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One of the major challenges for computational models of timing and time perception is to identify a neurobiological plausible implementation that predicts various behavioral properties, including the scalar property and retrospective timing. The available timing models primarily focus on the scalar property and prospective timing, while virtually ignoring the computational accessibility. Here, we first selectively review timing models based on ramping activity, oscillatory pattern, and time cells, and discuss potential challenges for the existing models. We then propose a multifrequency oscillatory model that offers computational accessibility, which could account for a much broader range of timing features, including both retrospective and prospective timing.

The major tenets of beat-frequency/coincidence-detection models of reward-related timing are reviewed in light of recent behavioral and neurobiological findings. This includes the emphasis on a core timing network embedded in the motor system that is comprised of a corticothalamic-basal ganglia circuit. Therein, a central hub provides timing pulses (i.e., predictive signals) to the entire brain, including a set of distributed satellite regions in the cerebellum, cortex, amygdala, and hippocampus that are selectively engaged in timing in a manner that is more dependent upon the specific sensory, behavioral, and contextual requirements of the task. Oscillation/coincidence-detection models also emphasize the importance of a tuned ‘perception’ learning and memory system whereby target durations are detected by striatal networks of medium spiny neurons (MSNs) through the coincidental activation of different neural populations, typically utilizing patterns of oscillatory input from the cortex and thalamus or derivations thereof (e.g., population coding) as a time base. The measure of success of beat-frequency/coincidence-detection accounts, such as the Striatal Beat-Frequency model of reward-related timing (SBF), is their ability to accommodate new experimental findings while maintaining their original framework, thereby making testable experimental predictions concerning diagnosis and treatment of issues related to a variety of dopamine-dependent basal ganglia disorders, including Huntington’s and Parkinson’s disease.

Animals can learn to repeat behaviors to earn desired rewards, a process commonly known as reinforcement learning. While previous work has implicated the ascending dopaminergic projections to the basal ganglia in reinforcement learning, little is known about the role of the hippocampus. Here we report that a specific population of hippocampal neurons and their dopaminergic innervation contribute to operant self-stimulation. These neurons are located in the dentate gyrus, receive dopaminergic projections from the locus coeruleus, and express D1 dopamine receptors. Activation of D1+ dentate neurons is sufficient for self-stimulation: mice will press a lever to earn optogenetic activation of these neurons. A similar effect is also observed with selective activation of the locus coeruleus projections to the dentate gyrus, and blocked by D1 receptor antagonism. Calcium imaging of D1+ dentate neurons revealed significant activity at the time of action selection, but not during passive reward delivery. These results reveal the role of dopaminergic innervation of the hippocampus in supporting operant reinforcement.

Durations are defined by a beginning and an end, and a major distinction is drawn between durations that start in the present and end in the future ('prospective timing') and durations that start in the past and end either in the past or the present ('retrospective timing'). Different psychological processes are thought to be engaged in each of these cases. The former is thought to engage a clock-like mechanism that accurately tracks the continuing passage of time, whereas the latter is thought to engage a reconstructive process that utilizes both temporal and non-temporal information from the memory of past events. We propose that, from a biological perspective, these two forms of duration estimation are supported by computational processes that are both reliant on population state dynamics but are nevertheless distinct. Prospective timing is effectively carried out in a single step where the ongoing dynamics of population activity directly serve as the computation of duration, whereas retrospective timing is carried out in two steps: the initial generation of population state dynamics through the process of event segmentation and the subsequent computation of duration utilizing the memory of those dynamics.

The ability to represent time in the brain relies on network interactions across multiple brain areas. While much attention has been paid to the role of prefrontal cortex and basal ganglia in timing, little work has been aimed towards understanding the role of the thalamus in timing. To this end, we utilized pharmacological and optogenetic techniques in mice to test the role of the mediodorsal nucleus of the thalamus (MD) in interval timing. The MD is strongly connected with the prefrontal cortex and receives major inputs from the basal ganglia output nuclei. We used an operant temporal production task, in which mice indicate their expected timing of available rewards by pressing a lever in anticipation. On probe trials, inactivation of the MD with muscimol produced rightward shifts in peak pressing as well as increases in peak spread, thus significantly altering both temporal accuracy and precision. Optogenetic inhibition of glutamatergic projection neurons in the MD resulted in similar changes in timing; the shift in peak time is proportional to the duration of inhibition. The observed effects were found to be independent of significant changes in movement. Taken together, these findings provide strong evidence for the importance of thalamo-cortical projections in maintaining proper timing behavior. Significance Statement While extensive research has been dedicated to the involvement of the prefrontal cortex in interval timing behavior, the degree to which thalamic inputs contribute to timing is unclear. Using pharmacological and optogenetic inhibition of the MD, a prefrontal projecting thalamic nucleus, we demonstrate a key role of this thalamic nucleus in timing behavior.

