The human cerebellum is essential for modulating perceptual sensitivity based on temporal expectations

The impact of emotion on temporal prediction ability in different timing contexts

Our ability to predict temporal events (TP) is dynamically modulated by contextual factors (i.e., different predictive contexts) and closely intertwined with emotional states, shaping our adaptive responses within the environment. While studies have extensively probed how emotions distort time perception, their impact on predictive ability remains unexplored. Here, we investigated emotions' impact on temporal prediction. Participants (N = 23) completed a standard implicit TP task and its emotional version (TP-E), using positive (i.e., joy), negative (i.e., fear), and neutral faces as visual stimuli. Reaction times (RTs) to the target were recorded in two predictive contexts: rhythmic (i.e., interstimulus intervals (ISIs) were constant, 900 ms) and single-interval condition (i.e., target's timing estimation was based on the prior exposure of the train of stimuli) and random (no-time context). We found a specific decrease in RTs, in the single-interval context, when fearful stimuli were used, compared to neutral stimuli. This suggests that negative emotion influences temporal prediction, aligning with emotional adjustments in processing threatening situations, including modulation of physiological arousal, cognitive appraisal, and time estimation. Indeed, such modulation of RTs, specifically in the single-interval condition, may be attributed to improved memory and attention, essential cognitive abilities for single-based predictions, enhanced by the exposure to fearful stimuli.

The Relationship Between Physical Activity and Gait Rhythm with Motor Imagery -Trial Using the Finger Tap Test

OBJECTIVES

The purpose of this study was to investigate the relationship of any error (delta; ∆) between the image of one's own walking rhythm and the actual walking rhythm and physical activity, as a new motor imagery assessment.

METHODS

The subjects were classified into two groups: a high activity group (HA-Group) having high physical activity with less than four hours of sitting time per day, and a low activity group (LA-Group) having low physical activity with more than four hours of daily sitting time. Visual rhythm, auditory rhythm, mental comfortable walking rhythm, and mental maximum walking rhythm were used to assess new motor imagery. Their beats per minute were measured and any error (delta; ∆) from the actual rhythm was calculated: ∆ visual rhythm, ∆ auditory rhythm, ∆ mental normal gait rhythm, and ∆ mental maximal gait rhythm.

RESULTS

When comparing the two groups, the HA-Group had significantly higher ∆ visual rhythm, lower ∆ auditory rhythm, higher ∆ mental comfortable walking rhythm, and lower ∆ mental maximum walking rhythm ability than the LA-Group. Furthermore, in an ANCOVA with age, ∆visual rhythm, and ∆auditory rhythm as adjustment factors, the HA-Group had significantly lower ∆mental maximum walking rhythm than the LA-Group.

CONCLUSIONS

These results showed that the rhythmic assessment of the imagery of maximum walking was associated with stationery time. It is possible that the more inaccurate the imagery of maximum walking, the longer the sitting or lying time.

Neural signatures of temporal anticipation in human cortex represent event probability density

Temporal prediction is a fundamental function of neural systems. Recent results show that humans anticipate future events by calculating probability density functions, rather than hazard rates. However, direct neural evidence for this hypothesized mechanism is lacking. We recorded neural activity using magnetoencephalography as participants anticipated auditory and visual events distributed in time. We show that temporal anticipation, measured as reaction times, approximates the event probability density function, but not hazard rate. Temporal anticipation manifests as spatiotemporally patterned activity in three anatomically and functionally distinct parieto-temporal and sensorimotor cortical areas. Each of these areas revealed a marked neural signature of anticipation: Prior to sensory cues, activity in a specific frequency range of neural oscillations, spanning alpha and beta ranges, encodes the event probability density function. These neural signals predicted reaction times to imminent sensory cues. These results demonstrate that supra-modal representations of probability density across cortex underlie the anticipation of future events.

