Abstract
SummaryIt has been 40 years since the report of long-term synaptic plasticity on the rodent brain. Transcranial ultrasound stimulation (TUS) shows advantages in spatial resolution and penetration depth when compared with electrical or magnetic stimulation. The repetitive TUS (rTUS) can induce cortical excitability alteration on animals, and persistent aftereffects were observed. However, the effects of rTUS on synaptic plasticity in humans remain unelucidated. In the current study, we applied a 15-min rTUS protocol to stimulate left primary motor cortex (l-M1) in 24 male healthy participants. The single-pulsed transcranial magnetic stimulation-evoked motor evoked potential and Stop-signal task was applied to measure the rTUS aftereffects. Here, we report that conditioning the human motor cortex using rTUS may produce long-lasting and statistically significant effects on motor cortex excitability as well as motor behavior, without harmful side effects observed. These findings suggest a considerable potential of rTUS in cortical plasticity modulation and clinical intervention for impulsivity-related disorders.
Highlights
Synaptic plasticity represents one important cellular mechanism underlying learning and memory (Martin et al, 2000)
Transcranial ultrasound stimulation (TUS) over frontal eye fields modulated the choice behavior in the macaque monkey (Kubanek et al, 2020), TUS over visual cortex induced phosphene phenomenon (Lee et al, 2016b), TUS over somatosensory cortex elicited tactile sensations in the hands and improved sensory discrimination capability (Lee et al, 2015; Legon et al, 2014; Liu et al, 2021), TUS over right anterior insula/frontal operculum and dorsal anterior cingulate cortex (ACC) reduced parasympathetic fear responses and emotional distraction interference on performance (Fini and Tyler, 2020a, 2020b), and TUS over primary motor cortex altered motor cortical excitability, which was reflected by motor evoked potential (MEP) measurement (Fomenko et al, 2020; Gibson et al, 2018; Legon et al, 2018b)
No significant differences were observed in resting motor threshold (RMT), sleep quality, alcohol, cigarette use, anxiety, depression, impulsivity scores between the active-repetitive TUS (rTUS) visit, and sham-rTUS visit (Table 1)
Summary
Synaptic plasticity represents one important cellular mechanism underlying learning and memory (Martin et al, 2000). Transcranial ultrasound stimulation (TUS) has been an emerging approach to generate relatively focal activation in different brain regions (including deep regions), such as the frontal cortex (Fine et al, 2019, 2020; Verhagen et al, 2019), the primary visual cortex (V1) (Lee et al, 2016b), the temporal cortex (Hameroff et al, 2013), the somatosensory cortex (Lee et al, 2015; Legon et al, 2014; Mueller et al, 2014), caudate (Ai et al, 2016), hippocampus (Nicodemus et al, 2019), and thalamus (Legon et al, 2018a; Monti et al, 2016). TUS over frontal eye fields modulated the choice behavior in the macaque monkey (Kubanek et al, 2020), TUS over visual cortex induced phosphene phenomenon (Lee et al, 2016b), TUS over somatosensory cortex elicited tactile sensations in the hands and improved sensory discrimination capability (Lee et al, 2015; Legon et al, 2014; Liu et al, 2021), TUS over right anterior insula/frontal operculum and dorsal ACC reduced parasympathetic fear responses and emotional distraction interference on performance (Fini and Tyler, 2020a, 2020b), and TUS over primary motor cortex altered motor cortical excitability, which was reflected by motor evoked potential (MEP) measurement (Fomenko et al, 2020; Gibson et al, 2018; Legon et al, 2018b)
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