A robust adaptation to environmental changes is vital for survival. Almost all living organisms have a circadian timing system that allows adjusting their physiology to cyclic variations in the surrounding environment. Among vertebrates, many birds are also seasonal species, adapting their physiology to annual changes in photoperiod (amplitude, length and duration). Tawny Owls (Strix aluco) are nocturnal birds of prey that use vocalization as their principal mechanism of communication. Diurnal and seasonal changes in vocalization have been described for several vocal species, including songbirds. Comparable studies are lacking for owls. In the present work, we show that male Tawny Owls present a periodic vocalization pattern in the seconds-to-minutes range that is subject to both daily (early vs. late night) and seasonal (spring vs. summer) rhythmicity. These novel theory-generating findings appear to extend the role of the circadian system in regulating temporal events in the seconds-to-minutes range to other species.

The majority of studies in the field of timing and time perception have generally focused on sub- and supra-second time scales, specific behavioral processes, and/or discrete neuronal circuits. In an attempt to find common elements of interval timing from a broader perspective, we review the literature and highlight the need for cell and molecular studies that can delineate the neural mechanisms underlying temporal processing. Moreover, given the recent attention to the function of microtubule proteins and their potential contributions to learning and memory consolidation/re-consolidation, we propose that these proteins play key roles in coding temporal information in cerebellar Purkinje cells (PCs) and striatal medium spiny neurons (MSNs). The presence of microtubules at relevant neuronal sites, as well as their adaptability, dynamic structure, and longevity, makes them a suitable candidate for neural plasticity at both intra- and inter-cellular levels. As a consequence, microtubules appear capable of maintaining a temporal code or engram and thereby regulate the firing patterns of PCs and MSNs known to be involved in interval timing. This proposed mechanism would control the storage of temporal information triggered by postsynaptic activation of mGluR7. This, in turn, leads to alterations in microtubule dynamics through a “read-write” memory process involving alterations in microtubule dynamics and their hexagonal lattice structures involved in the molecular basis of temporal memory.

Accurate and precise timing is crucial for complex and purposeful behaviors, such as foraging for food or playing a musical instrument. The brain is capable of processing temporal information in a coordinated manner, as if it contains an ‘internal clock’. Similar to the need for the brain to orient itself in space in order to understand its surroundings, temporal orientation and tracking is an essential component of cognition as well. While there have been multiple models explaining the neural correlates of timing, independent lines of research appear to converge on the conclusion that populations of neurons in the dorsal striatum encode information relating to where a subject is in time relative to an anticipated goal. Similar to other learning processes, acquisition and maintenance of this temporal information is dependent on synaptic plasticity. Microtubules are cytoskeletal proteins that have been implicated in synaptic plasticity mechanisms and therefore are considered key elements in learning and memory. In this study, we investigated the role of microtubule dynamics in temporal learning by local infusions of microtubule stabilizing and destabilizing agents into the dorsolateral striatum. Our results suggested a bidirectional role for microtubules in timing, such that microtubule stabilization improves the maintenance of learned target durations, but impairs the acquisition of a novel duration. On the other hand, microtubule destabilization enhances the acquisition of novel target durations, while compromising the maintenance of previously learned durations. These findings suggest that microtubule dynamics plays an important role in synaptic plasticity mechanisms in the dorsolateral striatum, which in turn modulates temporal learning and time perception.