Time perception in cerebellar and basal ganglia stroke patients

The neural mechanisms underlying time perception remain elusive. Although the cerebellum (CE) and basal ganglia (BG) are considered fundamental, evidence primarily stems from studies on neurodegenerative diseases, where progressive and widespread damage complicates linking deficits to specific brain structures. In contrast, brain stroke affects focal areas suddenly, allowing for the assessment of immediate functional consequences. Here, we compared patients with acute stroke in the CE and BG to age-matched healthy controls (HC) on both explicit (time bisection, free and 1-second finger tapping) and implicit (rhythmic, temporal orienting) timing tasks. Concerning explicit timing, both CE and BG patients were faster than HC in their free finger tapping, while BG lesions showed greater variability than HC in the 1-second tapping. Similarly, performance on the bisection task suggested deficits more related to cognitive complaints in stroke than specific temporal dysfunction. In implicit timing tasks, BG patients, like HC, effectively used information provided by the rhythm and the temporal orienting cues to anticipate the target onset, whereas CE patients failed and showed longer reaction times. Therefore, before compensatory mechanisms can take effect, acute CE damage might hinder implicit timing, whereas BG lesions could disrupt explicit temporal representation when processed alongside other cognitive functions.

No significant relationship found between spontaneous motor tempo, heartbeat, and individual alpha frequency: an analysis of internal tempos

Many theories of time perception propose the existence of an internal pacemaker, and studies across behavioral, physiological, and neuroscience fields have explored this concept. Specifically, Spontaneous Motor Tempo (SMT), the most comfortable and natural tapping tempo for each individual, is thought to reflect this internal pacemaker's tempo. Changes in heart rate are also linked to time estimation, while Individual Alpha Frequency (IAF), the peak in the alpha range (8-13 Hz) observed in EEG, is reported to reflect the brain's temporal processing. Despite the associations of SMT, heart rate, and IAF with intrinsic tempo, their interrelations remain unexplored. In this pre-registered study, we measured SMT, IAF, and heart rate in 32 healthy university students aged 18-21 and examined how these variables relate to each other. During the experiment, participants sat with their eyes closed for 5 min while we recorded their EEG and heart rate. They then tapped the space key with their index finger at their most comfortable tempo, which we used to determine SMT. Participants also completed a questionnaire about their age, chronotype, and musical experience. Our results showed no significant correlations among SMT, heart rate, and IAF. Regression analysis further confirmed that SMT is not influenced by heart rate or IAF. Therefore, no significant relationships among behavioral, physiological, and neuroscience-related tempo were uncovered. Our contribution lies in measuring SMT, heart rate, and IAF within the same experimental context. All procedures, including scripts used for the analyses, were pre-registered before data collection, and we report these null results to mitigate publication bias.

Psychological characteristics and structural brain changes in women with endometriosis and endometriosis-independent chronic pelvic pain

STUDY QUESTION

Are there neurobiological changes induced by endometriosis?

SUMMARY ANSWER

Women with endometriosis demonstrate specific neurobiological changes distinct from those in patients with chronic pelvic pain (CPP) in the absence of endometriosis.

WHAT IS KNOWN ALREADY

Endometriosis is a chronic disease affecting women of reproductive age that presents with pain and infertility often accompanied by comorbid mental disorders. Only one study with a number of limitations has investigated changes in gray matter volumes and functional connectivity in a small group of patients with endometriosis.

