A right hemispheric prefrontal system for cognitive time measurement

Embodying Time in the Brain: A Multi-Dimensional Neuroimaging Meta-Analysis of 95 Duration Processing Studies

Time is an omnipresent aspect of almost everything we experience internally or in the external world. The experience of time occurs through such an extensive set of contextual factors that, after decades of research, a unified understanding of its neural substrates is still elusive. In this study, following the recent best-practice guidelines, we conducted a coordinate-based meta-analysis of 95 carefully-selected neuroimaging papers of duration processing. We categorized the included papers into 14 classes of temporal features according to six categorical dimensions. Then, using the activation likelihood estimation (ALE) technique we investigated the convergent activation patterns of each class with a cluster-level family-wise error correction at p < 0.05. The regions most consistently activated across the various timing contexts were the pre-SMA and bilateral insula, consistent with an embodied theory of timing in which abstract representations of duration are rooted in sensorimotor and interoceptive experience, respectively. Moreover, class-specific patterns of activation could be roughly divided according to whether participants were timing auditory sequential stimuli, which additionally activated the dorsal striatum and SMA-proper, or visual single interval stimuli, which additionally activated the right middle frontal and inferior parietal cortices. We conclude that temporal cognition is so entangled with our everyday experience that timing stereotypically common combinations of stimulus characteristics reactivates the sensorimotor systems with which they were first experienced.

Subjective time perception in musical imagery: An fMRI study on musicians

The cognitive preparation of an operation without overt motor execution is referred to as imagery (of any kind). Over the last two decades of progress in brain timing studies, the timing of imagery has received little focus. This study compared the time perception of ten professional violinists' actual and imagery performances to see if such an analysis could offer a different model of timing in musicians' imagery skills. When comparing the timing profiles of the musicians between the two situations (actual and imagery), we found a significant correlation in overestimation of time in the imagery. In our fMRI analysis, we found high activation in the left cerebellum. This finding seems consistent with dedicated models of timing such as the cerebellar timing hypothesis, which assigns a "specialized clock" for tasks. In addition, the present findings might provide empirical data concerning imagery, creativity, and time. Maintaining imagery over time is one of the foundations of creativity, and understanding the underlying temporal neuronal mechanism might help us to apprehend the machinery of creativity per se.

Studies in patients with temporomandibular disorders pain: Can scales of hypnotic susceptibility predict the outcome on pain relief?

Many medical conditions are claimed to benefit when hypnosis is incorporated into their treatment. For some conditions, the claims are largely anecdotal, but the treatment of pain stands out in two ways. First, there is a strong body of evidence that hypnosis can produce clinically useful analgesic effects. Second, since innocuous pain can be induced in the laboratory, the process can be explored rigorously. This idea assumes that experimentally induced pain and clinical pain behave identically. We describe using experimentally induced pain in patients already suffering from temporomandibular disorders. Scanning results indicate that the pain and its amelioration are the same in the two circumstances. Moreover, the absence of any impact upon a nociceptive trigemino-facial reflex implies that the impact of hypnosis is purely cortical. Finally, we address the observation that clinical success correlates poorly with hypnotic susceptibility scores. It is proposed that a painful experimental situation induces anxiety. This, like hypnosis, has been associated with an emphasis on right hemisphere activity. Thus, clinical anxiety may render a person more responsive to hypnosis than would be indicated by a susceptibility test delivered in stress-free circumstances.

Electrophysiological Evidence for a Common Magnitude Representation of Spatiotemporal Information in Working Memory

Spatiotemporal interference has attracted increasing attention because it provides a window for studying the neural representation of magnitude in the brain. We aimed to identify the neural basis of spatiotemporal interference using a Kappa effect task in which two circles were presented in sequence with two time intervals and three space distances. Participants reproduced the time intervals while ignoring the space distance when electroencephalogram signals were recorded synchronously. The behavior results showed that production time increased with time interval and space distance. Offset of the time intervals elicited typical P2 and P3b components. Larger parietal P2 and P3b amplitudes were elicited by the combination of longer time intervals and longer space distances. The parietal P2 and P3b amplitudes were positively correlated with the production time, and the corresponding neural source was located in the parietal cortex. The results suggest that the parietal P2 and P3b index updates a common representation of spatiotemporal information in working memory, which provides electrophysiological evidence for the mechanisms underlying spatiotemporal interferences. Our study supports a theory of magnitude, in which different dimensions can be integrated into a common magnitude representation in a generalized magnitude system that is localized at the parietal cortex.

Subjective Time in Dementia: A Critical Review

The capacity for subjective time in humans encompasses the perception of time's unfolding from moment to moment, as well as the ability to traverse larger temporal expanses of past- and future-oriented thought via mental time travel. Disruption in time perception can result in maladaptive outcomes-from the innocuous lapse in timing that leads to a burnt piece of toast, to the grievous miscalculation that produces a traffic accident-while disruption to mental time travel can impact core functions from planning appointments to making long-term decisions. Mounting evidence suggests that disturbances to both time perception and mental time travel are prominent in dementia syndromes. Given that such disruptions can have severe consequences for independent functioning in everyday life, here we aim to provide a comprehensive exposition of subjective timing dysfunction in dementia, with a view to informing the management of such disturbances. We consider the neurocognitive mechanisms underpinning changes to both time perception and mental time travel across different dementia disorders. Moreover, we explicate the functional implications of altered subjective timing by reference to two key and representative adaptive capacities: prospective memory and intertemporal decision-making. Overall, our review sheds light on the transdiagnostic implications of subjective timing disturbances in dementia and highlights the high variability in performance across clinical syndromes and functional domains.

Development of Young Children's Time Perception: Effect of Age and Emotional Localization

Time perception is a fundamental aspect of young children’s daily lives and is affected by a number of factors. The present study aimed to investigate the precise developmental course of young children’s time perception from 3 to 5 years old and the effects of emotion localization on their time perception ability. A total of 120 children were tested using an adapted time perception task with black squares (Experiment 1) and emotional facial expressions (Experiment 2). Results suggested that children’s time perception was influenced by stimulus duration and improved gradually with increasing age. Both accuracy and reaction time were affected by the presentation sequence of emotional faces, indicating an effect of emotion localization. To summarize, young children’s time perception showed effects of age, stimulus duration, and emotion localization.