Time and memory are inextricably linked, but it is far from clear how event durations and temporal sequences are encoded in memory. In this review, we focus on resource allocation models of working memory which suggest that memory resources can be flexibly distributed amongst several items such that the precision of working memory decreases with the number of items to be encoded. This type of model is consistent with human performance in working memory tasks based on visual, auditory as well as temporal stimulus patterns. At the neural-network level, we focus on excitatory–inhibitory oscillatory processes that are able to encode both interval timing and working memory in a coupled excitatory–inhibitory network. This modification of the striatal beat-frequency model of interval timing shows how memories for multiple time intervals are represented by neural oscillations and can also be used to explain the mechanisms of resource allocation in working memory.

The contributions of cortico-cerebellar and cortico-striatal circuits to timing and time perception have often been a point of contention. In this review we propose that the cerebellum principally functions to reduce variability, through the detection of stimulus onsets and the sub-division of longer durations, thus contributing to both sub-second and supra-second timing. This sensitivity of the cerebellum to stimulus dynamics and subsequent integration with motor control allows it to accurately measure intervals within a range of 100–2000 ms. For intervals in the supra-second range (e.g., >2000 ms), we propose that cerebellar output signals from the dentate nucleus pass through thalamic connections to the striatum, where cortico-thalamic-striatal circuits supporting higher-level cognitive functions take over. Moreover, the importance of intrinsic circuit dynamics as well as behavioral, neuroimaging, and lesion studies of the cerebellum and striatum are discussed in terms of a framework positing initiation, continuation, adjustment, and termination phases of temporal processing.

Male Sprague–Dawley rats were exposed to social defeat and subordination by aggressive male Long–Evans rats. The social defeat procedure involved the continuous exposure to an aggressive resident for 10 days, while living in a protective cage within the resident’s home cage with daily brief confrontations. These stress experiences resulted in 1) reduced body weight; 2) decreased social interaction; 3) increased ultrasonic vocalizations; 4) reduced sucrose preference (anhedonia); and 5) decreased clock speed while timing 15-s and 45-s target durations in a bi-peak procedure. Treatment with ketamine (15 mg/kg, i.p.) produced a rapid reversal of anhedonia and overproduction of duration. Taken together, these data provide the first evaluation of the effects of continuous social defeat and its associated depression-like symptoms on timing and time perception using a ‘state change’ design.

Various personal dimensions of students—particularly motivation, self-efficacy beliefs, and epistemic beliefs—can change in response to teaching, affect student learning, and be conceptualized as learning dispositions. We propose that these learning dispositions serve as learning outcomes in their own right; that patterns of interrelationships among these specific learning dispositions are likely; and that differing constellations (or learning disposition profiles) may have meaningful implications for instructional practices. In this observational study, we examine changes in these learning dispositions in the context of six courses at four institutions designed to scaffold undergraduate thesis writing and promote students’ scientific reasoning in writing in science, technology, engineering, and mathematics. We explore the utility of cluster analysis for generating meaningful learning disposition profiles and building a more sophisticated understanding of students as complex, multidimensional learners. For example, while students’ self-efficacy beliefs about writing and science increased across capstone writing courses on average, there was considerable variability at the level of individual students. When responses on all of the personal dimensions were analyzed jointly using cluster analysis, several distinct and meaningful learning disposition profiles emerged. We explore these profiles in this work and discuss the implications of this framework for describing developmental trajectories of students’ scientific identities. We thank Mine Çetinkaya-Rundel for her insights regarding our statistical analyses. This research was funded by National Science Foundation award DUE-1525602.

Basic mechanisms of interval timing and associative learning are shared by many animal species, and develop quickly in early life, particularly across infancy, and childhood. Indeed, John Wearden in his book “The Psychology of Time Perception”, which is based on decades of his own research with colleagues, and which our commentary serves to primarily review, has been instrumental in implementing animal models and methods in children and adults, and has revealed important similarities (and differences) between human timing (and that of animals) when considered within the context of scalar timing theory. These seminal studies provide a firm foundation upon which the contemporary multifaceted field of timing and time perception has since advanced. The contents of the book are arguably one piece of a larger puzzle, and as Wearden cautions, “The reader is warned that my own contribution to the field has been exaggerated here, but if you are not interested in your own work, why would anyone else be?” Surely there will be many interested readers, however the book is noticeably lacking in it neurobiological perspective. The mind (however it is conceived) needs a brain (even if behaviorists tend to say “the brain behaves”, and most neuroscientists currently have a tenuous grasp on the neural mechanisms of temporal cognition), and to truly understand the psychology of time, brain and behavior must go hand in hand regardless of the twists, turns, and detours along the way.

