Showing papers on "Time perception published in 2014"

Properties of the Internal Clock: First- and Second-Order Principles of Subjective Time

Abstract: Humans share with other animals an ability to measure the passage of physical time and subjectively experience a sense of time passing. Subjective time has hallmark qualities, akin to other senses, which can be accounted for by formal, psychological, and neurobiological models of the internal clock. These include first-order principles, such as changes in clock speed and how temporal memories are stored, and second-order principles, including timescale invariance, multisensory integration, rhythmical structure, and attentional time-sharing. Within these principles there are both typical individual differences—influences of emotionality, thought speed, and psychoactive drugs—and atypical differences in individuals affected with certain clinical disorders (e.g., autism, Parkinson's disease, and schizophrenia). This review summarizes recent behavioral and neurobiological findings and provides a theoretical framework for considering how changes in the properties of the internal clock impact time perception and other psychological domains.

Enhanced repertoire of brain dynamical states during the psychedelic experience

Abstract: The study of rapid changes in brain dynamics and functional connectivity (FC) is of increasing interest in neuroimaging. Brain states departing from normal waking consciousness are expected to be accompanied by alterations in the aforementioned dynamics. In particular, the psychedelic experience produced by psilocybin (a substance found in "magic mushrooms") is characterized by unconstrained cognition and profound alterations in the perception of time, space and selfhood. Considering the spontaneous and subjective manifestation of these effects, we hypothesize that neural correlates of the psychedelic experience can be found in the dynamics and variability of spontaneous brain activity fluctuations and connectivity, measurable with functional Magnetic Resonance Imaging (fMRI). Fifteen healthy subjects were scanned before, during and after intravenous infusion of psilocybin and an inert placebo. Blood-Oxygen Level Dependent (BOLD) temporal variability was assessed computing the variance and total spectral power, resulting in increased signal variability bilaterally in the hippocampi and anterior cingulate cortex. Changes in BOLD signal spectral behavior (including spectral scaling exponents) affected exclusively higher brain systems such as the default mode, executive control, and dorsal attention networks. A novel framework enabled us to track different connectivity states explored by the brain during rest. This approach revealed a wider repertoire of connectivity states post-psilocybin than during control conditions. Together, the present results provide a comprehensive account of the effects of psilocybin on dynamical behavior in the human brain at a macroscopic level and may have implications for our understanding of the unconstrained, hyper-associative quality of consciousness in the psychedelic state.

Musically Cued Gait-Training Improves Both Perceptual and Motor Timing in Parkinson’s Disease

Abstract: It is well established that auditory cueing improves gait in patients with Idiopathic Parkinson’s Disease (IPD). Disease-related reductions in speed and step length can be improved by providing rhythmical auditory cues via a metronome or music. However, effects on cognitive aspects of motor control have yet to be thoroughly investigated. If synchronization of movement to an auditory cue relies on a supramodal timing system involved in perceptual, motor and sensorimotor integration, auditory cueing can be expected to affect both motor and perceptual timing. Here we tested this hypothesis by assessing perceptual and motor timing in 15 IPD patients before and after a four-week music training program with rhythmic auditory cueing. Long-term effects were assessed one month after the end of the training. Perceptual and motor timing was evaluated with the Battery for the Assessment of Auditory Sensorimotor and Timing Abilities (BAASTA) and compared to that of age-, gender-, and education-matched healthy controls. Prior to training, IPD patients exhibited impaired perceptual and motor timing. Training improved patients’ performance in tasks requiring synchronization with isochronous sequences, and enhanced their ability to adapt to durational changes in a sequence in hand tapping tasks. Benefits of cueing extended to time perception (duration discrimination and detection of misaligned beats in musical excerpts). The current results demonstrate that auditory cueing leads to benefits beyond gait and support the idea that coupling gait to rhythmic auditory cues in IPD patients relies on a neuronal network engaged in both perceptual and motor timing.

Time perception: the bad news and the good.

Abstract: 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.