The Role of the Dorsolateral Prefrontal Cortex for Speech and Language Processing

This review article summarizes various functions of the dorsolateral prefrontal cortex (DLPFC) that are related to language processing. To this end, its connectivity with the left-dominant perisylvian language network was considered, as well as its interaction with other functional networks that, directly or indirectly, contribute to language processing. Language-related functions of the DLPFC comprise various aspects of pragmatic processing such as discourse management, integration of prosody, interpretation of nonliteral meanings, inference making, ambiguity resolution, and error repair. Neurophysiologically, the DLPFC seems to be a key region for implementing functional connectivity between the language network and other functional networks, including cortico-cortical as well as subcortical circuits. Considering clinical aspects, damage to the DLPFC causes psychiatric communication deficits rather than typical aphasic language syndromes. Although the number of well-controlled studies on DLPFC language functions is still limited, the DLPFC might be an important target region for the treatment of pragmatic language disorders.

Interval Timing in Pediatric Multiple Sclerosis: Impaired in the Subsecond Range but Unimpaired in the One-Second Range

Background: For adult multiple sclerosis (MS) patients, impaired temporal processing of simultaneity/successiveness has been frequently reported although interval timing has been investigated in neither adult nor pediatric MS patients. We aim to extend previous research in two ways. First, we focus on interval timing (instead of simultaneity/successiveness) and differentiate between sensory-automatic processing of intervals in the subsecond range and cognitive processing of intervals in the one-second range. Second, we investigate whether impaired temporal information processing would also be observable in pediatric MS patients' interval timing in the subsecond and one-second ranges.

Methods: Participants were 22 pediatric MS patients and 22 healthy controls, matched for age, gender, and psychometric intelligence as measured by the Culture Fair Test 20-R. They completed two auditory interval-timing tasks with stimuli in the subsecond and one-second ranges, respectively, as well as a frequency discrimination task.

Results: Pediatric MS patients showed impaired interval timing in the subsecond range compared to healthy controls with a mean difference of the difference limen (DL) of 6.3 ms, 95% CI [1.7, 10.9 ms] and an effect size of Cohen's d = 0.830. The two groups did not differ significantly in interval timing in the one-second range (mean difference of the DL = 26.9 ms, 95% CI [−14.2, 67.9 ms], Cohen's d = 0.399) or in frequency discrimination (mean difference of the DL = 0.4 Hz, 95% CI [−1.1, 1.9 Hz], Cohen's d = 0.158).

Conclusion: The results indicate that, in particular, the sensory-automatic processing of intervals in the subsecond range but not the cognitive processing of longer intervals is impaired in pediatric MS patients. This differential pattern of results is unlikely to be explained by general deficits of auditory information processing. A tentative explanation, to be tested in future studies, points to subcortical deficits in pediatric MS patients, which might also underlie deficits in speech and visuomotor coordination typically reported in pediatric MS patients.

Somatosensory temporal discrimination threshold changes during motor learning

PURPOSE

Mechanisms underlying the somatosensory temporal discrimination threshold and its relationship with motor control have been reported; however, little is known regarding the change in temporal processing of tactile information during motor learning. We investigated the somatosensory temporal discrimination threshold changes during motor learning in a feedback-control task.

MATERIALS AND METHODS

We included 15 healthy individuals. The somatosensory temporal discrimination threshold was measured on the index finger. A 10-session coin rotation task was performed, with 2 min' training per session. The coin rotation scores were determined through tests (continuous coin rotation at 180° at maximum speed for 10 s). The coin rotation test score and the somatosensory temporal discrimination threshold were determined at baseline and after 5 and 10 sets of training, as follows: pre-test; training_5set (1 set × 5); post-test_5block; training_5set (1 set × 5); and post-test_10block. The coin rotation score and the somatosensory temporal discrimination threshold were compared between the tests. The latter was also compared between the right (the within-subject control) and left fingers.

RESULTS

The coin rotation score showed significant differences among all tests. In the somatosensory temporal discrimination threshold, there was a significant difference between the pre-test and post-test_5block values, pre-test and post-test_10block values of the left side and between the right and left sides in the post-test_5block and the post-test_10block values.

CONCLUSIONS

The somatosensory temporal discrimination threshold decreased along with task-performance progress following motor learning during a feedback-control task.

Mindfulness Meditation Biases Visual Temporal Order Discrimination but Not Under Conditions of Temporal Ventriloquism

This study examined how cognitive plasticity acquired from a long (8 weeks) course of mindfulness training can modulate the perceptual processing of temporal order judgment (TOJ) on a sub-second scale. Observers carried out a TOJ on two visual disks, with or without concurrent paired beeps. A temporal ventriloquism paradigm was used in which the sound beeps either were synchronized with the two disks or bracketed the visual stimuli by leading the first disk by 50 ms and lagging the other by 50 ms. A left-to-right bias in TOJ was found under the visual-only condition after mindfulness training. This bias was positively correlated with “acting with awareness,” a factor in the Five Facet Mindfulness Questionnaire, showing that awareness of every moment and enhanced attention focus magnify the left-to-right bias. However, the effect of mindfulness training may be short-lived and was not present when attention was diverted by auditory events in the cross-modal temporal ventriloquism illusion.

Duration reproduction in regular and irregular contexts after unilateral brain damage: Evidence from voxel-based lesion-symptom mapping and atlas-based hodological analysis

It has been proposed that not completely overlapping brain networks support interval timing depending on whether or not an external, predictable temporal cue is provided during the task, aiding time estimation. Here we tested this hypothesis in a neuropsychological study, using both a topological approach - through voxel-based lesion-symptom mapping (VLSM), that assesses the relation between continuous behavioral scores and lesion information on a voxel-by-voxel basis - and a hodological approach, using an atlas-based tractography. A group of patients with unilateral focal brain lesions and their matched controls performed a duration reproduction task assessing time processing in two conditions, namely with regularly spaced stimuli during encoding and reproduction (Regular condition), and with irregularly spaced stimuli during the same task (Irregular condition). VLSM analyses showed that scores in the two conditions were associated with lesions involving partly separable clusters of voxels, with lower performance only in the Irregular condition being related to lesions involving the right insular cortex. Performance in both conditions correlated with the probability of disconnection of the right frontal superior longitudinal tract, and of the superior and middle branches of the right superior longitudinal fasciculus. These findings suggest that the dissociation between timing in regular and irregular contexts is not complete, since performance in both conditions relies on the integrity of a common suprasecond timing network. Furthermore, they are consistent with the hypothesis that tracking time without the aid of external cues selectively relies on the integration of psychophysiological changes in the right insula.