Time is a universal psychological dimension, but time perception has often been studied and discussed in relative isolation. Increasingly, researchers are searching for unifying principles and integrated models that link time perception to other domains. In this review, we survey the links between temporal cognition and other psychological processes. Specifically, we describe how subjective duration is affected by nontemporal stimulus properties (perception), the allocation of processing resources (attention), and past experience with the stimulus (memory). We show that many of these connections instantiate a "processing principle," according to which perceived time is positively related to perceptual vividity and the ease of extracting information from the stimulus. This empirical generalization generates testable predictions and provides a starting-point for integrated theoretical frameworks. By outlining some of the links between temporal cognition and other domains, and by providing a unifying principle for understanding these effects, we hope to encourage time-perception researchers to situate their work within broader theoretical frameworks, and that researchers from other fields will be inspired to apply their insights, techniques, and theorizing to improve our understanding of the representation and judgment of time. (PsycINFO Database Record

The ability to decipher where one needs to be and when it is most beneficial to be there are fundamental to the success of an organism. Humans along with other animals are able to extract duration and temporal order from external as well as internal stimuli, though lacking a dedicated sensory organ for time. A plethora of studies have focused on dorsal striatal and cerebellar networks as primary timing circuits with medium spiny neurons and Purkinje cells acting as the core temporal integrators within these circuits, respectively. However, recent findings have also made a strong case for the inclusion of the hippocampus with the discovery of hippocampal ‘time cells’. The denoted cells are pyramidal cells within the hippocampal CA1 area that exhibit increased firing rates in relation to elapsing durations, independent of the space and distance traveled. Previous behavioral work had implicated the role of the hippocampus in temporal processing, but only as of late has this work been substantiated with direct electrophysiological evidence. We describe the most recent evidence supporting the identification of ‘time cells’ in the subcortical structures of the striatum, hippocampus, and cerebellum and indicate how these different timing systems might be integrated into a common percept for time.

Bilateral intratympanic sodium arsenate injections (100 mg/ml in isotonic saline) in adult male Long Evans rats produced impairments in allocentric navigation using a 12-arm radial maze procedure as well as a motor test battery designed to evaluate vestibular function. In contrast, no impairments in the accuracy or precision of duration reproduction using 20-s and 80-s peak-interval procedures were observed when both target durations were associated with the same lever response, but distinguished by signal modality (e.g., light or sound). In contrast, an ordinal-reproduction procedure with 800, 3200, and 12,800 ms standards requiring the timing of self-initiated movements during the production phase revealed large impairments in the accuracy and precision of timing for vestibular lesioned rats. These impairments were greater on trials in which self-initiated body movements (e.g., holding down the response lever for a fixed duration) were required without the support of external stimuli signaling the onset and offset of the reproduced duration in contrast to trials in which such external support was provided. The conclusion is that space and time are separable entities and not simply the product of a generalized system, but they can be integrated into a common metric using gravity and self-initiated movement as a reference.

An integral component to the validity of timing models is their ability to accurately fit behavioral data from detection and discrimination tasks such as the temporal bisection procedure. Two of the most prominent timing models are the Sample Known Exactly (SKE), based on scalar timing theory, and the pseudo-logistic model (PLM). Recently, evidence accumulation models based on drift–diffusionprocesses (DDM) have been utilized for modeling temporal bisection data. Currently, there is no standard by which timing behavioral data are fit, resulting in the implementation of both theoretical and atheoretical models, such as generalized logistic functions (L4P). As differences in timing behavior have been shown across sub- and supra-second durations, a comparative evaluation of these 4 different types of models (SKE, PLM, L4P, and DDM) was conducted to assess each model’s ability to capture these differences using timing data from the temporal bisection procedure. Psychometric functions from rats, trained on a bisection task using sub-sec (200 ms vs. 800 ms.) and supra-sec (2 s vs. 8 s) conditions, were fit with each of the four models. Using Akaike Information Criterion (AIC) we demonstrate that theoretical models vastly outperformed the L4P across both duration ranges, Furthermore, significant differences existed in key parameters between L4P and PLM. Three DDM models were analyzed with varying degrees of freedom, which showed that allowing for non-decision time, drift rate, and starting point to vary across signal durations outperform simpler models ( Δ i ≥ 10) that only allowed for variation in drift rate or drift rate and starting point. These models explained variance in both choice and reaction time data. While we were unable to directly compare timing and temporal decision models the results from both demonstrate the need for a shift toward theoretically based models such as the SKE, PLM, or DDM which provide greater parsimony as well as provide for greater qualitative analysis and interpretation of the data.