STUDY DESIGN, SIZE, DURATION

This prospective study recruited 53 women undergoing a laparoscopy due to suspicion of symptomatic endometriosis and 25 healthy, pain-free women. Clinical and psychological characteristics, thermal pain perception, and voxel- and surface-based morphology were assessed in all study participants. Thereafter, the patients underwent a laparoscopy, where endometriosis was either histologically confirmed and removed, or ruled out. Correspondingly, patients were assigned into the group with endometriosis (n = 27) or with endometriosis-independent CPP (n = 26) and compared to the pain-free controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study groups were generally representative for the population of women with endometriosis. Sociodemographic, medical, clinical, and psychological characteristics were collected using various questionnaires and a structured clinical interview. Thermal pain perception and voxel- and surface-based morphometry were assessed using thermode and MRI, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

Despite comparable pain intensity and burden of mental disorders, both patient groups demonstrated distinct neurobiological patterns. Women with endometriosis exhibited increased gray matter volume (GMV) in the left cerebellum, lingual gyrus and calcarine gyrus, compared to those with endometriosis-independent CPP. Patients with CPP had decreased GMV in the right cerebellum as compared to controls. Dysmenorrhoea severity correlated positively with GMV in the left inferior parietal lobule, whereas depressive symptoms were associated with decreased GMV in the right superior medial gyrus across patient groups. Dyspareunia correlated negatively with cortical thickness in the left inferior temporal gyrus and left middle temporal gyrus.

LIMITATIONS, REASONS FOR CAUTION

The study groups differed in a few baseline-characteristics, including educational levels, smoking and BMI. While measuring pain perception thresholds, we did not attempt to mimic CPP by placement of the thermode on the abdominal wall.

WIDER IMPLICATIONS OF THE FINDINGS

Changes in gray matter volume associated with endometriosis differ from those observed in women with endometriosis-independent CPP. Our results underline an involvement of the cerebellum in pain perception and the pathogenesis of pain associated with endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the START Program of the Faculty of Medicine, RWTH Aachen, Germany, and supported by the International Research Training Group (IRTG 2150) of the German Research Foundation (DFG)-269953372/GRK2150, Germany. S.T. was supported by postdoctoral fellowship of the Faculty of Medicine, RWTH Aachen, Germany. There are no conflicts of interest.

TRIAL REGISTRATION NUMBER

DRKS00021236.

Challenges and Approaches in the Study of Neural Entrainment

When exposed to rhythmic stimulation, the human brain displays rhythmic activity across sensory modalities and regions. Given the ubiquity of this phenomenon, how sensory rhythms are transformed into neural rhythms remains surprisingly inconclusive. An influential model posits that endogenous oscillations entrain to external rhythms, thereby encoding environmental dynamics and shaping perception. However, research on neural entrainment faces multiple challenges, from ambiguous definitions to methodological difficulties when endogenous oscillations need to be identified and disentangled from other stimulus-related mechanisms that can lead to similar phase-locked responses. Yet, recent years have seen novel approaches to overcome these challenges, including computational modeling, insights from dynamical systems theory, sophisticated stimulus designs, and study of neuropsychological impairments. This review outlines key challenges in neural entrainment research, delineates state-of-the-art approaches, and integrates findings from human and animal neurophysiology to provide a broad perspective on the usefulness, validity, and constraints of oscillatory models in brain-environment interaction.

Mechanically Induced Motor Tremors Disrupt the Perception of Time

Contemporary research has begun to show a strong relationship between movements and the perception of time. More specifically, concurrent movements serve to both bias and enhance time estimates. To explain these effects, we recently proposed a mechanism by which movements provide a secondary channel for estimating duration that is combined optimally with sensory estimates. However, a critical test of this framework is that by introducing "noise" into movements, sensory estimates of time should similarly become noisier. To accomplish this, we had human participants move a robotic arm while estimating intervals of time in either auditory or visual modalities (n = 24, ea.). Crucially, we introduced an artificial "tremor" in the arm while subjects were moving, that varied across three levels of amplitude (1-3 N) or frequency (4-12 Hz). The results of both experiments revealed that increasing the frequency of the tremor led to noisier estimates of duration. Further, the effect of noise varied with the base precision of the interval, such that a naturally less precise timing (i.e., visual) was more influenced by the tremor than a naturally more precise modality (i.e., auditory). To explain these findings, we fit the data with a recently developed drift-diffusion model of perceptual decision-making, in which the momentary, within-trial variance was allowed to vary across conditions. Here, we found that the model could recapitulate the observed findings, further supporting the theory that movements influence perception directly. Overall, our findings support the proposed framework, and demonstrate the utility of inducing motor noise via artificial tremors.

