Abstract
BackgroundThe somatosensory temporal discrimination threshold (STDT) measures the ability to perceive two stimuli as being sequential. Precisely how the single cerebral structures contribute in controlling the STDT is partially known and no information is available about whether STDT can be modulated by plasticity-inducing protocols.Methodology/Principal FindingsTo investigate how the cortical and cerebellar areas contribute to the STDT we used transcranial magnetic stimulation and a neuronavigation system. We enrolled 18 healthy volunteers and 10 of these completed all the experimental sessions, including the control experiments. STDT was measured on the left hand before and after applying continuous theta-burst stimulation (cTBS) on the right primary somatosensory area (S1), pre-supplementary motor area (pre-SMA), right dorsolateral prefrontal cortex (DLPFC) and left cerebellar hemisphere. We then investigated whether intermittent theta-burst stimulation (iTBS) on the right S1 improved the STDT. After right S1 cTBS, STDT values increased whereas after iTBS to the same cortical site they decreased. cTBS over the DLPFC and left lateral cerebellum left the STDT statistically unchanged. cTBS over the pre-SMA also left the STDT statistically unchanged, but it increased the number of errors subjects made in distinguishing trials testing a single stimulus and those testing paired stimuli.Conclusions/SignificanceOur findings obtained by applying TBS to the cortical areas involved in processing sensory discrimination show that the STDT is encoded in S1, possibly depends on intrinsic S1 neural circuit properties, and can be modulated by plasticity-inducing TBS protocols delivered over S1. Our findings, giving further insight into mechanisms involved in somatosensory temporal discrimination, help interpret STDT abnormalities in movement disorders including dystonia and Parkinson's disease.
Highlights
Precise timing of sensory information is crucial for nearly every aspect of human perception and behavior
Because we found that continuous theta-burst stimulation (cTBS) over S1 altered the somatosensory temporal discrimination threshold (STDT) whereas cTBS over the pre-supplementary motor area (pre-SMA), dorsolateral prefrontal cortex (DLPFC) and left lateral cerebellum did not, and because in a previous study intermittent theta-burst stimulation (iTBS) over S1 improved tactile spatial discrimination [19], we investigated whether iTBS applied to the right S1 improved the STDT
Post hoc analysis showed that STDT significantly increased after cTBS (STDT at T0:75.863 ms vs. T1:86.764 and T2:87.864 ms) and the increase was significant at T1 (P = 0.03) and T2 (P = 0.004) (Figure 1)
Summary
Precise timing of sensory information is crucial for nearly every aspect of human perception and behavior. An experimental approach for investigating how cerebral structures contribute to timing for sensory information entails studying the temporal threshold for perceiving two tactile stimuli applied to the skin as clearly distinct, namely the somatosensory temporal discrimination threshold (STDT). STDT testing activates neural processes involved in a sensory discrimination task uninfluenced by memory formation [3,4,5]. Current knowledge implies that the pre-SMA intervenes in the STDT, even though precisely how it contributes to STDT processing remains unclear. The somatosensory temporal discrimination threshold (STDT) measures the ability to perceive two stimuli as being sequential. How the single cerebral structures contribute in controlling the STDT is partially known and no information is available about whether STDT can be modulated by plasticity-inducing protocols
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