We present an integrated view of interval timing and reinforcement learning (RL) in the brain. The computational goal of RL is to maximize future rewards, and this depends crucially on a representation of time. Different RL systems in the brain process time in distinct ways. A model-based system learns 'what happens when', employing this internal model to generate action plans, while a model-free system learns to predict reward directly from a set of temporal basis functions. We describe how these systems are subserved by a computational division of labor between several brain regions, with a focus on the basal ganglia and the hippocampus, as well as how these regions are influenced by the neuromodulator dopamine.

This chapter reviews recent human and nonhuman animal studies investigating neural signatures of time estimation. Investigation of the neural correlates of time estimation as measured by electrophysiology, electroencephalography, magnetoencephalography, and functional magnetic resonance imaging (fMRI) in humans and other animals has largely been focused on the to‐be‐timed period. Climbing neural activity (eg, ramping) originating from the supplementary motor area has been implicated as a primary neural marker that coincides with the development of subjective experience of duration. However, it has recently been questioned whether such climbing neural activity directly reflects the neural mechanism (s) underpinning the sense of time. Given that the neural signatures recorded during the to‐be‐timed period are insufficient to explain various aspects of interval timing.

Interval timing and working memory are critical components of cognition that are supported by neural oscillations in prefrontal-striatal-hippocampal circuits. In this review, the properties of interval timing and working memory are explored in terms of behavioral, anatomical, pharmacological, and neurophysiological findings. We then describe the various neurobiological theories that have been developed to explain these cognitive processes - largely independent of each other. Following this, a coupled excitatory - inhibitory oscillation (EIO) model of temporal processing is proposed to address the shared oscillatory properties of interval timing and working memory. Using this integrative approach, we describe a hybrid model explaining how interval timing and working memory can originate from the same oscillatory processes, but differ in terms of which dimension of the neural oscillation is utilized for the extraction of item, temporal order, and duration information. This extension of the striatal beat-frequency (SBF) model of interval timing (Matell and Meck, 2000, 2004) is based on prefrontal-striatal-hippocampal circuit dynamics and has direct relevance to the pathophysiological distortions observed in time perception and working memory in a variety of psychiatric and neurological conditions. (C) 2014 Elsevier Ltd. All rights reserved.

Ordinal comparison of successively presented signal durations requires (a) the encoding of the first signal duration (standard), (b) maintenance of temporal information specific to the standard duration in memory, and (c) timing of the second signal duration (comparison) during which a comparison is made of the first and second durations. Rats were first trained to make ordinal comparisons of signal durations within three time ranges using 0.5, 1.0, and 3.0-s standard durations. Local field potentials were then recorded from the dorsal striatum and sensorimotor cortex in order to investigate the pattern of neural oscillations during each phase of the ordinal-comparison process. Increased power in delta and theta frequency ranges was observed during both the encoding and comparison stages. Active maintenance of a selected response, "shorter" or "longer" (counter-balanced across left and right levers), was represented by an increase of theta and delta oscillations in the contralateral striatum and cortex. Taken together, these data suggest that neural oscillations in the delta-theta range play an important role in the encoding, maintenance, and comparison of signal durations.

Summary Considerable evidence implicates the basal ganglia in interval timing, yet the underlying mechanisms remain poorly understood. Using a novel behavioral task, we demonstrate that head-fixed mice can be trained to show the key features of timing behavior within a few sessions. Single-trial analysis of licking behavior reveals stepping dynamics with variable onset times, which is responsible for the canonical Gaussian distribution of timing behavior. Moreover, the duration of licking bouts decreased as mice became sated, showing a strong motivational modulation of licking bout initiation and termination. Using optogenetics, we examined the role of the basal ganglia output in interval timing. We stimulated a pathway important for licking behavior, the GABAergic output projections from the substantia nigra pars reticulata to the deep layers of the superior colliculus. We found that stimulation of this pathway not only cancelled licking but also delayed the initiation of anticipatory licking for the next interval in a frequency-dependent manner. By combining quantitative behavioral analysis with optogenetics in the head-fixed setup, we established a new approach for studying the neural basis of interval timing.