ANO10-Related Spinocerebellar Ataxia: MDSGene Systematic Literature Review and a Romani Case Series

BACKGROUND

Biallelic pathogenic variants in the ANO10 gene cause autosomal recessive progressive ataxia (ATX-ANO10).

METHODS

Following the MDSGene protocol, we systematically investigated genotype-phenotype relationships in ATX-ANO10 based on the clinical and genetic data from 82 published and 12 newly identified patients.

RESULTS

Most patients (>80%) had loss-of-function (LOF) variants. The most common variant was c.1150_1151del, found in all 29 patients of Romani ancestry, who had a 14-year earlier mean age at onset than patients homozygous for other LOF variants. We identified previously undescribed clinical features of ATX-ANO10 (e.g., facial muscle involvement and strabismus) suggesting the involvement of brainstem pathology, and we propose a diagnostic algorithm that may aid clinical ATX-ANO10 diagnosis.

CONCLUSIONS

The early disease onset in patients with c.1150_1151del may indicate the existence of genetic/environmental disease-modifying factors in the Romani population. Our findings will inform patient counseling and may improve our understanding of the disease mechanism. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A matter of time: how musical training affects time perception

Musical training has been linked to changes in early attentional and perceptual processing. Thus, such an altered attentional and perceptual processing has enabled musicians to judge the duration differently than non-musicians. Although these claims seem intriguing, there are many questions that are not addressed yet, for example, how would the performance of musically-trained differ from that of untrained on visual and auditory temporal judgments? Is there any advantage to musically-trained person in temporal processing? To understand these questions, we thus conducted a series of Auditory and Visual Temporal Bisection Tasks on 32 musically-trained and 32 musically-untrained participants. We hypothesized that if music training modulates general sensitivity to temporal dimensions, then the temporal judgments of musically-trained participants would differ from those of untrained participants in both visual and auditory tasks. Each participant performed a total of 140 trials (70 visual and 70 auditory) in two different blocks. For each participant, a Point of Subjective Equality (PSE) was obtained for visual and auditory conditions. The findings revealed a significant modality effect on time perception, with auditory stimuli being consistently overestimated compared to visual stimuli. Surprisingly, the musically-trained group exhibited a tendency to underestimate duration relative to the musically-untrained participants. Although these results may appear counterintuitive at first glance, a detailed analysis indicates that the length of musical training plays a significant role in modulating temporal processing within the musically-trained group.

Keeping time and rhythm by internal simulation of sensory stimuli and behavioral actions

Effective behavior often requires synchronizing our actions with changes in the environment. Rhythmic changes in the environment are easy to predict, and we can readily time our actions to them. Yet, how the brain encodes and maintains rhythms is not known. Here, we trained primates to internally maintain rhythms of different tempos and performed large-scale recordings of neuronal activity across the sensory-motor hierarchy. Results show that maintaining rhythms engages multiple brain areas, including visual, parietal, premotor, prefrontal, and hippocampal regions. Each recorded area displayed oscillations in firing rates and oscillations in broadband local field potential power that reflected the temporal and spatial characteristics of an internal metronome, which flexibly encoded fast, medium, and slow tempos. The presence of widespread metronome-related activity, in the absence of stimuli and motor activity, suggests that internal simulation of stimuli and actions underlies timekeeping and rhythm maintenance.

