Motor Timing Task Research Articles

Isolation of Distinct Networks Driving Action and Cognition in Psychomotor Processes

BackgroundPsychomotor disturbances are observed across psychiatric disorders and often manifest as psychomotor slowing, agitation, disorganized behavior, or catatonia. Psychomotor function includes both cognitive and motor components, but the neural circuits driving these subprocesses and how they relate to symptoms have remained elusive for centuries. MethodsWe analyzed data from the HCP-EP (Human Connectome Project for Early Psychosis), a multisite study of 125 participants with early psychosis and 58 healthy participants with resting-state functional magnetic resonance imaging and clinical characterization. Psychomotor function was assessed using the 9-hole pegboard task, a timed motor task that engages mechanical and psychomotor components of action, and tasks assessing processing speed and task switching. We used multivariate pattern analysis of whole-connectome data to identify brain correlates of psychomotor function. ResultsWe identified discrete brain circuits driving the cognitive and motor components of psychomotor function. In our combined sample of participants with psychosis (n = 89) and healthy control participants (n = 52), the strongest correlates of psychomotor function (pegboard performance) (p < .005) were between a midline cerebellar region and left frontal region and presupplementary motor area. Psychomotor function was correlated with both cerebellar-frontal connectivity (r = 0.33) and cerebellar–presupplementary motor area connectivity (r = 0.27). However, the cognitive component of psychomotor performance (task switching) was correlated only with cerebellar-frontal connectivity (r = 0.19), whereas the motor component (processing speed) was correlated only with cerebellar–presupplementary motor area connectivity (r = 0.15), suggesting distinct circuits driving unique subprocesses of psychomotor function. ConclusionsWe identified cerebellar-cortical circuits that drive distinct subprocesses of psychomotor function. Future studies should probe relationships between cerebellar connectivity and psychomotor performance using neuromodulation.

74 Timed Motor Performance in Children Medically Cleared for Return to Activities Post Mild Traumatic Brain Injury

Objective:Children who sustain a mild traumatic brain injury (mTBI) are at increased odds of additive injury and continue to show altered motor performance relative to never-injured peers after being medically cleared (MC) to return to normal activities. There is a critical need to determine when children can return to activities without risk of short and long-term adverse effects, with research showing high reinjury rates for 3-12 months after RTP. The Physical and Neurological Examination for Subtle Signs (PANESS) measures subtle signs of motor impairment during gait, balance, and timed motor functions. Recent literature has demonstrated that PANESS timed motor function can distinguish between children medically cleared post-mTBI compared to never-injured controls. The present study examined performance on timed motor tasks in youth medically cleared from mTBI following medical clearance and 3-months later, compared to never-injured peers.Participants and Methods:25 children (Mage=14.16, SD=2.46; Male=68%) were enrolled within 6 weeks of medical clearance from mTBI (Mdays post MC=33, SD=13.4, Range=2-59) along with 66 typically developing, never-injured controls (Mage=13.9, SD=2.22; Male=50%). Group differences were evaluated for the Timed Motor section of the PANESS at enrollment and at a 3-month follow-up (Mdays from enrollment to follow-up=95.90, SD=12.69, Range=62-129). This 3-month follow-up occurred on average 4 months after medical clearance (Mdays from MC to follow-up=130.08, SD=17.58, Range=92 - 164). The Timed Motor section includes Repetitive (foot tapping, hand patting, and finger tapping) and Sequential (heel-toe rocking, hand pronate/supinate, finger sequencing) raw time scores, measured in seconds. The Total Timed Motor Speed score is the combination of Repetitive and Sequential Movement and the side-to-side tongue item.Results:At 3-month follow-up, mTBI participants (M=67.55, SD=8.26, Range=53.66-83.88) performed worse than controls (M=63.09, SD=10.23, Range=39.86-100.51) on Total Timed Motor Speed, t(89)= 1.95, p&lt;0.05), including when controlling for age and sex, F(1, 87)=4.67, p&lt;0.05. At the same time point, mTBI participants (M=36.54, SD=5.47, Range=28.74-49.17) performed worse on Sequential Speed than controls (M=32.93, SD=6.1, Range=21.49-56.76), t(89)=2.59, p&lt;0.01, including when controlling for age and sex, F(1, 87)=7.687, p&lt;0.01). Although groups performed similarly on Sequential Speed at the initial time point, mTBI participants exhibited a trend of less improvement from initial to follow-up (MmTBI=-1.69, Mcontrol=-3.68, t(90)=1.445, p=0.076).Conclusions:Although groups did not significantly differ on Timed Motor Speed items at the initial time point, the mTBI group showed consistently lower scores than controls at both time points and less improvement over time. Results indicate that Total Timed Motor Speed, specifically Sequential Speed, may be a sensitive marker of persisting differences in high-level motor and cognitive learning/control in children who have been medically cleared after mTBI. More data are needed to evaluate these findings over a longer time period, and future studies should examine behavioral markers concurrently with physiologic brain recovery over time.

