Investigating neuronal noise as a mechanism of tic generation
Poster No:
447
Submission Type:
Abstract Submission
Authors:
Aikaterini Gialopsou1, Caitlin Smith1, Mairi Houlgreave1, Isabel Farr1, Stephen Jackson1
Institutions:
1University of Nottingham, Nottingham, England
First Author:
Co-Author(s):
Introduction:
Tourette syndrome (TS) is a neurodevelopmental disorder characterised by chronic involuntary motor and vocal tics. TS is linked to sensory hypersensitivity (Isaacs & Riordan, 2020) which could reflect the reduced sensorimotor gating and the altered perceptual processing.
Moreover, prior research has suggested that tics could reflect motor noise, resulting in uncertainty of the voluntary movement and the occurrence of tics. This enhanced neuronal noise may reflect the imprecise forward model of action planning, inherent in TS (Münchau et al., 2021; Albin & Mink, 2006). Experimental data has confirmed increased 1/f or pink noise in the TS population during a sensorimotor task (Adelhöfer et al., 2021).
Hence in this study, we aimed to quantify the difference in the neuronal noise between TS participants and age and gender-matched controls (HC). We defined neuronal noise as the variability of the cortical oscillations during median nerve stimulation (MNS).
Moreover, prior research has suggested that tics could reflect motor noise, resulting in uncertainty of the voluntary movement and the occurrence of tics. This enhanced neuronal noise may reflect the imprecise forward model of action planning, inherent in TS (Münchau et al., 2021; Albin & Mink, 2006). Experimental data has confirmed increased 1/f or pink noise in the TS population during a sensorimotor task (Adelhöfer et al., 2021).
Hence in this study, we aimed to quantify the difference in the neuronal noise between TS participants and age and gender-matched controls (HC). We defined neuronal noise as the variability of the cortical oscillations during median nerve stimulation (MNS).
Methods:
Data were collected from a group of 19 right-handed participants, who were diagnosed with TS or other tic disorders (10F, mean age (± SD): 30.8 ±10.9). Additionally, 19 right-handed HC participants with no prior neuropsychological diagnosis were included (10 F, mean age (± SD): 28.3, ± 6.7).
Cortical measurements were conducted utilizing a 64-channel system to record Somatosensory Evoked Potentials (SEPs) elicited by a single pulse of MNS. MNS electrodes were placed on the dominant hand over the median nerve with the anode proximal to the hand. A total of 75 single pulses were delivered, interspersed with an inter-trial interval of 11 s (±2 s). The MNS motor threshold (MT) was individually determined for each participant as the minimum intensity necessary to evoke a visible thumb twitch. We focused our analysis on small time windows around the well-defined SEP component; N20 (20ms ±10), N60 (60 ms±20), P100(100ms ±20) and P260 (260ms ±50).
We assessed the variability in the latency and amplitude of SEPs across and between the two groups.
Cortical measurements were conducted utilizing a 64-channel system to record Somatosensory Evoked Potentials (SEPs) elicited by a single pulse of MNS. MNS electrodes were placed on the dominant hand over the median nerve with the anode proximal to the hand. A total of 75 single pulses were delivered, interspersed with an inter-trial interval of 11 s (±2 s). The MNS motor threshold (MT) was individually determined for each participant as the minimum intensity necessary to evoke a visible thumb twitch. We focused our analysis on small time windows around the well-defined SEP component; N20 (20ms ±10), N60 (60 ms±20), P100(100ms ±20) and P260 (260ms ±50).
We assessed the variability in the latency and amplitude of SEPs across and between the two groups.
Results:
The component analysis revealed enhanced variability in SEPs within the TS group compared to the HC. Specifically, Figure 1 llustrates the grand average TS and HC SEPs, revealing increased amplitude in the former across all onset components. Significant differences in RMS of SEP amplitude were observed between the two groups (N20: TS 2.13 HP:2.27, N60: TS 3.9 HP 4.7, P100: TS: 9.06 HP: 5.6, P260: TS 10.28 HC 9.5). Similarly, figure 2 shows the average time onset of each SEP component between the two groups. The temporal RMS was significantly different between the TS (blue) and the HC (red) groups for the N20, N60, and P100 components but not for the P260 (N20: TS 20 HP:19.06, N60: TS 60.8 HP 60.1 P100: TS: 100.55 HP: 99.17).
·Grand average responses between the TS (blue) and HC (red) group. The vertical lines inidcate the component onset and circular marks show the significant RMS differences (p<0.05).
·Temporal variability of the SEP components between the TS (blue) and HC (red) groups. The red and blue traces show the idividual data, and the black asterisk indicatesthe significant RMS difference.
Conclusions:
The significantly enhanced variability in TS amplitude and latency could reflect the increased asynchronous neuronal activity, i.e. neuronal noise. These findings contribute to our comprehension of the mechanisms underlying tic generation in Tourette Syndrome.
Innovative interventions seeking to synchronize specific neuronal oscillations may mitigate neuronal noise, offering therapeutic benefits.
Innovative interventions seeking to synchronize specific neuronal oscillations may mitigate neuronal noise, offering therapeutic benefits.
Disorders of the Nervous System:
Neurodevelopmental/ Early Life (eg. ADHD, autism) 1
Modeling and Analysis Methods:
EEG/MEG Modeling and Analysis 2
Keywords:
Electroencephaolography (EEG)
Tourette's Syndrome
1|2Indicates the priority used for review
Provide references using author date format
Albin, R.L. and Mink, J.W. (2006) ‘Recent advances in Tourette Syndrome Research’, Trends in Neurosciences, 29(3), pp. 175–182. doi:10.1016/j.tins.2006.01.001.
Isaacs, D. and Riordan, H. (2020) ‘Sensory hypersensitivity in Tourette Syndrome: A Review’, Brain and Development, 42(9), pp. 627–638. doi:10.1016/j.braindev.2020.06.003.
Adelhöfer N, Paulus T, Mückschel M, Bäumer T, Bluschke A, Takacs A, et al. Increased scale-free and aperiodic neural activity during sensorimotor integration—a novel facet in tourette syndrome. Brain Communications. 2021;3(4).