Maintenance vs. Manipulation in Auditory Verbal Working Memory in the Elderly: New Insights Based on Temporal Dynamics of Information Processing in the Millisecond Time Range

Working memory (WM) is a limited-capacity cognitive system that allows the storage and use of a limited amount of information for a short period of time. Two WM processes can be distinguished: maintenance (i.e., storing, monitoring, and matching information) and manipulation (i.e., reordering and updating information). A number of studies have reported an age-related decline in WM, but the mechanisms underlying this deterioration need to be investigated. Previous research, including studies conducted in our laboratory, revealed that age-related cognitive deficits are related to decreased millisecond timing, i.e., the ability to perceive and organize incoming events in time. The aim of the current study was: (1) to identify in the elderly the brain network involved in the maintenance and manipulation WM processes; and (2) to use an fMRI task to investigate the relation between the brain activity associated with these two processes and the efficiency of temporal information processing (TIP) on a millisecond level reflected by psychophysical indices. Subjects were 41 normal healthy elderly people aged from 62 to 78 years. They performed: (1) an auditory verbal n-back task for assessing WM efficiency in an MRI scanner; and (2) a psychophysical auditory temporal-order judgment (TOJ) task for assessing temporal resolution in the millisecond domain outside the scanner. The n-back task comprised three conditions (0-, 1-, and 2-back), which allowed maintenance (1- vs. 0-back comparisons) and manipulation (2- vs. 1-back comparisons) processes to be distinguished. Results revealed the involvement of a similar brain network in the elderly to that found in previous studies. However, during maintenance processes, we found relatively limited and focused activations, which were significantly extended during manipulation. A novel result of our study, never reported before, is an indication of significant moderate correlations between the efficiency of WM and TIP. These correlations were found only for manipulation but not for maintenance. Our results confirmed the hypothesis that manipulation in the elderly is a dynamic process requiring skilled millisecond timing with high temporal resolution. We conclude that millisecond timing contributes to WM manipulation in the elderly, but not to maintenance.

Altered Time Awareness in Dementia

Our awareness of time, specifically of longer intervals spanning hours, days, months, and years, is critical for ensuring our sense of self-continuity. Disrupted time awareness over such intervals is a clinical feature in a number of frontotemporal dementia syndromes and Alzheimer's disease, but has not been studied and compared systematically in these diseases. We used a semi-structured caregiver survey to capture time-related behavioral alterations in 71 patients representing all major sporadic and genetic syndromes of frontotemporal dementia, in comparison to 28 patients with typical Alzheimer's disease and nine with logopenic aphasia, and 32 healthy older individuals. Survey items pertained to apparent difficulties ordering past personal events or estimating time intervals between events, temporal rigidity and clockwatching, and propensity to relive past events. We used a logistic regression model including diagnosis, age, gender, and disease severity as regressors to compare the proportions of individuals exhibiting each temporal awareness symptom between diagnostic groups. Gray matter associations of altered time awareness were assessed using voxel-based morphometry. All patient groups were significantly more prone to exhibit temporal awareness symptoms than healthy older individuals. Clinical syndromic signatures were identified. While patients with typical and logopenic Alzheimer's disease most frequently exhibited disturbed event ordering or interval estimation, patients with semantic dementia were most prone to temporal rigidity and clockwatching and those with behavioral variant frontotemporal dementia commonly exhibited all these temporal symptoms as well as a propensity to relive past events. On voxel-based morphometry, the tendency to relive past events was associated with relative preservation of a distributed left-sided temporo-parietal gray matter network including hippocampus. These findings reveal a rich and complex picture of disturbed temporal awareness in major dementia syndromes, with stratification of frontotemporal dementia syndromes from Alzheimer's disease. This is the first study to assess symptoms of altered temporal awareness across frontotemporal dementia syndromes and provides a motivation for future work directed to the development of validated clinical questionnaires, analysis of underlying neurobiological mechanisms and design of interventions.

Rating the Intensity of a Laser Stimulus, but Not Attending to Changes in Its Location or Intensity Modulates the Laser-Evoked Cortical Activity

Top-down attention towards nociceptive stimuli can be modulated by asking participants to pay attention to specific features of a stimulus, or to provide a rating about its intensity/unpleasantness. Whether and how these different top-down processes may lead to different modulations of the cortical response to nociceptive stimuli remains an open question. We recorded electroencephalographic (EEG) responses to brief nociceptive laser stimuli in 24 healthy participants while they performed a task in which they had to compare two subsequent stimuli on their Spatial location (Location task) or Intensity (Intensity Task). In two additional blocks (Location + Ratings, and Intensity + Ratings) participants had to further provide a rating of the perceived intensity of the stimulus. Such a design allowed us to investigate whether focusing on spatial or intensity features of a nociceptive stimulus and rating its intensity would exert different effects on the EEG responses. We did not find statistical evidence for an effect on the signal while participants were focusing on different features of the signal. We only observed a significant cluster difference in frontoparietal leads at approximately 300-500 ms post-stimulus between the magnitude of the signal in the Intensity and Intensity + Rating conditions, with a less negative response in the Intensity + Rating condition in frontal electrodes, and a less positive amplitude in parietal leads. We speculatively propose that activity in those electrodes and time window reflects magnitude estimation processes. Moreover, the smaller frontal amplitude in the Intensity + Rating condition can be explained by greater working memory engagement known to reduce the magnitude of the EEG signal. We conclude that different top-down attentional processes modulate responses to nociceptive laser stimuli at different electrodes and time windows depending on the underlying processes that are engaged.