Representation of interval timing by temporally scalable firing patterns in rat prefrontal cortex

Abstract: Perception of time interval on the order of seconds is an essential component of cognition, but the underlying neural mechanism remains largely unknown. In rats trained to estimate time intervals, we found that many neurons in the medial prefrontal cortex (PFC) exhibited sustained spiking activity with diverse temporal profiles of firing-rate modulation during the time-estimation period. Interestingly, in tasks involving different intervals, each neuron exhibited firing-rate modulation with the same profile that was temporally scaled by a factor linearly proportional to the instructed intervals. The behavioral variability across trials within each task also correlated with the intertrial variability of the temporal scaling factor. Local cooling of the medial PFC, which affects neural circuit dynamics, significantly delayed behavioral responses. Thus, PFC neuronal activity contributes to time perception, and temporally scalable firing-rate modulation may reflect a general mechanism for neural representation of interval timing.

Decoupling Interval Timing and Climbing Neural Activity: A Dissociation between CNV and N1P2 Amplitudes

Abstract: It is often argued that climbing neural activity, as for example reflected by the contingent negative variation (CNV) in the electroencephalogram, is the signature of the subjective experience of time. According to this view, the resolution of the CNV coincides with termination of subjective timing processes. Paradoxically, behavioral data indicate that participants keep track of timing even after the standard interval (SI) has passed. This study addresses whether timing continues after CNV resolution. In Experiment 1, human participants were asked to discriminate time intervals while evoked potentials (EPs) elicited by the sound terminating a comparison interval (CI) were measured. As the amplitude of N1P2 components increases as a function of the temporal distance from the SI, and the latency of the P2 component followed the hazard rate of the CIs, timing processes continue after CNV resolution. Based on a novel experimental paradigm, statistical model comparisons and trial-by-trial analyses, Experiment 2 supports this finding as subjective time is more accurately indexed by the amplitude of early EPs than by CNV amplitude. These results provide the first direct evidence that subjective timing of multisecond intervals does not depend on climbing neural activity as indexed by the CNV and that the subjective experience of time is better reflected by distinct features of post-CI evoked potentials.

Superior time perception for lower musical pitch explains why bass-ranged instruments lay down musical rhythms

Abstract: The auditory environment typically contains several sound sources that overlap in time, and the auditory system parses the complex sound wave into streams or voices that represent the various sound sources. Music is also often polyphonic. Interestingly, the main melody (spectral/pitch information) is most often carried by the highest-pitched voice, and the rhythm (temporal foundation) is most often laid down by the lowest-pitched voice. Previous work using electroencephalography (EEG) demonstrated that the auditory cortex encodes pitch more robustly in the higher of two simultaneous tones or melodies, and modeling work indicated that this high-voice superiority for pitch originates in the sensory periphery. Here, we investigated the neural basis of carrying rhythmic timing information in lower-pitched voices. We presented simultaneous high-pitched and low-pitched tones in an isochronous stream and occasionally presented either the higher or the lower tone 50 ms earlier than expected, while leaving the other tone at the expected time. EEG recordings revealed that mismatch negativity responses were larger for timing deviants of the lower tones, indicating better timing encoding for lower-pitched compared with higher-pitch tones at the level of auditory cortex. A behavioral motor task revealed that tapping synchronization was more influenced by the lower-pitched stream. Results from a biologically plausible model of the auditory periphery suggest that nonlinear cochlear dynamics contribute to the observed effect. The low-voice superiority effect for encoding timing explains the widespread musical practice of carrying rhythm in bass-ranged instruments and complements previously established high-voice superiority effects for pitch and melody.

Neurobiology of interval timing

Abstract: Introduction to the Neurobiology of Interval Timing.- About the (non)scalar property for time perception.- Elucidating the internal structure of psychophysical timing performance in the sub-second and second range by utilizing confirmatory factor analysis.- Neurocomputational models of time perception.- Dedicated Clock/Timing-Circuit Theories of Time Perception and Timed Performance.- Neural Dynamics Based Timing in the Subsecond to Seconds Range.- Signs of timing in motor cortex during movement preparation and cue anticipation.- Neurophysiology of timing in the hundreds of milliseconds: multiple layers of neuronal clocks in the medial premotor areas.- The Olivo-Cerebellar System as a Neural Clock.- From duration and distance comparisons to goal encoding in prefrontal cortex.- Probing Interval Timing with Scalp-recorded Electroencephalography (EEG).- Searching for the Holy Grail: Temporally Informative Firing Patterns in the Rat.- Getting the timing right: experimental protocols for investigating time with functional neuroimaging and psychopharmacology.- Motor and Perceptual timing in Parkinson's disease.- Music Perception: Information Flow within the Human Auditory Cortices.- Perceiving temporal regularity in music: The role of auditory event-related potentials (ERPs) in probing beat perception.- Neural Mechanisms of Rhythm Perception: Present Findings and Future Directions.- Neural underpinnings of music: The polyrhythmic brain.

