Periodic Reporting for period 3 - TIMECODE (How does the brain code time?)
Reporting period: 2023-09-01 to 2025-02-28
Does the brain have an internal clock? How come “a watched pot never boils?” Time perception is a distinct area of study that attempts to characterize what exactly it means to perceive the passage of time, and how our sensory and motor systems alter our perception of elapsed time. Although numerous studies have addressed this enigmatic topic, our understanding of how timing is coded in the brain remains relatively limited, and we still do not know of a single organ or part of the brain that serves as an “internal clock.” The EU-funded TIMECODE project takes a holistic approach based on the hypothesis that time perception integrates local and global representations of timing by means of coordinated rhythmic activity. In other words, our subjective experience of time results from a shared effort between sensory cortices engaged in perceptual processing and a brain-wide “central clock.” The hypothesized interaction between these two brain areas is putatively driven by synchronized neural oscillations. Combining behavioral and physiological studies of human and non-human primates, together with computational tools, TIMECODE aims to shed light on the underlying neural substrates and the resulting cognitive perception of timing in the brain.
Despite the ubiquity of time in our daily lives and activities, our understanding of the neural mechanisms enabling us to measure time duration is very limited. We measured the electrical field produced by the brain as individuals performed a task in which they judged the duration of a visual or tactile event. Was the event short? Or did it seem long? We found a neural signature that reflects the elapsed time perceived by our participants as they made their temporal decisions (Ofir and Landau, 2022, Curr Bio). In addition, we fit the neurophysiological data with a computational model that we developed and related temporal estimation both to sensory aspects as well as motor aspects (Ofir and Landau, 2025, J Neuro). This finding provides a breakthrough in our ability to track the neural dynamics of interval timing, and gives insight into the cognitive processes and computations that make up our daily experience time. The initial computational framework devised in the initial publications from the action have also been expanded and further developed in order to account for different temporal tasks (Ofir and Landau, favorably reviewed, revised and resubmitted) . TIMECODE also investigates which aspects of motor production - from force exertion to complex movements - play an integral role in timing. For this, we have constructed a novel experimental platform that permits users to engage in full body interactions using a free-flowing range of movements and found an oscillatory signature of the duration of stored intervals in working memory (Guarnieri and Landau, near submission). In addition to the main studies on explicit time perception, TIMECODE also aims to discern links and distinctions between explicit time perception and implicit timing. In order to advance this aim we have run studies and devices cognitive computational models of temporal anticipation (Vishne et al., 2025 BioRxiv) as well as looked at monitored continuous measures of motor behavior in paradigms that incorporate implicit temporal regularities (Tzionit et al. near submission). In addition, we are also investigating ways in which implicit timing impacts performance on sustained tasks which will help understand whether processing of temporal intervals is a reflexive process or whether implicit timing is, indeed, a separate capacity compared to time perception (Shlesinger et al., submitted). To better understand the computational aspects of interval timing we had also investigated neural responses in a task where two different intervals need to be tracked, simultaneously (Haim et al., 2025, J Neuro). Finally, during the last academic year we were finally able to advance studies from work package 2 in which we investigate brain wide connectivity supporting temporal cognition in patients with Parkinson's Disease who have electrodes implanted in their basal ganglia.
Many projects described in the previous section also include rich data that are currently being prepared for publication as well as being further analytically explored. Such explorations span both computational efforts as well as physiological ones. Seeing that our work uniquely combined both studies of temporal estimation and studies of temporal production (i.e. sensory studies and motor studies) we are currently devising ways to gain an interested view over the results. In addition to running studies that clarify this link we also plan on writing an opinion piece that will provide a novel framework, informed by the empirical work. Most importantly, until the end of the project, I plan considerable analytic development for the data we are finally acquiring in the patient population. Establishing the clinical link during COVID first, and then during war have been a challenge that we finally overcame over the past year and I look forward to exploring the rich data acquired with the patients. Those include (1) behavioral data (2) EEG recorded from the scalp and (3) Local field potentials recorded from the basal ganglia. Linking the three elements as well as pairs of this triad will result in profound insights about brain orchestration as well as brain-behavior links supporting temporal cognition. Thus, this work package is probably the most ambitious of all projects proposed in TIMECODE and I am glad to say that we currently have managed the logistic obstacles and are eager to be challenged by the data itself as we devise analytic tools for our unique measurement.