Morrow Erin, Huang Ringo, Clewett David
Department of Psychology, University of California, Los Angeles, USA 90095.
bioRxiv. 2025 May 18:2025.05.14.654133. doi: 10.1101/2025.05.14.654133.
Our memories do not simply keep time - they warp it, bending the past to fit the structure of our experiences. For example, people tend to remember items as occurring farther apart in time if they spanned a change in context, or 'event boundary,' compared to the same context. While these distortions can sacrifice precise timing, they may serve to help separate temporally adjacent memories. However, the neural bases of this phenomenon are poorly understood. Here, we combined functional magnetic resonance imaging (fMRI; = 32) with eye-tracking ( = 28) to test whether the dopaminergic system, known to influence encoding and time perception, predicts time dilation between adjacent events in memory. Participants encoded item sequences while listening to tones that mostly repeated over time, forming a stable auditory context, but occasionally switched, creating an event boundary. We found that boundaries predicted greater retrospective estimates of time between item pairs. Critically, tone switches significantly activated the ventral tegmental area (VTA), a key midbrain dopaminergic region, and these responses in turn predicted greater time dilation between item pairs spanning those switches. Boundaries furthermore predicted a momentary increase in blinks. VTA activation also predicted blinking in general, consistent with the idea that blink behavior is a potential marker of dopaminergic activity. On a larger timescale, higher blink rates predicted greater time dilation in memory, but only for boundary-spanning pairs. Together, these findings suggest that dopaminergic processes are sensitive to event structure and may drive temporal distortions that help disjoin memories of distinct events.
我们的记忆并非简单地记录时间——它们会扭曲时间，使过去适应我们的经历结构。例如，与处于相同情境相比，如果事件跨越了情境变化或“事件边界”，人们往往会记得这些事件在时间上相隔更远。虽然这些扭曲可能会牺牲精确的时间记录，但它们可能有助于区分时间上相邻的记忆。然而，这种现象的神经基础却鲜为人知。在这里，我们将功能磁共振成像（fMRI；n = 32）与眼动追踪（n = 28）相结合，以测试已知会影响编码和时间感知的多巴胺能系统是否能预测记忆中相邻事件之间的时间膨胀。参与者在听音调时对项目序列进行编码，这些音调大多随时间重复，形成一个稳定的听觉情境，但偶尔会切换，从而产生一个事件边界。我们发现，边界预示着对项目对之间时间的更大回顾性估计。关键的是，音调切换显著激活了腹侧被盖区（VTA），这是中脑一个关键的多巴胺能区域，而这些反应反过来又预示着跨越这些切换的项目对之间有更大的时间膨胀。此外，边界还预示着眨眼会瞬间增加。VTA激活一般也预示着眨眼，这与眨眼行为是多巴胺能活动的一个潜在标志的观点一致。在更大的时间尺度上，更高的眨眼频率预示着记忆中有更大的时间膨胀，但仅适用于跨越边界的对。总之，这些发现表明，多巴胺能过程对事件结构敏感，并可能驱动时间扭曲，从而有助于区分不同事件的记忆。