Interoceptive focus shapes the experience of time.

Abstract: The perception of time is a fundamental part of human experience. Recent research suggests that the experience of time emerges from emotional and interoceptive (bodily) states as processed in the insular cortex. Whether there is an interaction between the conscious awareness of interoceptive states and time distortions induced by emotions has rarely been investigated so far. We aimed to address this question by the use of a retrospective time estimation task comparing two groups of participants. One group had a focus on interoceptive states and one had a focus on exteroceptive information while watching film clips depicting fear, amusement and neutral content. Main results were that attention to interoceptive processes significantly affected subjective time experience. Fear was accompanied with subjective time dilation that was more pronounced in the group with interoceptive focus, while amusement led to a quicker passage of time which was also increased by interoceptive focus. We conclude that retrospective temporal distortions are directly influenced by attention to bodily responses. These effects might crucially interact with arousal levels. Sympathetic nervous system activation affecting memory build-up might be the decisive factor influencing retrospective time judgments. Our data substantially extend former research findings underscoring the relevance of interoception for the effects of emotional states on subjective time experience.

About the (non)scalar property for time perception.

Abstract: Approaching sensation scientifically is relatively straightforward. There are physical attributes for stimulating the central nervous system, and there are specific receptors for each sense for translating the physical signals into codes that brain will recognize. When studying time though, it is far from obvious that there are any specific receptors or specific stimuli. Consequently, it becomes important to determine whether internal time obeys some laws or principles usually reported when other senses are studied. In addition to reviewing some classical methods for studying time perception, the present chapter focusses on one of these laws, Weber law, also referred to as the scalar property in the field of time perception. Therefore, the question addressed here is the following: does variability increase linearly as a function of the magnitude of the duration under investigation? The main empirical facts relative to this question are reviewed, along with a report of the theoretical impact of these facts on the hypotheses about the nature of the internal mechanisms responsible for estimating time.

Introduction to the neurobiology of interval timing.

Abstract: Time is a fundamental variable that organisms must quantify in order to survive. In humans, for example, the gradual development of the sense of duration and rhythm is an essential skill in many facets of social behavior such as speaking, dancing to-, listening to- or playing music, performing a wide variety of sports, and driving a car (Merchant H, Harrington DL, Meck WH. Annu Rev Neurosci. 36:313–36, 2013). During the last 10 years there has been a rapid growth of research on the neural underpinnings of timing in the subsecond and suprasecond scales, using a variety of methodological approaches in the human being, as well as in varied animal and theoretical models. In this introductory chapter we attempt to give a conceptual framework that defines time processing as a family of different phenomena. The brain circuits and neural underpinnings of temporal quantification seem to largely depend on its time scale and the sensorimotor nature of specific behaviors. Therefore, we describe the main time scales and their associated behaviors and show how the perception and execution of timing events in the subsecond and second scales may depend on similar or different neural mechanisms.

Timing in reward and decision processes

Abstract: Sensitivity to time, including the time of reward, guides the behaviour of all organisms. Recent research suggests that all major reward structures of the brain process the time of reward occurrence, including midbrain dopamine neurons, striatum, frontal cortex and amygdala. Neuronal reward responses in dopamine neurons, striatum and frontal cortex show temporal discounting of reward value. The prediction error signal of dopamine neurons includes the predicted time of rewards. Neurons in the striatum, frontal cortex and amygdala show responses to reward delivery and activities anticipating rewards that are sensitive to the predicted time of reward and the instantaneous reward probability. Together these data suggest that internal timing processes have several well characterized effects on neuronal reward processing.

A general theory of intertemporal decision-making and the perception of time.