The Neural Correlates of Time: A Meta-analysis of Neuroimaging Studies

During the last two decades, our inner sense of time has been repeatedly studied with the help of neuroimaging techniques. These investigations have suggested the specific involvement of different brain areas in temporal processing. At least two distinct neural systems are likely to play a role in measuring time: One is mainly constituted of subcortical structures and is supposed to be more related to the estimation of time intervals below the 1-sec range (subsecond timing tasks), and the other is mainly constituted of cortical areas and is supposed to be more related to the estimation of time intervals above the 1-sec range (suprasecond timing tasks). Tasks can then be performed in motor or nonmotor (perceptual) conditions, thus providing four different categories of time processing. Our meta-analytical investigation partly confirms the findings of previous meta-analytical works. Both sub- and suprasecond tasks recruit cortical and subcortical areas, but subcortical areas are more intensely activated in subsecond tasks than in suprasecond tasks, which instead receive more contributions from cortical activations. All the conditions, however, show strong activations in the SMA, whose rostral and caudal parts have an important role not only in the discrimination of different time intervals but also in relation to the nature of the task conditions. This area, along with the striatum (especially the putamen) and the claustrum, is supposed to be an essential node in the different networks engaged when the brain creates our sense of time.

Amygdala-prefrontal cortex connectivity increased during face discrimination but not time perception

Time sensitivity is affected by emotional stimuli such as fearful faces. The effect of threatening stimuli on time perception depends on numerous factors, including task type and duration range. We applied a two-interval forced-choice task using face stimuli to healthy volunteers to evaluate time perception and emotion interaction using functional magnetic resonance imaging. We conducted finite impulse response analysis to examine time series for the significantly activated brain areas and psycho-physical interaction to investigate the connectivity between selected regions. Time perception engaged a right-lateralised frontoparietal network, while a face discrimination task activated the amygdala and fusiform face area (FFA). No voxels were active with regard to the effect of expression (fearful versus neutral). In parallel with this, our behavioural results showed that attending to the fearful faces did not cause duration overestimation. Finally, connectivity of the amygdala and FFA to the middle frontal gyrus increased during the face processing condition compared to the timing task. Overall, our results suggest that the prefrontal-amygdala connectivity might be required for the emotional processing of facial stimuli. On the other hand, attentional load, task type and task difficulty are discussed as possible factors that influence the effects of emotion on time perception.

The right dorsolateral prefrontal cortex is essential in seconds range timing, but not in milliseconds range timing: An investigation with transcranial direct current stimulation

It is unclear whether altering the activity of the right dorsolateral prefrontal cortex (right DLPFC) affects an individual's timing performance in milliseconds- and seconds range timing. Here we investigated the causal role of right DLPFC in milliseconds- and seconds range timing with a temporal bisection task under the application of transcranial direct current stimulation (tDCS) that altered the neural activities of the right DLPFC. The tDCS conditions consisted of anodal, cathodal, and sham conditions. The electrodes were placed over the F4 position (10-20 system) and on the left supraorbital forehead. In current study, participants completed two blocks of trials involving short ("Short blocks": 200-800 ms) or longer ("Long blocks": 1400-2600 ms) durations. The results showed that no significant differences in the bisection point (BP) were found among anodal condition, sham condition and cathodal condition in "Short blocks". However, in "Long blocks", the BP were found to be shifted toward the left for the anodal condition, sham condition, compared to cathodal condition, suggesting that the stimulus duration was judged to last longer for anodal condition compared to sham condition, whereas shorter for cathodal condition compared to sham condition. The results demonstrated that the right DLPFC played a causal role in seconds range timing (average duration 2000 ms), but not in milliseconds range timing (average duration 500 ms), which is shown it might be involved in the cognitive processing (for example, working memory process) based on dual-timing system and scalar timing theory.

Humans derive task expectancies from sub-second and supra-second interval durations

Recent studies in the field of task switching have shown that humans can base expectancies for tasks on temporal cues. When tasks are predictable based on the duration of the preceding pre-target interval, humans implicitly adapt to this predictability, indicated by better performance in trials with validly compared to invalidly predicted tasks. Yet, it is not clear which internal timing mechanisms are involved. Previous research has suggested that intervals from the sub- and supra-second range are processed by distinct cognitive timing systems. As earlier studies on temporally predictable task switching have used predictive intervals stemming from both ranges, it was not yet clear if the time-based expectancy effect was driven by just one of the two internal timing systems. The present study used clearly sub-second intervals (10 ms and 500 ms) in Experiment 1, while clearly supra-second intervals (1500 ms and 3000 ms) were used in Experiment 2. Substantial adaptation effects were observed in both experiments, showing that sub- as well as supra-second timing systems are involved in time-based expectancies for tasks. The present findings offer important implications for our theoretical understanding of the internal timing mechanisms involved in time-based task expectancy.

A MEG Study on the Processing of Time and Quantity: Parietal Overlap but Functional Divergence

A common magnitude system for the processing of time and numerosity, supported by areas in the posterior parietal cortex, has been proposed by some authors. The present study aims to investigate possible intersections between the neural processing of non-numerical (time) and numerical magnitudes in the posterior parietal lobe. Using Magnetoencephalography for the comparison of brain source activations during the processing of duration and numerosity contrasts, we demonstrate parietal overlap as well as dissociations between these two dimensions. Within the parietal cortex, the main areas of overlap were bilateral precuneus, bilateral intraparietal sulci, and right supramarginal gyrus. Interestingly, however, these regions did not equivalently correlated with the behavior for the two dimensions: left and right precuneus together with the right supramarginal gyrus accounted functionally for durational judgments, whereas numerosity judgments were accounted by the activation pattern in the right intraparietal sulcus. Present results, indeed, demonstrate an overlap between the neural substrates for processing duration and quantity. However, the functional relevance of parietal overlapping areas for each dimension is not the same. In fact, our data indicates that the same parietal sites rule differently non-numerical and numerical dimensions, as parts of broader networks.