The neural basis of somatosensory temporal discrimination threshold as a paradigm for time processing in the sub-second range: An updated review

BACKGROUND AND OBJECTIVE

The temporal aspect of somesthesia is a feature of any somatosensory process and a pre-requisite for the elaboration of proper behavior. Time processing in the milliseconds range is crucial for most of behaviors in everyday life. The somatosensory temporal discrimination threshold (STDT) is the ability to perceive two successive stimuli as separate in time, and deals with time processing in this temporal range. Herein, we focus on the physiology of STDT, on a background of the anatomophysiology of somesthesia and the neurobiological substrates of timing.

METHODS

A review of the literature through PubMed & Cochrane databases until March 2023 was performed with inclusion and exclusion criteria following PRISMA recommendations.

RESULTS

1151 abstracts were identified. 4 duplicate records were discarded before screening. 957 abstracts were excluded because of redundancy, less relevant content or not English-written. 4 were added after revision. Eventually, 194 articles were included.

CONCLUSIONS

STDT encoding relies on intracortical inhibitory S1 function and is modulated by the basal ganglia-thalamic-cortical interplay through circuits involving the nigrostriatal dopaminergic pathway and probably the superior colliculus.

Temporal Information Processing in the Cerebellum and Basal Ganglia

Temporal information processing in the range of a few hundred milliseconds to seconds involves the cerebellum and basal ganglia. In this chapter, we present recent studies on nonhuman primates. In the studies presented in the first half of the chapter, monkeys were trained to make eye movements when a certain amount of time had elapsed since the onset of the visual cue (time production task). The animals had to report time lapses ranging from several hundred milliseconds to a few seconds based on the color of the fixation point. In this task, the saccade latency varied with the time length to be measured and showed stochastic variability from one trial to the other. Trial-to-trial variability under the same conditions correlated well with pupil diameter and the preparatory activity in the deep cerebellar nuclei and the motor thalamus. Inactivation of these brain regions delayed saccades when asked to report subsecond intervals. These results suggest that the internal state, which changes with each trial, may cause fluctuations in cerebellar neuronal activity, thereby producing variations in self-timing. When measuring different time intervals, the preparatory activity in the cerebellum always begins approximately 500 ms before movements, regardless of the length of the time interval being measured. However, the preparatory activity in the striatum persists throughout the mandatory delay period, which can be up to 2 s, with different rate of increasing activity. Furthermore, in the striatum, the visual response and low-frequency oscillatory activity immediately before time measurement were altered by the length of the intended time interval. These results indicate that the state of the network, including the striatum, changes with the intended timing, which lead to different time courses of preparatory activity. Thus, the basal ganglia appear to be responsible for measuring time in the range of several hundred milliseconds to seconds, whereas the cerebellum is responsible for regulating self-timing variability in the subsecond range. The second half of this chapter presents studies related to periodic timing. During eye movements synchronized with alternating targets at regular intervals, different neurons in the cerebellar nuclei exhibit activity related to movement timing, predicted stimulus timing, and the temporal error of synchronization. Among these, the activity associated with target appearance is particularly enhanced during synchronized movements and may represent an internal model of the temporal structure of stimulus sequence. We also considered neural mechanism underlying the perception of periodic timing in the absence of movement. During perception of rhythm, we predict the timing of the next stimulus and focus our attention on that moment. In the missing oddball paradigm, the subjects had to detect the omission of a regularly repeated stimulus. When employed in humans, the results show that the fastest temporal limit for predicting each stimulus timing is about 0.25 s (4 Hz). In monkeys performing this task, neurons in the cerebellar nuclei, striatum, and motor thalamus exhibit periodic activity, with different time courses depending on the brain region. Since electrical stimulation or inactivation of recording sites changes the reaction time to stimulus omission, these neuronal activities must be involved in periodic temporal processing. Future research is needed to elucidate the mechanism of rhythm perception, which appears to be processed by both cortico-cerebellar and cortico-basal ganglia pathways.