Abstract: Animals and humans make decisions based on their expected outcomes. Since relevant outcomes are often delayed, perceiving delays and choosing between earlier versus later rewards (intertemporal decision-making) is an essential component of animal behavior. The myriad observations made in experiments studying intertemporal decision-making and time perception have not yet been rationalized within a single theory. Here we present a theory—Training-Integrated Maximized Estimation of Reinforcement Rate (TIMERR)—that explains a wide variety of behavioral observations made in intertemporal decision-making and the perception of time. Our theory postulates that animals make intertemporal choices to optimize expected reward rates over a limited temporal window which includes a past integration interval—over which experienced reward rate is estimated—as well as the expected delay to future reward. Using this theory, we derive mathematical expressions for both the subjective value of a delayed reward and the subjective representation of the delay. A unique contribution of our work is in finding that the past integration interval directly determines the steepness of temporal discounting and the nonlinearity of time perception. In so doing, our theory provides a single framework to understand both intertemporal decision-making and time perception.

Attentional entrainment and perceived event duration

Abstract: This study considered the contribution of dynamic attending theory (DAT) and attentional entrainment to systematic distortions in perceived event duration. Three experiments were conducted using an auditory oddball paradigm, in which listeners judged the duration of a deviant (oddball) stimulus embedded within a series of identical (standard) stimuli. To test for a role of attentional entrainment in perceived oddball duration, oddballs were presented at either temporally expected (on time) or unexpectedly early or late time points relative to extrapolation of the context rhythm. Consistent with involvement of attentional entrainment in perceived duration, duration judgements about the oddball were least distorted when the oddball occurred on time with respect to the entrained rhythm, whereas durations of early and late oddballs were perceived to be shorter and longer, respectively. This pattern of results was independent of the absolute time interval preceding the oddball. Moreover, as expected, an irregularly timed sequence context weakened observed differences between oddballs with on-time and late onsets. Combined with other recent work on the role of temporal preparation in duration distortions, the present findings allot at least a portion of the oddball effect to increased attention to events that are more expected, rather than on their unexpected nature per se.

Subjective Duration as a Signature of Coding Efficiency : Emerging Links Among Stimulus Repetition, Predictive Coding, and Cortical GABA Levels

Abstract: Immediate repetition of a stimulus reduces its apparent duration relative to a novel item. Recent work indicates that this may reflect suppressed cortical responses to repeated stimuli, arising from neural adaptation and/or the predictive coding of expected stimuli. This article summarizes recent behavioral and neurobiological studies linking perceived time to the magnitude of cortical responses, including work suggesting that variations in GABA-mediated cortical inhibition may underlie some of the individual differences in time perception. We suggest that the firing of cortical neurons can be modified using simple recurrent networks with time-dependent processes that are modulated by GABA levels. These local networks feed into a core-timing network used to integrate across stimulus inputs/modalities, thereby allowing for the coordination of multiple duration ranges and effector systems.