Reservoir computing using self-sustained oscillations in a locally connected neural network

Understanding how the structural organization of neural networks influences their computational capabilities is of great interest to both machine learning and neuroscience communities. In our previous work, we introduced a novel learning system, called the reservoir of basal dynamics (reBASICS), which features a modular neural architecture (small-sized random neural networks) capable of reducing chaoticity of neural activity and of producing stable self-sustained limit cycle activities. The integration of these limit cycles is achieved by linear summation of their weights, and arbitrary time series are learned by modulating these weights. Despite its excellent learning performance, interpreting a modular structure of isolated small networks as a brain network has posed a significant challenge. Here, we investigate how local connectivity, a well-known characteristic of brain networks, contributes to reducing neural system chaoticity and generates self-sustained limit cycles based on empirical experiments. Moreover, we present the learning performance of the locally connected reBASICS in two tasks: a motor timing task and a learning task of the Lorenz time series. Although its performance was inferior to that of modular reBASICS, locally connected reBASICS could learn a time series of tens of seconds while the time constant of neural units was ten milliseconds. This work indicates that the locality of connectivity in neural networks may contribute to generation of stable self-sustained oscillations to learn arbitrary long-term time series, as well as the economy of wiring cost.

Spatiotemporal motor learning with reward-modulated Hebbian plasticity in modular reservoir computing

Generation of complex patterns at a specific timing is crucial to most forms of learning and behavior, which are acquired through dopamine-modulated plasticity in the striatum. However, the neural mechanisms of such reward-based spatiotemporal processing remain unknown. Inspired by the cortico-striatal circuits, this study developed a new reservoir computing method, a class of recurrent neural networks, based on reward-modulated Hebbian learning (RMHL) for the spatiotemporal motor learning. We utilized a reservoir of basal dynamics (reBASICS), which generated self-sustained limit cycle oscillations with various frequencies, as a reservoir structure. Then, the oscillations were linearly integrated as readout output, in which readout weights were modulated with RMHL. The simulations showed that reBASICS-based RMHL was able to accomplish both motor timing and pattern drawing tasks, for which existing reservoir-based RMHL failed. Further, introducing an eligibility trace mechanism into RMHL allowed the model to learn motor timing even when reward-based modulation was delayed. In conclusion, this model is proposed as a new computational model of temporal processing of the striatum, where the cortical areas generate stable oscillations. From the oscillatory dynamics, spatiotemporal patterns are learned using RMHL in the striatum.

The role of cerebellum in timing processing: A contingent negative variation study

Time management is an important aspect of human behaviour and cognition. Several brain regions are thought to be involved in motor timing and time estimation tasks. However, subcortical regions such as the basal nuclei and cerebellum seem to play a role in timing control.The aim of this study was to investigate the role of the cerebellum in temporal processing. For this purpose, we transitorily inhibited cerebellar activity by means of cathodal transcranial direct current stimulation (tDCS) and studied the effects of this inhibition on contingent negative variation (CNV) parameters elicited during a S1-S2 motor task in healthy subjects.Sixteen healthy subjects underwent a S1-S2 motor task prior to and after cathodal and sham cerebellar tDCS in separate sessions. The CNV task consisted of a duration discrimination task in which subjects had to determine whether the duration of a probe interval trial was shorter (800 ms), longer (1600 ms), or equal to the target interval of 1200 ms.A reduction in total CNV amplitude emerged only after cathodal tDCS for short and target interval trials, while no differences were detected for the long interval trial. Errors were significantly higher after cathodal tDCS than at baseline evaluation of short and target intervals. No reaction time differences were found for any time interval after the cathodal and sham sessions.These results point to a role of the cerebellum in time perception. In particular, the cerebellum seems to regulate temporal interval discrimination for second and sub-second ranges.