Time perception is fundamental and heavily researched, but the field faces a number of obstacles to theoretical progress. In this advanced review, we focus on three pieces of ‘bad news’ for time perception research: temporal perception is highly labile across changes in experimental context and task; there are pronounced individual differences not just in overall performance but in the use of different timing strategies and the effect of key variables; and laboratory studies typically bear little relation to timing in the ‘real world’. We describe recent examples of these issues and in each case offer some ‘good news’ by showing how new research is addressing these challenges to provide rich insights into the neural and information-processing bases of timing and time perception. © 2014 The Authors.

The overlap of neural circuits involved in episodic memory, relational learning, trace conditioning, and interval timing suggests the importance of hippocampal-dependent processes. Identifying the functional and neural mechanisms whereby the hippocampus plays a role in timing and decision-making, however, has been elusive. In this article we describe recent neurobiological findings, including the discovery of hippocampal ‘time cells’, dependency of duration discriminations in the minutes range on hippocampal function, and the correlation of hippocampal theta rhythm with specific features of temporal processing. These results provide novel insights into the ways in which the hippocampus might interact with the striatum in order to support both retrospective and prospective timing. Suggestions are also provided for future research on the role of the hippocampus in memory for elapsed time.

The journal Timing & Time Perception (Brill Publishers) was initiated with the realization that the study of ‘timing and time perception’ is growing exponentially with interest from fields as diverse as cognitive science, computer science, economics, philosophy, psychology, robotics, and neuroscience … to name just a few. As with any scientific endeavor, once a sufficient empirical base has been established it becomes both necessary and desirable to support such a rapidly growing enterprise with a platform for publishing integrative and multidisciplinary reviews. We are pleased to announce that Timing & Time Perception Reviews (a joint publication of the University of Groningen and Brill Publishers) is being launched as a diamond open-access journal with that goal firmly in mind. Some of the highlights of the inaugural issue are presented in our editorial along with examples of the types of ideas we would like to see developed in future submissions to the journal.

Animals, including fish, birds, rodents, non-human primates, and pre-verbal infants are able to discriminate the duration and number of events without the use of language. In this paper, we present the results of six experiments exploring the capability of adult rats to count 2–6 sequentially presented white-noise stimuli. The investigation focuses on the animal’s ability to exhibit spontaneous subtraction following the presentation of novel stimulus inversions in the auditory signals being counted. Results suggest that a subtraction operation between two opposite sensory representations may be a general processing strategy used for the comparison of stimulus magnitudes. These findings are discussed within the context of a mode-control model of timing and counting that relies on an analog temporal-integration process for the addition and subtraction of sequential events.

Interval timing within the seconds-to-minutes range involves the interaction of the prefrontal cortex and basal ganglia via dopaminergic–glutamatergic pathways. Because the secreted protein brain-derived neurotrophic factor (BDNF) is able to modulate dopamine release as well as glutamatergic activity, we hypothesized that BDNF may be important for these timing mechanisms. Recently, the calcium-responsive transcription factor (CaRF) was identified as an important modulator of BDNF expression in the cerebral cortex. In this study, a strain of Carf knockout mice was evaluated for their ability to acquire the ‘Start’ and ‘Stop’ response thresholds under sequential and simultaneous training conditions, using multiple (15-second and 45-second) or single (30-second) target durations in the peak-interval procedure. Both Carf+/− and Carf−/− mice were impaired in their ability to acquire timed response thresholds relative to Carf+/+ mice. Additionally, control mice given microinjections of BDNF antisense oligodeoxynucleotide to inhibit protein expression in the prefrontal cortex showed timing impairments during acquisition similar to Carf mice. Together, these results suggest that the inhibitory processes required to update response thresholds and exert temporal control of behavior during acquisition may be dependent on CaRF regulation of genes including Bdnf in cortico-striatal circuits.