Timing and time perception: A selective review and commentary on recent reviews

Abstract: A clear example of the progress in the field of timing and time perception could be obtained by contrasting two articles published 30 years apart in the influential Annual Review of Psychology (ARP): one by Fraisse (1984), and one by Allman et al. (2014). The fact that there was one author 30 years ago, and a group of authors now, is a tangible sign of the contemporary way of approaching scientific research. In his review, Fraisse emphasized the distinction between time perception and time estimation; in their review, Allman et al. focused on the internal clock and the cerebral bases of timing and time perception. Fraisse's review was published when a very important event happened in the field of timing and time perception: a conference was held in New York, in 1983, where researchers from both human and animal time perception met to communicate with one another. The conference led to the publication of the classical book edited by the late John Gibbon and the late Lorraine Allan (Gibbon and Allan, 1984). This meeting probably catalyzed the research on timing and time perception, especially the one emphasizing the scalar expectancy theory and, more generally speaking, the internal clock perspective, a clock described as a pacemaker-counter device. It is somewhat surprising that there was no mention in Fraisse (1984) of this promising (to say the least) pacemaker-counter perspective, which was already available in the human timing literature (Creelman, 1962; Treisman, 1963). Moreover, the modest portions of information in Fraisse dedicated to the cerebral bases of timing exemplify the gap between the contemporary research in the field and the state of the literature 30 years ago. With its emphasis on neuroscience literature (e.g., brain areas, cortical circuits, pharmacological effects, and pathologies), Allman et al. wrote an important, well-structured, and interesting state-of-the-art review on the cerebral bases of the time perception mechanisms. It is a bit surprising though that the scalar property is taken for granted, given actually Fraisse's fundamental distinction between time perception and time estimation, a distinction that could find some echoes in the limitation of the stability of the Weber fraction for time (see Figure 3 in Gibbon et al., 1997; or, for instance, Grondin, 2001, 2010b, 2012, 2015). Moreover, assuming the linearity between psychological and physical time (psychophysical law) remains disputable (Eisler, 1976). By emphasizing the internal clock perspective, it was not possible for Allman et al. (2014) to refer to other recent developments in the field. Amongst the portions of the literature the reader might want to consider, there is one on retrospective timing (Block and Zakay, 1997; Tobin et al., 2010). There is also some interesting research (e.g., Boltz, 1998; Brown, 2008) offering a purely cognitive explanation of psychological time and timing—without reference to an internal clock (see reviews by Block et al., 1999, 2010; Block, 2003). Even within the perspective of an internal clock, the attentional-gate model (see for example, Zakay and Block, 1995 and later articles), which in an extension of the scalar expectancy theory, is worth mentioning. Indeed, with the large increase of research in the field of timing and time perception in the Twenty-first century, it is not surprising to see so many recent special issues of journals on this topic, or close variants of them. The explosion is such that researchers have written a large number of recent review articles (see Table ​Table1).1). This was partly described in an annotated bibliography on “Time Perception” (Block and Hancock, 2013). Another tangible sign of the vitality of this research field is exemplified by a large COST grant funded by the E.U. (title: “Time In MEntaL activitY,” or “TIMELY”) and the resulting founding of the Brill's new scientific journal dedicated to the psychology of time, Timing and Time Perception, co-edited by Meck et al. Table 1 Selected list (in reverse chronological order) of reviews since 2010 on the psychology of time. In conclusion, being a researcher in the field of timing and time perception has never been as exciting as it is at present, given the growth of its popularity, which has been enhanced by the arrival of contributions from neuroscientists. This excitement could be extended if one considers psychological time in an even larger perspective, or larger scale from the memory for the past events (Friedman, 1993) to the capacity to predict the duration of future events (Roy et al., 2005).

How much time has passed? Ask your heart.

Abstract: Internal signals like one's heartbeats are centrally processed via specific pathways and both their neural representations as well as their conscious perception (interoception) provide key information for many cognitive processes. Recent empirical findings propose that neural processes in the insular cortex, which are related to bodily signals, might constitute a neurophysiological mechanism for the encoding of duration. Nevertheless, the exact nature of such a proposed relationship remains unclear.We aimed to address this question by searching for the effects of cardiac rhythm on time perception by the use of a duration reproduction paradigm. Time intervals used were of 0.5, 2, 3, 7, 10, 14, 25 and 40 seconds length. In a framework of synchronization hypothesis, measures of phase locking between the cardiac cycle and start/stop signals of the reproduction task were calculated to quantify this relationship.The main result is that marginally significant synchronization indices between the heart cycle and the time reproduction responses for the time intervals of 2, 3, 10, 14 and 25 seconds length were obtained, while results were not significant for durations of 0.5, 7 and 40 seconds length. On the single participant level, several subjects exhibited some synchrony between the heart cycle and the time reproduction responses, most pronounced for the time interval of 25 seconds (8 out of 23 participants for 20% quantile). Better time reproduction accuracy was not related with larger degree of phase locking, but with greater vagal control of the heart. A higher interoceptive sensitivity was associated with a higher synchronization index for the 2s time interval only.We conclude that information obtained from the cardiac cycle is relevant for the encoding and reproduction of time in the time span of 2 to 25 seconds. Sympathovagal tone as well as interoceptive processes mediate the accuracy of time estimation.

Perceiving the passage of time: neural possibilities

Abstract: Although the study of time has been central to physics and philosophy for millennia, questions of how time is represented in the brain and how this representation is related to time perception have only recently started to be addressed. Emerging evidence subtly yet profoundly challenges our intuitive notions of time over short scales, offering insight into the nature of the brain's representation of time. Numerous different models, specified at the neural level, of how the brain may keep track of time have been proposed. These models differ in various ways, such as whether time is represented by a centralized or distributed neural system, or whether there are neural systems dedicated to the problem of timing. This paper reviews the insight offered by behavioral experiments and how these experiments refute and guide some of the various models of the brain's representation of time.