Methylphenidate modifies activity in the prefrontal and parietal cortex accelerating the time judgment

Methylphenidate produces its effects via actions on cortical areas involved with attention and working memory, which have a direct role in time estimation judgment tasks. In particular, the prefrontal and parietal cortex has been the target of several studies to understand the effect of methylphenidate on executive functions and time interval perception. However, it has not yet been studied whether acute administration of methylphenidate influences performance in time estimation task and the changes in alpha band absolute power in the prefrontal and parietal cortex. The current study investigates the influence of the acute use of methylphenidate in both performance and judgment in the time estimation interpretation through the alpha band absolute power activity in the prefrontal and parietal cortex. This is a double-blind, crossover study with a sample of 32 subjects under control (placebo) and experimental (methylphenidate) conditions with absolute alpha band power analysis during a time estimation task. We observed that methylphenidate does not influence task performance (p > 0.05), but it increases the time interval underestimation by over 7 s (p < 0.001) with a concomitant decrease in absolute alpha band power in the ventrolateral prefrontal cortex and dorsolateral prefrontal cortex and parietal cortex (p < 0.001). Acute use of methylphenidate increases the time interval underestimation, consistent with reduced accuracy of the internal clock mechanisms. Furthermore, acute use of methylphenidate influences the absolute alpha band power over the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, and parietal cortex.

Does the insula contribute to emotion-related distortion of time? A neuropsychological approach

The literature points to a large distributed brain network involved in the estimation of time. Among these regions, the role of the insular cortex is still poorly understood. At the confluence of emotional, interoceptive, and environmental signals, this brain structure has been proposed to underlie awareness of the passage of time and emotion related time dilation. Yet, this assumption has not been tested so far. This study aimed at exploring how a lesion of the insula affects subjective duration, either in an emotional context or in a non-emotional context. Twenty-one patients with a stroke affecting the insula, either left or right, were studied for their perception of sub and supra second durations. A verbal estimation task and a temporal bisection task were used with either pure tones or neutral and emotional sounds lasting between 300 and 1500 ms and presented monaurally. Results revealed that patients with a right insular lesion, showed less temporal sensitivity than both control participants and patients with a left insular lesion. Unexpectedly, emotional effects were similar in patients and control participants. Altogether, these results suggest a specific role of the right insula in the discrimination of durations, but not in emotion related temporal distortion. In addition, an ear × emotion interaction in control participants suggests that temporal processing of positive and negative sounds may be lateralized in the brain.

Retrospective time estimation following damage to the prefrontal cortex

Time estimation in patients with prefrontal cortex (PFC) damage is often inaccurate. The relationship between PFC and estimation of short time intervals has been examined. However, it remains unclear whether PFC damage affects estimation of longer time intervals. Here, we investigated the ability of patients and healthy subjects to verbally estimate a period of 30 min, using a method easily applied in clinical settings. In 99 patients with brain damage, we compared under and normal ranges of time in patients with PFC damage or damage to other brain areas with the chi-squared test. Subsequently, we conducted a discriminant analysis and a multiple linear regression analysis to identify specific brain areas affecting time estimation. We observed a significantly larger number of patients who overestimated 30 min in the group with bilateral PFC damage compared to patients with damage to other regions. Discriminant analysis revealed that damage of right lateral PFC and left medial PFC contributed to discrimination between the normal range and overestimation groups. Multiple linear regression analysis indicated that right lateral PFC damage strongly affected overestimation of a 30-min interval. Neuropsychological test results revealed lower general cognitive function scores and orientation scores in overestimation group. The length of estimated time and the score of delayed word recall were negatively correlated. We propose that these may require encoding, maintenance, and updating of memory and are indirectly related to contextual memory. We discuss hypotheses on contextual memory segmentation and reconstruction to clarify the mechanism of impaired time overestimation in PFC-damaged patients.

A case of Capgras syndrome and folie à duex in monozygotic twins

Both Capgras syndrome and folie à deux (insanity of two) are rare and fascinating psychopathological syndromes. Their etiology and the nosological position remain unclear. We present a case of substance-induced Capgras syndrome emerging as folie à deux (insanity of two) in monozygotic twins with strongly overlapping life histories. Then, we discuss the etiology and the nosological position of these two conditions as well as their significance for understanding the concept of psychosis.

Bidirectional examination of the interaction between time and numerosity corroborates that numerosity influences time estimation but not vice versa

There has been great interest in the idea that time, number, and space share a common magnitude system. However, only a handful of studies examined bidirectional interaction between time and number and the results varied depending on the specifics of the methods and stimulus properties of each study. The present study investigated bidirectional interaction between time and number using estimation tasks. We used duration (Experiment 1) and numerosity (Experiment 2) estimation tasks to investigate the effect of numerosity-on-duration and duration-on-numerosity estimation. The results from the two experiments demonstrated that numerosity influences duration processing but not vice versa; that is, there was unidirectional interaction between numerosity and time. The duration of stimulus presentation was overestimated for stimuli larger in (task-irrelevant) numerosity. Possible mechanisms underlying the unidirectional interaction between time and number are discussed.

Neural Mechanisms Underlying Time Perception and Reward Anticipation

Findings suggest that the physiological mechanisms involved in the reward anticipation and time perception partially overlap. But the systematic investigation of a potential interaction between time and reward systems using neuroimaging is lacking. Eighteen healthy volunteers (all right-handed) participated in an event-related functional magnetic resonance imaging (fMRI) experiment that employs a visual paradigm that consists monetary reward to assess whether the functional neural representations of time perception and reward prospection are shared or distinct. Subjects performed a time perception task in which observers had to extrapolate the velocity of an occluded moving object in “reward” vs. “no-reward” sessions during fMRI scanning. There were also “control condition” trials in which participants judged about the color tone change of the stimuli. Time perception showed a fronto-parietal (more extensive in the right) cingulate and peristriate cortical as well as cerebellar activity. On the other hand, reward anticipation activated anterior insular cortex, nucleus accumbens, caudate nucleus, thalamus, cerebellum, postcentral gyrus, and peristriate cortex. Interaction between the time perception and the reward prospect showed dorsolateral, orbitofrontal, medial prefrontal and caudate nucleus activity. Our findings suggest that a prefrontal-striatal circuit might integrate reward and timing systems of the brain.