Anaesthetics and time perception: A review.

Consciousness requires subjective experience in the "now." Establishing "now," however, necessitates temporal processing. In the current article, we review one method of altering consciousness, anaesthetic drug administration, and its effects on perceived duration. We searched PubMed, PsycInfo, and ScienceDirect databases, and article reference sections, for combinations of anaesthetic drugs and time perception tasks, finding a total of 36 articles which met our inclusion criteria. We categorised these articles with regard to whether they altered the felt passage of time, short or long interval timing, or were motor timing tasks. We found that various drugs alter the perceived passage of time; ketamine makes time subjectively slow down while GABAergic drugs make time subjectively speed up. At a short interval there is little established evidence of a shift in time perception, though temporal estimates appear more variable. Similarly, when asked to use time to optimise responses (i.e., in motor timing tasks), various anaesthetic agents make timing more variable. Longer durations are estimated as lasting longer than their objective duration, though there is some variation across articles in this regard. We conclude by proposing further experiments to examine time perception under altered states of consciousness and ask whether it is possible to perceive the passage of time of events which do not necessarily reach the level of conscious perception. The variety of methods used raises the need for more systematic investigations of time perception under anaesthesia. We encourage future investigations into the overlap of consciousness and time perception to advance both fields.

Improving Prediction of Amyloid Deposition in Mild Cognitive Impairment With a Timed Motor Task.

Cortical amyloid deposition is one of the hallmark biomarkers of Alzheimer's disease (AD). However, given how cost- and time-intensive amyloid imaging can be, there is a continued need for a low-cost, non-invasive, and accessible enrichment strategy to pre-screen individuals for their likelihood of amyloid prior to imaging. Previous work supports the use of coordinated limb movement as a potential screening tool, even after controlling for cognitive and daily function. Thirty-six patients diagnosed with amnestic mild cognitive impairment over the age of 65 underwent 18F-Flutemetamol amyloid-positron emission tomography (PET) imaging and then completed a timed motor task involving upper limb coordination. This task takes ∼5 minutes to administer and score. Multivariate linear regression and receiver operator characteristic analyses showed that including motor task performance improved model prediction of amyloid burden. Results support the rationale for including functional upper extremity motor assessment as a cost- and time-effective means to screen participants for amyloid deposition.

Time to imagine moving: Simulated motor activity affects time perception

Sensing the passage of time is important for countless daily tasks, yet time perception is easily influenced by perception, cognition, and emotion. Mechanistic accounts of time perception have traditionally regarded time perception as part of central cognition. Since proprioception, action execution, and sensorimotor contingencies also affect time perception, perception-action integration theories suggest motor processes are central to the experience of the passage of time. We investigated whether sensory information and motor activity may interactively affect the perception of the passage of time. Two prospective timing tasks involved timing a visual stimulus display conveying optical flow at increasing or decreasing velocity. While doing the timing tasks, participants were instructed to imagine themselves moving at increasing or decreasing speed, independently of the optical flow. In the direct-estimation task, the duration of the visual display was explicitly judged in seconds while in the motor-timing task, participants were asked to keep a constant pace of tapping. The direct-estimation task showed imagining accelerating movement resulted in relative overestimation of time, or time dilation, while decelerating movement elicited relative underestimation, or time compression. In the motor-timing task, imagined accelerating movement also accelerated tapping speed, replicating the time-dilation effect. The experiments show imagined movement affects time perception, suggesting a causal role of simulated motor activity. We argue that imagined movements and optical flow are integrated by temporal unfolding of sensorimotor contingencies. Consequently, as physical time is relative to spatial motion, so too is perception of time relative to imaginary motion.

Do Inattention/Hyperactivity and Motor Timing Predict Children’s Virtual Road-Crossing Performance?