Attention to space and time: Independent or interactive systems? A narrative review

While there is ample evidence for the ability to selectively attend to where in space and when in time a relevant event might occur, it remains poorly understood whether spatial and temporal attention operate independently or interactively to optimize behavior. To elucidate this important issue, we provide a narrative review of the literature investigating the relationship between the two. The studies were organized based on the attentional manipulation employed (endogenous vs. exogenous) and the type of task (detection vs. discrimination). Although the reviewed findings depict a complex scenario, three aspects appear particularly important in promoting independent or interactive effects of spatial and temporal attention: task demands, attentional manipulation, and their combination. Overall, the present review provides key insights into the relationship between spatial and temporal attention and identifies some critical gaps that need to be addressed by future research.

Predictability awareness rather than mere predictability enhances the perceptual benefits for targets in auditory rhythms over targets following temporal cues

Sounds following a cue or embedded in a periodic rhythm are processed more effectively than sounds that are part of an aperiodic rhythm. One might also expect that a sound embedded in a periodic rhythm is processed more effectively than a sound following a single temporal cue. Such a finding would follow the theory that the entrainment of neural rhythmic activity by periodic stimuli renders the prediction of upcoming stimuli more efficient. We conducted a psychophysical experiment in which we tested the behavioral elements of this idea. Targets in periodic and aperiodic rhythms, if they occurred, always appeared at the same moment in time, and thus were fully predictable. In a first condition, participants remained unaware of this. In a second condition, an explicit instruction on the temporal location of the targets embedded in rhythms was provided. We assessed sensitivity and reaction times to the target stimuli in a difficult temporal detection task, and contrasted performance in this task to that obtained for targets temporally cued by a single preceding cue. Irrespective of explicit information about target predictability, target detection performance was always better in the periodic and temporal cue conditions, compared to the aperiodic condition. However, we found that the mere predictability of an acoustic target within a periodic rhythm did not allow participants to detect the target any better than in a condition where the target's timing was predicted by a single temporal cue. Only when participants were made aware of the specific moment in the periodic rhythm where the target could occur, did sensitivity increase. This finding suggests that a periodic rhythm is not automatically sufficient to provide perceptual benefits compared to a condition predictable yet not rhythmic condition (a cue). In some conditions, as shown here, these benefits may only occur in interaction with other factors such as explicit instruction and directed attention.

Association between self-perceived hearing status and cognitive impairment in the older Brazilian population: a population-based study

Cognitive health plays an important role in the quality of life and autonomy of older adults. and it is influenced by hearing ability. This article aims to analyze the association between self-perceived hearing status and cognitive impairment in Brazilian older adults. This cross-sectional population-based study was conducted with 4,977 older adults who participated in ELSI Brazil 2015. The cognitive impairment status (outcome. categorized as "yes" and "no") and variable of interest (self-perceived hearing status. categorized as "good" "fair" and "poor") were obtained using a self-report method. The following domains were considered for cognition: temporal orientation. memory (short and long term). and language (recent and late). Poisson regression with robust variance estimation was used to assess the self-perceived hearing status-cognitive impairment association in the crude and adjusted analyses. Sociodemographic. lifestyle. and medical history variables were used to adjust the analyses. We found that 31.8% of the participants reported fair or poor hearing and 42% had cognitive impairment. In the adjusted analysis. older adults with poor hearing were revealed to have a stronger association with cognitive impairment than their peers with good hearing. Therefore. in older Brazilian adults. lower self-perceived hearing status is associated higher levels of cognitive impairment.