Feel the Time. Time Perception as a Function of Interoceptive Processing

The nature of time is rooted in our body. Constellations of impulses arising from the flesh constantly create our interoceptive perception and, in turn, the unfolding of these perceptions defines human awareness of time. This study explored the connection between time perception and interoception and proposes the Interoceptive Buffer saturation (IBs) index. IBs evaluates subjects’ ability to process salient stimuli from the body by measuring subjective distortions of interoceptive time perception, i.e., the estimated duration of tactile interoceptive stimulations. Thirty female healthy subjects were recruited through consecutive sampling and assessed for common variables related to interoceptive alterations: depressive symptoms (Beck Depression Inventory, BDI-II), eating disorders (EDI-3) risk, and anxiety levels (State Trait Anxiety Inventory, STAI). Interoceptive cardiac accuracy (IAc) was assessed as well. Subjects performed verbal time estimation of interoceptive stimuli (IBs) delivered using a specifically designed interoceptive tactile stimulator, as well as verbal time estimation of visual and auditory stimuli. Results showed that IBs index positively correlated with IAc, and negatively with EDI-3 Drive for Thinness (DT) risk subscale. Moreover, IBs index was positively predicted by IAc, and negatively predicted by DT and somatic factors of depression. Our results suggest that underestimations in interoceptive time perception are connected to different psychological conditions characterized by a diminished processing of high salience stimuli from the body. Conversely, overestimations of the duration of interoceptive stimuli appear to be function of subjects’ ability to correctly perceive their own bodily information. Evidence supported IBs index, fostering the concept of interoceptive treatments for clinical purposes.

Visual-auditory differences in duration discrimination depend on modality-specific, sensory-automatic temporal processing: Converging evidence for the validity of the Sensory-Automatic Timing Hypothesis

The Sensory-Automatic Timing Hypothesis assumes visual-auditory differences in duration discrimination to originate from sensory-automatic temporal processing. Although temporal discrimination of extremely brief intervals in the range of tens-of-milliseconds is predicted to depend mainly on modality-specific, sensory-automatic temporal processing, duration discrimination of longer intervals is predicted to require more and more amodal, higher order cognitive resources and decreasing input from the sensory-automatic timing system with increasing interval duration. In two duration discrimination experiments with sensory modality as a within- and a between-subjects variable, respectively, we tested two decisive predictions derived from the Sensory-Automatic Timing Hypothesis: (1) visual-auditory differences in duration discrimination were expected to be larger for brief intervals in the tens-of-milliseconds range than for longer ones, and (2) visual-auditory differences in duration discrimination of longer intervals should disappear when statistically controlled for modality-specific input from the sensory-automatic timing system. In both experiments, visual-auditory differences in duration discrimination were larger for the brief than for the longer intervals. Furthermore, visual-auditory differences observed with longer intervals disappeared when statistically controlled for modality-specific input from the sensory-automatic timing system. Thus, our findings clearly confirmed the validity of the Sensory-Automatic Timing Hypothesis.

Brain processing of the temporal dimension of acute pain in short-term memory

The dynamics of noxious sensation shapes pain perception, yet the memory of the temporal dimension of pain remains almost completely unexplored. Here, brain activity during the memory of pain duration was contrasted with that associated with the memory of pain intensity using functional magnetic resonance imaging and a delayed reproduction task. Participants encoded, maintained during a short delay, and reproduced (1) the "duration" of pain (ie, onset-to-offset), (2) the "dynamics" of pain (ie, evolution of pain over time), or (3) the intensity of pain (ie, control with no explicit temporal processing required). Results show that the inferior frontal gyrus/insula and adjacent striatal structures as well as the supramarginal and middle temporal gyri are activated in the duration task compared to the control intensity task. Specific examination of the memory delay of the duration task further revealed activation in the supramarginal gyrus extending to the parietal operculum (possibly SII) and primary somatosensory cortex (SI). In contrast, the memory delay of the dynamic task involved the bilateral supplementary motor area and the frontoparietal attentional network. Although SI, SII, and insula may contribute to the memory trace of pain sensation, other areas less commonly reported in pain studies are associated with time processing and may therefore contribute to the processing of temporal aspects of pain. Results further suggest a differential role of core timing regions of the brain depending on specific task instructions and attentional allocations to the single dimension of time, as compared to the joint processing of both time and intensity.

Motor Timing and Covariation with Time Perception: Investigating the Role of Handedness

Time is a fundamental dimension of our behavior and enables us to guide our actions and to experience time such as predicting collisions or listening to music. In this study, we investigate the regulation and covariation of motor timing and time perception functions in left- and right-handers who are characterized by distinct brain processing mechanisms for cognitive-motor control. To this purpose, we use a combination of tasks that assess the timed responses during movements and the perception of time intervals. The results showed a positive association across left- and right-handers between movement-driven timing and perceived interval duration when adopting a preferred tempo, suggesting cross-domain coupling between both abilities when an intrinsic timescale is present. Handedness guided motor timing during externally-driven conditions that required cognitive intervention, which specifies the relevance of action expertise for the performance of timed-based motor activities. Overall, our results reveal that individual variation across domain-general and domain-specific levels of organization plays a steering role in how one predicts, perceives and experiences time, which accordingly impacts on cognition and behavior.

Time perception, pacing and exercise intensity: maximal exercise distorts the perception of time

INTRODUCTION

Currently there are no data examining the impact of exercise on the perception of time, which is surprising as optimal competitive performance is dependent on accurate pacing using knowledge of time elapsed.

METHODS

With institutional ethics approval, 12 recreationally active adult participants (f=7, m=5) undertook both 30s Wingate cycles and 20min (1200s) rowing ergometer bouts as short and long duration self-paced exercise trials, in each of three conditions on separate occasions: 1) light exertion: RPE 11, 2) heavy exertion: RPE 15, 3) maximal exertion: RPE 20. Participants were unaware of exercise duration and were required to verbally indicate when they perceived (subjective time) 1) 25%, 2) 50%, 3) 75% and 4) 100% of each bout's measured (chronological) time had elapsed.

RESULTS

In response to the Wingate task, there was no difference between durations of subjective time at the 25%, nor at the 50% interval. However, at the 75% and 100% intervals, the estimate for the RPE 20 condition was shortest (P<0.01). In response to rowing, there were no differences at the 25% interval, but there was some evidence that the RPE 20 condition was perceived shorter at 50%. At 75% and 100%, the RPE 20 condition was perceived to be shorter than both RPE 15 (P=0.04) and RPE 11 (P=0.008) conditions.

CONCLUSION

This study is the first to empirically demonstrate that exercise intensity distorts time perception, particularly during maximal exercise. Consequently external feedback of chronological time may be an important factor for athletes undertaking maximal effort tasks or competitions.