The goal of this investigation was to examine how individual variation in inattention and hyperactivity is related to motor timing difficulties and whether children's performance on simple laboratory timing tasks is related to their performance on a virtual road-crossing task using a head-mounted virtual reality display system. Participants were a community sample of 92 9- to 11-year-old children. Parents completed questionnaires assessing their child's inattention and hyperactivity. Children completed two simple motor timing tasks (duration discrimination and synchronization-continuation) and crossed roads with continuous traffic in a head-mounted VR system. Higher parent-reported inattention and hyperactivity predicted poorer performance in the duration discrimination and synchronization-continuation tasks, but not the virtual pedestrian road-crossing task. Children with higher tap onset asynchrony in the synchronization-continuation task had poorer timing of entry into the gap in the virtual pedestrian road-crossing task. The findings provide further evidence that timing deficits are associated with individual differences in inattention and hyperactivity and that timing difficulties may be a risk factor for functional difficulties in everyday life.

Movement-Related Potentials Associated with Motor Timing Errors as Determined by Internally Cued Movement Onset.

ObjectiveAccurate motor timing is critical for efficient motor control of behaviors; however, the effect of motor timing abilities on movement-related neural activities has rarely been investigated. The current study aimed to examine the electrophysiological correlates of motor timing errors. MethodsTwenty-two healthy volunteers performed motor timing tasks while their electroencephalographic and electromyographic (EMG) activities were simultaneously recorded. The average of intervals between consecutive EMG onsets was calculated separately for each subject. Motor timing error was calculated as an absolute discrepancy value between the subjects’ produced and given time interval. A movement-related potential (MRP) analysis was conducted using readings from Cz electrode. ResultsMotor timing errors and MRPs were significantly correlated. Our principal finding was that only Bereitschaftpotential (BP) and motor potential (MP), not movement monitoring potential, were significantly attenuated in individuals with motor timing errors. Motor timing error had a significant effect on the amplitude of the late BP and MP. ConclusionThe findings provide electrophysiological evidence that motor timing errors correlate with the neural processes involved in the generation of self-initiated voluntary movement. Alterations in MRPs reflect central motor control processes and may be indicative of motor timing deficits.

Time Distortion in Parkinsonism.

Although animal studies and studies on Parkinson’s disease (PD) suggest that dopamine deficiency slows the pace of the internal clock, which is corrected by dopaminergic medication, timing deficits in parkinsonism remain to be characterized with diverse findings. Here we studied patients with PD and progressive supranuclear palsy (PSP), 3–4 h after drug intake, and normal age-matched subjects. We contrasted perceptual (temporal bisection, duration comparison) and motor timing tasks (time production/reproduction) in supra- and sub-second time domains, and automatic versus cognitive/short-term memory–related tasks. Subjects were allowed to count during supra-second production and reproduction tasks. In the time production task, linearly correlating the produced time with the instructed time showed that the “subjective sense” of 1 s is slightly longer in PD and shorter in PSP than in normals. This was superposed on a prominent trend of underestimation of longer (supra-second) durations, common to all groups, suggesting that the pace of the internal clock changed from fast to slow as time went by. In the time reproduction task, PD and, more prominently, PSP patients over-reproduced shorter durations and under-reproduced longer durations at extremes of the time range studied, with intermediate durations reproduced veridically, with a shallower slope of linear correlation between the presented and produced time. In the duration comparison task, PD patients overestimated the second presented duration relative to the first with shorter but not longer standard durations. In the bisection task, PD and PSP patients estimated the bisection point (BP50) between the two supra-second but not sub-second standards to be longer than normal subjects. Thus, perceptual timing tasks showed changes in opposite directions to motor timing tasks: underestimating shorter durations and overestimating longer durations. In PD, correlation of the mini-mental state examination score with supra-second BP50 and the slope of linear correlation in the reproduction task suggested involvement of short-term memory in these tasks. Dopamine deficiency didn’t correlate significantly with timing performances, suggesting that the slowed clock hypothesis cannot explain the entire results. Timing performance in PD may be determined by complex interactions among time scales on the motor and sensory sides, and by their distortion in memory.

Validation of Parkinson's Disease-Related Questionnaires in South Africa.

