in real time and throughout the whole process [13]. Although LSCI cannot directly measure absolute velocity at present, the experimental equipment is simple to use, inexpensive, noninvasive, and fast and captures real-time data to obtain the two-dimensional flow velocity distribution map, which is clear and intuitive for scientific researchers or clinicians.…”

Therapeutic non-invasive brain treatments in Alzheimer’s disease: recent advances and challenges

“…Similar to the human finding, the anodal tDCS also increased cerebral blood flow in rats [261]. However, unlike the human study noted previously, the effect of tDCS can last after tDCS therapy, suggesting that tDCS may have long-lasting after-effects in regulating cerebral blood flow [261]. Consistent with this result, there is an increased oxygen delivery in the vicinity of the anode after tDCS with after-effects lasting for several minutes after stimulation [262].…”

“…Unlike anodal tDCS, the cathodal tDCS induced a reduced cerebral blood flow during stimulation and a continuous decrease compared to baseline [260]. Similar to the human finding, the anodal tDCS also increased cerebral blood flow in rats [261]. However, unlike the human study noted previously, the effect of tDCS can last after tDCS therapy, suggesting that tDCS may have long-lasting after-effects in regulating cerebral blood flow [261].…”

Direct current stimulation increases blood flow and permeability of cortical microvasculature in vivo

“…The low stimulation intensities applied in the present study are known to enhance neuronal excitability and plasticity [1, 3] below the thresholds for induction of neurodegeneration or inflammation [36]. In contrast, intensities used in other rodent studies investigating cerebral perfusion during DCS used much higher intensities bearing the danger of aforementioned detrimental cellular responses [14, 15] or very short stimulation periods [15]. Such deviating parameters limit these studies in gaining sufficient insight into processes involved in conventional clinical DCS protocols, which apply tDCS at intensities usually between 0.4 and 1.6 A/m 2 for at least several minutes [37, 38].…”

“…Neurons and their supplying vessels form a spatially and functionally related neurovascular unit [5], with neurovascular coupling referring to a local variability in cerebral blood flow (CBF) in response to neural metabolic demand [6, 7]. Regional CBF is altered by tDCS in humans [8–13] as well as in animal models [14–16]. Data on microvasculature on the single‐vessel level via two‐photon microscopy during and after anodal DCS in vivo at intensities and durations close to clinical protocols are not available.…”