Innate and Cultural Spatial Time: A Developmental Perspective

We reviewed literature to understand when a spatial map for time is available in the brain. We carefully defined the concepts of metrical map of time and of conceptual representation of time as the mental time line (MTL) in order to formulate our position. It is that both metrical map and conceptual representation of time are spatial in nature. The former should be innate, related to motor/implicit timing, it should represent all magnitudes with an analogic and bi-dimensional structure. The latter MTL should be learned, available at about 8-10 years-old and related to cognitive/explicit time. It should have uni-dimensional, linear and directional structure (left-to-right in Western culture). We bear the centrality of the development of number cognition, of time semantic concepts and of reading/writing habits for the development of ordinality and linearity of the MTL.

The brain and the subjective experience of time. A voxel based symptom-lesion mapping study

The aim of the study was to identify the anatomical bases involved in the subjective experience of time, by means of a voxel based symptom-lesion mapping (VLSM) study on patients with focal brain damage. Thirty-three patients (nineteen with right-hemisphere lesions -RBD, and fourteen with left lesion- LBD) and twenty-eight non-neurological controls (NNC) underwent the semi-structured QUEstionnaire for the Subjective experience of Time (QUEST) requiring retrospective and prospective judgements on self-relevant time intervals. All participants also completed tests to assess general cognitive functioning and two questionnaires to evaluate their emotional state. Both groups of brain-damaged patients achieved significantly different scores from NNC on the time performance, without differences between RBD and LBD. VLSM showed a cluster of voxels located in the right inferior parietal lobule significantly related to errors in the prospective items. The lesion subtraction analysis revealed two different patterns possibly associated with errors in the prospective items (the right inferior parietal cortex, rolandic operculum and posterior middle temporal gyrus) and in the retrospective items (superior middle temporal gyrus, white matter posterior to the insula).

Adolescents with Developmental Dyscalculia Do Not Have a Generalized Magnitude Deficit - Processing of Discrete and Continuous Magnitudes

The link between number and space has been discussed in the literature for some time, resulting in the theory that number, space and time might be part of a generalized magnitude system. To date, several behavioral and neuroimaging findings support the notion of a generalized magnitude system, although contradictory results showing a partial overlap or separate magnitude systems are also found. The possible existence of a generalized magnitude processing area leads to the question how individuals with developmental dyscalculia (DD), known for deficits in numerical-arithmetical abilities, process magnitudes. By means of neuropsychological tests and functional magnetic resonance imaging (fMRI) we aimed to examine the relationship between number and space in typical and atypical development. Participants were 16 adolescents with DD (14.1 years) and 14 typically developing (TD) peers (13.8 years). In the fMRI paradigm participants had to perform discrete (arrays of dots) and continuous magnitude (angles) comparisons as well as a mental rotation task. In the neuropsychological tests, adolescents with dyscalculia performed significantly worse in numerical and complex visuo-spatial tasks. However, they showed similar results to TD peers when making discrete and continuous magnitude decisions during the neuropsychological tests and the fMRI paradigm. A conjunction analysis of the fMRI data revealed commonly activated higher order visual (inferior and middle occipital gyrus) and parietal (inferior and superior parietal lobe) magnitude areas for the discrete and continuous magnitude tasks. Moreover, no differences were found when contrasting both magnitude processing conditions, favoring the possibility of a generalized magnitude system. Group comparisons further revealed that dyscalculic subjects showed increased activation in domain general regions, whilst TD peers activate domain specific areas to a greater extent. In conclusion, our results point to the existence of a generalized magnitude system in the occipito-parietal stream in typical development. The detailed investigation of spatial and numerical magnitude abilities in DD reveals that the deficits in number processing and arithmetic cannot be explained with a general magnitude deficiency. Our results further indicate that multiple neuro-cognitive components might contribute to the explanation of DD.

Neural Networks for Time Perception and Working Memory

Time is an important concept which determines most human behaviors, however questions remain about how time is perceived and which areas of the brain are responsible for time perception. The aim of this study was to evaluate the relationship between time perception and working memory in healthy adults. Functional magnetic resonance imaging (fMRI) was used during the application of a visual paradigm. In all of the conditions, the participants were presented with a moving black rectangle on a gray screen. The rectangle was obstructed by a black bar for a time period and then reappeared again. During different conditions, participants (n = 15, eight male) responded according to the instructions they were given, including details about time and the working memory or dual task requirements. The results showed activations in right dorsolateral prefrontal and right intraparietal cortical networks, together with the anterior cingulate cortex (ACC), anterior insula and basal ganglia (BG) during time perception. On the other hand, working memory engaged the left prefrontal cortex, ACC, left superior parietal cortex, BG and cerebellum activity. Both time perception and working memory were related to a strong peristriate cortical activity. On the other hand, the interaction of time and memory showed activity in the intraparietal sulcus (IPS) and posterior cingulate cortex (PCC). These results support a distributed neural network based model for time perception and that the intraparietal and posterior cingulate areas might play a role in the interface of memory and timing.

Magnitude Processing in the Brain: An fMRI Study of Time, Space, and Numerosity as a Shared Cortical System

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, studies investigating the degree of neural overlap across several dimensions are inconclusive, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional magnetic resonance imaging study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex/SMA, and inferior frontal gyrus. Together with previous research highlighting intraparietal sulcus, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest.

Time distortions in Alzheimer's disease: a systematic review and theoretical integration

Time perception is an essential function of the human brain, which is compromised in Alzheimer’s disease (AD). Here, we review empirical findings on time distortions in AD and provide a theoretical framework that integrates time and memory distortions in AD and explains their bidirectional modulation. The review was based on a literature survey performed on the PubMed and PsycInfo databases. According to our theoretical framework, time distortions may induce decline in the ability to mentally project oneself in time (i.e., mental time travel), and consequently may contribute to an episodic memory compromise in AD. Conversely, episodic memory compromise in AD may result in a loss of the ability to retrieve information about time and/or the ability to project oneself in subjective time. The relationship between time distortions and memory decline in AD can be jointly attributed to hippocampus involvement, as this brain area supports both time perception and memory and is preferentially targeted by the neuropathological processes of AD. Clinical implications of time distortions are discussed and directions for future research are suggested.