Background There are very few epidemiological studies investigating Parkinson's disease (PD) in Africa. The hundreds of local languages and dialects make traditional screening and clinical evaluation tools difficult to use. Objective The objective of the study was to validate two commonly used PD questionnaires in an African population. Methods The PD Screening Questionnaire (PDSQ) and Parkinson's Disease Questionnaire (PDQ-39) were modified and translated into Afrikaans, Setswana, and isiZulu and administered to a sample of healthy local residents. We assessed the internal consistencies and cluster characteristics of the questionnaires, using a Cronbach's alpha test and exploratory factor analysis. The questionnaires were then administered to a population-based sample of 416 research participants. We evaluated the correlations between the questionnaires and both a timed motor task and the Unified Parkinson's Disease Rating Scale motor subsection 3 (UPDRS3), using locally weighted scatterplot smoothing (LOWESS) regression analysis and Spearman's rank correlation. Results Both questionnaires had high overall internal consistency (Cronbach's alpha = 0.86 and 0.95, respectively). The modified PDQ-39 had evidence of five subscales, with Factor 1 explaining 57% and Factor 2 explaining 14%, of the variance in responses. The PDSQ and PDQ-39 scores were correlated with the UPDRS3 score (ρ = 0.35, P < 0.001; and ρ = 0.28, P < 0.001, respectively). Conclusion The translated PDSQ and PDQ-39 questionnaires demonstrated high internal consistency and correlations with clinical severity of parkinsonism and a timed motor task, suggesting that they are valid tools for field-based epidemiological studies.

Motor Timing as a Predictor of Attention, Working Memory and Impulsivity in Alcohol and/or Cocaine Use Disorders

In recent years, there has been a growing interest in neuropsychological deficits in patients with Cocaine Use Disorder (CUD) and Alcohol Use Disorder (AUD). Besides deficits in working memory (WM), impulsivity and attention, chronic alcohol and cocaine use have neurotoxic effects on frontostriatal areas in the brain. Individuals with deficits in these brain regions experience motor-timing deficits. It is unclear whether observed temporal processing deficits, in fact, reflect increased sustained attention or WM demands (which are required by timing tasks), or whether motor-timing deficits reflect some other process. The main questions of this were: (i) Can attention and WM be explained by motor-timing performance, and (ii), is impulsivity related to motor timing performance, in an inpatient SUD population? The study sample consisted of 74 abstinent patients who completed selected neuropsychological and motor-timing tasks. No significant correlation was found between performance on motor tasks and impulsivity. With regard to visual and auditory WM, motor timing was a significant predictor but only under conditions that required increased cognitive demands. Motor-timing performance contributed to a small portion of the variance in attention, but only for spatial abilities and only at increased cognitive demands. These preliminary findings suggest that, in line with the literature, millisecond timing engages other cognitive functions, but only minimally. As such motor timing should be regarded as a separate neurocognitive concomitant. Impulsivity was not associated with millisecond motor timing. More research is needed to further investigate these preliminary findings.

Motor Timing as a Predictor of Attention, Working Memory and Impulsivity in Alcohol and/or Cocaine Use Disorders

In recent years, there has been a growing interest in neuropsychological deficits in patients with Cocaine Use Disorder (CUD) and Alcohol Use Disorder (AUD). Besides deficits in working memory (WM), impulsivity and attention, chronic alcohol and cocaine use have neurotoxic effects on frontostriatal areas in the brain. Individuals with deficits in these brain regions experience motor-timing deficits. It is unclear whether observed temporal processing deficits, in fact, reflect increased sustained attention or WM demands (which are required by timing tasks), or whether motor-timing deficits reflect some other process. The main questions of this were: (i) Can attention and WM be explained by motor-timing performance, and (ii), is impulsivity related to motor timing performance, in an inpatient SUD population? The study sample consisted of 74 abstinent patients who completed selected neuropsychological and motor-timing tasks. No significant correlation was found between performance on motor tasks and impulsivity. With regard to visual and auditory WM, motor timing was a significant predictor but only under conditions that required increased cognitive demands. Motor-timing performance contributed to a small portion of the variance in attention, but only for spatial abilities and only at increased cognitive demands. These preliminary findings suggest that, in line with the literature, millisecond timing engages other cognitive functions, but only minimally. As such motor timing should be regarded as a separate neurocognitive concomitant. Impulsivity was not associated with millisecond motor timing. More research is needed to further investigate these preliminary findings.

Quantitative but Not Qualitative Performance Changes in Predictive Motor Timing as a Result of Overtraining.