Sensory and motor representations of internalized rhythms in the cerebellum and basal ganglia

Both the cerebellum and basal ganglia are involved in rhythm processing, but their specific roles remain unclear. During rhythm perception, these areas may be processing purely sensory information, or they may be involved in motor preparation, as periodic stimuli often induce synchronized movements. Previous studies have shown that neurons in the cerebellar dentate nucleus and the caudate nucleus exhibit periodic activity when the animals prepare to respond to the random omission of regularly repeated visual stimuli. To detect stimulus omission, the animals need to learn the stimulus tempo and predict the timing of the next stimulus. The present study demonstrates that neuronal activity in the cerebellum is modulated by the location of the repeated stimulus and that in the striatum (STR) by the direction of planned movement. However, in both brain regions, neuronal activity during movement and the effect of electrical stimulation immediately before stimulus omission were largely dependent on the direction of movement. These results suggest that, during rhythm processing, the cerebellum is involved in multiple stages from sensory prediction to motor control, while the STR consistently plays a role in motor preparation. Thus, internalized rhythms without movement are maintained as periodic neuronal activity, with the cerebellum and STR preferring sensory and motor representations, respectively.

A transcranial magnetic stimulation study on the role of the left intraparietal sulcus in temporal orienting of attention

Adaptive behavior requires the ability to orient attention to the moment in time at which a relevant event is likely to occur. Temporal orienting of attention has been consistently associated with activation of the left intraparietal sulcus (IPS) in prior fMRI studies. However, a direct test of its causal involvement in temporal orienting is still lacking. The present study tackled this issue by transiently perturbing left IPS activity with either online (Experiment 1) or offline (Experiment 2) transcranial magnetic stimulation (TMS). In both experiments, participants performed a temporal orienting task, alternating between blocks in which a temporal cue predicted when a subsequent target would appear and blocks in which a neutral cue provided no information about target timing. In Experiment 1 we used an online TMS protocol, aiming to interfere specifically with cue-related temporal processes, whereas in Experiment 2 we employed an offline protocol whereby participants performed the temporal orienting task before and after receiving TMS. The right IPS and/or the vertex were stimulated as active control regions. While results replicated the canonical pattern of temporal orienting effects on reaction time, with faster responses for temporal than neutral trials, these effects were not modulated by TMS over the left IPS (as compared to the right IPS and/or vertex regions) regardless of the online or offline protocol used. Overall, these findings challenge the causal role of the left IPS in temporal orienting of attention inviting further research on its underlying neural substrates.

Interaction of dynamic error signals in saccade adaptation

Motor adaptation maintains movement accuracy. To evaluate movement accuracy, motor adaptation relies on an error signal, generated by the movement target, while suppressing error signals from irrelevant objects in the vicinity. Previous work used static testing environments, where all information required to evaluate movement accuracy was available simultaneously. Using saccadic eye movements as a model for motor adaptation, we tested how movement accuracy is maintained in dynamic environments, where the availability of conflicting error signals varied over time. Participants made a vertical saccade toward a target (either a small square or a large ring). Upon saccade detection, two candidate stimuli were shown left and right of the target, and participants were instructed to discriminate a feature on one of the candidates. Critically, candidate stimuli were presented sequentially, and saccade adaptation, thus, had to resolve a conflict between a task-relevant and a task-irrelevant error signal that were separated in space and time. We found that the saccade target influenced several aspects of oculomotor learning. In presence of a small target, saccade adaptation evaluated movement accuracy based on the first available error signal after the saccade, irrespective of its task relevance. However, a large target not only allowed for greater flexibility when evaluating movement accuracy, but it also promoted a stronger contribution of strategic behavior when compensating inaccurate saccades. Our results demonstrate how motor adaptation maintains movement accuracy in dynamic environments, and how properties of the visual environment modulate the relative contribution of different learning processes.NEW & NOTEWORTHY Motor adaptation is typically studied in static environments, where all information that is required to evaluate movement accuracy is available simultaneously. Here, using saccadic eye movements as a model, we studied motor adaptation in a dynamic environment, where the availability of conflicting information about movement accuracy varied over time. We demonstrate that properties of the visual environment determine how dynamic movement errors are corrected.