Attentional Mechanisms during the Performance of a Subsecond Timing Task

There is evidence that timing processes in the suprasecond scale are modulated by attentional mechanisms; in addition, some studies have shown that attentional mechanisms also affect timing in the subsecond scale. Our aim was to study eye movements and pupil diameter during a temporal bisection task in the subsecond range. Subjects were trained to discriminate anchor intervals of 200 or 800 msec, and were then confronted with intermediate durations. Eye movements revealed that subjects used different cognitive strategies during the bisection timing task. When the stimulus to be timed appeared randomly at a central or 4 peripheral positions on a screen, some subjects choose to maintain their gaze toward the central area while other followed the peripheral placement of the stimulus; some others subjects used both strategies. The time of subjective equality did not differ between subjects who employed different attentional mechanisms. However, differences emerged in the timing variance and attentional indexes (time taken to initial fixation, latency to respond, pupil dilatation and duration and number of fixations to stimulus areas). Timing in the subsecond range seems invariant despite the use of different attentional strategies. Future research should determine whether the selection of attentional mechanisms is related to particular timing tasks or instructions or whether it represents idiosyncratic cognitive “styles”.

Do not count too slowly: evidence for a temporal limitation in short-term memory

Some data in the time perception literature have indicated that Weber's law for time does not hold: The Weber fraction gets higher with longer intervals. It is posited that this increase may reflect a fundamental information-processing limitation. If that is true, counting at a pace at which the intervals between counts remain within this capacity limitation should be more accurate than counting with intervals exceeding this capacity. In a task in which participants had to count up to a target number for a series of trials, the variability of the durations covered for reaching the target was higher when the intercount interval lasted 1,600 ms than when it lasted 800 ms. This finding provides evidence pointing toward the existence of a fundamental temporal limitation for processing information efficiently.

Visual-auditory differences in duration discrimination of intervals in the subsecond and second range

A common finding in time psychophysics is that temporal acuity is much better for auditory than for visual stimuli. The present study aimed to examine modality-specific differences in duration discrimination within the conceptual framework of the Distinct Timing Hypothesis. This theoretical account proposes that durations in the lower milliseconds range are processed automatically while longer durations are processed by a cognitive mechanism. A sample of 46 participants performed two auditory and visual duration discrimination tasks with extremely brief (50-ms standard duration) and longer (1000-ms standard duration) intervals. Better discrimination performance for auditory compared to visual intervals could be established for extremely brief and longer intervals. However, when performance on duration discrimination of longer intervals in the 1-s range was controlled for modality-specific input from the sensory-automatic timing mechanism, the visual-auditory difference disappeared completely as indicated by virtually identical Weber fractions for both sensory modalities. These findings support the idea of a sensory-automatic mechanism underlying the observed visual-auditory differences in duration discrimination of extremely brief intervals in the millisecond range and longer intervals in the 1-s range. Our data are consistent with the notion of a gradual transition from a purely modality-specific, sensory-automatic to a more cognitive, amodal timing mechanism. Within this transition zone, both mechanisms appear to operate simultaneously but the influence of the sensory-automatic timing mechanism is expected to continuously decrease with increasing interval duration.

Stimulus onset predictability modulates proactive action control in a Go/No-go task

The aim of the study was to evaluate whether the presence/absence of visual cues specifying the onset of an upcoming, action-related stimulus modulates pre-stimulus brain activity, associated with the proactive control of goal-directed actions. To this aim we asked 12 subjects to perform an equal probability Go/No-go task with four stimulus configurations in two conditions: (1) uncued, i.e., without any external information about the timing of stimulus onset; and (2) cued, i.e., with external visual cues providing precise information about the timing of stimulus onset. During task both behavioral performance and event-related potentials (ERPs) were recorded. Behavioral results showed faster response times in the cued than uncued condition, confirming existing literature. ERPs showed novel results in the proactive control stage, that started about 1 s before the motor response. We observed a slow rising prefrontal positive activity, more pronounced in the cued than the uncued condition. Further, also pre-stimulus activity of premotor areas was larger in cued than uncued condition. In the post-stimulus period, the P3 amplitude was enhanced when the time of stimulus onset was externally driven, confirming that external cueing enhances processing of stimulus evaluation and response monitoring. Our results suggest that different pre-stimulus processing come into play in the two conditions. We hypothesize that the large prefrontal and premotor activities recorded with external visual cues index the monitoring of the external stimuli in order to finely regulate the action.

End effects and cross-dimensional interference in identification of time and length: Evidence for a common memory mechanism

Memory plays a critical role in time estimation, yet detailed mechanisms underlying temporal memory have not been fully understood. The current functional magnetic resonance imaging (fMRI) study investigated memory phenomena in absolute identification of time durations and line lengths. In both time and length identification, participants responded faster to end-of-range stimuli (e.g., the shortest or longest items of the stimulus set) than to middle stimuli. Participants performed worse in the incongruent condition (mismatch between time and length in the stimulus position) than in the congruent condition, indicating cross-dimensional interference between time and length. Both phenomena reflect increased difficulty of retrieving information relevant to the current context in the presence of context-irrelevant information. A region in the lateral inferior prefrontal cortex showed a greater response to the middle stimuli and in the incongruent condition suggesting greater demands for controlled memory retrieval. A cognitive model based on the ACT-R (Adaptive Control of Thought - Rational) declarative memory mechanisms accounted for the major behavioral and imaging results. The results suggest that contextual effects in temporal memory can be understood in terms of domain-general memory principles established outside the time estimation domain.

Dissociating movement from movement timing in the rat primary motor cortex

Neural encoding of the passage of time to produce temporally precise movements remains an open question. Neurons in several brain regions across different experimental contexts encode estimates of temporal intervals by scaling their activity in proportion to the interval duration. In motor cortex the degree to which this scaled activity relies upon afferent feedback and is guided by motor output remains unclear. Using a neural reward paradigm to dissociate neural activity from motor output before and after complete spinal transection, we show that temporally scaled activity occurs in the rat hindlimb motor cortex in the absence of motor output and after transection. Context-dependent changes in the encoding are plastic, reversible, and re-established following injury. Therefore, in the absence of motor output and despite a loss of afferent feedback, thought necessary for timed movements, the rat motor cortex displays scaled activity during a broad range of temporally demanding tasks similar to that identified in other brain regions.