The possibilities of substantial long-term improvement of predictive timing might be sometimes seen as limited, with scanty information of neural substrates underlying the potential learning process. To address this issue, we have investigated the performance of 21 baseball professionals and 21 matched controls in a predictive motor timing task previously shown to engage the cerebellum. Baseball players, hypothesized as a model of overtraining of the prediction of future state of the surroundings, showed significantly higher quantitative performance than nonathletic controls, with a substantial part of the baseball players reaching levels far beyond the range observed in common population. Furthermore, the qualitative performance profile of baseball players under various conditions as target speed and acceleration modes did not differ from the profile of healthy controls. Our results suggest that regular exigent training has the potential to vastly improve predictive motor timing. Moreover, the quantitative but not qualitative difference in the performance profile allows us to hypothesize that the selective honing of the same cerebellar processes and networks as in non-trained individuals is the substrate for the quantitative performance improvement, without substantial engagement of further neural nodes.

Modulation of Beta Oscillations for Implicit Motor Timing in Primate Sensorimotor Cortex during Movement Preparation.

Motor timing is an important part of sensorimotor control. Previous studies have shown that beta oscillations embody the process of temporal perception in explicit timing tasks. In contrast, studies focusing on beta oscillations in implicit timing tasks are lacking. In this study, we set up an implicit motor timing task and found a modulation pattern of beta oscillations with temporal perception during movement preparation. We trained two macaques in a repetitive visually-guided reach-to-grasp task with different holding intervals. Spikes and local field potentials were recorded from microelectrode arrays in the primary motor cortex, primary somatosensory cortex, and posterior parietal cortex. We analyzed the association between beta oscillations and temporal interval in fixed-duration experiments (500ms as the Short Group and 1500ms as the Long Group) and random-duration experiments (500ms to 1500ms). The results showed that the peak beta frequencies in both experiments ranged from 15Hz to 25Hz. The beta power was higher during the hold period than the movement (reach and grasp) period. Further, in the fixed-duration experiments, the mean power as well as the maximum rate of change of beta power in the first 300ms were higher in the Short Group than in the Long Group when aligned with the Center Hit event. In contrast, in the random-duration experiments, the corresponding values showed no statistical differences among groups. The peak latency of beta power was shorter in the Short Group than in the Long Group in the fixed-duration experiments, while no consistent modulation pattern was found in the random-duration experiments. These results indicate that beta oscillations can modulate with temporal interval in their power mode. The synchronization period of beta power could reflect the cognitive set maintaining working memory of the temporal structure and attention.

A screening tool to detect clinical manganese neurotoxicity

Manganese (Mn) over-exposure in occupational settings is associated with basal ganglia toxicity and a movement disorder characterized by parkinsonism (i.e., the signs and symptoms of Parkinson disease). A simple test to help non-neurologists identify workers with clinical Mn neurotoxicity represents an unmet need. In a cohort of Mn-exposed workers from welding worksites, with extensive clinical data, we developed a linear regression model to predict the Unified Parkinson Disease Rating Scale motor subsection part 3 (UPDRS3) score. We primarily considered factors easily obtained in a primary care or occupational medicine clinic, specifically easily assessed signs of parkinsonism and factors likely to be associated with UPDRS3 such as age, timed motor task results, and selected symptoms/conditions. Secondarily we considered other demographic variables and welding exposure. We based the model on 596 examined workers age≤65years and with timed motor task data. We selected the model based on simplicity for clinical application, biologic plausibility, and statistical significance and magnitude of regression coefficients. The model contained age, timed motor task scores for each hand, and indicators of action tremor, speech difficulty, anxiety, depression, loneliness, pain and current cigarette smoking. When we examined how well the model identified workers with clinically significant parkinsonism (UPDRS3≥15) the receiver operating characteristic area under the curve (AUC) was 0.72 (95% confidence interval [CI] 0.67, 0.77). With a cut point that provided 80% sensitivity, specificity was 52%, the positive predictive value in our cohort was 29%, and the negative predictive value was 92%. Using the same cut point for predicted UPDRS3, the AUC was nearly identical for UPDRS3≥10, and was 0.83 (95% CI 0.76, 0.90) for UPDRS3≥20. Since welding exposure data was not required after including its putative effects, this model may help identify workers with clinically significant Mn neurotoxicity in a variety of settings, as a first step in a tiered occupational screening program.

Sleep to the beat: A nap favours consolidation of timing.

