Suppression of EEG visual-evoked potentials in rats through neuromodulatory focused ultrasound

Abstract

We investigated the use of pulsed low-intensity focused ultrasound (FUS) to suppress the visual neural response induced by light stimulation in rodents. FUS was administered transcranially to the rat visual cortex using different acoustic intensities and pulsing duty cycles. The visual evoked potentials (VEP) generated by an external strobe light stimulation were measured three times before, once during, and five times after the sonication. The VEP magnitude was suppressed during the sonication using a 5% duty cycle (pulse-repetition frequency of 100 Hz) and spatial-peak pulse-average acoustic intensity of 3 W/cm2; however, this suppressive effect was not present when a lower acoustic intensity and duty cycle were used. The application of a higher intensity and duty cycle resulted in a slight elevation of VEP magnitude, which suggested excitatory neuromodulation. Our findings demonstrate that the application of pulsed FUS to the region-specific brain area not only suppresses its excitability, but also can enhance the excitability depending on the acoustic intensity and rate of energy deposition. This bimodal feature of FUS-mediated neuromodulation, which has been predicted by numerical models on neural membrane capacitance change by the external acoustic pressure waves, suggests its versatility for neurotherapeutic applications.

On the neuromodulatory pathways of the in vivo brain by means of transcranial focused ultrasound

“…As reported by Min et al , ultrasound may induce a suppression of seizure activity [21] and EEG based visual evoked response potentials [47]. Since calcium imaging is an imaging modality that relies on neural depolarization, neural suppression, characterized by a lack of depolarization, is difficult to observe due to the lack of increase in intracellular calcium.…”

Frequency Dependence of Ultrasound Neurostimulation in the Mouse Brain

“…Ultrasound neuromodulation has been successfully performed transcranially in various animal species, including mice (King et al 2013; King et al 2014; Mehić et al 2014; Tufail et al 2010), rats (Kim et al 2012; Kim et al 2014; Kim et al 2015; Min et al 2011; Younan et al 2013), sheep (Lee et al 2016), monkeys (Deffieux et al 2013), and even humans (Lee et al 2015; Legon et al 2014). Histological techniques have confirmed that it is possible to deliver sonications powerful enough to elicit ultrasound neuromodulation without causing damage to tissues (Tufail et al 2010; Yoo et al 2011).…”

Simultaneous acoustic stimulation of human primary and secondary somatosensory cortices using transcranial focused ultrasound

“…The acoustic neuromodulatory effects can be tailored as either excitatory or suppressive, depending on the sonication parameters [11, 12]. Accumulating ex vivo [13, 14] and in vivo [12, 15–18] evidence shows that acoustic pressure waves delivered to localized brain structures modulate their excitability using low-level acoustic intensity (i.e., compatible with potential human application [19, 20]).…”