Differential changes in somatosensory evoked potentials and motor performance: pursuit movement task versus force matching tracking task

Abstract

Force modulation relies on accurate proprioception, and force-matching tasks alter cortico-cerebellar connectivity. Cortico-cerebellar (N24) and cortico-motor pathways are impacted following acquisition of a motor tracing task (MTT), measured using both somatosensory evoked potentials (SEPs) and transcranial magnetic stimulation. This study compared changes in early SEP peak amplitudes and motor performance following a force matching tracking task (FMTT) to an MTT. 30 (18 females) right-handed, participants aged 21.4 ± 2.76, were electrically stimulated over the right-median nerve at 2.47 Hz and 4.98Hz (Averaged 1000 sweeps/rate) to elicit SEPs, recorded via a 64-channel electroencephalography cap, pre and post task acquisition using the right abductor pollicis brevis muscle. Retention was measured 24 hours later. Significant time by group interactions occurred for the N20 SEP: 6.3% decrease post FMTT vs 5.5% increase post MTT (p = 0.013). P25 SEP: 4.0 % decrease post FMTT vs 10.3% increase post MTT (p = 0.006). N18 SEP 113.4 % increase post FMTT vs 4.4 % decrease post MTT (p = 0.006). N18 and N30 showed significant effect of time (both p < 0.001). Motor Performance: Significant time by group interactions - post-acquisition: FMTT improved 15.3% vs 24.3% for MTT (p = 0.025), retention: FMTT improved 17.4 % and MTT by 30.1% (p= 0.004). Task-dependent differences occurred in SEP peaks associated with cortical somatosensory processing (N20 and P25), and cerebellar input (N18), with similar changes in sensorimotor integration (N30), with differential improvements in motor performance, indicating neurophysiological differences in cerebellar and sensory processing for tasks reliant on proprioception.

Sensorimotor integration and motor learning during a novel force-matching task in young adults with attention-deficit/hyperactivity disorder

“…Furthermore, when completing their retention test, scores remained similar to their post-acquisition measures, if not ever so slightly improved, as error was approximately ∼18-19% less than that of their baseline measures. Previous research has noted similar improvements in performance in response to learning a motor task dependent on force modulation (Ambalavanar et al, 2022). In the current study, similar results were present when assessing absolute performance scores, although those with ADHD had increased absolute error and variability at each phase when compared to neurotypical controls.…”

“…Interestingly, McCracken et al (2022 found contrasting results in those with ADHD when performing a motor acquisition paradigm utilizing different task demands. When completing a visuomotor task, those with ADHD had an increase in the N18, whereas controls had a decrease (McCracken et al, 2022). It is likely that the different task demands in the current study, which were heavily dependent on force-modulation and proprioception, resulted in the reduced N18 in those with ADHD.…”

“…This posits that the N18 reflects alterations to cerebellar activity, such as activity related to cerebellar SMI (Haavik and Murphy, 2013). The increased N18 in controls at post measures has been noted in prior literature utilizing a similar motor paradigm (Ambalavanar et al, 2022). This may reflect increased inhibitory activity in olivary-cerebellar-M1 networks, suggestive of greater dependence on cerebellar SMI and inhibitory activity for feedback during processing related to force modulation in the thumb, to control force output during this task as a result of learning (Ambalavanar et al, 2022).…”

“…If this is the case, it may be a result of altered neural structure and function in those with ADHD, such as those in prefrontal cortical regions (Barkley, 1997;Sowell et al, 2003;Seidman et al, 2006), affecting processes related to SMI. McCracken et al (2022) also showed a reduction in the N30 in those with ADHD compared to a control group whose N30 SEP peak increased post motor-acquisition. In the future, incorporating further assessment techniques that are sensitive to neural activity, such as fMRI or source localization, as an initial cost-effective starting point, would elucidate the role of localized neural regions or structures in such processes, which may prove to be invaluable, to further enhance the understanding of how ADHD influences motor learning and SMI.…”

“…Graphic was created with BioRender.com. controls after acquisition of a novel force-matching task (FMT) (Ambalavanar et al, 2022). The N18 is recognized as having neural generators within the brainstem, in particular between the lower medulla and the midbrain pontine regions (Sonoo et al, 1991;Noël et al, 1996;Haavik and Murphy, 2013).…”