Growing evidence suggests that sleep is important for procedural learning, but few studies have investigated the effect of sleep on the temporal aspects of motor skill learning. We assessed the effect of a 90-min day-time nap on learning a motor timing task, using 2 adaptations of a serial interception sequence learning (SISL) task. Forty-two right-handed participants performed the task before and after a 90-min period of sleep or wake. Electroencephalography (EEG) was recorded throughout. The motor task consisted of a sequential spatial pattern and was performed according to 2 different timing conditions, that is, either following a sequential or a random temporal pattern. The increase in accuracy was compared between groups using a mixed linear regression model. Within the sleep group, performance improvement was modeled based on sleep characteristics, including spindle- and slow-wave density. The sleep group, but not the wake group, showed improvement in the random temporal, but especially and significantly more strongly in the sequential temporal condition. None of the sleep characteristics predicted improvement on either general of the timing conditions. In conclusion, a daytime nap improves performance on a timing task. We show that performance on the task with a sequential timing sequence benefits more from sleep than motor timing. More important, the temporal sequence did not benefit initial learning, because differences arose only after an offline period and specifically when this period contained sleep. Sleep appears to aid in the extraction of regularities for optimal subsequent performance. (PsycINFO Database Record

The genetic architecture of correlations between perceptual timing, motor timing, and intelligence

Psychometric intelligence correlates with performance on a wide range of sensory and motor tasks that involve processing of temporal information in the millisecond-second range. For some timing tasks, e.g. reaction time and discrimination of temporal stimuli in working memory, the associations with intelligence are likely to involve top–down mechanisms such as attention. However, studies on repetitive, automatic motor timing tasks indicate that correlations between intelligence and timing also may reflect bottom-up mechanisms, i.e. basic neural properties that influence both the temporal accuracy of behavior and cognitive processes. Here, we study the genetic architecture of the associations between intelligence, perceptual timing (auditory rhythm discrimination) and motor timing (finger tapping) in a large twin cohort. Specifically, we hypothesized that the associations between these tasks on the phenotypic level involve broad pleiotropic genetic effects that influence all three tasks, as well as additional genetic effects on the covariation between perceptual and motor timing. Phenotypic associations between the variables were low to moderate, with Pearson's correlations in the range 0.17–0.32. Trivariate twin modeling showed that the associations between the three variables were essentially due to shared genetic influences. In support of the hypotheses, we found evidence for pleiotropic effects on motor timing, perceptual timing, and intelligence, as well as additional genetic covariation between the two timing tasks that was not shared with intelligence. We conclude, first, that genetic factors underlying intelligence may involve genes which influence brain properties of importance for the temporal accuracy of neural processing. We discuss possible neural substrates of such effects. Secondly, the correlation between motor and perceptual timing also partly explained by genetic influences that are unrelated to intelligence.

Essential tremor, the olivocerebellar system and motor timing – An fMRI study

Background Essential tremor (ET) is the most common tremor disorder. It has been repeatedly shown that the olivocerebellar system is involved in ET, consisting of the inferior olive nucleus (ION), dentate nucleus (DN) and cerebellar cortex. Impairment of the central timing mechanism in ET has been suggested. The olivocerebellar system plays an important role in motor timing. In order to study the functional involvement of this system in ET, we employed a task involving motor timing during functional MRI (fMRI). Methods Thirty propranolol sensitive ET patients with familial upper limb tremor and 30 healthy controls were included. T2 ∗ -weighted EPI sequences were acquired (180 volumes, TR: 2s, voxel size: 3.5 × 3.5 × 3.5 mm, 3TMRI). The task consisted of alternating rest and finger tapping (rate of 2 Hz) blocks. Task performance was measured by electromyography. Analysis was performed in SPM8 (standard preprocessing, normalization according to the spatially unbiased infra-tentorial template, 4 mm smoothing kernel). The left ION was localized with a conjunction analysis of patients and controls. For this abstract, quantified tapping performance is not yet incorporated. Results Within-group random-effects analysis restricted to the brainstem and cerebellum showed activations throughout the cerebellum (bilateral lobules V, VI, VIIIA) and in both left and right ION. Preliminary between-group analysis of the ION and CB right lobule VI showed significantly higher activations in controls compared to ET patients. Conclusions Exploratory analysis suggests altered activity in the olivocerebellar system in ET patients compared to controls during a motor timing task. Inclusion of task performance and effective connectivity analysis will be carried out to aid us in discriminating between altered activity due to task performance and pathological motor timing related to ET. Understanding the role of the olivocerebellar system in ET is of great importance for unraveling the mechanism of tremor genesis.