In silico gene expression and pathway analysis of DEK in the human brain across the lifespan

DEK, a chromatin-remodelling phosphoprotein, is associated with various functions and biological pathways in the periphery, including inflammation, oncogenesis, DNA repair, and transcriptional regulation. We recently identified an association between DEK loss and central nervous system diseases, such as Alzheimer's. To understand DEK's potential role in disease, it is critical to characterize DEK in healthy human brain to distinguish between neural DEK expression and function in healthy versus diseased states like dementia. We utilized two public databases, BrainCloud and Human Brain Transcriptome, and analysed DEK mRNA expression across the lifespan in learning and memory relevant brain regions. Since DEK loss induces phenotypes associated with brain ageing (e.g., DNA damage and apoptosis), we hypothesized that neural DEK expression may be highest during foetal development and lower in elderly individuals. In agreement with this hypothesis, DEK was most prominently expressed during foetal development in all queried forebrain areas, relative to other ages. Consistent with its roles in the periphery, pathways related to DEK in the brain were associated with cellular proliferation, DNA replication and repair, apoptosis, and inflammation. We also found novel neural development-relevant pathways (e.g., synaptic transmission, neurite outgrowth, and myelination) to be enriched from genes correlated with DEK expression. These findings suggest that DEK is important for human brain development. Overall, we highlight age-related changes in neural DEK expression across the human lifespan and illuminate novel biological pathways associated with DEK that are distinct from normal brain ageing. These findings may further our understanding of how DEK impacts brain function and disease susceptibility.

Neural signals regulating motor synchronization in the primate deep cerebellar nuclei

Movements synchronized with external rhythms are ubiquitous in our daily lives. Despite the involvement of the cerebellum, the underlying mechanism remains unclear. In monkeys performing synchronized saccades to periodically alternating visual stimuli, we found that neuronal activity in the cerebellar dentate nucleus correlated with the timing of the next saccade and the current temporal error. One-third of the neurons were active regardless of saccade direction and showed greater activity for synchronized than for reactive saccades. During the transition from reactive to predictive saccades in each trial, the activity of these neurons coincided with target onset, representing an internal model of rhythmic structure rather than a specific motor command. The behavioural changes induced by electrical stimulation were explained by activating different groups of neurons at various strengths, suggesting that the lateral cerebellum contains multiple functional modules for the acquisition of internal rhythms, predictive motor control, and error detection during synchronized movements.

Immediate Temporal Information Modulates the Target Identification in the Attentional Blink

It has been shown that learned temporal information can be exploited to help facilitate the target identification in the attentional blink task. Here, we tested whether similar exploitation also worked on short-term temporal information, even when it did not reliably predict the target onset. In two experiments, we randomly manipulated either the interval between targets (T1 and T2; Experiment 1) or the temporal regularity of stimulus presentation (Experiment 2) in each trial. The results revealed evidence of effects of immediate temporal experience mainly on T2 performances but also occasionally on T1 performances. In general, the accuracy of T2 was enhanced when a longer inter-target interval was explicitly processed in the preceding trial (Experiment 1) or the temporal regularity, regardless of being explicitly or implicitly processed, was present in the stimulus stream, especially after T1 (Experiment 2). These results suggest that, under high temporal uncertainty, both interval and rhythmic cues can still be exploited to regulate the allocation of processing resources, thus, modulating the target identification in the attentional blink task, consistent with the view of flexible attentional allocation, and further highlighting the importance of the interplay between temporal processing and attentional control in the conscious visual perception.

The neurologist who could not stop rhyming and rapping

.A neurologist, at age 55, developed an irrepressible urge to rhyme after a series of strokes and seizures. His strokes included right posterior cerebellar and right thalamic infarctions, and his subsequent focal-onset seizures emanated from the left frontotemporal region. On recovery, he described the emergence of an irresistible urge to rhyme, even in thought and daily speech. His pronounced focus on rhyming led him to actively participate in freestyle rap and improvisation. This patient's rhyming and rapping may have been initially facilitated by epileptiform activation of word sound associations but perpetuated as compensation for impaired cerebellar effects on timed anticipation.