Five experiments were conducted to determine the effects of hippocampal damage on timing and the memory for temporal events. In Experiments 1-3, rats were trained to discriminate between auditory signals that differed in both duration (2 or 8 s) and rate (2 or 16 cycles/s). Half of the rats were trained to discriminate duration, and half were trained to discriminate rate. After rats acquired the relevant discrimination, signals with intermediate durations and rates were presented to obtain psychophysical functions that related signal duration and/or rate to response choice. Rats then received either lesions of the fimbria-fornix or control operations. Postoperatively, the accuracy of duration and rate discriminations as measured by the difference limen (DL) was unaffected by the lesion, but the point of subjective equality (PSE) was shifted to a shorter duration and a slower rate by the lesion in Experiment 1. Both rats with lesions and rats with control operations showed cross-modal transfer of duration and rate from the auditory signals used in training to visual signals used in testing in Experiment 2. A 5-s delay was imposed between the end of a signal and the opportunity to respond in Experiment 3. The delay served as a retention interval for the rats trained in the rate discrimination, and the rats with fimbria-fornix lesions were selectively impaired by the addition of the delay as measured by an increase in the DL. The delay did not serve as a retention interval for rats trained in the duration discrimination because they were able to continue timing through the delay. A peak procedure was employed in Experiment 4. The maximum response rate of control rats was approximately at the time of scheduled reinforcement (20 s), but the maximum response rate of rats with fimbria-fornix lesions was reliably earlier than the time of scheduled reinforcement. When a 5-s gap was imposed in the signal, control rats summed the signal durations before and after the gap, whereas rats with fimbria-fornix lesions showed no retention of the signal duration prior to the gap. Experiment 5 continued the testing of the rats used in Experiments 1-4 and showed that rats with lesions had an impairment in a test of spatial working memory in an eight-arm radial maze. Taken together, these results demonstrate that a fimbria-fornix lesion interferes with temporal and spatial working memory, reduces the remembered time of reinforcement stored in reference memory, and has no effect on the animal's sensitivity to stimulus duration.

Temporal and social processing are intricately linked. The temporal extent and organization of interactional behaviors both within and between individuals critically determine interaction success. Conversely, social signals and social context influence time perception by, for example, altering subjective duration and making an event seem ‘out of sync'. An ‘internal clock' involving subcortically orchestrated cortical oscillations that represent temporal information, such as duration and rhythm, as well as insular projections linking temporal information with internal and external experiences is proposed as the core of these reciprocal interactions. The timing of social relative to non-social stimuli augments right insular activity and recruits right superior temporal cortex. Together, these reciprocal pathways may enable the exchange and respective modulation of temporal and social computations.

This review outlines the basic psychological and neurobiological processes associated with age-related distortions in timing and time perception in the hundredths of milliseconds-to-minutes range. The difficulty in separating indirect effects of impairments in attention and memory from direct effects on timing mechanisms is addressed. The main premise is that normal aging is commonly associated with increased noise and temporal uncertainty as a result of impairments in attention and memory as well as the possible reduction in the accuracy and precision of a central timing mechanism supported by dopamine-glutamate interactions in cortico-striatal circuits. Pertinent to these findings, potential interventions that may reduce the likelihood of observing age-related declines in timing are discussed. Bayesian optimization models are able to account for the adaptive changes observed in time perception by assuming that older adults are more likely to base their temporal judgments on statistical inferences derived from multiple trials than on a single trial's clock reading, which is more susceptible to distortion. We propose that the timing functions assigned to the age-sensitive fronto-striatal network can be subserved by other neural networks typically associated with finely-tuned perceptuo-motor adjustments, through degeneracy principles (different structures serving a common function).

The claustrum has been proposed as a possible neural candidate for the coordination of conscious experience due to its extensive ‘connectome’. Herein we propose that the claustrum contributes to consciousness by supporting the temporal integration of cortical oscillations in response to multisensory input. A close link between conscious awareness and interval timing is suggested by models of consciousness and conjunctive changes in meta-awareness and timing in multiple contexts and conditions. Using the striatal beat-frequency model of interval timing as a framework, we propose that the claustrum integrates varying frequencies of neural oscillations in different sensory cortices into a coherent pattern that binds different and overlapping temporal percepts into a unitary conscious representation. The proposed coordination of the striatum and claustrum allows for time-based dimensions of multisensory integration and decision-making to be incorporated into consciousness.