Modeling time perception and its dopaminergic modulation

• Applicants: Dr. Thomas Theodor Gerd Hahn; Professor Dr. Joachim Hass
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 390956983

The ability to tell time is a crucial requirement for almost everything we do, from simple perceptions and actions to complex cognitive functions. Time perception is also one of the abilities that are impaired in many psychiatric conditions, like e. g. schizophrenia. Despite this tremendous importance, the neural mechanisms of time perception are still largely unknown, partly due to a lack of integrating results from different levels of investigation, such as psychology, electrophysiology, neuroimaging, pharmacology and theoretical modelling. In this project, we aim towards an integrated understanding of the basic properties of time perception in terms of psychophysical laws and the identification of the underlying neural mechanisms, with a focus on the effects of the neuromodulator dopamine. To achieve this, we combine theoretical modeling with behavioral and electrophysiological experiments in freely behaving rats. On the theoretical side, we test whether a number of established models of time perception can be successfully implemented into a highly realistic network model of the prefrontal cortex we recently developed, and whether they are able to reproduce a number of experimental findings from psychophysical and pharmacological studies. Furthermore, we develop and test an additional model based on recent information-theoretical considerations, which we believe to overcome problems that are inherent in the existing models. On the experimental side, we assess time perception in rats while manipulating its dopaminergic modulation by drugs and direct optogenetic stimulation of the ventral tegmental area (VTA), which projects specifically to the prefrontal cortex. During these behavioral tests, we record a variety of extracellular signals from the rat's prefrontal cortex and striatum while the freely moving animals perform the tasks. Finally, we simulate the experimental setup of our experiments using the different theoretical models and directly compare their predictions on both the behavioral and electrophysiological measures with the experimental results, allowing further assessment and adjustment of these models, and to derive conclusions about the nature of the mechanisms underlying time perception. Because of the close interaction of theory and experiment, the unprecedented combination of behavioral tests with electrophysiological recordings of unique precision, we believe that this project has ideal preconditions to make substantial progress towards an integrated understanding of time perception.

• DFG Programme: Research Grants